Angelika Sorteberg

• Ghafaji, Hajar & Sorteberg, Angelika (2025). Nicotine replacement therapy during the acute phase of aneurysmal subarachnoid hemorrhage. Acta Neurochirurgica. ISSN 0001-6268. 167. doi: 10.1007/s00701-025-06698-y. Full text in Research Archive
• Eide, Paulina; Melin, Erik; Ringstad, Geir; Eide, Per Kristian & Sorteberg, Angelika (2025). Volume of parasagittal dura is associated with blood markers of systemic inflammation | Acta Neurochirurgica. Acta Neurochirurgica. ISSN 0001-6268. 167, p. 1–10. doi: 10.1007/s00701-025-06682-6. Full text in Research Archive Show summary

  The parasagittal dura (PSD) has been hypothesized to act as a neuro-immunological hub, though evidence in favor of the hypothesis is limited. The present study explored whether there is any association between volume and function of PSD and blood markers that may be indicative of systemic inflammation. The patient material included 76 subjects examined with intrathecal contrast-enhanced magnetic resonance imaging (MRI) where the contrast served as a cerebrospinal fluid (CSF) tracer. They were dichotomized into a control- (Ctrl) and a CSF-group. We investigated the correlations between blood markers indicative of systemic inflammation and the volume of PSD, enrichment of tracer in the PSD, and blood-measures of CSF clearance. The blood markers included C-reactive protein (CRP), erythrocyte volume fraction (EVF), hemoglobin (Hb), platelet count, neutrophiles, lymphocytes, and the neutrophil-to-lymphocyte ratio as well as the platelet-to-lymphocyte ratio. Assessment of subjective sleep quality also was included in the analysis. The main finding was that higher CRP indicative of systemic inflammation was correlated with lower volume of PSD. There was an association between lower EVF and Hb levels and lower volume of PSD, but this finding could be explained by confounders such as age, sex and disease. Confounders also explained a correlation between EVF and CSF clearance variables. Impaired subjective sleep quality was associated with markers of systemic inflammation, but not with PSD volume. Higher CRP was correlated with lower volume of PSD suggesting that the size of this anatomical structure associates with systemic inflammation. Further studies are needed to determine whether PSD volume could serve as an imaging marker of systemic inflammation.

• Eide, Per Kristian; Pripp, Are Hugo; Rønning, Pål Andre; Sorteberg, Angelika & Sorteberg, Wilhelm (2025). Comparative analysis of surgical and endovascular aneurysm repair in subarachnoid hemorrhage: a single-center study with 1,171 patients | Acta Neurochirurgica. Acta Neurochirurgica. ISSN 0001-6268. 167, p. 1–15. doi: 10.1007/s00701-025-06670-w. Full text in Research Archive Show summary

  To compare surgical and endovascular therapy (EVT) approaches to aneurysm repair in all aneurysmal subarachnoid hemorrhage (aSAH) patients treated within our institution over a 12-year period from 2011 to 2022. The study comprised a retrospective analysis of prospectively collected data extracted from a hospital quality registry that we established in 2011, containing comprehensive information about all patients treated for aSAH. We included SAH patients within the institution's catchment area who underwent surgical or endovascular aneurysm repair. Exclusion criteria involved patients from external regions, those treated at other institutions, no aneurysm repair performed, or instances undergoing a combination of surgery and EVT. Pretreatment data encompassed the clinical condition at admission, comorbidity, radiological details, aneurysm characteristics, and duration between the bleed and aneurysm repair. Mortality was primary outcome measure; secondary outcome included modified Rankin Score after approximately six months. The study encompassed 1,171 patients (65% women and 35% men) undergoing aneurysm repair from 2011 to 2022. Admission data revealed 31.1% in Hunt-Hess grade 4–5. Surgical repair was performed in 573 (48.9%) patients, and EVT in 598 (51.1%) patients. Pretreatment information was comparable for both groups. Kaplan–Meier survival curves demonstrated lower mortality in the surgical than the EVT group (P = 0.023; Log-rank test) over the 12-year period. The 1-year, 5-year, and 10-year mortality rates were 12.4%, 19.5%, and 27.7% for the surgery group, and 18.7%, 25.2%, and 31.7% for the EVT group, respectively. Modified Rankin Score was worse for EVT. There was lower mortality in surgical than EVT groups in patients treated for anterior communicating artery (ACOM, n = 420) and posterior communicating artery (PCOM, n = 177) aneurysms. Shorter time to aneurysm repair and more extensive cerebrospinal fluid (CSF) drainage characterized the surgery group. Mortality was lower in surgical patients. Plausible explanations are the maintenance of surgical skills and prompt reduction of intracranial pressure.

• Eide, Per Kristian; Undseth, Ragnhild Marie; Pripp, Are Hugo; Lashkarivand, Aslan; Nedregaard, Bård & Sletteberg, Ruth [Show all 10 contributors for this article] (2025). Impact of Subarachnoid Hemorrhage on Human Glymphatic Function: A Time-Evolution Magnetic Resonance Imaging Study. Stroke. ISSN 0039-2499. 56(3), p. 678–691. doi: 10.1161/STROKEAHA.124.047739. Full text in Research Archive Show summary

  BACKGROUND: Subarachnoid hemorrhage (SAH) is associated with significant mortality and morbidity. The impact of SAH on human glymphatic function remains unknown. METHODS: This prospective, controlled study investigated whether human glymphatic function is altered after SAH, how it differs over time, and possible underlying mechanisms. Glymphatic enrichment was examined by intrathecal contrastenhanced magnetic resonance imaging (MRI, glymphatic MRI), utilizing the MRI contrast agent gadobutrol (Gadovist, Bayer AG, GE; 0.50 mmol) as a cerebrospinal fluid (CSF) tracer. The distribution of the tracer in the brain and the subarachnoid and ventricular CSF spaces was assessed using standardized multi-phase MRI T1 sequences, and between-group differences in percentage change of standardized T1 signal unit ratios over time were analyzed by linear mixed models. RESULTS: The study comprised 27 patients with SAH (19 female/8 male; 59.3±10.2 years) who were examined <3 months (n=5), 3 to 6 months (n=10), 6 to 12 months (n=5), or >12 months (n=7) after bleed. A sex- and age-matched control group of 22 individuals (15 female/7 male; 55.5±10.5 years) underwent the same glymphatic MRI protocol but had no neurological or CSF disease. The patients with SAH showed a marked impairment of glymphatic enrichment throughout the brain (particularly addressing the cerebral cortex and subcortical white matter), especially after 24 hours. The glymphatic impairment was accompanied by redistribution of CSF tracer from subarachnoid spaces toward ventricles. These alterations were most pronounced after 3 to 6 months and less after 12 months, though with interindividual variation. CSF tracer transport within perivascular subarachnoid spaces was impaired and coincided with impaired glymphatic enrichment. CONCLUSIONS: Human glymphatic function is severely impaired by SAH, particularly shortly after the event. Glymphatic failure is associated with redistribution of CSF from subarachnoid spaces toward ventricles. SAH-related impairment of fluid transport within perivascular subarachnoid spaces may contribute to reduced glymphatic influx. Since patient groups are small, care should be made when concluding about the impact of time on glymphatic function.

• Ghafaji, Hajar; Nordenmark, Tonje Kristin Haug; Western, Elin; Sorteberg, Wilhelm; Karic, Tanja & Sorteberg, Angelika (2025). Resilience in good outcome patients with fatigue after aneurysmal subarachnoid hemorrhage. Behavioural Brain Research. ISSN 0166-4328. 483. doi: 10.1016/j.bbr.2025.115466. Full text in Research Archive
• Netteland, Dag Ferner; Aarhus, Mads; Sandset, Else Charlotte; Sorteberg, Angelika; Padayachy, Llewellyn & Helseth, Eirik [Show all 7 contributors for this article] (2025). Real-Time Automated Measurements of Optic Nerve Sheath Diameter for Noninvasive Assessment of Intracranial Pressure in Aneurysmal Subarachnoid Hemorrhage. Neurocritical Care. ISSN 1541-6933. 42, p. 1043–1053. doi: 10.1007/s12028-024-02194-w. Full text in Research Archive Show summary

  Background Optic nerve sheath diameter (ONSD) is a promising noninvasive parameter for intracranial pressure (ICP) assessment. However, in the setting of aneurysmal subarachnoid hemorrhage (aSAH), several previous studies have reported no association between ultrasonically measured ONSD and ICP. In this study, we evaluate ONSD in patients with aSAH using a novel method of automated real-time ultrasonographic measurements and explore whether factors such as having undergone surgery affects its association to ICP. Methods We prospectively included adult patients with aSAH undergoing invasive ICP monitoring. ONSD was obtained using a prototype ultrasound machine with software for real-time automated measurements at the bedside. Correlation between ONSD and ICP was explored, and the ability of ONSD to discriminate dichotomized ICP was evaluated. Abovementioned analyses were performed for the whole cohort and repeated for subgroups by whether the basal cisterns had been surgically entered before ultrasound examination. Results Twenty-six ultrasound examinations were performed in 20 patients. There was a positive correlation between ONSD and ICP (R = 0.43; p = 0.03). In the subgroup where the basal cisterns had not been surgically entered before ultrasound examination, there was a stronger correlation (R = 0.55; p = 0.01), whereas no correlation was seen in the subgroup where the basal cisterns had been surgically entered (R = − 0.16; p = 0.70). ONSD displayed an ability to discriminate ICP dichotomized at ≥ 15 mm Hg (area under the curve [AUC] = 0.84, 95% confidence interval [CI] 0.65–0.96). Subgroup analysis revealed a perfect discriminatory ability (AUC = 1, 95% CI 0.81–1) where the basal cisterns had not been surgically entered and no discriminatory ability (AUC = 0.47, 95% CI 0.16–0.84) where the basal cisterns had been surgically entered before ultrasound examination. Conclusions Automatically measured ONSD correlated well with ICP and displayed a perfect discriminatory ability in patients with aSAH in whom the basal cisterns had not been entered surgically before ultrasound examination, and may be a clinically valuable noninvasive marker of ICP in these patients. Caution should be exercised in using ONSD in patients in whom the basal cisterns have been entered surgically before ONSD measurements, as no association was observed in this subgroup.

• Skytioti, Maria; Wiedmann, Markus; Sorteberg, Angelika; Romundstad, Luis Georg; Hassan, Yasin Ali & Ayoubi, Atiq Mohammad [Show all 8 contributors for this article] (2024). Dynamic cerebral autoregulation is preserved during orthostasis and intrathoracic pressure regulation in healthy subjects: A pilot study. Physiological Reports. 12(9). doi: 10.14814/phy2.16027. Full text in Research Archive Show summary

  Resistance breathing may restore cardiac output (CO) and cerebral blood flow (CBF) during hypovolemia. We assessed CBF and cerebral autoregulation (CA) during tilt, resistance breathing, and paced breathing in 10 healthy subjects. Blood velocities in the internal carotid artery (ICA), middle cerebral arteries (MCA, four subjects), and aorta were measured by Doppler ultrasound in 30° and 60° semi-recumbent positions. ICA blood flow and CO were calculated. Arterial blood pressure (ABP, Finometer), and end-tidal CO2 (ETCO2) were recorded. ICA blood flow response was assessed by mixed-models regression analysis. The synchronization index (SI) for the variable pairs ABP–ICA blood velocity, ABP–MCA velocities in 0.005–0.08 Hz frequency interval was calculated as a measure of CA. Passive tilting from 30° to 60° resulted in 12% decrease in CO (p = 0.001); ICA blood flow tended to fall (p = 0.04); Resistance breathing restored CO and ICA blood flow despite a 10% ETCO2 drop. ETCO2 and CO contributed to ICA blood flow variance (adjusted R2: 0.9, p < 0.0001). The median SI was low (<0.2) indicating intact CA, confirmed by surrogate date testing. The peak SI was transiently elevated during resistance breathing in the 60° position. Resistance breathing may transiently reduce CA efficiency. Paced breathing did not restore CO or ICA blood flow.

• Mijderwijk, Hendrik-Jan; Winkel, Jordi de; Nieboer, Daan; Abdelaal, Ahmed; Germans, Menno R. & Karadag, Cihat [Show all 12 contributors for this article] (2024). External Validation of the ARISE Prediction Models for Aneurysmal Rebleeding After Aneurysmal Subarachnoid Hemorrhage. Neurosurgery. ISSN 0148-396X. doi: 10.1227/neu.0000000000003275. Full text in Research Archive
• Capion, Tenna; Lilja-Cyron, Alexander; Juhler, Marianne; Moeller, Kirsten; Sorteberg, Angelika & Rønning, Pål Andre [Show all 15 contributors for this article] (2024). Prompt closure versus gradual weaning of external ventricular drain for hydrocephalus following aneurysmal subarachnoid haemorrhage: a statistical analysis plan for the DRAIN randomised clinical trial. Trials. 25(1). doi: 10.1186/s13063-024-08305-4. Full text in Research Archive Show summary

  Background - Insertion of an external ventricular drain (EVD) is a first-line treatment of acute hydrocephalus caused by aneurysmal subarachnoid haemorrhage (aSAH). Once the patient is clinically stable, the EVD is either removed or replaced by a permanent internal shunt. The optimal strategy for cessation of the EVD is unknown. Prompt closure carries a risk of acute hydrocephalus or redundant shunt implantations, whereas gradual weaning may increase the risk of EVD-related infections.<p> <p>Methods - DRAIN (Danish RAndomised Trial of External Ventricular Drainage Cessation IN Aneurysmal Subarachnoid Haemorrhage) is an international multicentre randomised clinical trial comparing prompt closure versus gradual weaning of the EVD after aSAH. The primary outcome is a composite of VP-shunt implantation, all-cause mortality, or EVD-related infection. Secondary outcomes are serious adverse events excluding mortality and health-related quality of life (EQ-5D-5L). Exploratory outcomes are modified Rankin Scale, Fatigue Severity Scale, Glasgow Outcome Scale Extended, and length of stay in the neurointensive care unit and hospital. Outcome assessment will be performed 6 months after ictus. Based on the sample size calculation (event proportion 80% in the gradual weaning group, relative risk reduction 20%, alpha 5%, power 80%), 122 participants are required in each intervention group. Outcome assessment for the primary outcome, statistical analyses, and conclusion drawing will be blinded. Two independent statistical analyses and reports will be tracked using a version control system, and both will be published. Based on the final statistical report, the blinded steering group will formulate two abstracts.<p> <p>Conclusion - We present a pre-defined statistical analysis plan for the randomised DRAIN trial, which limits bias, p-hacking, and data-driven interpretations. This statistical analysis plan is accompanied by tables with simulated data, which increases transparency and reproducibility.

• Sorteberg, Angelika; Lashkarivand, Aslan & Western, Elin (2024). Return to work after aneurysmal subarachnoid hemorrhage. Frontiers in Neurology. 15. doi: 10.3389/fneur.2024.1401493. Full text in Research Archive Show summary

  Introduction: Survivors of aneurysmal subarachnoid hemorrhage (aSAH) often recover without severe physical or cognitive deficits. However, strikingly low levels of engagement in productive employment have also been reported in aSAH patients with good or excellent outcomes. Knowledge about return to work (RTW) after aSAH and predictors of no RTW remain limited and controversial. The study aimed to delineate the return to maximum work capacity up to 5 years after the ictus in a larger number of consecutive aSAH patients from the entire aSAH severity spectrum and to identify demographic and medical predictors of no RTW. Methods: Data were acquired from a prospective institutional database. We included all 500 aSAH survivors aged > 18 years who were treated between January 2012 and March 2018. In addition to gathering data on work status and the type of work at ictus, we retrieved demographical data and assessed aSAH severity based on the quantification of subarachnoid, intraventricular, and intraparenchymal blood (ICH), as well as the World Federation of Neurological Societies (WFNS) grade. We registered the mode of aneurysm repair (endovascular or surgical) and recorded complications such as vasospasm, newly acquired cerebral infarctions, and chronic hydrocephalus. Results: Furthermore, work status and the grade of fatigue at follow-up were registered. RTW was assessed among 299 patients who were employed at ictus. Among them, 63.2% were women, and their age was 51.3 ± 9.4 (20–71) years. Return to gainful employment was 51.2%, with complete RTW accounting for 32.4%. The independent predictors of no RTW at ictus were age, the WFNS grade 3, and active smoking. The strongest independent predictor was the presence of clinically significant fatigue, which increased the risk of not returning to work by 5-fold. The chance to return to gainful employment significantly increased with the individual's years of education prior to their hemorrhage. The mode of aneurysm repair was not relevant with regard to RTW. Patients in the WFNS grades 1–2 more often returned to work than those in the WFNS grades 3–5, but our results indicate that neurological motor deficits are linked closer to no RTW than aSAH severity per se. Conclusion: Fatigue needs to be addressed as an important element on the path to return to work integration.

• Ghafaji, Hajar; Nordenmark, Tonje Kristin Haug; Western, Elin; Sorteberg, Wilhelm; Karic, Tanja & Sorteberg, Angelika (2023). Coping strategies in patients with good outcome but chronic fatigue after aneurysmal subarachnoid hemorrhage. Acta Neurochirurgica. ISSN 0001-6268. p. 1–13. doi: 10.1007/s00701-023-05549-y. Full text in Research Archive Show summary

  Abstract Background Fatigue is a highly prevalent and debilitating symptom among patients in the chronic phase of aneurysmal subarachnoid haemorrhage (aSAH) with no identified effective treatment. Cognitive therapy has been shown to have moderate effects on fatigue. Delineating the coping strategies used by patients with post-aSAH fatigue and relating them to fatigue severity and emotional symptoms could be a step towards developing a behavioural therapy for post-aSAH fatigue. Methods Ninety-six good outcome patients with chronic post-aSAH fatigue answered the questionnaires Brief COPE, (a questionnaire defining 14 coping strategies and three Coping Styles), the Fatigue Severity Scale (FSS), Mental Fatigue Scale (MFS), Beck Depression Inventory (BDI-II) and Beck Anxiety Inventory (BAI). The Brief COPE scores were compared with fatigue severity and emotional symptoms of the patients. Results The prevailing coping strategies were “Acceptance”, “Emotional Support”, “Active Coping” and “Planning”. “Acceptance” was the sole coping strategy that was significantly inversely related to levels of fatigue. Patients with the highest scores for mental fatigue and those with clinically significant emotional symptoms applied significantly more maladaptive avoidant strategies. Females and the youngest patients applied more “Problem-Focused” strategies. Conclusion A therapeutic behavioural model aiming at furthering “Acceptance” and reducing passivity and “Avoidant” strategies may contribute to alleviate post-aSAH fatigue in good outcome patients. Given the chronic nature of post-aSAH fatigue, neurosurgeons may encourage patients to accept their new situation so that they can start a process of positive reframing instead of being trapped in a spiral of futile loss of energy and secondary increased emotional burden and frustration.

• Andersen, Sindre; Western, Elin; Sorteberg, Wilhelm & Sorteberg, Angelika (2023). The impact of pre-ictal statin use on vasospasm and outcome in aneurysmal subarachnoid hemorrhage. Acta Neurochirurgica. ISSN 0001-6268. 165, p. 3325–3338. doi: 10.1007/s00701-023-05812-2. Full text in Research Archive Show summary

  Abstract Background Pleiotropic effects of statins may be beneficial in alleviating cerebral vasospasm (VS) and improving outcome after aneurysmal subarachnoid hemorrhage (aSAH). Initiation of statin treatment at aSAH is not recommended; however, the effect of pre-ictal and continued statin use is not fully investigated. Methods Retrospective study comparing aSAH patients admitted in 2012 to 2021 with pre-ictal statin use versus those not using statins. Patient entry variables, radiological/sonological VS, symptomatic VS, and radiologically documented delayed cerebral ischemia (DCI) were registered. Outcome was scored in terms of mortality, modified Rankin score, Glasgow outcome score extended, and levels of fatigue. Patients were compared on group level and in a case–control design. Results We included 961 patients, with 204 (21.2%) statin users. Statin users were older and had more often hypertension. Severe radiological/sonological VS, symptomatic VS, and DCI were less frequent in statin users, and their length of stay was shorter. Mortality, functional outcome, and levels of fatigue were similar in both groups. When analyzing 89 pairs of statin users and non-statin users matched for age, aSAH severity, gender, and hypertension, we confirmed decreased radiological/sonological and symptomatic VS as well as shorter length of stay in statin users. They also had more often a favorable functional outcome and lower levels of fatigue. Conclusions Patients with pre-ictal and continued use of statins have a reduced occurrence of radiological/sonological and symptomatic VS, shorter length of stay, and more often favorable functional outcome, whereas mortality is similar to non-statin users. Even though larger multicenter studies with common, strict protocols for prevention, diagnosis, and treatment of vasospasm are needed to finally establish the value of statins in aSAH, continuation of pre-ictal statin use seems worthwhile.

• Eide, Per Kristian; Sorteberg, Angelika; Nome, Terje; Rønning, Pål Andre & Sorteberg, Wilhelm (2022). Early surgical versus endovascular repair of ruptured blood-blister aneurysm of the internal carotid artery: a single-center 20-year experience. Journal of Neurosurgery. ISSN 0022-3085. 137(6), p. 1766–1775. doi: 10.3171/2022.3.JNS2216. Full text in Research Archive Show summary

  OBJECTIVE Early repair of ruptured blood-blister aneurysms (BBAs) of the internal carotid artery (ICA) remains challenging. Although both surgical and endovascular therapies have been established, their relative superiority remains debated. The authors assessed their single-center experience and compared early deconstructive versus reconstructive repair and early reconstructive surgical versus endovascular repair of ruptured BBAs of the ICA. METHODS The study included patients who underwent repair of ruptured BBAs of the ICA within 1 week after the ictus during a 20-year period. Multiple variables were recorded, including clinical state, severity of subarachnoid hemorrhage (SAH), characteristics of the BBA, treatment details, complication profile, need for secondary treatment, and clinical outcome. RESULTS In total, 27 patients underwent early surgical (n = 16) or endovascular (n = 11) repair of BBAs at a median of 24 hours (range 9–120 hours) after the ictus during the period from September 2000 to June 2021 (20.4 years). Primary deconstructive repair (n = 6) without bypass was accompanied by middle cerebral artery (MCA) territory infarction in 5 of 6 (83%) patients and a high mortality rate (4/6 [67%]). Among the 21 patients who underwent early reconstructive repair, surgery was performed in 11 patients (clipping in 6 and clip-wrapping in 5 patients) and endovascular repair in 10 patients (flow diversion in 7 and stent/stent-assisted coiling in 3 patients). No differences were found in complication profiles or clinical outcomes between the surgical and endovascular groups. The mortality rate was low (2/21 [9.5%]), with 1 fatality in each group. CONCLUSIONS From the authors’ experience, both surgical and endovascular approaches permitted reconstructive repair of ruptured BBAs of the ICA, with no modality proving superior. Reconstructive treatment is preferable to ICA sacrifice, and if sacrifice is chosen, it should be accompanied with bypass surgery or delayed to the phase when cerebral vasospasm has resumed. The rare occurrence of this disease calls for prospective multicenter studies to improve treatment and delineate which modality is preferable in individual cases.

• Frič, Radek; Sorteberg, Angelika; Wallace, Sean Ciaran; Server, Andrés; Due-Tønnessen, Bernt Johan & Wiedmann, Markus (2022). Moyamoya hos barn. Tidsskrift for Den norske legeforening (Tidsskriftet). ISSN 0029-2001. 142(13), p. 1–9. doi: 10.4045/tidsskr.21.0776. Full text in Research Archive Show summary

  Moyamoya er en sjelden sykdom som rammer hjernens blodårer hos barn og unge voksne. Den kan forårsake både hjerneinfarkt og hjerneblødninger. Selv om det finnes etablerte diagnostiske kriterier og undersøkelser, fører begrenset kunnskap ofte til feildiagnostisering og forsinket diagnose. Behandlingen består av platehemmende medisiner og kirurgisk revaskularisering. Prognosen etter vellykket kirurgi er god, men sykdommen krever et dedikert behandlerteam. Moyamoya er en kronisk og progressiv sykdom, karakterisert av gradvis stenosering/okklusjon av den intrakraniale delen av arteria carotis interna samt proksimale segment av a. cerebri anterior, a. cerebri media og (sjeldnere) blodårene i bakre kretsløp. Ettersom sykdommen progredierer langsomt, utvikler det seg et nettverk av nye kollaterale blodårer rundt de stenoserte/okkluderte karsegmentene som opprettholder vevsperfusjonen. Disse kollateralkarene er små og utsatt for ruptur med blødning, aneurismedannelse og trombosering. Kollateralnettverket sees ved konvensjonell cerebral angiografi hvor det minner om en «sky av røyk» (moyamoya på japansk). Ytterligere kollaterale blodårer danner seg fra hjernehinnene (leptomeningene) eller gjennom dura fra grener til a. carotis externa. Vi gir i denne kliniske oversikten en oppdatering om sykdommen, med fokus på barn, basert på egne erfaringer og gjennomgang av relevant litteratur.

• Aamodt, Anne Hege; Taubøll, Erik; Ele, Tom Eich; Romundstad, Luis Georg; Sorteberg, Angelika & Wallace, Sean Ciaran [Show all 24 contributors for this article] (2021). Brain monitoring in hospitals needs to be strengthened. Tidsskrift for Den norske legeforening (Tidsskriftet). ISSN 0029-2001. 141(15), p. 1–8. doi: 10.4045/tidsskr.21.0412. Full text in Research Archive
• Western, Elin; Nordenmark, Tonje Haug; Sorteberg, Wilhelm; Karic, Tanja & Sorteberg, Angelika (2021). Fatigue after aneurysmal subarachnoid hemorrhage: Clinical characteristics and associated factors in patients with good outcome. Frontiers in Behavioral Neuroscience. 15, p. 1–15. doi: 10.3389/fnbeh.2021.633616. Full text in Research Archive Show summary

  Fatigue after aneurysmal subarachnoid hemorrhage (post-aSAH fatigue) is a frequent, often long-lasting, but still poorly studied sequel. The aim of the present study was to characterize the nature of post-aSAH fatigue with an itemized analysis of the Fatigue Severity Scale (FSS) and Mental Fatigue Scale (MFS). We further wanted to assess the association of fatigue with other commonly observed problems after aSAH: mood disorders, cognitive problems, health-related quality of life (HRQoL), weight gain, and return to work (RTW). Ninety-six good outcome aSAH patients with fatigue completed questionnaires measuring fatigue, depression, anxiety, and HRQoL. All patients underwent a physical and neurological examination. Cognitive functioning was assessed with a neuropsychological test battery. We also registered prior history of fatigue and mood disorders as well as occupational status and RTW. The patients experienced fatigue as being among their three most disabling symptoms and when characterizing their fatigue they emphasized the questionnaire items “low motivation,” “mental fatigue,” and “sensitivity to stress.” Fatigue due to exercise was their least bothersome aspect of fatigue and weight gain was associated with depressive symptoms rather than the severity of fatigue. Although there was a strong association between fatigue and mood disorders, especially for depression, the overlap was incomplete. Post-aSAH fatigue related to reduced HRQoL. RTW was remarkably low with only 10.3% of patients returning to their previous workload. Fatigue was not related to cognitive functioning or neurological status. Although there was a strong association between fatigue and depression, the incomplete overlap supports the notion of these two being distinct constructs. Moreover, post-aSAH fatigue can exist without significant neurological or cognitive impairments, but is related to reduced HRQoL and contributes to the low rate of RTW.

• Sorteberg, Wilhelm; Sorteberg, Angelika; Jacobsen, Eva Astrid; RØNNING, PÅL ANDRE; Nome, Terje & Eide, Per Kristian (2021). Endovascular versus surgical treatment of cranial dural arteriovenous fistulas: a single-center 8-year experience. Acta Neurochirurgica. ISSN 0001-6268. 164(1), p. 151–161. doi: 10.1007/s00701-021-04950-9. Full text in Research Archive Show summary

  Background Cranial dural arteriovenous fistulas (dAVFs) are rare lesions managed mainly with endovascular treatment (EVT) and/or surgery. We hypothesize that there may be subtypes of dAVFs responding better to a specific treatment modality in terms of successful obliteration and cessation of symptoms and/or risks. Methods All dAVFs treated during 2011–2018 at our hospital were analyzed retrospectively. Presenting symptoms, radiological variables, treatment modality, complications, and residual symptoms were related to dAVF type using the original Djindjian classification. Results We treated 112 dAVFs in 107 patients (71, 66% males). They presented with hemorrhage (n = 23; 21%), non-hemorrhagic symptoms (n = 75; 70%), or were discovered incidentally (n = 9; 8%). There were 25 (22%) type I, 29 (26%) type II, 26 (23%) type III, and 32 (29%) type IV fistulas. EVT was the primary treatment modality in 72/112 (64%) dAVFs whereas 40/112 (36%) underwent primary surgery with angiographic obliteration rates of 60% and 90%, respectively. Using a secondary treatment modality in 23 dAVFs, we obtained a final obliteration rate of 93%, including all type III/IV and 26/27 (96%) type II dAVFs. Except for headache, residual symptoms were rare and minor. Permanent neurological complications consisted of five cranial nerve deficits. Conclusions We recommend EVT as first treatment modality in types I, II, and in non-hemorrhagic type III/IV dAVFs. We recommend surgery as first treatment choice in acute hemorrhagic dAVFs and as secondary choice in type III/IV dAVFs not successfully occluded by EVT. Combining the two modalities provides obliteration in 9/10 dAVF cases at a low procedural risk.

• Sorteberg, Angelika; Romundstad, Luis Georg & Sorteberg, Wilhelm (2021). Timelines and rebleeds in patients admitted into neurosurgical care for aneurysmal subarachnoid haemorrhage. Acta Neurochirurgica. ISSN 0001-6268. 163(3), p. 771–781. doi: 10.1007/s00701-020-04673-3. Full text in Research Archive Show summary

  Abstract Background Mortality and morbidity of aneurysmal subarachnoid haemorrhage (aSAH) remain high, and prognosis is influenced by multiple non-modifiable factors such as aSAH severity. By analysing the chronology of aSAH management, we aim at identifying modifiable factors with emphasis on the occurrence of rebleeds in a setting with 24/7 surgical and endovascular availability of aneurysm repair and routine administration of tranexamic acid. Methods Retrospective analysis of institutional quality registry data of aSAH cases admitted into neurosurgical care during the time period 01 January 2013–31 December 2017. We registered time and mode of aneurysm repair, haemorrhage patterns, course of treatment, mortality and functional outcome. Rebleeding was scored along the entire timeline from ictus to discharge from the primary stay. Results We included 544 patients (368, 67.6% female), aged 58 ± 14 years (range 1–95 years). Aneurysm repair was performed in 486/544 (89.3%) patients at median 7.4 h after arrival and within 3, 6, 12 and 24 h in 26.8%, 44.7%, 73.0% and 96.1%, respectively. There were circadian variations in time to repair and in rebleeds. Rebleeding prior to aneurysm repair occurred in 9.7% and increased with aSAH severity and often in conjunction with patient relocations or interventions. Rebleeds occurred more often during surgical repair outside regular working hours, whereas rebleeds after repair (1.8%) were linked to endovascular repair. Conclusions The risk of rebleed is imminent throughout the entire timeline of aSAH management even with ultra-early aneurysm repair. Several modifiable factors can be linked to the occurrence of rebleeds and they should be identified and optimised within neurosurgical departments.

• Western, Elin; Nordenmark, Tonje Kristin Haug; Sorteberg, Wilhelm; Sorteberg, Agnes; Karic, Tanja & Sorteberg, Angelika (2021). (−)-OSU6162 in the treatment of fatigue and other sequelae after aneurysmal subarachnoid hemorrhage: a double-blind, randomized, placebo-controlled study. Journal of Neurosurgery. ISSN 0022-3085. 136(6), p. 1705–1715. doi: 10.3171/2021.7.JNS211305. Full text in Research Archive Show summary

  OBJECTIVE Fatigue after aneurysmal subarachnoid hemorrhage (aSAH) is common and usually long-lasting, and it has a considerable negative impact on health-related quality of life (HRQOL), social functioning, and the ability to return to work (RTW). No effective treatment exists. The dopaminergic regulator (−)-OSU6162 has shown promising results regarding the mitigation of fatigue in various neurological diseases, and therefore the authors aimed to investigate the efficacy of (−)-OSU6162 in alleviating fatigue and other sequelae after aSAH. METHODS A double-blind, randomized, placebo-controlled, single-center trial was performed in which 96 participants with post-aSAH fatigue were administered 30–60 mg/day of (−)-OSU6162 or placebo over a period of 12 weeks. Efficacy was assessed using the Fatigue Severity Scale (FSS), the Mental Fatigue Scale (MFS), the Beck Anxiety Inventory (BAI), the Beck Depression Inventory II (BDI-II), the SF-36 questionnaire, and a neuropsychological test battery. Assessments were performed at baseline, after 1, 4, 8, and 12 weeks of treatment, and at follow-up, 8 weeks after treatment. RESULTS The 96 participants with post-aSAH fatigue were randomized to treatment with (−)-OSU6162 (n = 49) or placebo (n = 47). The FSS, MFS, and BDI scores improved significantly in both groups after 12 weeks of treatment, whereas the BAI scores improved in the placebo group only. HRQOL improved significantly in the SF-36 domain “Vitality” in both groups. Neuropsychological test performances were within the normal range at baseline and not affected by treatment. The FSS score was distinctly improved in patients with complete RTW upon treatment with (−)-OSU6162. Concomitant use of antidepressants improved the efficacy of (−)-OSU6162 on the FSS score at week 1 beyond the placebo response, and correspondingly the use of beta- or calcium-channel blockers improved the (−)-OSU6162 efficacy beyond the placebo response in MFS scores at week 4 of treatment. There was a significant correlation between improvement in FSS, BAI, and BDI scores and the plasma concentration of (−)-OSU6162 at the dose of 60 mg/day. No serious adverse events were attributable to the treatment, but dizziness was reported more often in the (−)-OSU6162 group. CONCLUSIONS Fatigue and other sequelae after aSAH were similarly alleviated by treatment with (−)-OSU6162 and placebo. (−)-OSU6162 improved fatigue, as measured with the FSS score, significantly in patients with complete RTW. There seemed to be synergetic effects of (−)-OSU6162 and medications interfering with dopaminergic pathways that should be explored further. The strong placebo response may be exploited in developing nonpharmacological treatment programs for post-aSAH fatigue.

• Lashkarivand, Aslan; Sorteberg, Wilhelm; Rosseland, Leiv Arne & Sorteberg, Angelika (2020). Survival and outcome in patients with aneurysmal subarachnoid hemorrhage in Glasgow coma score 3–5. Acta Neurochirurgica. ISSN 0001-6268. 162(3), p. 533–544. doi: 10.1007/s00701-019-04190-y. Full text in Research Archive Show summary

  Background Outcome of early, aggressive management of aneurysmal subarachnoid hemorrhage (aSAH) in patients with Hunt and Hess grade V is hitherto limited, and we therefore present our results. Methods Retrospective study analyzing the medical data of 228 aSAH patients in Glasgow Coma Score 3–5 admitted to our hospital during the years 2002–2012. Background and treatment variables were registered. Outcome was evaluated after 3 and 12 months. Results We intended to treat 176 (77.2%) patients, but only 146 went on to aneurysm repair. Of 52 patients managed conservatively, 27 had abolished cerebral circulation around arrival and 25 were deemed unsalvageable. One-year overall mortality was 65.8% and most (84.7%) of the fatalities occurred within 30 days. One-year mortality was higher in patients > 70 years. Without aneurysm repair, mortality was 100%. After 1 year, 21.9% of all patients lived independently and 4.8% lived permanently in an institution. Outcome in the 78 survivors (34.2%) was favorable in 64.1% in terms of modified Rankin Scale score 0–2, and 85.9% of survivors were able to live at home. Return to work was low for all 228 patients with 14.0% of those employed prior to the hemorrhage having returned to paid work, and respectively, 26.3% in the subgroup of survivors. Conclusions Even with aggressive, early treatment, 1-year mortality is high in comatose aSAH patients with 65.8%. A substantial portion of the survivors have a favorable outcome at 1 year (64.1%, corresponding to 21.9% of all patients admitted) and 85.9% of the survivors could live at home alone or aided.

• Western, Elin; Sorteberg, Angelika; Brunborg, Cathrine & Nordenmark, Tonje Haug (2020). Prevalence and predictors of fatigue after aneurysmal subarachnoid hemorrhage. Acta Neurochirurgica. ISSN 0001-6268. 162(12), p. 3107–3116. doi: 10.1007/s00701-020-04538-9. Full text in Research Archive Show summary

  Abstract Background Fatigue is a common and disabling sequel after aneurysmal subarachnoid hemorrhage (aSAH). At present, prevalence estimates of post-aSAH fatigue in the chronic phase are scarce and vary greatly. Factors from the acute phase of aSAH have hitherto barely been associated with post-aSAH fatigue in the chronic phase. Methods Prospective study assessing prevalence of fatigue using the Fatigue Severity Scale (FSS) in patients who were living independently 1 to 7 years after aSAH. We compared demographic, medical, and radiological variables from the acute phase of aSAH between patients with and without fatigue (FSS ≥ 4 versus &lt; 4) and searched for predictors of fatigue among these variables applying univariable and multivariable regression analyses. Results Of 726 patients treated for aSAH in the period between January 2012 and December 2017, 356 patients completed the assessment. The mean FSS score was 4.7 ± 1.7, and fatigue was present in 69.7%. The frequency of patients with fatigue did not decline significantly over time. Univariable analysis identified nicotine use, loss of consciousness at ictus (LOCi), rebleed prior to aneurysm repair, reduced consciousness to Glasgow Coma Scale (GCS) &lt; 14, large amounts of subarachnoid blood, the presence of acute hydrocephalus, and severe vasospasm as factors that were significantly associated with fatigue. In multivariable analysis, nicotine use, reduced GCS, and severe vasospasm were independent predictors that all more than doubled the risk to develop post-aSAH fatigue. Conclusions Fatigue is a frequent sequel persisting several years after aSAH. Nicotine use, reduced consciousness at admission, and severe vasospasm are independent predictors of fatigue from the acute phase of aSAH. We propose inflammatory cytokines causing dopamine imbalance to be a common denominator for post-aSAH fatigue and the presently identified predictors.

• Sorteberg, Wilhelm; Sorteberg, Angelika; Jacobsen, Eva Astrid; RØNNING, PÅL ANDRE & Eide, Per Kristian (2020). Intracranial Hemorrhage From Dural Arteriovenous Fistulas: Symptoms, Early Rebleed, and Acute Management: A Single-Center 8-Year Experience. Neurosurgery. ISSN 0148-396X. 1(4). doi: 10.1093/neuopn/okaa019. Full text in Research Archive Show summary

  BACKGROUND Cerebral dural arteriovenous fistulas (dAVFs) presenting with hemorrhage are so rare that reports on their characteristics and guidelines for their acute management are scarce. OBJECTIVE To identify characteristics of the clinical and radiological presentation of hemorrhaging dAVFs, and establish their frequency of early rebleed so that implications for their acute management can be drawn. METHODS Retrospective analysis of all patients admitted with intracranial hemorrhage from a dAVF during the years 2011 to 2018. RESULTS Twenty patients (14 males) with a median age of 61 yr (27-75 yr) were included. Thunderclap headache was the presenting symptom in 13 (65%) patients. Rebleed prior to treatment occurred in 35% of the patients at median 7.5 h (range 3-96 h) after the ictus. All dAVFs had retrograde venous drainage and a venous aneurysm with a bleb was the source of hemorrhage in 16 (80%) patients, all of them presenting with headache. In contrast, patients bleeding due to diffuse venous hypertension presented with neurological deficits. Endovascular treatment was successful in 2 cases; hence, definite dAVF treatment was surgical in 18 (90%) patients. At median 7 mo (2-29 mo) after the ictus, 13 (65%) patients were in Glasgow Outcome Scale-Extended 7 or 8. CONCLUSION The typical presentation of hemorrhage from a cranial dAVF is thunderclap headache. The origin of hemorrhage is often a ruptured venous aneurysm with a bleb. The high frequency of early rebleeds warrants management strategies equivalent to those established for aneurysmal subarachnoid hemorrhage. Overall outcome is favorable.

• Slettebø, Haldor; Karic, Tanja & Sorteberg, Angelika (2020). Impact of smoking on course and outcome of aneurysmal subarachnoid hemorrhage. Acta Neurochirurgica. ISSN 0001-6268. 162(12), p. 3117–3128. doi: 10.1007/s00701-020-04506-3. Full text in Research Archive Show summary

  Abstract Background While the smoking-related risk of experiencing an aneurysmal subarachnoid hemorrhage (aSAH) is well established, it remains unclear whether smoking has an unexpected “protective effect” in aSAH, or if smokers are more at risk for complications and poor outcomes. Methods Prospective, observational study investigating the course and outcome of aSAH in patients admitted during the years 2011 and 2012. Smoking status at admittance, demographic, medical, and radiological variables were registered along with management, complications, and outcome at 1 year in terms of mortality, modified Rankin score, and Glasgow outcome score extended. We compared current smokers with nonsmokers on group level and by paired analysis matched by aSAH severity, age, and severity of vasospasm. Results We included 237 patients, thereof 138 current smokers (58.2%). Seventy-four smoker/nonsmoker pairs were matched. Smokers presented more often in poor clinical grade, had less subarachnoid blood, and were younger than nonsmokers. Ruptured aneurysms were larger, and multiple aneurysms more common in smokers. Severe multi-vessel vasospasm was less frequent in smokers, whereas all other complications occurred at similar rates. Mortality at 30 days was lower in smokers and functional outcome was similar in smokers and nonsmokers. Poor clinical grade, age, cerebral infarction, and vertebrobasilar aneurysms were independent predictors of 1-year mortality and of poor functional outcome. Serious comorbidity was a predictor of 1-year mortality. Smoking did not predict mortality or poor functional outcome. Conclusions Notwithstanding clinically more severe aSAH, smokers developed less frequently severe vasospasm and had better outcome than expected. The risk for complications after aSAH is not increased in smokers.

• Lindstrøm, Erika; Ringstad, Geir; Sorteberg, Angelika; Sorteberg, Wilhelm; Mardal, Kent-Andre & Eide, Per (2019). Magnitude and direction of aqueductal cerebrospinal fluid flow: large variations in patients with intracranial aneurysms with or without a previous subarachnoid hemorrhage. Acta Neurochirurgica. ISSN 0001-6268. 161. Full text in Research Archive
• Skodvin, Torbjørn; Evju, Øyvind; Sorteberg, Angelika & Isaksen, Jørgen Gjernes (2019). Prerupture intracranial aneurysm morphology in predicting risk of rupture: A matched case-control study. Neurosurgery. ISSN 0148-396X. 84(1), p. 132–140. doi: 10.1093/neuros/nyy010. Full text in Research Archive
• Khalid, Zaid; Sorteberg, Wilhelm; Nedregaard, Bård & Sorteberg, Angelika (2019). Efficiency and complications of Woven EndoBridge (WEB) devices for treatment of larger, complex intracranial aneurysms-a single-center experience. Acta Neurochirurgica. ISSN 0001-6268. 161(2), p. 393–401. doi: 10.1007/s00701-018-3752-0. Full text in Research Archive
• Nordenmark, Tonje Haug; Karic, Tanja; Sorteberg, Wilhelm & Sorteberg, Angelika (2019). Predictors of cognitive function in the acute phase after aneurysmal subarachnoid hemorrhage. Acta Neurochirurgica. ISSN 0001-6268. 161(1), p. 177–184. doi: 10.1007/s00701-018-3760-0. Full text in Research Archive
• Nordenmark, Tonje Haug; Karic, Tanja; Røe, Cecilie; Sorteberg, Wilhelm & Sorteberg, Angelika (2019). The post-aSAH syndrome: a self-reported cluster of symptoms in patients with aneurysmal subarachnoid hemorrhage. Journal of Neurosurgery. ISSN 0022-3085. p. 1–10. doi: 10.3171/2019.1.JNS183168. Full text in Research Archive
• Sorteberg, Angelika; Bredmose, Per Poelhøi; Hansen, Ernst Andreas & Sorteberg, Wilhelm (2019). The path from ictus to Neurosurgery: chronology and transport logistics of patients with aneurysmal subarachnoid haemorrhage in the South-Eastern Norway Health Region. Acta Neurochirurgica. ISSN 0001-6268. 161(8), p. 1497–1506. doi: 10.1007/s00701-019-03971-9. Full text in Research Archive
• Eide, Per; Sorteberg, Angelika; Sorteberg, Wilhelm; Lindstrøm, Erika; Mardal, Kent-Andre & Ringstad, Geir (2018). “Bucket” cerebrospinal fluid bulk flow: when the terrain disagrees with the map. Acta Neurochirurgica. ISSN 0001-6268. 161(2). doi: 10.1007/s00701-018-3775-6. Full text in Research Archive
• Lindstrøm, Erika Kristina; Ringstad, Geir; Sorteberg, Angelika; Sorteberg, Wilhelm; Mardal, Kent-Andre & Eide, Per Kristian (2018). Magnitude and direction of aqueductal cerebrospinal fluid flow: large variations in patients with intracranial aneurysms with or without a previous subarachnoid hemorrhage. Acta Neurochirurgica. ISSN 0001-6268. 161(2), p. 247–256. doi: 10.1007/s00701-018-3730-6. Full text in Research Archive Show summary

  Background Net cerebrospinal fluid (CSF) flow within the cerebral aqueduct is usually considered to be antegrade, i.e., from the third to the fourth ventricle with volumes ranging between 500 and 600 ml over 24 h. Knowledge of individual CSF flow dynamics, however, is hitherto scarcely investigated. In order to explore individual CSF flow rate and direction, we assessed net aqueductal CSF flow in individuals with intracranial aneurysms with or without a previous subarachnoid hemorrhage (SAH). Methods A prospective observational study was performed utilizing phase-contrast magnetic resonance imaging (PCMRI) to determine the magnitude and direction of aqueductal CSF flow with an in-depth, pixel-by-pixel approach. Estimation of net flow was used to calculate CSF flow volumes over 24 h. PC-MRI provides positive values when flow is retrograde. Results The study included eight patients with intracranial aneurysms. Four were examined within days after their SAH; three were studied in the chronic stage after SAH while one patient had an unruptured intracranial aneurysm. There was a vast variation in magnitude and direction of aqueductal CSF flow between individuals. Net aqueductal CSF flow was retrograde, i.e., directed towards the third ventricle in 5/8 individuals. For the entire patient cohort, the estimated net aqueductal CSF volumetric flow rate (independent of direction) was median 898 ml/24 h (ranges 69 ml/24 h to 12.9 l/ 24 h). One of the two individuals who had a very high estimated net aqueductal CSF volumetric flow rate, 8.7 l/24 h retrograde, later needed a permanent CSF shunt. Conclusions The magnitude and direction of net aqueductal CSF flow vary extensively in patients with intracranial aneurysms. Following SAH, PC-MRI may offer the possibility to perform individualized assessments of the CSF circulation.

• Skodvin, Torbjørn; Johnsen, Liv-Hege; Gjertsen, Øivind; Isaksen, Jørgen Gjernes & Sorteberg, Angelika (2017). Cerebral aneurysm morphology before and after rupture: nation-wide case series of 29 aneurysms. Stroke. ISSN 0039-2499. doi: 10.1161/STROKEAHA.116.015288. Full text in Research Archive Show summary

  <p><i>Background and Purpose</i>: Using postrupture morphology to predict rupture risk of an intracranial aneurysm may be inaccurate because of possible morphological changes at or around the time of rupture. The present study aims at comparing morphology from angiograms obtained prior to and just after rupture and to evaluate whether postrupture morphology is an adequate surrogate for rupture risk.</p> <p><i>Methods</i>: Case series of 29 aneurysms from a nationwide retrospective data collection. Two neuroradiologists who were blinded to pre- versus postrupture images assessed predefined morphological parameters independently and reached consensus regarding all measurements. Prerupture morphology and respective changes after rupture were quantified and linked to risk factors and to the risk of rupture according to the PHASES (population, hypertension, age, size of aneurysm, earlier subarachnoid hemorrhage from another aneurysm, site of aneurysm) and unruptured intracranial aneurysm treatment (UIAT) scores.</p> <p><i>Results</i>: All 1-dimensional parameter medians were significantly larger after rupture, except neck diameter. Number of aneurysms with daughter sacs was 9 (31%) before and 17 (59%) after rupture (P=0.005). Aneurysm growth from the images prior to and just after rupture increased with the time elapsed between images. Aneurysms in patients with hypertension were significantly larger at diagnosis. Prerupture morphology did not differ in relation to smoke status. Clinical risk factors were not significantly associated with morphological change.</p> <p><i>Conclusions</i>: The changes in aneurysm morphology observed after rupture reflect the compound effect of time with successive growth and formation of irregularities and the impact of rupture per se. Postrupture morphology should not be considered an adequate surrogate for the prerupture morphology in the evaluation of rupture risk.

• Karic, Tanja; Røe, Cecilie; Nordenmark, Tonje Haug; Becker, Frank; Sorteberg, Wilhelm & Sorteberg, Angelika (2017). Effect of early mobilization and rehabilitation on complications in aneurysmal subarachnoid hemorrhage. Journal of Neurosurgery. ISSN 0022-3085. 126(2), p. 518–526. doi: 10.3171/2015.12.JNS151744. Full text in Research Archive Show summary

  OBJECTIVE: Early rehabilitation is effective in an array of acute neurological disorders but it is not established as part of treatment guidelines after aneurysmal subarachnoid hemorrhage (aSAH). This may in part be due to the fear of aggravating the development of cerebral vasospasm, which is the most feared complication of aSAH. The aim of this study was to evaluate the effect of early rehabilitation and mobilization on complications during the acute phase and within 90 days after aSAH. METHODS: This was a prospective, interventional study that included patients with aSAH at the neuro-intermediate ward after aneurysm repair. The control group received standard treatment, whereas the early rehab group underwent early rehabilitation and mobilization in addition to standard treatment. Clinical and radiological characteristics of patients with aSAH, progression in mobilization, and treatment variables were registered. The frequency and severity of cerebral vasospasm, cerebral infarction acquired in conjunction with the aSAH, and acute and chronic hydrocephalus, as well as pulmonary and thromboembolic complications, were compared between the 2 groups. RESULTS: Clinical and radiological characteristics of patients with aSAH were similar between the groups. The early rehab group was mobilized beginning on the first day after aneurysm repair. The significantly quicker and higher degree of mobilization in the early rehab group did not increase complications. Clinical cerebral vasospasm was not as frequent in the early rehab group and it also tended to be less severe. Each step of mobilization achieved during the first 4 days after aneurysm repair reduced the risk of severe vasospasm by 30%. Acute and chronic hydrocephalus were similar in both groups, but there was a tendency toward earlier shunt implantation among patients in the control group. Pulmonary infections, thromboembolic events, and death before discharge or within 90 days after the ictus were similar between the 2 groups. CONCLUSIONS: Early rehabilitation of patients after aSAH is safe and feasible. The earlier and higher degree of mobilization does not increase neurosurgical complications. Rather, the frequency and severity of cerebral vasospasm following aSAH are alleviated and are not aggravated by early rehabilitation. © 2017 American Association of Neurological Surgeons

• Skodvin, Torbjørn; Johnsen, Liv-Hege; Gjertsen, Øivind; Isaksen, Jørgen Gjernes & Sorteberg, Angelika (2017). Cerebral aneurysm morphology before and after rupture: nationwide case series of 29 aneurysms. Stroke. ISSN 0039-2499. 48(4), p. 880–886. doi: 10.1161/STROKEAHA.116.015288. Full text in Research Archive
• Meling, Torstein Ragnar; Romundstad, Luis Georg; Niemi, Geir; Narum, Jon; Eide, Per Kristian & Sorteberg, Angelika [Show all 7 contributors for this article] (2017). Adenosine-assisted clipping of intracranial aneurysms. Neurosurgical review. ISSN 0344-5607. 41(2), p. 585–592. doi: 10.1007/s10143-017-0896-y. Full text in Research Archive
• Karic, Tanja; Røe, Cecilie; Nordenmark, Tonje Haug; Becker, Frank & Sorteberg, Angelika (2016). Impact of early mobilization and rehabilitation on global functional outcome one year after aneurysmal subarachnoid haemorrhage. Journal of Rehabilitation Medicine. ISSN 1650-1977. 48(8), p. 676–682. doi: 10.2340/16501977-2121. Full text in Research Archive
• Rosseland, Leiv Arne; Narum, Jon; Stubhaug, Audun; Kongsgaard, Ulf; Sorteberg, Wilhelm & Sorteberg, Angelika Gabriel (2015). The effect of tracheotomy on drug consumption in patients with acute aneurysmal subarachnoid hemorrhage: An observational study. BMC Anesthesiology. 15(47). doi: 10.1186/s12871-015-0029-5. Full text in Research Archive Show summary

  Background Patients with aneurysmal subarachnoid hemorrhage (aSAH) are common in intensive care units (ICU). In patients with aSAH, sedation is used as a neuroprotective measure in order to secure adequate cerebral perfusion pressure (CPP). Compared with the use of an endotracheal tube, a tracheotomy has the advantage of securing the airway at a much lower level of distress, and aSAH patients can often be awakened more rapidly. Little is known about the impact of tracheotomy on the consumption of sedative/analgesic and vasoactive drugs and the maintenance of CPP within defined limits in aSAH patients. Methods We conducted an observational study of aSAH patients who underwent percutaneous tracheotomy. A prospective registry of patient data was supplemented with retrospective retrievals from medical records. Sedative, analgesic and vasoactive drug doses were registered for 3 days prior to and after percutaneous tracheotomy, respectively. Blood pressure, CPP, and the mode of mechanical ventilation were registered 24 h prior to and after tracheotomy. Results Between January 2001 and June 2009, 902 aSAH patients were admitted to our hospital; 74 (8%) were deeply comatose/dying upon arrival. The ruptured aneurysm was repaired in 828 patients (surgical repair 50%) and percutaneous tracheotomy was performed 182 times in 178 patients (59 men and 119 women). This subpopulation (178 of 828 patients) was significantly older (56 vs. 53 years) and presented with a more severe Hunt & Hess grade (p < 0.001). Percutaneous tracheotomy caused a marked decline in mean daily consumption of the analgesics/sedatives fentanyl, midazolam, and propofol, as well as the vasoactive drugs noradrenaline and dopamine. These declines were statistically and clinically significant. The mean CPP was 76 mmHg (SD 8.6) the day before and 79 mmHg (SD 9.6) 24 h after percutaneous tracheotomy. After percutaneous tracheotomy, mechanical ventilatory support could be reduced to a patient-controlled ventilatory support mode in a significant number of patients (p < 0.001). Conclusions Percutaneous tracheotomy in aSAH patients is a swift procedure with low risk that is associated with a significant decline in the consumption of sedative/analgesic and vasoactive drugs while clinical surveillance parameters remain stable or improve.

• Karic, Tanja; Sorteberg, Angelika Gabriel; Nordenmark, Tonje Haug; Becker, Frank & Røe, Cecilie (2015). Early rehabilitation in patients with acute aneurysmal subarachnoid hemorrhage. Disability and Rehabilitation. ISSN 0963-8288. 37(16), p. 1446–1454. doi: 10.3109/09638288.2014.966162. Full text in Research Archive Show summary

  Purpose: The aim of this study was to describe and quantify the content of early rehabilitation adapted to patients with acute aneurysmal subarachnoid hemorrhage (aSAH) and to assess its feasibility. Methods: This was a prospective, observational study including 37 aSAH patients. Early rehabilitation was applied according to a mobilization algorithm. Clinical parameters, the time that rehabilitation team used on early rehabilitation and progression in mobilization were recorded. The patients’ clinical conditions were graded according to the World Federation of Neurological Surgeons scale (WFNS). Results: Poor-grade patients (WFNS 3, 4, 5) (n = 12) received more rehabilitation (median 412 min) than did good-grade patients (WFNS 1, 2) (median 240 min). Mobilization to 60° of head elevation in good-grade patients began on day one after securing the aneurysm. Out-of-bed mobilization was possible on day three. Poor-grade patients were mobilized to 60° after two days and were out of bed on day seven. At discharge, 67% of poor-grade patients were mobilized to walking versus 78% of good-grade patients. No serious adverse effects to early rehabilitation were observed. Conclusions: Early rehabilitation in aSAH patients is feasible from the first day after securing the aneurysm. The rehabilitation content varied according to the patient’s clinical grade.

• Alnæs, Martin Sandve; Mardal, Kent-Andre; Bakke, Søren Jacob & Sorteberg, Angelika (2015). Computational fluid dynamics evaluation of flow reversal treatment of giant basilar tip aneurysm. Interventional Neuroradiology. ISSN 1591-0199. 21(5), p. 586–591. doi: 10.1177/1591019915597415. Full text in Research Archive
• Eide, Per Kristian; Sorteberg, Angelika Gabriel; Meling, Torstein & Sorteberg, Wilhelm (2014). The effect of baseline pressure errors on an intracranial pressure-derived index: Results of a prospective observational study. Biomedical engineering online. 13(99), p. 1–17. doi: 10.1186/1475-925X-13-99. Full text in Research Archive Show summary

  Background In order to characterize the intracranial pressure-volume reserve capacity, the correlation coefficient (R) between the ICP wave amplitude (A) and the mean ICP level (P), the RAP index, has been used to improve the diagnostic value of ICP monitoring. Baseline pressure errors (BPEs), caused by spontaneous shifts or drifts in baseline pressure, cause erroneous readings of mean ICP. Consequently, BPEs could also affect ICP indices such as the RAP where in the mean ICP is incorporated. Methods A prospective, observational study was carried out on patients with aneurysmal subarachnoid hemorrhage (aSAH) undergoing ICP monitoring as part of their surveillance. Via the same burr hole in the scull, two separate ICP sensors were placed close to each other. For each consecutive 6-sec time window, the dynamic mean ICP wave amplitude (MWA; measure of the amplitude of the single pressure waves) and the static mean ICP, were computed. The RAP index was computed as the Pearson correlation coefficient between the MWA and the mean ICP for 40 6-sec time windows, i.e. every subsequent 4-min period (method 1). We compared this approach with a method of calculating RAP using a 4-min moving window updated every 6 seconds (method 2). Results The study included 16 aSAH patients. We compared 43,653 4-min RAP observations of signals 1 and 2 (method 1), and 1,727,000 6-sec RAP observations (method 2). The two methods of calculating RAP produced similar results. Differences in RAP ≥0.4 in at least 7% of observations were seen in 5/16 (31%) patients. Moreover, the combination of a RAP of ≥0.6 in one signal and <0.6 in the other was seen in ≥13% of RAP-observations in 4/16 (25%) patients, and in ≥8% in another 4/16 (25%) patients. The frequency of differences in RAP >0.2 was significantly associated with the frequency of BPEs (5 mmHg ≤ BPE <10 mmHg). Conclusions Simultaneous monitoring from two separate, close-by ICP sensors reveals significant differences in RAP that correspond to the occurrence of BPEs. As differences in RAP are of magnitudes that may alter patient management, we do not advocate the use of RAP in the management of neurosurgical patients.

• Eide, Per Kristian; Sorteberg, Angelika Gabriel; Meling, Torstein & Sorteberg, Wilhelm (2014). Baseline pressure errors (BPEs) extensively influence intracranial pressure scores: Results of a prospective observational study. Biomedical engineering online. 13(7), p. 1–15. doi: 10.1186/1475-925X-13-7. Full text in Research Archive
• Erixon, Hampus; Sorteberg, Angelika Gabriel; Sorteberg, Wilhelm & Eide, Per Kristian (2014). Predictors of shunt dependency after aneurysmal subarachnoid hemorrhage: results of a single-center clinical trial. Acta Neurochirurgica. ISSN 0001-6268. 156(11), p. 2059–2069. doi: 10.1007/s00701-014-2200-z. Full text in Research Archive
• Eide, Per Kristian; Sorteberg, Angelika Gabriel; Meling, Torstein & Sorteberg, Wilhelm (2013). Directional Intraoperative Doppler Ultrasonography During Surgery on Cranial Dural Arteriovenous Fistulas. Neurosurgery. ISSN 0148-396X. 73, p. 211–223. doi: 10.1227/NEU.0000000000000061. Full text in Research Archive
• Sorteberg, Angelika & Dahlberg, Daniel (2013). Intracranial Non-traumatic Aneurysms in Children and Adolescents. Current pediatric reviews. ISSN 1573-3963. 9(4), p. 343–352. doi: 10.2174/221155281120100005. Full text in Research Archive
• Eide, Per Kristian; Sorteberg, Angelika Gabriel; Bentsen, Gunnar; Marthinsen, Pål Bache; Stubhaug, Audun & Sorteberg, Wilhelm (2012). Pressure-derived versus pressure wave amplitude-derived indices of cerebrovascular pressure reactivity in relation to early clinical state and 12-month outcome following aneurysmal subarachnoid hemorrhage. Journal of Neurosurgery. ISSN 0022-3085. 116(5), p. 961–971. doi: 10.3171/2012.1.JNS111313. Full text in Research Archive
• Eide, Per Kristian; Bentsen, Gunnar; Sorteberg, Angelika Gabriel; Marthinsen, Pål Bache; Stubhaug, Audun & Sorteberg, Wilhelm (2011). A Randomized and Blinded Single-Center Trial Comparing the Effect of Intracranial Pressure and Intracranial Pressure Wave Amplitude-Guided Intensive Care Management on Early Clinical State and 12-Month Outcome in Patients With Aneurysmal Subarachnoid Hemorrhage. Neurosurgery. ISSN 0148-396X. 69(5), p. 1105–1115. doi: 10.1227/NEU.0b013e318227e0e1. Full text in Research Archive
• Haug, Tonje Kristin; Sorteberg, Angelika Gabriel; Finset, Arnstein; Lindegaard, Karl-Fredrik; Lundar, Tryggve & Sorteberg, Wilhelm (2010). Cognitive Functioning and Health-Related Quality of Life 1 Year After Aneurysmal Subarachnoid Hemorrhage in Preoperative Comatose Patients (Hunt and Hess Grade V Patients). Neurosurgery. ISSN 0148-396X. 66(3), p. 475–484. doi: 10.1227/01.NEU.0000365364.87303.AC. Full text in Research Archive
• Fjelstad, Anne-Berit; Hommelstad, Jorunn & Sorteberg, Angelika Gabriel (2009). Infections related to intrathecal baclofen therapy in children and adults: frequency and risk factors. Journal of Pediatric Neurosciences. ISSN 1817-1745. 4(5), p. 487–493. doi: 10.3171/2009.6.PEDS0921. Full text in Research Archive
• Haug, Tonje; Sorteberg, Angelika; Sorteberg, Wilhelm; Lindegaard, Karl-Fredrik; Lundar, Tryggve & Finset, Arnstein (2009). Surgical repair of unruptured and ruptured middle cerebral artery aneurysms: impact on cognitive functioning and health-related quality of life. Neurosurgery. ISSN 0148-396X. 64(3), p. 412–420. Full text in Research Archive
• Meling, Torstein Ragnar; Sorteberg, Angelika; Slettebø, Haldor; Bakke, Søren Jacob; Hernesniemi, Juha & Sorteberg, Wilhelm (2008). Blood-blisterlike aneurysms of the internal carotid artery trunk causing subarachnoid haemorrhage – treatment and outcome. Journal of Neurosurgery. ISSN 0022-3085. 108(4), p. 662–667. Full text in Research Archive
• Sorteberg, Wilhelm; Slettebø, Haldor; Eide, Per Kristian; Stubhaug, Audun & Sorteberg, Angelika (2008). Surgical treatment of aneurysmal subarachnoid haemorrhage in the presence of 24-h endovascular availability: management and results. British Journal of Neurosurgery. ISSN 0268-8697. 22(1), p. 53–62. Full text in Research Archive
• Meling, Torstein Ragnar; Sorteberg, Angelika; Bakke, Søren Jacob; Slettebø, Haldor; Hernesniemi, Juha & Sorteberg, Wilhelm (2008). Blood blister-like aneurysms of the internal carotid artery trunk causing subarachnoid hemorrhage: treatment and outcome. Journal of Neurosurgery. ISSN 0022-3085. 108(4), p. 662–671. Full text in Research Archive
• Sorteberg, Angelika & Bakke, Søren Jacob (2008). The Hydrodynamic Effect of Bare Platinum Coils versus Hydrogel-Coated Platinum Coils. Interventional Neuroradiology. ISSN 1591-0199. 14(4), p. 403–413. Full text in Research Archive
• Sorteberg, Angelika & Sorteberg, Wilhelm (2007). Transcranial Doppler ultrasonography. Part IV: Pitfalls in interpretation. Contemporary Neurosurgery. ISSN 0163-2108. 29(8), p. 1–6. Full text in Research Archive
• Sorteberg, Angelika & Sorteberg, Wilhelm (2007). Transcranial Doppler ultrasonography. Part I: Basic Principles and dynamic Tests. Contemporary Neurosurgery. ISSN 0163-2108. 29(5), p. 1–8. Full text in Research Archive
• Sorteberg, Angelika & Sorteberg, Wilhelm (2007). Transcranial Doppler ultrasonography. Part II: Basic principles and applications in Neurosurgery. Contemporary Neurosurgery. ISSN 0163-2108. 29(6), p. 1–8. Full text in Research Archive
• Sorteberg, Angelika & Sorteberg, Wilhelm (2007). Transcranial Doppler ultrasonography. Part III: Pitfalls in methodology and evaluation of the cerebral collateral capacity. Contemporary Neurosurgery. ISSN 0163-2108. 29(7), p. 1–8. Full text in Research Archive
• Haug, Tonje; Sorteberg, Angelika; Sorteberg, Wilhelm; Lindegaard, Karl-Fredrik; Lundar, Tryggve & Finset, Arnstein (2007). Cognitive outcome after aneurysmal subarachnoid hemorrhage: time course of recovery and relationship to clinical, radiological, and management parameters. Neurosurgery. ISSN 0148-396X. 60(4), p. 649–657. Full text in Research Archive
• Sorteberg, Angelika & Farhoudi, Daniel (2006). The influence of aneurysm configuration on intra-aneurysmal pressure and flow. Interventional Neuroradiology. ISSN 1591-0199. 12(3), p. 203–214. Full text in Research Archive
• Streefkerk, HJN; Wolfs, JS; Sorteberg, Wilhelm; Sorteberg, Angelika & Tulleken, CAF (2004). The ELANA technique: constructing a high flow bypass using a non-occlusive anastomosis on the ICA and a conventional anastomosis on the SCA in the treatment of a fusiform giant basilar trunk aneurysm. Acta Neurochirurgica. ISSN 0001-6268. 146(9), p. 1009–1019. Full text in Research Archive
• Sorteberg, Angelika; Eide, Per Kristian & Fremming, Asbjørn (2004). A prospective study on the clinical effect of surgical treatment of normal pressure hydrocephalus: the value of hydrodynamic evaluation. British Journal of Neurosurgery. ISSN 0268-8697. 18(2), p. 149–157. Full text in Research Archive
• Sorteberg, Angelika; Sorteberg, Wilhelm; Aagaard, Beverly; Rappe, Alan & Strother, Charles M (2004). Hemodynamic versus hydrodynamic effects of Guglielmi detachable coils on intra-aneurysmal pressure and flow at varying pulse rate and systemic pressure. American Journal of Neuroradiology. ISSN 0195-6108. 25(6), p. 1049–1057. Full text in Research Archive
• Eide, Per Kristian; Fremming, Asbjørn & Sorteberg, Angelika (2003). Lack of relationship between resistance to cerebrospinal fluid outflow and intracranial pressure in normal pressure hydrocephalus. Acta Neurologica Scandinavica. ISSN 0001-6314. 108(6), p. 381–388. Full text in Research Archive
• Sorteberg, Angelika; Sorteberg, Wilhelm; Rappe, Alan & Strother, Charles M (2002). Effect of Guglielmi detachable coils on intraaneurysmal flow: experimental study in canines. American Journal of Neuroradiology. ISSN 0195-6108. 23(2), p. 288–294. Full text in Research Archive
• Sorteberg, Angelika; Sorteberg, Wilhelm; Turk, Aquilla; Rappe, Alan; Nakstad, Per Hjalmar & Strother, Charles M (2001). Effect of Guglielmi detachable coil placement on intraaneurysmal pressure: experimental study in canines. American Journal of Neuroradiology. ISSN 0195-6108. 22(9), p. 1750–1759. Full text in Research Archive
• Taubøll, Erik; Sorteberg, Wilhelm; Owe, Jone Furulund; Lindegaard, Karl-Fredrik; Rusten, Knut & Sorteberg, Angelika [Show all 7 contributors for this article] (1999). Cerebral artery blood velocity in normal subjects during acute decreases in barometric pressure. Aviation, Space and Environmental Medicine. ISSN 0095-6562. 70(7), p. 692–697. Full text in Research Archive
• Sorteberg, Wilhelm; Sorteberg, Angelika; Lindegaard, Karl-Fredrik; Boysen, Morten Ebbe & Nornes, Helge (1999). Transcranial Doppler ultrasonography-guided management of internal carotid artery closure. Neurosurgery. ISSN 0148-396X. 45(1), p. 76–88. Full text in Research Archive
• Sorteberg, Angelika; Sorteberg, Wilhelm; Bakke, Søren Jacob; Lindegaard, Karl-Fredrik; Boysen, Morten Ebbe & Nornes, Helge (1998). Varying impact of common carotid artery digital compression and internal carotid artery balloon test occlusion on cerebral hemodynamics. Head and Neck. ISSN 1043-3074. 20(8), p. 687–694. Full text in Research Archive
• Sorteberg, Angelika (1997). Cerebral haemodynamics in internal carotid artery trial occlusion - Comments - Reply. Acta Neurochirurgica. ISSN 0001-6268. 139(11), p. 1073–1073. Full text in Research Archive
• Sorteberg, Angelika; Sorteberg, Wilhelm; Bakke, Søren Jacob; Lindegaard, Karl-Fredrik; Boysen, Morten Ebbe & Nornes, Helge (1997). Cerebral haemodynamics in internal carotid artery trial occlusion. Acta Neurochirurgica. ISSN 0001-6268. 139(11), p. 1066–1073. Full text in Research Archive
• Sorteberg, Angelika; Sorteberg, Wilhelm; Lindegaard, Karl-Fredrik & Nornes, Helge (1996). Cerebral haemodynamic considerations in obstructive carotid artery disease. Acta Neurochirurgica. ISSN 0001-6268. 138(1), p. 68–76. Full text in Research Archive
• Sorteberg, Angelika; Sorteberg, Wilhelm; Lindegaard, Karl-Fredrik; Bakke, Søren Jacob & Nornes, Helge (1996). Haemodynamic classification of symptomatic obstructive carotid artery disease. Acta Neurochirurgica. ISSN 0001-6268. 138(9), p. 1079–1087. Full text in Research Archive

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• Netteland, Dag Ferner; Aarhus, Mads; Sandset, Else Charlotte; Sorteberg, Angelika; Padayachy, Llewellyn & Helseth, Eirik [Show all 7 contributors for this article] (2025). In Reply: Comment on “Real-Time Automated Measurements of Optic Nerve Sheath Diameter for Noninvasive Assessment of Intracranial Pressure in Aneurysmal Subarachnoid Hemorrhage”. Neurocritical Care. ISSN 1541-6933. doi: 10.1007/s12028-025-02279-0. Full text in Research Archive
• Skytioti, Maria; Tveit, Lars Hansen; Sorteberg, Angelika; Elstad, Maja; Romundstad, Luis & Wiedmann, Markus [Show all 8 contributors for this article] (2024). ASYMMETRY OF CEREBRAL AUTOREGULATION QUANTIFIED BY WAVELET ANALYSIS IN PATIENTS SUFFERING FROM SPONTANEOUS SUBARACHNOID HAEMORRHAGE. Full text in Research Archive
• Tveit, Lars H.; Sorteberg, Angelika; Wiedmann, Markus K. H.; Romundstad, Luis Georg; Elstad, Maja & Zilakos, Ilias [Show all 7 contributors for this article] (2024). ASYMMETRY OF CEREBRAL AUTOREGULATION QUANTIFIED BY WAVELET ANALYSIS IN PATIENTS SUFFERING FROM SPONTANEOUS SUBARACHNOID HAEMORRHAGE. Full text in Research Archive
• Capion, Tenna; Lilja-Cyron, Alexander; Olsen, Markus Harboe; Juhler, Marianne; Moeller, Kirsten & Sorteberg, Angelika [Show all 14 contributors for this article] (2023). Prompt closure versus gradual weaning of external ventricular drainage for hydrocephalus following aneurysmal subarachnoid haemorrhage: Protocol for the DRAIN randomised clinical trial. Acta Anaesthesiologica Scandinavica. ISSN 0001-5172. 67(8), p. 1121–1127. doi: 10.1111/aas.14263. Full text in Research Archive Show summary

  Background: Aneurysmal subarachnoid haemorrhage (aSAH) is a life-threatening disease caused by rupture of an intracranial aneurysm. A common complication following aSAH is hydrocephalus, for which placement of an external ventricular drain (EVD) is an important first-line treatment. Once the patient is clinically stable, the EVD is either removed or replaced by a ventriculoperitoneal shunt. The optimal strategy for cessation of EVD treatment is, however, unknown. Gradual weaning may increase the risk of EVD-related infection, whereas prompt closure carries a risk of acute hydrocephalus and redundant shunt implantations. We designed a randomised clinical trial comparing the two commonly used strategies for cessation of EVD treatment in patients with aSAH.<p> <p>Methods: DRAIN is an international multi-centre randomised clinical trial with a parallel group design comparing gradual weaning versus prompt closure of EVD treatment in patients with aSAH. Participants are randomised to either gradual weaning which comprises a multi-step increase of resistance over days, or prompt closure of the EVD. The primary outcome is a composite outcome of VP-shunt implantation, all-cause mortality, or ventriculostomy-related infection. Secondary outcomes are serious adverse events excluding mortality, functional outcome (modified Rankin scale), health-related quality of life (EQ-5D) and Fatigue Severity Scale (FSS). Outcome assessment will be performed 6 months after ictus. Based on the sample size calculation (event proportion 80% in the gradual weaning group, relative risk reduction 20%, type I error 5%, power 80%), 122 patients are needed in each intervention group. Outcome assessment for the primary outcome, statistical analyses and conclusion drawing will be blinded.

• Sorteberg, Wilhelm; Sorteberg, Angelika; Jacobsen, Eva Astrid; Rønning, Pål Andre; Nome, Terje & Eide, Per Kristian (2022). Microsurgery as first-line treatment in acute hemorrhagic cranial dural arteriovenous fistulas (dAVFs) and ruptured intracranial aneurysms—anachronism or duty? Acta Neurochirurgica. ISSN 0001-6268. 164, p. 1303–1305. doi: 10.1007/s00701-022-05197-8. Full text in Research Archive
• Sorteberg, Angelika; Romundstad, Luis Georg & Sorteberg, Wilhelm (2021). How preventable are rebleeds?: Reply to: Letter to the editor of Acta Neurochirurgica: “Predictive factors and timelines of rebleeding in Aneurysmal SAH: What have we gleaned?”. Acta Neurochirurgica. ISSN 0001-6268. 163(5), p. 1481–1483. doi: 10.1007/s00701-021-04775-6. Full text in Research Archive
• Lindegaard, Karl-Fredrik; Lundar, Tryggve; Hauglie-Hanssen, E.; Sorteberg, Angelika; Sorteberg, Wilhelm & Magnæs, B [Show all 8 contributors for this article] (2019). OBITUARY HELGE NORNES, has works published, Professor. Tidsskrift for Den norske legeforening (Tidsskriftet). ISSN 0029-2001. doi: 10.4045/tidsskr.19.0200. Full text in Research Archive
• Eide, Per Kristian; Sorteberg, Angelika; Sorteberg, Wilhelm; Lindstrøm, Erika Kristina; Mardal, Kent-Andre & Ringstad, Geir (2018). "Bucket" cerebrospinal fluid bulk flow: when the terrain disagrees with the map. Acta Neurochirurgica. ISSN 0001-6268. 161(2), p. 259–261. doi: 10.1007/s00701-018-3775-6. Full text in Research Archive
• Skodvin, Torbjørn; Evju, Øyvind; Sorteberg, Angelika & Isaksen, Jørgen Gjernes (2017). Morphological Predictors of Future Intracranial Aneurysm Rupture: A Matched Case-Control Study. Full text in Research Archive
• Sorteberg, Angelika (2014). Balloon occlusion tests and therapeutic vessel occlusions revisited: when, when not, and how. American Journal of Neuroradiology. ISSN 0195-6108. 35(5), p. 862–865. Full text in Research Archive
• Meling, Torstein Ragnar; Romundstad, Luis Georg; Niemi, Geir; Narum, Jon; Eide, Per Kristian & Sorteberg, Wilhelm [Show all 7 contributors for this article] (2014). Adenosine-induced Temporary Cardiac Arrest During Intracranial Aneurysm Surgery. Full text in Research Archive
• Ragauskas, Arthur J.; Petkus, V.; Chomskis, R.; Ferenets, R.; Eide, Per Kristian & Sorteberg, Angelika Gabriel (2013). Clinical assessment of innovative intracranial pressure and volume wave monitoring system. Cerebrovascular Diseases. ISSN 1015-9770. 35, p. 44–45. Full text in Research Archive
• Sorteberg, Angelika; Nordermark, Tonje Haug; Finset, Arnstein; Lindegaard, Karl-Fredrik; Lundar, Tryggve & Sorteberg, Wilhelm (2013). Over-aggressive treatment of grade V SAH patients. Neurosurgery. ISSN 0148-396X. 73(3), p. 560–561. Full text in Research Archive
• Sorteberg, Angelika (2009). Så heldig du har vært! 129, p. 1246–1246. Full text in Research Archive
• Meling, Torstein Ragnar; Sorteberg, Angelika; Bakke, Søren Jacob; Slettebø, Haldor; Hernesniemi, Juha & Sorteberg, Wilhelm (2007). Blood-blisterlike Aneurysms of the ICA Trunk causing SAH Treatment and Outcome. Full text in Research Archive
• Sorteberg, Wilhelm; Meling, Torstein Ragnar; Bakke, Søren Jacob; Slettebø, Haldor & Sorteberg, Angelika (2006). Acute ICA closure as treatment option in ICA aneurysmal bleed. Full text in Research Archive

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