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Featured researches published by Roar Kloster.


Annals of Oncology | 2017

Surgical resection versus watchful waiting in low-grade gliomas

Asgeir Store Jakola; Anne Jarstein Skjulsvik; Kristin Smistad Myrmel; Kristin Sjåvik; Geirmund Unsgård; Sverre Helge Torp; K. Aaberg; Thomas Berg; Hong Yan Dai; K. Johnsen; Roar Kloster; Ole Solheim

Abstract Background Infiltrating low-grade gliomas (LGG; WHO grade 2) typically present with seizures in young adults. LGGs grow continuously and usually transform to higher grade of malignancy, eventually causing progressive disability and premature death. The effect of up-front surgery has been controversial and the impact of molecular biology on the effect of surgery is unknown. We now present long-term results of upfront surgical resection compared with watchful waiting in light of recently established molecular markers. Materials and methods Population-based parallel cohorts were followed from two Norwegian university hospitals with different surgical treatment strategies and defined geographical catchment regions. In region A watchful waiting was favored while early resection was favored in region B. Thus, the treatment strategy in individual patients depended on their residential address. The inclusion criteria were histopathological diagnosis of supratentorial LGG from 1998 through 2009 in patients 18 years or older. Follow-up ended 1 January 2016. Making regional comparisons, the primary end-point was overall survival. Results A total of 153 patients (66 from region A, 87 from region B) were included. Early resection was carried out in 19 (29%) patients in region A compared with 75 (86%) patients in region B. Overall survival was 5.8 years (95% CI 4.5–7.2) in region A compared with 14.4 years (95% CI 10.4–18.5) in region B (P < 0.01). The effect of surgical strategy remained after adjustment for molecular markers (P = 0.001). Conclusion In parallel population-based cohorts of LGGs, early surgical resection resulted in a clinical relevant survival benefit. The effect on survival persisted after adjustment for molecular markers.


Acta Neurochirurgica | 1997

No association between peridural scar and outcome after lumbar microdiscectomy.

Øystein P. Nygaard; Roar Kloster; R. Dullerud; E. A. Jacobsen; Svein Ivar Mellgren

SummaryThe association between postoperative scar formation on MRI and outcome was investigated in 54 out of one hundred patients operated on with microdiscectomy in a prospective cohort study with a one year follow up. The patients were classified as failures or successes at the 12 months follow up according to a clinical overall score. All the 14 failures were investigated with MRI, and 40 patients classified as successes were picked at random for MRI. Patients with signs of recurrent disc herniation on MRI were excluded. The MRI scans were rated according to the presence or absence of scar formation within the spinal canal and the degree of scar enhancement by two independent neuroradiologists ignorant of treatment outcome. No evidence of scar formation was found in 4 patients, a small amount in 11, intermediate in 38 and extensive scar tissue in 1 patient. Slightly enhancing scar tissue was found in 18 patients, intermediate in 27 patients and strong enhancement in 5 patients.No association between the amount or enhancement of peridural scar formation and clinical outcome was found. Both the total clinical score and the difference between pre- and post-operative clinical score were used in the calculations. Testing the different subsets in the clinical overall score, as well as the patient satisfaction VAS score, did not reveal any association.


PLOS ONE | 2012

Low Grade Gliomas in Eloquent Locations – Implications for Surgical Strategy, Survival and Long Term Quality of Life

Asgeir S. Jakola; Geirmund Unsgård; Kristin Smistad Myrmel; Roar Kloster; Sverre Helge Torp; Sigurd Lindal; Ole Solheim

Background Surgical management of suspected LGG remains controversial. A key factor when deciding a surgical strategy is often the tumors’ perceived relationship to eloquent brain regions Objective To study the association between tumor location, survival and long-term health related quality of life (HRQL) in patients with supratentorial low-grade gliomas (LGG). Methods Adults (≥18 years) operated due to newly diagnosed LGG from 1998 through 2009 included from two Norwegian university hospitals. After review of initial histopathology, 153 adults with supratentorial WHO grade II LGG were included in the study. Tumors’ anatomical location and the relationship to eloquent regions were graded. Survival analysis was adjusted for known prognostic factors and the initial surgical procedure (biopsy or resection). In long-term survivors, HRQL was assessed with disease specific questionnaires (EORTC QLQ-C30 and BN20) as well as a generic questionnaire (EuroQol 5D). Results There was a significant association between eloquence and survival (log-rank, p<0.001). The estimated 5-year survival was 77% in non-eloquent tumors, 71% in intermediate located tumors and 54% in eloquent tumors. In the adjusted analysis the hazard ratio of increasing eloquence was 1.5 (95% CI 1.1–2.0, p = 0.022). There were no differences in HRQL between patients with eloquent and non-eloquent tumors. The most frequent self-reported symptoms were related to fatigue, cognition, and future uncertainty. Conclusion Eloquently located LGGs are associated with impaired survival compared to non-eloquently located LGG, but in long-term survivors HRQL is similar. Although causal inference from observational data should be done with caution, the findings illuminate the delicate balance in surgical decision making in LGGs, and add support to the probable survival benefits of aggressive surgical strategies, perhaps also in eloquent locations.


Journal of Clinical Neuroscience | 2014

Surgical strategies in low-grade gliomas and implications for long-term quality of life.

Asgeir Store Jakola; Geirmund Unsgård; Kristin Smistad Myrmel; Roar Kloster; Sverre Helge Torp; Lisa Millgård Sagberg; Sigurd Lindal; Ole Solheim

Reports on long-term health related quality of life (HRQL) after surgery for World Health Organization grade II diffuse low-grade gliomas (LGG) are rare. We aimed to compare long-term HRQL in two hospital cohorts with different surgical strategies. Biopsy and watchful waiting was favored in one hospital, while early resections guided with three-dimensional (3D) ultrasound was favored in the other. With a population-based approach 153 patients with histologically verified LGG treated from 1998-2009 were included. Patients still alive were contacted for HRQL assessment (n=91) using generic (EQ-5D; EuroQol Group, Rotterdam, The Netherlands) and disease specific (EORTC QLQ-C30 and BN20; EORTC Quality of Life Department, Brussels, Belgium) questionnaires. Results on HRQL were available in 79 patients (87%), 25 from the hospital that favored biopsy and 54 from the hospital that favored early resection. Among living patients there was no difference in EQ-5D index scores (p=0.426). When imputing scores defined as death (zero) in patients dead at follow-up, a clinically relevant difference in EQ-5D score was observed in favor of early resections (p=0.022, mean difference 0.16, 95% confidence interval 0.02-0.29). In EORTC questionnaires pain, depression and concern about disruption in family life were more common with a strategy of initial biopsy only (p=0.043, p=0.032 and p=0.045 respectively). In long-term survivors an aggressive surgical approach using intraoperative 3D ultrasound image guidance in LGG does not lower HRQL compared to a more conservative surgical approach. This finding further weakens a possible role for watchful waiting in LGG.


Apmis | 2005

Carcinoid tumour metastatic to the orbit with infiltration to the extraocular orbital muscle

Olivera Casar Borota; Roar Kloster; Sigurd Lindal

Ninety‐three percent of symptomatic patients with small intestinal carcinoid tumours have metastases. The most common sites of metastases are lymph nodes and liver. Orbital metastases have rarely been described and the majority of them involve the choroid rather than extraocular orbital structures. We report a patient who developed proptosis, impairment of vision and reduced ocular motility on the left side, eighteen months after operation for primary intestinal carcinoid tumour with hepatic metastases. CT and MR studies revealed the tumour mass infiltrating the inferior rectus muscle. Biopsy examined by imprint and frozen section showed tumour consistent with metastatic carcinoid. The tumour was removed. HE and staining for cytokeratin, chromogranin, NSE, serotonin, somatostatin and gastrin showed that the tumour tissue corresponded to that of the primary intestinal carcinoid tumour. Intramuscular orbital metastasis from a carcinoid tumour is a rare occurrence. Diagnosis may be difficult, especially where no evidence of primary carcinoid tumour is present. Metastatic orbital carcinoid should be suspected in patients with a clinical history of carcinoid tumour and who develop ocular complaints and mass lesion in the orbit. Complete surgical removal of the tumour is important for optimal restitution of vision and eye movements.


Acta Neurochirurgica | 1999

Nerve root signs on postoperative lumbar MR imaging. A prospective cohort study with contrast enhanced MRI in symptomatic and asymptomatic patients one year after microdiscectomy.

Øystein P. Nygaard; E. A. Jacobsen; Tore Solberg; Roar Kloster; R. Dullerud

Summary The association between postoperative nerve root signs and outcome was investigated in 54 out of one hundred patients operated on by lumbar microdiscectomy in a prospective cohort study with one year follow up. The patients were classified as failures or successes at the 12 month follow up according to a clinical overall score. All the 14 failures were investigated with MRI at the one year follow up, and 40 patients classified as successes were picked at random for MRI. Three patients with signs of recurrent disc herniation on MRI were excluded from the study. The MRI scans were independently read by two neuroradiologists who were ignorant of treatment outcome. No association between nerve root thickening, nerve root enhancement or nerve root displacement and the clinical outcome was found when patients with recurrent disc herniation were excluded.


Journal of Spinal Disorders | 2000

Recovery of function in adjacent nerve roots after surgery for lumbar disc herniation: use of quantitative sensory testing in the exploration of different populations of nerve fibers.

Øystein P. Nygaard; Roar Kloster; Tore Solberg; Svein Ivar Mellgren

Results from experimental and clinical studies indicate that adjacent nerve roots may be affected in sciatica because of lumbar disc hemiation. This may be caused by proinflammatory mediators in the epidural space being transported into nerve roots at the same or neighboring lumbar segments. The aim of the present study was to investigate the recovery of function of sensory nerve fibers in the adjacent noncompressed nerve roots. Thirty-nine patients undergoing microdiscectomy for monoradiculopathy were investigated with quantitative sensory testing immediately before surgery, and at 6 weeks, 4 months, and 12 months after the operation. Twenty-one healthy volunteers were used as controls. The patients were classified as having a good or a poor result at the 1-year follow-up according to a clinical score. Significant improvement of function in the noncompressed nerve roots were only observed in the 31 patients with a good result. The improvement in small myelinated nerve fibers came within 12 months in the adjacent nerve roots in both the symptomatic as well as the asymptomatic leg. The improvement of function in small unmyelinated fibers also came within 12 months after surgery; however, significant improvement was only observed in the ipsilateral neighboring nerve root. The function in large myelinated fibers did not improve in any of the adjacent nerve roots during the observation period. The observed recovery of function in adjacent noncompressed nerve roots after successful surgical decompression in monoradiculopathy may be because of less production of proinflammatory mediators when the disc herniation is removed.


Acta Radiologica | 1999

Postoperative Nerve Root Displacement and Scar Tissue A prospective cohort study with contrast-enhanced MR imaging one year after microdiscectomy

Ø. P. Nygaard; E. A. Jacobsen; T. Solberg; Roar Kloster; R. Dullerud

Purpose: To investigate the association between postoperative nerve root displacement and epidural scar tissue. Material and Methods: One hundred patients who had undergone lumbar microdiscectomy were included in a prospective cohort study with a 1-year follow-up. the patients were classified as failures or successes at the 12-month follow-up according to a clinical score. Patients with signs of recurrent disc herniation on MR were excluded from the study. All the 13 patients classified as failures were investigated with MR at the 1-year follow-up, and 40 patients classified as successes were picked at random for MR imaging; thus MR was performed in 53 patients. the MR images were independently evaluated by two neuroradiologists. the images were rated according to the presence or absence of nerve root displacement at the surgically treated disc interspace. Scar formation was rated according to two different classification systems. Results: Nerve root displacement was observed in 13 patients. No evidence of scar formation was found in 4 patients, a small amount in 11, intermediate in 37 and extensive scar formation in 1 patient. No association between nerve root displacement and the amount of scar tissue was found. Conclusion: Postoperative nerve root displacement seems to be an independent clinical entity not associated to postoperative scar tissue.


Acta Neurologica Scandinavica | 2002

Results of surgery for aneurysmal subarachnoid haemorrhage in northern Norway: a retrospective study with special focus on timing of surgery in a rural area.

Arild Egge; Bertil Romner; Knut Waterloo; Jørgen Gjernes Isaksen; Roar Kloster; Tor Ingebrigtsen; J. H. Trumpy

Egge A, Romner B, Waterloo K, Isaksen J, Kloster R, Ingebrigtsen T, Trumpy JH. Results of surgery for aneurysmal subarachnoid haemorrhage in northern Norway: a retrospective study with special focus on timing of surgery in a rural area. Acta Neurol Scand 2002: 106: 355–360.


Acta Radiologica | 2009

Introduction of Endovascular Embolization for Intracranial Aneurysms in a Low-volume Institution

Haakon Lindekleiv; E. A. Jacobsen; Roar Kloster; T. Sandell; Jørgen Gjernes Isaksen; Bertil Romner; Tor Ingebrigtsen; R. Bajic

Background: Studies indicate a relationship between hospital caseload and health outcomes after both surgical and endovascular repair of intracranial aneurysms. Purpose: To evaluate outcomes after introduction of endovascular embolization for intracranial aneurysms in a low-volume regional university hospital. Material and Methods: Retrospective study of 243 consecutive patients treated for 284 intracranial aneurysms with endovascular embolization or surgical clipping from 2000 to 2006 at the University Hospital of North Norway. Postoperative complications were registered. The Glasgow Outcome Scale (GOS) was used for assessment of outcome. Results: The mean annual number of procedures was 39 (microsurgery 23, embolization 16). Seventy-four percent of patients with ruptured aneurysms and all patients with unruptured aneurysms had a favorable outcome (GOS 4 or 5) at 1 year follow-up. Patients with subarachnoid hemorrhage were more likely to experience postoperative complications than patients treated for unruptured aneurysms (42% versus 8% of the patients, P<0.01). The immediate incomplete occlusion rate (Raymond II–III) in the initial embolization procedure was 29%. Ten endovascularly treated patients and one surgically treated patient required retreatments due to residual aneurysm or neck remnants. Conclusion: The present study indicates that acceptable outcome from aneurysm treatment, both endovascular and microsurgical, is possible in a low-volume institution.

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Geirmund Unsgård

Norwegian University of Science and Technology

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Ole Solheim

Norwegian University of Science and Technology

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E. A. Jacobsen

University Hospital of North Norway

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Sigurd Lindal

University Hospital of North Norway

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Sverre Helge Torp

Norwegian University of Science and Technology

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Øystein P. Nygaard

Norwegian University of Science and Technology

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Asgeir S. Jakola

Norwegian University of Science and Technology

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Asgeir Store Jakola

Sahlgrenska University Hospital

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