Lars Thomassen

University of Bergen, Bergen, Hordaland, Norway

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Publications (135)310.54 Total impact

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    ABSTRACT: Vasospasm (VSP) is one of the major causes for prolonged neurologic deficit in patients with aneurysmal subarachnoid hemorrhage. Few case series have reported about continuous local intra-arterial nimodipine administration (CLINA) in refractory VSP. We report our experience with CLINA in a patient with refractory cerebral VSP.
    No preview · Article · Mar 2015 · Journal of Neurological Surgery
  • Christopher Elnan Kvistad · Lars Thomassen

    No preview · Article · Jan 2015 · Tidsskrift for Den norske legeforening
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    Preview · Article · Jan 2015 · Tidsskrift for Den norske legeforening
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    Annette Fromm · Lars Thomassen

    Full-text · Article · Jan 2015 · Tidsskrift for Den norske legeforening
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    Tove Sørensen · Kari Dyb · Ellen Rygh · Rolf Salvesen · Lars Thomassen
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    ABSTRACT: Background To assist small hospitals in providing advanced stroke treatment, the Norwegian Directorate of Health has recommended telemedicine services. Telestroke enables specialists to examine patients via videoconferencing supplemented by teleradiology and to provide decision support to local health care personnel. There is evidence that telestroke increases thrombolysis rates.In Norway, telemedicine has mainly been used in non-critical situations. The first telestroke trials took place in 2008. The aim of this paper is to present an overview of telestroke trials and today¿s status with telestroke in Norway. Based on the divergent experience from two health regions in Norway, the paper discusses crucial factors for the integration of telestroke in clinical practice.Methods This is a descriptive study based on multiple methods to obtain an overview of the practice and experience with telestroke in Norway. A Web and literature search for `telestroke in Norway¿ was performed and compared with a survey of telemedicine services at the country's largest hospitals. These findings were supplemented by interviews with key personnel involved in telestroke in two of four health regions, as well as hospital field observations and log data of telestroke transmissions from five of the hospitals involved.ResultsIn Norway, experience in telemedicine for acute stroke care is limited. At the beginning of 2014, three of four regional health authorities were working with telestroke projects and services. Integration of the service in practice is challenging, with varying experience.The problems are not attributed to the technology in itself, but to organization (availability of staff on duty 24/7 and surveillance of the systems), motivation of staff, logistics (patient delay), and characteristics of the buildings (lack of space).Conclusions Prerequisites for successful integration of telestroke in clinical practice include realization of the collaboration potential in the technology with consistent procedures for training and triage, availability of the equipment, and providing advice beyond questions concerning thrombolysis.
    Full-text · Article · Dec 2014 · BMC Health Services Research
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    ABSTRACT: Background: MR diffusion-weighted imaging (DWI) has revolutionized neuroimaging and contributed to a tissue-based redefinition of transient ischemic attack (TIA). Stroke patients with DWI lesions may have neurological symptoms that resolve completely within 24 h, suggesting successful vessel recanalization. Prior studies of stroke patients with transient symptoms have not found any predilection for DWI lesions in any specific territory. Other studies have, however, reported an association between higher brain dysfunction and presence of DWI lesions in patients with transient ischemic symptoms, suggesting a high rate of cortical affection in these patients. We sought to see whether DWI location in stroke patients with transient symptoms <24 h differed from those with persistent symptoms ≥ 24 h. We hypothesized an association between transient symptoms <24 h and cortical DWI lesion localization due to a possible higher rate of vessel recanalization in patients with transient symptoms causing distal cortical infarctions. Methods: Ischemic stroke patients examined with DWI and admitted within 24 h after symptom onset between February 2006 and November 2013 were prospectively registered in a database (The Bergen NORSTROKE Registry). Based on neurological examination 24 h after admission, patients were classified as having either transient symptoms <24 h (DWI <24) or persistent symptoms ≥ 24 h (DWI ≥ 24). DWI lesions were classified into different groups depending on lesion location: cortical lesions, confined to the supratentorial cortex; large subcortical lesions, located in the hemispheric white matter, basal ganglia, internal capsule, thalamus or corona radiate with a diameter ≥ 15 mm; lacunar lesions, located in the same territory as large subcortical lesions with a diameter <15 mm; mixed cortical-subcortical lesions, located in both supratentorial cortex and subcortex; cerebellar lesions, confined to the cerebellum; brain stem lesions, confined to the brain stem; multiple locations, located in more than one of the above defined areas. Results: A total of 142 ischemic stroke patients had DWI <24 and 830 DWI ≥ 24. Cortical DWI location was more frequent in patients with DWI <24 (54.2% vs. 29.5%, p < 0.001), while proportions of mixed cortical-subcortical lesions (13.4% vs. 26.5%, p = 0.001) and lesions with multiple locations (5.6% vs. 11.1%, p = 0.048) were less frequent as compared to DWI ≥ 24. Cortical DWI location was independently associated with DWI <24 when adjusted for confounders in multiple regression analyses (OR 1.89, 95% CI 1.28-2.81, p = 0.001). Conclusion: Cortical DWI location was independently associated with transient stroke symptoms <24 h. This may be explained by vessel recanalization, resulting in upstream transportation of remaining particles and distal cortical lesions.
    No preview · Article · Oct 2014 · Cerebrovascular Diseases
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    Preview · Article · Oct 2014 · Tidsskrift for den Norske laegeforening
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    ABSTRACT: Background and purpose: Diffusion-weighted imaging (DWI) is highly accurate in identifying and locating ischemic stroke injury. Few studies using DWI have investigated large subcortical infarctions (LSIs). We aimed to study clinical characteristics, cause, and outcome in patients with ischemic stroke with LSI diagnosed on DWI and compare these with those who had lacunar DWI lesions or DWI lesions located elsewhere. Methods: Patients with stroke admitted between February 2006 and July 2013 were prospectively registered in a stroke database and examined with DWI. Patients with DWI lesions classified as LSI (subcortical, ≥15 mm) were compared with those with lacunar lesions (subcortical, <15 mm, lacunar infarction [LI]), cortical lesions (cortical infarction [CI]), or no LSI, which included LI, CI, mixed cortical-subcortical, cerebellar, brain stem, and combined lesion locations. Results: A total of 1886 patients with ischemic stroke were included, of which 128 patients (6.8%) had LSI, 317 (16.8%) LI, and 544 (28.8%) CI. The no LSI group included 1758 patients. Occlusive pathology in the proximal middle cerebral artery was more frequent in patients with acute stroke with LSI. Lacunar syndrome was associated with LSI when compared with CI and no LSI. Unknown cause was frequent in the LSI group (60.4%) and independently associated with LSI in the LSI versus LI (P<0.001), LSI versus CI (P=0.002), and LSI versus no LSI population (P<0.001). LSI was independently associated with unfavorable outcome, whether compared with LI (P=0.002), CI (P<0.001), or no LSI (P=0.002). Conclusions: LSI is associated with distinct clinical characteristics, unknown cause, and unfavorable outcome, which separates this stroke entity from patients with lacunar subcortical DWI lesions or DWI lesions located elsewhere.
    Preview · Article · Jul 2014 · Stroke
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    ABSTRACT: Background There is no data about prevalence of intracranial stenosis (IS) in Northern Europe. This study aimed to investigate the prevalence of symptomatic and asymptomatic IS in a Norwegian, community-based ischemic stroke population. Methods In a prospective study, all ischemic stroke or transient ischemic attack (TIA) patients were screened for IS by transcranial color-coded sonography, magnetic resonance angiography, and/or computed tomography angiography. Patients with IS and any cardiac arrhythmia or other possible causes of IS than atherosclerosis were excluded. IS was defined as symptomatic if the infarct/symptoms were related to the territory of the stenotic artery. Risk factors for cerebrovascular disease were registered on admission. Results During an 18-month study period, 607 patients had an ischemic stroke or a TIA. Out of 69 patients with IS (11.4%), 7 patients were excluded because having atrial fibrillation, and IS of possible atherosclerotic etiology was therefore diagnosed in 62 patients (10.2%). IS was symptomatic in 45 patients (7.4%). Diabetes mellitus was the only risk factor significantly associated with symptomatic IS (odds ratio 2.39, 95% confidence interval [CI] 1.03-5.54, P = .04). Conclusions IS occurs in approximately 10% and is symptomatic in about 7% of a Norwegian ischemic stroke/TIA population. Diabetes mellitus appears to be the major risk factor for IS.
    No preview · Article · Jul 2014 · Journal of stroke and cerebrovascular diseases: the official journal of National Stroke Association
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    ABSTRACT: Background Alteplase is the only approved thrombolytic agent for acute ischaemic stroke. The overall benefit from alteplase is substantial, but some evidence indicates that alteplase also has negative effects on the ischaemic brain. Tenecteplase may be more effective and less harmfull than alteplase, but large randomised controlled phase 3 trials are lacking. The Norwegian Tenecteplase Stroke Trial (NOR-TEST) aims to compare efficacy and safety of tenecteplase vs. alteplase. Methods/Design NOR-TEST is a multi-centre PROBE (prospective randomised, open-label, blinded endpoint) trial designed to establish superiority of tenecteplase 0.4 mg/kg (single bolus) as compared with alteplase 0.9 mg/kg (10% bolus + 90% infusion/60 minutes) for consecutively admitted patients with acute ischaemic stroke eligible for thrombolytic therapy, i.e. patients a) admitted <4½ hours after symptoms onset; b) admitted <4½ hours after awakening with stroke symptoms c) receiving bridging therapy before embolectomy. Randomisation tenecteplase:alteplase is 1:1. The primary study endpoint is favourable functional outcome defined as modified Rankin Scale 0–1 at 90 days. Secondary study endpoints are: 1) haemorrhagic transformation (haemorrhagic infarct/haematoma); 2) symptomatic cerebral haemorrhage on CT 24–48 hours; 3) major neurological improvement at 24 hours; 4) recanalisation at 24–36 hours; 5) death. Discussion NOR-TEST may establish a novel approach to acute ischaemic stroke treatment. A positive result will lead to a more effective, safer and easier treatment for all acute ischaemic stroke pasients. NOR-TEST is reviewed and approved by the Regional Committee for Medical and Health Research Ethics (2011/2435), and The Norwegian Medicines Agency (12/01402). NOR-TEST is registered with EudraCT No 2011-005793-33 and in ClinicalTrials.gov (NCT01949948).
    Full-text · Article · May 2014 · BMC Neurology
  • A. Nacu · A. Fromm · K. Sand · U. Waje-Andreassen · L. Thomassen · H. Naess

    No preview · Conference Paper · May 2014
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    ABSTRACT: The aim of this study was to compare the short-term clinical outcome of patients with acute cerebral ischemia and mild symptoms receiving rt-PA with that of patients with acute cerebral ischemia and mild symptoms not treated with rt-PA, and to investigate the frequency of symptomatic intracranial hemorrhage (sICH) in these patients. All patients with confirmed ischemic stroke/TIA and mild symptoms were included. Mild symptoms were defined as NIHSS score ≤5 on admission. Functional outcome was assessed with modified Rankin Scale (mRS) at day 7 or at earlier discharge. Excellent outcome was defined as mRS = 0. sICH was defined according to both NINDS and ECASS III criteria. Of 2753 patients with confirmed ischemic stroke/TIA admitted between February 2006 and February 2013, 966 (35.3%) were excluded because of having admission NIHSS >5. A total of 1791 patients presented with mild symptoms on admission (NIHSS ≤5), of which 158 (8.8%) patients received rt-PA. Treatment with rt-PA and early admission were independently associated with excellent outcome. Higher NIHSS score on admission and prior ischemic stroke were independently associated with poor outcome. Three (1.9%) sICH were diagnosed in rt-PA-treated patients and one (0.1%) in patients not receiving rt-PA. This study highlights the efficacy of rt-PA in patients with acute cerebral ischemia presenting with mild symptoms and confirms the low-risk profile of this treatment.
    Full-text · Article · Apr 2014 · Acta neurologica Scandinavica. Supplementum
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    ABSTRACT: There is increasing knowledge about an association between migraine and ischaemic stroke. Cortical spreading depression (CSD) is the probable biological substrate of migrainous aura. To investigate the influence of CSD on the apparent stroke - migraine association, we hypothesized that magnetic resonance (MR) diffusion weighted images of acute ischaemic stroke patients would reveal an association between small cortical infarctions and migraine. We included all patients admitted to the Bergen stroke unit between 2006 and 2012 with verified acute ischaemic stroke by MR imaging. Patients were grouped in a migraine and a no-migraine group. Baseline data and clinical characteristics were analysed between the groups. Imaging data were analysed with respect to infarct location and size. Multivariate analyses were performed to adjust for confounders and provide risk estimates for observed associations. A total of 1703 subjects were enrolled, 787 subjects were excluded due to uncertain or unobtainable migraine diagnosis, leaving 196 and 720 subjects in the migraine and no-migraine group, respectively. The migraine group was younger and included a higher proportion of females. There were more infarctions due to cardio-embolism (P = 0.015) and fewer due to small vessel disease (P = 0.018) in the migraine group. A higher rate of patients in the migraine group presented symptoms from the posterior circulation (P = 0.008). Migraine was associated with cortical infarctions (OR 1.8 CI: 1.3-2.5, P = 0.001). Migraine was also associated with small infarctions (OR 1.9 CI: 1.04-3.5, P = 0.038). Migraine was associated with small cortical infarctions. This association may be due to cortical spreading depression.
    Full-text · Article · Apr 2014 · Acta neurologica Scandinavica. Supplementum
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    ABSTRACT: Vascular morbidity and mortality due to cardiovascular disease (CVD) are high after ischemic stroke at a young age. Data on carotid intima-media thickness (cIMT) as marker of atherosclerosis are scarce for young stroke populations. In this prospective case-control study, we examined cIMT, the burden of vascular risk factors (RF) and their associations among young and middle-aged ischemic stroke patients and controls. We aimed to detect clinical and sub-clinical arterial disease. This study was conducted in 150 patients aged 15-60 years and 84 controls free of CVD. We related RF to ultrasonographic B-mode cIMT-measurements obtained from 12 standardized multiangle measurements in the common carotid artery (CCA), carotid bifurcation (BIF) and internal carotid artery (ICA). RF burden was higher among patients than among controls (p < 0.001). In multivariate analyses of all 234 participants, increased cIMT was associated with age in each carotid segment. Incident stroke was associated with increased ICA-IMT. ICA-IMT increase was associated with a family history of CVD among patients aged 15-44 years, and with RF at mid-age. The overall cIMT difference between patients and controls was 12% for CCA, 17% for BIF and 29% for ICA. Further, increased CCA-IMT was associated with male sex and hypertension. Increased BIF-IMT was associated with dyslipidemia, coronary heart disease and smoking. Increased ICA-IMT was associated with dyslipidemia and stroke. Ischemic stroke is associated with increased ICA-IMT, related to a family history of CVD among patients aged <45 years, and to increasing RF burden with increasing age. Preventive strategies and aggressive RF treatment are indicated to avoid future cardiovascular events.Trial regestration: NOR-SYS is registered in ClinicalTrials.gov (NCT01597453).
    Full-text · Article · Mar 2014 · BMC Research Notes
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    ABSTRACT: Ultrasound contrast agents (UCA) salvage a considerable number of transcranial Doppler (TCD) exams which would have failed because of poor bone window. UCA bolus injection causes an undesirable increase in measured blood flow velocity (BFV). The effect of UCA continuous infusion on measured BFV has not been investigated, and some in vitro experiments suggest that gain reduction during UCA administration may also influence measured BFV. This study aimed to investigate the effect of UCA continuous infusion on BFV measured by TCD and the influence of gain reduction on these measurements in a clinical setting. The right middle cerebral artery of ten patients with optimal bone window was insonated using a 2 MHz probe. UCA were administered using an infusion pump. BFV was measured (1) at baseline, (2) during UCA infusion, (3) during UCA infusion with gain reduction, and (4) after UCA wash-out phase. Gain reduction was based on the agreement between two neurosonographers on the degree of gain reduction necessary to restore baseline Doppler signal intensity (DSI). Actual DSI was estimated offline by analysis of raw data. BFV measured during UCA infusion with no gain adjustment was significantly higher than baseline BFV [peak systolic velocity (PSV): 85.1 ± 19.7 vs. 74.4 ± 19.7 cm/s, p < 0.0001; Mean velocity (MV): 56.5 ± 11.8 vs. 50.2 ± 12.3 cm/s, p < 0.0001]. BFV measured during UCA infusion with gain reduction was not significantly higher than baseline BFV (PSV: 74.3 ± 18.9 vs. 74.4 ± 19.4 cm/s, p = 0.8; MV: 49.4 ± 11.0 vs. 50.2 ± 12.3 cm/s, p = 0.8). Actual DSI during UCA infusion with gain reduction was not significantly higher than baseline DSI (13 ± 1 vs. 13 ± 1 dB). This study shows that UCA continuous infusion leads to an increase in measured BFV which may be counteracted by reducing Doppler gain thus restoring pre-contrast DSI.
    No preview · Article · Mar 2014 · Journal of Ultrasound
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    ABSTRACT: Smoking has been associated with improved outcome in thrombolysed patients with myocardial infarction and higher recanalization rates in stroke patients treated with tissue plasminogen activator (tPA). We hypothesized a positive association between smoking and favourable outcome in stroke patients treated with tPA and no such association in acute stroke patients not treated with tPA, suggesting a beneficial effect of smoking on thrombolysis with tPA. Stroke patients treated with tPA and stroke patients not treated with tPA, but presenting within 6 h after stroke onset, were included in two separate groups. Three groups were defined according to smoking habits: current smoking, previous smoking and no smoking. Functional outcome by modified Rankin Scale (mRS) was assessed after 1 week or at discharge, if discharged earlier. Favourable outcome was defined as mRS 0 or 1. A total of 399 patients were treated with tPA (94 current smokers, 148 previous smokers and 157 non-smokers), whereas 424 patients were not treated with tPA (90 current smokers, 164 previous smokers and 170 non-smokers). Current smoking was independently associated with favourable outcome in patients treated with tPA when adjusted for confounders (OR 2.08, 95% CI 1.09-3.95, P = 0.025). There was no such association in acute stroke patients not treated with tPA (OR 1.26, 95% CI 0.67-2.36, P = 0.472). Our study showed an association between current smoking and favourable short-term outcome in stroke patients treated with tPA, but not in acute stroke patients not treated with tPA. This may indicate a more effective thrombolysis with tPA in smokers.
    No preview · Article · Feb 2014 · Acta Neurologica Scandinavica
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    Mirza Jusufovic · Lars Thomassen · Mona Skjelland
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    ABSTRACT: Background: There is no sound scientific documentation of current guidelines for the treatment of cerebral infarction assumed to be due to patent foramen ovale. In this article, we present a young patient with this condition. In addition, we provide a general overview of the prevalence, recommended assessment and indications for treatment of patent foramen ovale in ischaemic stroke patients. Method: The article is based on a non-systematic search in PubMed. We emphasise three recently published randomised trials on the subject. Results: Transoesophageal echocardiography with saline contrast is the gold standard for detecting patent foramen ovale. Just who will benefit from the diagnosis and treatment of this condition remains unclear, however. None of the three randomised studies of antithrombotic treatment versus transcatheter closure in patients who have suffered ischaemic stroke show a difference in outcomes, but subgroup analyses indicate that closure in young patients (age <50 years) with a large foramen ovale reduces the number of recurrent ischaemic events. Two other randomised studies of antithrombotic treatment alone versus closure are presently ongoing. Interpretation: For stroke patients with patent foramen ovale, the choice between lifelong antithrombotic therapy alone and transcatheter closure is a difficult one. Treatment with antiplatelet agents remains the first choice in most cases. Well-designed studies are needed to identify which patients will benefit most from closure.
    Full-text · Article · Jan 2014 · Tidsskrift for den Norske laegeforening
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    ABSTRACT: Low body temperature is considered beneficial in ischemic stroke due to neuroprotective mechanisms, yet some studies suggest that higher temperatures may improve clot lysis and outcomes in stroke patients treated with tissue plasminogen activator (tPA). The effect of increased body temperature in stroke patients treated with tPA and with normal computed tomography angiography (CTA) on admission is unknown. We hypothesized a beneficial effect of higher body temperature in the absence of visible clots on CTA, possibly due to enhanced lysis of small, peripheral clots. Patients with ischemic stroke admitted to our Stroke Unit between February 2006 and April 2013 were prospectively registered in a database (Bergen NORSTROKE Registry). Ischemic stroke patients treated with tPA with normal CTA of the cerebral arteries were included. Outcomes were assessed by the modified Rankin Scale (mRS) after 1 week. An excellent outcome was defined as mRS=0, and a favorable outcome as mRS=0-1. A total of 172 patients were included, of which 48 (27.9%) had an admission body temperature ≥37.0°C, and 124 (72.1%) had a body temperature <37.0°C. Body temperature ≥37.0°C was independently associated with excellent outcomes (odds ratio [OR]: 2.8; 95% confidence interval [CI]: 1.24-6.46; P=0.014) and favorable outcomes (OR: 2.8; 95% CI: 1.13-4.98; P=0.015) when adjusted for confounders. We found an association between higher admission body temperature and improved outcome in tPA-treated stroke patients with normal admission CTA of the cerebral arteries. This may suggest a beneficial effect of higher body temperature on clot lysis in the absence of visible clots on CTA.
    Full-text · Article · Jan 2014 · Vascular Health and Risk Management
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    Ulrike Waje-Andreassen · Lars Thomassen

    Preview · Article · Jan 2014 · Tidsskrift for Den norske legeforening
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    ABSTRACT: Background. Migraine is prevalent in young patients and a frequent stroke mimic. To distinguish stroke mimics from true stroke can be difficult, and there is a possibility of misdiagnosing a stroke as a migrainous attack in patients with migraine. We aimed to investigate if a history of migraine affects the rate of thrombolytic therapy in young stroke patients. Methods. All patients below 50 years of age admitted in the period 2006-2013 to the Bergen Stroke Centre with acute ischaemic stroke were included. The rate of thrombolytic therapy in patients with migraine was compared to patients with no history of migraine. A multivariate analysis was performed to adjust confounding factors. Results. A total of 170 young stroke patients were enrolled, 49 with migraine and 121 with no migraine. In total, 10.2% of young patients with migraine received thrombolytic therapy, compared with 26.5% of young patients with nomigraine (P = 0.02). Migraine was associated with a low rate of thrombolytic therapy when adjusting for possible confounding factors (OR 0.19 CI: 0.05-0.72, P = 0.02). Conclusion. Migraine is associated with a low rate of thrombolytic therapy in young patients admitted with acute ischaemic stroke. Migraine patients admitted with acute ischaemic stroke are at risk of maltreatment.
    Full-text · Article · Nov 2013 · Stroke Research and Treatment