Prevalence of intracranial artery stenosis in a general population using 3D-time of flight magnetic resonance angiography.

BACKGROUND: Data on prevalence of intracranial artery stenosis (ICAS) in Western populations is sparse. The aim of the study was to assess the prevalence and risk factors for ICAS in a mainly Caucasian general population. METHODS: We assessed the prevalence of ICAS in 1847 men and women aged 40 to 84 years who participated in a cross-sectional population-based study, using 3-dimensional time-of-flight 3 Tesla magnetic resonance angiography. ICAS was defined as a focal luminal flow diameter reduction of ≥50 %. The association between cardiovascular risk factor levels and ICAS was assessed by multivariable regression analysis. RESULTS: The overall prevalence of ICAS was 6.0 % (95 % confidence interval (CI) 5.0-7.2), 4.3 % (95 % CI 3.1-5.7) in women and 8.0 % (95 % CI 6.3-10.0) in men. The prevalence increased by age from 0.8 % in 40-54 years age group to 15.2 % in the 75-84 years age group. The majority of stenoses was located to the internal carotid artery (52.2 %), followed by the posterior circulation (33.1 %), the middle cerebral artery (10.8 %) and the anterior cerebral artery (3.8 %). The risk of ICAS was independently associated with higher age, male sex, hypertension, hyperlipidemia, diabetes mellitus, current smoking and higher BMI. CONCLUSIONS: The prevalence of ICAS in a general population of Caucasians was relatively high and similar to the prevalence of extracranial internal carotid artery stenosis in previous population-based studies.

Anatomical variations in the circle of Willis are associated with increased odds of intracranial aneurysms: The Tromsø study.

PURPOSE: Studies on patients suggest an association between anatomical variations in the Circle of Willis (CoW) and intracranial aneurysms (IA), but it is unclear whether this association is present in the general population. In this cross-sectional population study, we investigated the associations between CoW anatomical variations and IA. METHODS: We included 1667 participants from a population sample with 3 T MRI time-of-flight angiography (40-84 years, 46.5% men). Saccular IAs were defined as protrusions in the intracranial arteries ≥2 mm, while variants of the CoW were classified according to whether segments were missing or hypoplastic (< 1 mm). We used logistic regression, adjusting for age and IA risk factors, to assess whether participants with incomplete CoW variants had a greater prevalence of IA and whether participants with specific incomplete variants had a greater prevalence of IA. RESULTS: Participants with an incomplete CoW had an increased prevalence of IA (OR, 2.3 [95% CI 1.05-5.04]). This was mainly driven by the variant missing all three communicating arteries (OR, 4.2 [95% CI 1.7-1 0.3]) and the variant missing the P1 segment of the posterior cerebral artery (OR, 3.6 [95% CI 1.2-10.1]). The combined prevalence of the two variants was 15.4% but accounted for 28% of the IAs. CONCLUSION: The findings suggest that an incomplete CoW is associated with an increased risk of IA for adults in the general population.

Gray matter volume and pain tolerance in a general population: the Tromsø study.

ABSTRACT: As pain is processed by an extensive network of brain regions, the structural status of the brain may affect pain perception. We aimed to study the association between gray matter volume (GMV) and pain sensitivity in a general population. We used data from 1522 participants in the seventh wave of the Tromsø study, who had completed the cold pressor test (3°C, maximum time 120 seconds), undergone magnetic resonance imaging (MRI) of the brain, and had complete information on covariates. Cox proportional hazards regression models were fitted with time to hand withdrawal from cold exposure as outcome. Gray matter volume was the independent variable, and analyses were adjusted for intracranial volume, age, sex, education level, and cardiovascular risk factors. Additional adjustment was made for chronic pain and depression in subsamples with available information on the respective item. FreeSurfer was used to estimate vertexwise cortical and subcortical gray matter volumes from the T1-weighted MR image. Post hoc analyses were performed on cortical and subcortical volume estimates. Standardized total GMV was associated with risk of hand withdrawal (hazard ratio [HR] 0.81, 95% confidence interval [CI] 0.71-0.93). The effect remained significant after additional adjustment for chronic pain (HR 0.84, 95% CI 0.72-0.97) or depression (HR 0.82, 95% CI 0.71-0.94). In post hoc analyses, positive associations between standardized GMV and pain tolerance were seen in most brain regions, with larger effect sizes in regions previously shown to be associated with pain. In conclusion, our findings indicate that larger GMV is associated with longer pain tolerance in the general population.

Prevalence of unruptured intracranial aneurysms: impact of different definitions - the Tromsø Study.

BACKGROUND: Management of incidental unruptured intracranial aneurysms (UIAs) remains challenging and depends on their risk of rupture, estimated from the assumed prevalence of aneurysms and the incidence of aneurysmal subarachnoid haemorrhage. Reported prevalence varies, and consistent criteria for definition of UIAs are lacking. We aimed to study the prevalence of UIAs in a general population according to different definitions of aneurysm. METHODS: Cross-sectional population-based study using 3-dimensional time-of-flight 3 Tesla MR angiography to identify size, type and location of UIAs in 1862 adults aged 40-84 years. Size was measured as the maximal distance between any two points in the aneurysm sac. Prevalence was estimated for different diameter cutoffs (≥1, 2 and 3 mm) with and without inclusion of extradural aneurysms. RESULTS: The overall prevalence of intradural saccular aneurysms ≥2 mm was 6.6% (95% CI 5.4% to 7.6%), 7.5% (95% CI 5.9% to 9.2%) in women and 5.5% (95% CI 4.1% to 7.2%) in men. Depending on the definition of an aneurysm, the overall prevalence ranged from 3.8% (95% CI 3.0% to 4.8%) for intradural aneurysms ≥3 mm to 8.3% (95% CI 7.1% to 9.7%) when both intradural and extradural aneurysms ≥1 mm were included. CONCLUSION: Prevalence in this study was higher than previously observed in other Western populations and was substantially influenced by definitions according to size and extradural or intradural location. The high prevalence of UIAs sized <5 mm may suggest lower rupture risk than previously estimated. Consensus on more robust and consistent radiological definitions of UIAs is warranted.

Long-Term Survival, Causes of Death, and Trends in 5-Year Mortality After Intracerebral Hemorrhage: The Tromsø Study.

BACKGROUND AND PURPOSE: Data on long-term survival after intracerebral hemorrhage (ICH) are scarce. In a population-based nested case-control study, we compared long-term survival and causes of death within 5 years in 30-day survivors of first-ever ICH and controls, assessed the impact of cardiovascular risk factors on 5-year mortality, and analyzed time trend in 5-year mortality in ICH patients over 2 decades. METHODS: We included 219 participants from the population-based Tromsø Study, who after the baseline participation had a first-ever ICH between 1994 to 2013 and 1095 age- and sex-matched participants without ICH. Cumulative survival was presented using the Kaplan-Meier method. Hazard ratios (HRs) for mortality and for the association between cardiovascular risk factors and 5-year mortality in 30-day survivors were estimated by stratified Cox proportional hazards models. Trend in 5-year mortality was assessed by logistic regression. RESULTS: Risk of death during follow-up (median time, 4.8 years) was increased in the ICH group compared with controls (HR, 1.62 [95% CI, 1.27-2.06]). Cardiovascular disease was the leading cause of death, with a higher proportion in ICH patients (22.9% versus 9.0%; P<0.001). Smoking increased the risk of 5-year mortality in cases and controls (HR, 1.59 [95% CI, 1.15-2.19]), whereas serum cholesterol was associated with 5-year mortality in cases only (HR, 1.39 [95% CI, 1.04-1.86]). Use of anticoagulants at ICH onset increased the risk of death (HR, 2.09 [95% CI, 1.09-4.00]). There was no difference according to ICH location (HR, 1.15 [95% CI, 0.56-2.37]). Five-year mortality did not change during the study period (odds ratio per calendar year, 1.01 [95% CI, 0.93-1.09]). CONCLUSIONS: Survival rates were significantly lower in cases than in controls, driven by a 2-fold increased risk of cardiovascular death. Smoking, serum cholesterol, and use of anticoagulant drugs were associated with increased risk of death in ICH patients. Five-year mortality rates in ICH patients remained stable over time.

Variations in the Circle of Willis in a large population sample using 3D TOF angiography: The Tromsø Study.

The main arteries that supply blood to the brain originate from the Circle of Willis (CoW). The CoW exhibits considerable anatomical variations which may have clinical importance, but the variability is insufficiently characterised in the general population. We assessed the anatomical variability of CoW variants in a community-dwelling sample (N = 1,864, 874 men, mean age = 65.4, range 40-87 years), and independent and conditional frequencies of the CoW's artery segments. CoW segments were classified as present or missing/hypoplastic (w/1mm diameter threshold) on 3T time-of-flight magnetic resonance angiography images. We also examined whether age and sex were associated with CoW variants. We identified 47 unique CoW variants, of which five variants constituted 68.5% of the sample. The complete variant was found in 11.9% of the subjects, and the most common variant (27.8%) was missing both posterior communicating arteries. Conditional frequencies showed patterns of interdependence across most missing segments in the CoW. CoW variants were associated with mean-split age (P = .0147), and there was a trend showing more missing segments with increasing age. We found no association with sex (P = .0526). Our population study demonstrated age as associated with CoW variants, suggesting reduced collateral capacity with older age.

The impact of risk factor trends on intracerebral hemorrhage incidence over the last two decades-The Tromsø Study.

BACKGROUND: Studies on the relationship between temporal trends in risk factors and incidence rates of intracerebral hemorrhage are scarce. AIMS: To analyze temporal trends in risk factors and incidence rates of intracerebral hemorrhage using individual data from a population-based study. METHODS: We included 28,167 participants of the Tromsø Study enrolled between 1994 and 2008. First-ever intracerebral hemorrhages were registered through 31 December 2013. Hazard ratios (HRs) for intracerebral hemorrhage were analyzed by Cox proportional hazards models, risk factor levels over time by generalized estimating equations, and incidence rate ratios (IRR) by Poisson regression. RESULTS: We registered 219 intracerebral hemorrhages. Age, male sex, systolic blood pressure (BP), diastolic BP, and hypertension were associated with intracerebral hemorrhage. Hypertension was more strongly associated with non-lobar intracerebral hemorrhage (HR 5.08, 95% CI 2.86-9.01) than lobar intracerebral hemorrhage (HR 1.91, 95% CI 1.12-3.25). In women, incidence decreased significantly (IRR 0.46, 95% CI 0.23-0.90), driven by a decrease in non-lobar intracerebral hemorrhage. Incidence rates in men remained stable (IRR 1.27, 95% CI 0.69-2.31). BP levels were lower and decreased more steeply in women than in men. The majority with hypertension were untreated, and a high proportion of those treated did not reach treatment goals. CONCLUSIONS: We observed a significant decrease in intracerebral hemorrhage incidence in women, but not in men. A steeper BP decrease in women may have contributed to the diverging trends. The high proportion of untreated and sub-optimally treated hypertension calls for improved strategies for prevention of intracerebral hemorrhage.

Cerebral Aneurysm Morphology Before and After Rupture: Nationwide Case Series of 29 Aneurysms.

BACKGROUND AND PURPOSE: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.

[Seriously injured patients transferred from local hospitals to a university hospital]. / Alvorlig skadede overført til universitetssykehus.

BACKGROUND: We studied diagnostics and stabilizing surgery in severely injured patients transferred from local hospitals to a university hospital. The purpose was to identify a potential for improvement of regional trauma care. MATERIAL AND METHODS: The material comprises all severely injured patients (Injury Severity [ISS] Score > 15) transferred from local hospitals to the University Hospital of Northern Norway in the period 01.01.2006 - 31.12.2007. Information about diagnostics, extent of injury and treatment during the first 24 hours after transferral was recorded by retrospective chart review. Emergency surgical interventions are defined according to plans for a national trauma system. RESULTS: 6/74 patients underwent emergency surgery at the local hospital (chest tube insertion, external fracture fixation); eight after arrival at the university hospital (chest tube insertion, hemostatic packing of the abdomen and pelvis, external fracture fixation). 66/74 were CT-scanned locally; 37 with a CT multitrauma series (CT caput, neck, thorax, abdomen and pelvis). Of the 62 who had head CT scans performed at a local hospital, the cervical spine was not imaged for 10. For eight of 55 patients who had CT scans of the thorax/abdomen/pelvis intravenous contrast agent was not administered. INTERPRETATION: Trauma care at local hospitals may be improved by more systematic imaging, a lower threshold for emergency surgery, and early communication with the university hospital.

[Elective stent treatment of abdominal aortic aneurysm]. / Elektiv stentgraftbehandling for abdominalt aortaaneurisme.

BACKGROUND: First described in 1991, endovascular treatment is a simplified method for abdominal aortic aneurysm repair (EVAR). The enthusiasm created by few complications and early mobilisation was replaced by scepticism because of the high frequency of secondary complications such as endoleak, stenosis, graft migration, aneurysm enlargement and late rupture. Though the method still is considered experimental, thousands of grafts are inserted every year. MATERIAL AND METHODS: From 1998, 53 patients underwent EVAR electively at our institution, 17 of whom were for medical reasons considered inoperable in open surgery. They were followed up with CT scans, which together with angiograms were evaluated retrospectively. Co-morbidity and complications were registered. Follow up was at 26 (4-50) months for 49 patients. RESULTS: Two patients died. There were two other complications in addition to two superficial wound infections. There were no surgical conversions. 18 patients had 25 secondary interventions. Cumulative intervention rate was 25% after 12 months, 28% after 24 months and 53% after 36 months. Four stenoses were seen the first 6 months. 19 patients had an endoleak (1 had type I after 24 months, 6 had type II endoleak, 5 had type III endoleak of which two appeared after 3 years). Graft migration was observed in 9 patients (5 at 3 years control). Two ruptures were corrected with endovascular technique. Survival and interventions were equal among inoperable and operable patients. INTERPRETATION: Few early complications are overshadowed by the frequent and unpredictable late complications after EVAR; patients have to be followed up for years. For patients unfit for open surgery this is, however, an optional treatment if intervention is otherwise indicated.