Basilar artery curvature increases the risk of posterior circulation infarction occurrence in patients without vertebrobasilar stenosis

INTRODUCTION

Limited cross-sectional or case-control studies have identified the relationship between basilar artery (BA) curvature and posterior circulation infarction (PCI). This study aimed to identify the influence of BA curvature severity on the risk of PCI occurrence in patients without vertebrobasilar stenosis through a prospective cohort study.

METHODS

In this study, we enrolled 171 patients with BA dolichosis but without vertebrobasilar stenosis. The BA geometric parameters were evaluated on MRA. The primary outcome was the occurrence of PCI, mainly referring to cerebellar and/or brainstem infarction. Cox proportional hazard models were used to detect possible predictors of PCI.

RESULTS

Among them, 134 (78.4%) patients were diagnosed with BA curvature, including 124 with moderate curvature and 10 with prominent curvature. The defined PCI occurrence was observed in 32 (18.7%) patients with a median follow-up time of 45.6 months. Cox proportional hazard analysis showed that BA prominent curvature (HR = 6.09; 95% CI: 1.36-27.28; P = 0.018) significantly increased the risk of PCI occurrence, and bending length (BL) was also significantly associated with PCI occurrence, with the adjusted HR per 1-mm increase of BL of 1.09 (95% CI: 1.01-1.18; P = 0.040). In the subgroup analysis stratified by age, BA prominent curvature was highly associated with PCI occurrence in patients aged > 61 years (HR = 11.76; 95% CI: 1.21-113.90; P = 0.033). Additionally, good antiplatelet therapy adherence could significantly reduce the risk of PCI occurrence.

CONCLUSION

BA curvature may increase the risk of PCI occurrence, especially in elderly patients with prominent curvature. Improving adherence to antiplatelet therapy can help reduce the risk of PCI occurrence.

Multidisciplinary Treatments of True Posterior Inferior Cerebellar Artery Aneurysms: Single-Center Retrospective Study and Treatment Algorithm

BACKGROUND

True posterior inferior cerebellar artery (PICA) aneurysms outside the vertebral artery-PICA region are rare, with approximately 30 cases reported in just a few papers; no treatment paradigm has been advocated. The objective of this study was to present detailed clinical features and outcomes for several treatments for true PICA aneurysms and suggest an algorithm for treatment strategies.

METHODS

We retrospectively analyzed outcomes of patients treated for PICA aneurysms with microsurgical and endovascular treatments. We also investigated the influence of several factors on the modified Rankin Scale score.

RESULTS

Cases with PICA aneurysms (n = 36) outside the vertebral artery-PICA region were identified angiographically. Aneurysm locations included anterior medullary (n = 7), lateral medullary (n = 10), tonsillomedullary (n = 4), telovelotonsillar (n = 12), and cortical (n = 3) segments of the PICA. Aneurysm morphology was as follows: dissecting: 22; fusiform: 6; and saccular: 8. On multivariate analysis, age (P = 0.028) and lack of vermian infarction (P =0.037) were associated with a significantly better prognosis. Prognosis was not significantly different for the 5 aneurysm locations and among the 4 treatment groups: clipping/coiling, trapping/parent artery occlusion, trapping/parent artery occlusion + bypass, and observation including external ventricular drainage.

CONCLUSIONS

This study suggests that factors associated with significantly better prognosis include age, clip/coil treatments, and no vermian infarction complication. A treatment algorithm for true PICA aneurysms was supported according to pretreatment H and K grade, PICA segments, aneurysm morphology, and 3 types of ischemia linked to the brainstem, cerebellar hemisphere, or vermis.

Insulin resistance and the risk of stroke and stroke subtypes in the nondiabetic elderly

Insulin resistance, which plays a key role in the development of diabetes mellitus, is a putative modifiable risk factor for stroke. The aim of this study was to investigate if markers of insulin resistance were associated with risk of stroke in the general elderly population. This study was part of the large population-based Rotterdam Study and included 5,234 participants who were aged 55 years or older and stroke free and diabetes free at baseline (1997-2001). Fasting insulin levels and homeostasis model assessment for insulin resistance were used as markers for insulin resistance. Cox regression was used to determine associations between insulin resistance markers and stroke risk, adjusted for age, sex, and potential confounders. During 42,806 person-years of follow-up (median: 8.6 years), 366 first-ever strokes occurred, of which 225 were cerebral infarctions, 42 were intracerebral hemorrhages, and 99 were unspecified strokes. Fasting insulin levels were not associated with risk of any stroke, cerebral infarction, or intracerebral hemorrhage. Homeostasis model assessment for insulin resistance, which almost perfectly correlated with fasting insulin levels, was also not associated with risk of stroke or stroke subtypes. In conclusion, in this population-based cohort study among nondiabetic elderly, insulin resistance markers were not associated with risk of stroke or any of its subtypes.

Claude's syndrome associated with neurocysticercosis

Claude's syndrome is a distinctive brainstem syndrome characterized by ipsilateral third cranial nerve palsy with contralateral hemiataxia and is due to an intrinsic or extrinsic lesion in the midbrain. We report a case of Claude's syndrome caused by neurocysticercosis infection. A 68 year-old Asian man was admitted to our hospital because of ataxia, left ptosis, and diplopia. Brain magnetic resonance imaging (MRI) showed a cystic lesion in the midbrain, which was surrounded by ring enhancement and peripheral edema. Neurocysticercosis infection was diagnosed by the cerebral spinal fluid study. The patient was treated with albendazole and steroids. A follow-up brain MRI three months later demonstrated the disappearance of a surrounding brain edema and rim enhancement. The most common cause of Claude's syndrome is cerebrovascular disease and malignancy. However, there is no report caused by neurocysticercosis infection. Therefore, if we encounter Claude's syndrome, we should consider neurocysticercosis infection as one of the etiologic factors.

The prevalence of thyrotoxicosis-related seizures

BACKGROUND

Central nervous system dysfunction, such as hyperexcitation, irritability, and disturbance of consciousness, may occur in patients with thyrotoxicosis. There are also a few case reports of seizures attributed to thyrotoxicosis. The objective of the present study was to determine the prevalence of seizures that appeared to be related to the thyrotoxic state in patients with thyrotoxicosis.

METHODS

We retrospectively determined the prevalence and clinical features of seizures in 3382 patients with hyperthyroidism. Among patients with seizures, we excluded those with other causes of seizures or a history of epilepsy. We did not exclude two patients in whom later work-up showed an abnormal magnetic resonance imaging, as their seizures resolved after they became euthyroid.

RESULTS

Among the 3382 patients with hyperthyroidism, there were seven patients (0.2%) with seizures who met our criteria. Primary generalized tonic-clonic seizures occurred in four patients (57%), complex partial seizures with secondary generalized tonic-clonic seizures occurred in two patients (29%), and one patient had a focal seizure (14%). The initial electroencephalography (EEG) was normal in two patients (29%), had generalized slow activity in four patients (57%), and had diffuse generalized beta activity in one patient (14%). On magnetic resonance imaging, one patient had diffuse brain atrophy, and one had an old basal ganglia infarct. After the patients became euthyroid, the EEG was repeated and was normal in all patients. During follow-up periods ranging from 18 to 24 months, none of the patients had seizures.

CONCLUSIONS

Hyperthyroidism is the precipitating cause of seizures in a small percentage of these patients. In these patients, the prognosis is good if they become euthyroid. The prevalence of thyrotoxicosis-related seizures reported here can be used in conjunction with the prevalence of thyrotoxicosis in the population to estimate the prevalence of thyrotoxicosis-related seizures in populations.

Aetiopathogenesis and long-term outcome of isolated pontine infarcts

BACKGROUND AND PURPOSE

Isolated pontine strokes cause characteristic neurological syndromes and have a good short-term prognosis. The aim of this study was to examine the long-term survival, cumulative recurrence rate and clinical handicap of patients with isolated pontine infarcts of different aetiology.

METHODS

One hundred consecutive patients with an isolated pontine infarction were identified by imaging studies and evaluated prospectively. After extensive study, cases were classified according to the aetiopathogenetic mechanisms: stroke due to basilar artery branch disease (BABD), small-artery disease (SAD) and large-artery-occlusive disease (LAOD). During a mean follow-up period of 46 months, stroke presentation and initial course, early and long-term mortality, disability and recurrence were evaluated.

RESULTS

BABD was the most frequent cause of isolated pontine ischaemia (43%), followed by SAD (34%) and LAOD (21%). Hypertension was the most prominent risk factor, especially among patients with SAD (94.1%). Neurological impairment on admission was more severe in the LAOD group, followed by BABD. After 1 month patients with LAOD had the highest cumulative mortality (14.3%, p = 0.026) and more severe disability (61.1%, p = 0.001). Five-year mortality rate was 20.6%, 14% and 23.8% in the SAD-, BABD- and in LAOD-group respectively (p = 0.776). Cumulative 5-year recurrence rate was 2.3 % for BABD, 14.3 % for LAOD, and 29.4 % for SAD (p = 0.011).

CONCLUSIONS

Overall long-term survival of patients with isolated pontine infarcts is good. Initial differences regarding short-term outcome in infarctions of different aetiology resolve with time. Effective secondary prevention among SAD patients may limit stroke recurrence and positively influence long-term prognosis.

Lateral and Medial Medullary Infarction

Background and Purpose— No large-scale study has ever compared the clinical and radiological features of lateral medullary infarction (LMI) and medial medullary infarction (MMI). The aim of this study was to investigate them through the use of cooperatively collected cases.

Methods— Medical information on all patients from 1996 to 2000 with medullary infarction (MI) proven by brain MR images at 35 stroke centers in the Tohoku district, Japan, was collected, and their clinical and radiological features were analyzed.

Results— A total of 214 cases of MI were registered. They included 167 cases (78%) of LMI, 41 (19%) of MMI, and 6 (3%) of LMI plus MMI. The mean age of onset and the male-to-female ratio were 60.7 years and 2.7:1 in LMI and 65.0 years and 3.6:1 in MMI, respectively. The middle medulla was most frequently affected in LMI, and the upper medulla was most frequently affected in MMI. Dissection of the vertebral artery was observed in 29% of LMI and 21% of MMI. Prognosis, assessed by the Barthel Index, was favorable in both LMI and MMI. Diabetes mellitus was more frequently associated with MMI than with LMI.

Conclusions— The present study surveyed a large number of MI cases and revealed that (1) the mean age of onset of MMI is higher than that of LMI, (2) the dissection of the vertebral artery is an important cause not only of LMI but also of MMI, and (3) diabetes mellitus is frequently associated with MMI.

Recurrent pontine base infarction: a controlled study

OBJECTIVES

To assess the clinical features of and risk factors for recurrent pontine base infarction.

METHODS

This study includes 5 patients with unilateral pontine base infarction who developed another infarction on the opposite side and, for comparison, 10 follow-up period-matched patients with unilateral pontine base infarction who did not develop recurrent pontine infarction. MRI and angiogram studies were performed in all cases. The two groups were compared.

RESULTS

The patients with recurrent pontine base infarction developed quadriparesis, dysarthria and dysphagia. MRI showed bilateral infarcts abutting on the basal surface of the pons. Angiogram studies revealed diseased basilar artery in 3 patients. There were no differences regarding age, gender, angiogram findings and frequency of hypertension, diabetes mellitus, cigarette smoking and hypercholesterolemia between the patients with recurrent stroke and those without. However, the former had a significantly higher number of risk factors for atherosclerosis (p < 0.05) and higher frequency of coronary heart disease (p < 0.05) than the latter.

CONCLUSIONS

The number of risk factors for atherosclerosis and a concomitant presence of coronary heart disease may be factors related to recurrent pontine base infarction in patients with unilateral pontine infarction. The main pathogenesis of recurrent pontine base infarction seems to be basilar artery branch atherothrombosis.

Clinical characteristics of patients with brainstem strokes admitted to a rehabilitation unit

OBJECTIVE

To examine the clinical characteristics of patients with brainstem strokes admitted to a rehabilitation unit.

DESIGN

Retrospective cohort.

SETTING

Inpatient rehabilitation unit.

PARTICIPANTS

Eighty-five consecutive admissions (56 men, 29 women; mean age, 61.9+/-14.4y; range, 18-85y) with radiologically confirmed focal evidence of specific lesions within the pons, midbrain, cerebellum, and medulla.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Various clinical characteristics, including stroke-related deficits and stroke risk factors, were identified and compared between brainstem subgroups. The incidence of complications, including pneumonia, deep vein thrombosis, and seizure disorder, was also reported.

RESULTS

Seventy (82%) of the strokes resulted from infarctions and 15 (18%) were caused by hemorrhages. The functional deficits of hemiparesis, ataxia, and diplopia were present in 41 (48%), 73 (86%), and 32 (38%) patients, respectively. Dysarthria was reported in 42 patients (49%) and dysphagia in 40 (47%). Pneumonia during hospitalization was a complication in 9 (11%) of the patients with brainstem stroke. The risk factors of diabetes and hypertension were present in 22 (26%) and 47 (55%) patients, respectively. Fourteen (17%) of these patients had suffered a previous stroke.

CONCLUSIONS

Rehabilitation patients experience a variety of functional impairments as a consequence of brainstem stroke. These include hemiparesis, dysarthria and dysphagia, diplopia, and ataxia. A significant number of patients had pneumonia as a complication. The characteristics and impairment profiles of patients within the subgroups were similar, with the exception of the incidence of ataxia and hemiparesis.