Lesion Patterns and Etiology of Ischemia in Superior Cerebellar Artery Territory Infarcts

Temporal lobe uncal herniation with contralateral superior cerebellar artery infarct

Herniation of the temporal lobe uncus typically leads to the compression of the ipsilateral oculomotor nerve, resulting in ipsilateral mydriasis, as well as compression of the ipsilateral posterior cerebral artery, leading to infarction in the posterior inferior temporal lobe and medial occipital cortex. In this report, we present the case of a 45-year-old man with a large left subdural hematoma. At autopsy, we observed left cingulate and uncal herniations, along with the characteristic lesions of Kernohan notch phenomenon due to compression of the contralateral cerebral peduncle. Additionally, a hemorrhagic infarct was identified in the right cerebellar hemisphere in the distribution of the superior cerebellar artery (SCA). This case provides the first autopsy report of uncal herniation with contralateral SCA infarct, an extremely rare condition. Importantly, this vascular complication may often go unnoticed in patients with Kernohan notch phenomenon although it may carry a grave clinical prognosis.

Patterns of Infarction on MRI in Patients With Acute Ischemic Stroke and Cardio-Embolism: A Systematic Review and Meta-Analysis

Background: Cardioembolic strokes are common however atrial fibrillation, the most common cause, is often asymptomatic and difficult to detect. There is evidence that infarct topography and volume on magnetic resonance imaging may be associated with specific stroke etiologies.

Aim: A systematic review and meta-analysis were undertaken to summarize the available evidence on the association between stroke etiology, infarct topography, and volume.

Methods: A systematic review was conducted using Medline (OVID), Embase (OVID), and PubMed databases. Hand searches of the gray literature and of reference lists in relevant articles were also performed. A quality assessment was undertaken, based on the STROBE checklist. For each study, the number of patients with and without a CE source of stroke and infarct topography was collected and outcomes presented as odds ratios (OR) with 95% CI and p-values.

Results: Four thousand eight hundred and seventy-three patients with ischemic stroke were included, of whom 1,559 were determined to have a CE source. Bilateral infarcts (OR 3.41; 95% CI 2.20–5.29; p < 0.0001) and multiple territory infarcts (OR 1.57; 95% CI 1.12–2.21; p = 0.009) were more common in patients with a CE source of stroke, than patients without a CE source. Lacunar infarcts (OR 0.49; 95% CI 0.31–0.80; p = 0.004) were more likely to occur in patients without a CE source. No significant difference between the frequency of multiple infarcts (OR 0.96; 95% CI 0.57–1.61; p = 0.87) anterior circulation (OR 1.45; 95% CI 0.83–2.53; p = 0.19) or posterior circulation infarcts (OR 1.06; 95% CI 0.72–1.57; p = 0.75), between the two groups were identified. Three out of four studies examining volume, found a significant association between increased infarct volume and CE source of stroke. A sensitivity analysis with cryptogenic and undetermined stroke sources assumed to be cardioembolic, did not alter the associations observed.

Conclusion: The findings of this systematic review and meta-analysis are broadly consistent with previous literature and provide more robust evidence on the association between infarct topography, volume and stroke etiology. Our findings may assist with refining cardiac investigations for patients with cryptogenic stroke, based on infarct topography.

The Usefulness of the TOAST Classification and Prognostic Significance of Pyramidal Symptoms During the Acute Phase of Cerebellar Ischemic Stroke

Cerebellar stroke is a rare condition with very nonspecific clinical features. The symptoms in the acute phase could imitate acute peripheral vestibular disorders or a brainstem lesion. The aim of this study was to assess the usefulness of the Trial of Org 10172 in Acute Stroke Treatment (TOAST) classification in cerebellar stroke and the impact of clinical features on the prognosis. We retrospectively analyzed 107 patients with diagnosed ischemic cerebellar infarction. We studied the clinical features and compared them based on the location of the ischemic lesion and its distribution in the posterior interior cerebellar artery (PICA), superior cerebellar artery (SCA), and anterior inferior cerebellar artery (AICA) territories. According to the TOAST classification, stroke was more prevalent in atrial fibrillation (26/107) and when the lesion was in the PICA territory (39/107). Pyramidal signs occurred in 29/107 of patients and were more prevalent when the lesion was distributed in more than two vascular regions (p = 0.00640). Mortality was higher among patients with ischemic lesion caused by cardiac sources (p = 0.00094) and with pyramidal signs (p = 0.00640). The TOAST classification is less useful in assessing supratentorial ischemic infarcts. Cardioembolic etiology, location of the ischemic lesion, and pyramidal signs support a negative prognosis.

Cerebellar infarct patterns: The SMART-Medea study

OBJECTIVE

Previous studies on cerebellar infarcts have been largely restricted to acute infarcts in patients with clinical symptoms, and cerebellar infarcts have been evaluated with the almost exclusive use of transversal MR images. We aimed to document the occurrence and 3D-imaging patterns of cerebellar infarcts presenting as an incidental finding on MRI.

METHODS

We analysed the 1.5 Tesla MRI, including 3D T1-weighted datasets, of 636 patients (mean age 62 ± 9 years, 81% male) from the SMART-Medea study. Cerebellar infarct analyses included an assessment of size, cavitation and gliosis, of grey and white matter involvement, and of infarct topography.

RESULTS

One or more cerebellar infarcts (mean 1.97; range 1-11) were detected in 70 out of 636 patients (11%), with a total amount of 138 infarcts identified, 135 of which showed evidence of cavitation. The average mean axial diameter was 7 mm (range 2-54 mm), and 131 infarcts (95%) were smaller than 20 mm. Hundred-thirty-four infarcts (97%) involved the cortex, of which 12 in combination with subcortical white matter. No infarcts were restricted to subcortical branches of white matter. Small cortical infarcts involved the apex of a deep (pattern 1) or shallow fissure (pattern 2), or occurred alongside one (pattern 3) or opposite sides (pattern 4) of a fissure. Most (87%) cerebellar infarcts were situated in the posterior lobe.

CONCLUSIONS

Small cerebellar infarcts proved to be much more common than larger infarcts, and preferentially involved the cortex. Small cortical infarcts predominantly involved the posterior lobes, showed sparing of subcortical white matter and occurred in characteristic topographic patterns.

A case of cerebellar infarction caused by acute subclavian thrombus following minor trauma

Subclavian steal syndrome caused by an acute thrombus is very rare. We present a case of cerebellar infarction with proximal subclavian artery thrombosis. A 56-year-old woman was admitted for sudden vertigo. One day prior to admission, she received a shoulder massage comprised of chiropractic manipulation. On examination, her left hand was pale and radial pulses were absent. Blood pressure was weak in the left arm. Downbeat nystagmus and a right falling tendency were observed. Brain MRI showed multiple acute infarctions in the left cerebellum. The findings of Doppler ultrasonography in the left vertebral artery were compatible with a partial subclavian artery steal phenomenon. Digital subtraction angiography demonstrated a large thrombus in the left subclavian artery. After heparin infusion, thrombus size markedly decreased. Cerebellar infarction caused by acute subclavian thrombosis following minor trauma is rare, but the thrombus can be successfully resolved with anticoagulation.

[Cerebellar infarction: prognosis and complications of vascular territories]

INTRODUCTION

Cerebellar infarction (CI) is uncommon, but may result in severe complications. The aim of our study was to determine the characteristics of patients with CI, as well as their outcomes as regards the territories affected.

PATIENTS AND METHODS

Data were collected from 124 patients admitted to our department during a five-year period, with a radiological diagnosis of CI, and with or without involvement of other brain territories.

RESULTS

The mean age in our series was 65.2 years, with most being male (68.5%). The posterior inferior cerebellar artery (PICA) was the most commonly affected territory at 49.2%, followed by superior cerebellar artery (SCA) at 17.7%, and anterior inferior cerebellar artery (AICA) at 10.5%. There was simultaneous supratentorial involvement in 13.7%, and two or three cerebellar arteries involved in 8.9%. The main aetiology in PICA was atherothrombosis (P=.02). On the other hand, cardio-embolism was the main origin in cases with more than one affected territory (P=.04). No particular aetiology could be found in SCA and AICA. There was haemorrhagic transformation in 29 patients (23.4%), particularly in the PICA and when other territories were involved. There was hydrocephalus in 15 patients (12.1%, 12 of them PICA; P=.02) in 2.9 ± 1.5 days from stroke onset. At discharge, the degree of disability was worse if more than one arterial territory was involved (Rankin ≥ 3, 64% versus 31-36%; P=.05). Four (3.2%) patients died.

CONCLUSIONS

CI is very heterogeneous. Nevertheless, it is noteworthy that PICA infarction is the most frequent type and its aetiology is usually atherothrombotic. Moreover, it is the territory most frequently associated with severe complications, which take place during the first week of the stroke.

[Cerebellar infarction]

Cerebellar infarction can be difficult to diagnose because the clinical picture is often dominated by fairly non-specific symptoms, which are more indicative of a benign condition. When cerebellar infarction affects the brainstem, the semiology is richer, and pure cerebellar signs are rendered less important. A perfect knowledge of the organisation of the cerebellar artery territories is required, regardless of the infarct topography. This knowledge is essential for making an accurate diagnosis, understanding the mechanisms and organising a treatment plan. Clinical algorithms for the treatment of dizziness, headaches and vomiting would improve the selection of candidates for brain imaging. Thus, the early identification of patients with a high risk of subsequent deterioration would lead to a better prognosis in cases of cerebellar artery territory infarction.

Clinical outcome following surgical treatment for bilateral cerebellar infarction

OBJECTIVES

To analyze the initial clinical and radiological findings, the surgical treatment, and the clinical outcome following surgical decompression in patients with space-occupying bilateral cerebellar infarction.

MATERIALS AND METHODS

Ten patients with expansive bilateral cerebellar infarction and decreased level of consciousness were operated with suboccipital craniectomy, removal of the infarcted tissue, and placement of external ventricular drainage. Long-term outcome was assessed using the modified Rankin scale (mRS).

RESULTS

Mean Glasgow coma scale (GCS) score before surgery was 8.9 ± 3.3 and improved to 12.6 ± 3.6 at discharge. At the long-term follow-up (median 57.6 months), six patients had a favorable outcome (mRS 1.3 ± 0.8). Four patients, all with an associated brain stem infarct, had a poor outcome.

CONCLUSIONS

In the absence of brain stem infarcts, surgical treatment resulted in a favorable clinical outcome and should be considered a treatment option for patients with expansive bilateral cerebellar infarction.

Superior cerebellar artery infarction in endovascular treatment for tentorial dural arteriovenous fistulas

BACKGROUND

Superior cerebellar artery (SCA) syndrome shows ipsilateral cerebellar ataxia and Horner's syndrome, contralateral superficial sensory disturbance, as well as nystagmus toward the impaired side, vertigo, and nausea. Occasionally, unilateral lesions may produce bilateral hypogeusia and contralateral hypoacusia.

OBJECTIVE

To report 2 patients with unilateral lower midbrain ischemic lesions of the inferior colliculus level caused by transarterial embolization for tentorial dural arteriovenous fistulas (TDAVFs).

METHODS

Hospital records for 21 patients with TDAVFs mainly treated by endovascular techniques between 2005 and 2008 were reviewed. Two patients with MRI evidence of unilateral SCA territory infarction were investigated.

RESULTS

Of 21 patients, 2 treated transarterially with Onyx-18 (a nonahesive liquid embolic agent) developed infarctions in the territory of SCA. One patient had lateral SCA infarction characterized by ipsilateral gait ataxia, contralateral hemihypoesthesia, with additional ipsilateral ocular motor palsy and bilateral gustatory loss. And the other patient had medial SCA infarction characterized by ipsilateral ataxia contralateral hemihypoesthesia with additional contralateral hypoacusia.

CONCLUSION

SCA infarction can be caused by transarterial injection of Onyx-18 via SCA or the posterior cerebral artery (PCA) for TDAVFs and additionally presented with gustatory loss and deafness, which is generally not a feature of the SCA syndrome.

Cerebellar infarction in the territory of the superior cerebellar artery in children

Posterior circulation infarction is uncommon in children. Vertebral artery dissection is an unusual cause of posterior circulation infarction in children. We report on a 12-year-old boy with spontaneous left-extracranial vertebral artery dissection associated with isolated ipsilateral superior cerebellar artery territory infarction, diagnosed clinically and by brain computed tomography, magnetic resonance imaging, and magnetic resonance angiography. Cerebral angiography demonstrated a flame-like occlusion of the left vertebral artery at level C(2)-C(3), and indicated that artery-to-artery embolus may be a mechanism of superior cerebellar artery territory infarction. We emphasize that vertebral artery dissection should be considered in a child with acute signs of posterior circulation ischemia.

Rostral cerebellar arterial infarct in two cats

A 10-year-old female neutered domestic shorthair (DSH) cat and a 6-year-old female neutered Siamese cat were presented following a peracute onset of decerebellate rigidity and a cerebellar vestibular syndrome, respectively. In both cats, physical examination and routine blood tests were unremarkable, as was routine analysis of cerebrospinal fluid obtained from the DSH cat. Based on the magnetic resonance imaging (MRI) features - focal wedge-shaped lesion in the cerebellum characterised by hyperintensity in T2-weighted, T2( *)-gradient echo and fluid attenuated inversion recovery (FLAIR) images - a presumptive diagnosis of cerebellar infarct was made in both cases. In the DSH cat, the post-mortem examination confirmed the diagnosis of cerebellar infarct and additionally found acute renal infarcts and a pulmonary neoplasia. In the Siamese cat, ultrasonographic evaluation of the heart revealed a probable low-grade chronic valvular endocarditis which was thought to be a potential source of thromboembolism. This paper describes the first two cases - one confirmed and the other suspected - of cerebellar infarct in the cat. The in vivo potential diagnostic value of the MRI study is highlighted. Cerebellar infarcts should be included in the differential diagnosis of cat with a peracute onset of cerebellar signs regardless of the severity of neurological deficits.

Dysarthria due to Supratentorial and Infratentorial Ischemic Stroke: A Diffusion-Weighted Imaging Study

BACKGROUND AND PURPOSE

Dysarthria characterized by slurring with imprecise articulation without evidence of aphasia is a frequent symptom in the acute phase of cerebral ischemia, although there is little knowledge on its anatomic specificity and spectrum of associated clinical characteristics regarding diffusion-weighted imaging (DWI).

METHODS

An investigation of 101 consecutive patients with sudden-onset dysarthria due to a single or multiple lesions on DWI, corresponding to 8.7% of 1,160 patients with ischemic stroke, was made. The presence of lesions of the cranial arteries was sought by magnetic resonance angiography and reviewed with a three-dimensional rotating cineangiographic method.

RESULTS

Dysarthria was mostly associated with a supratentorial lesion (63%) and with a classic lacunar stroke syndrome in 45% of patients. Lacunar lesions on DWI were found in 69 (68%) patients, while only 45 of the patients (65%) with a lacunar infarct presented a classic lacunar syndrome with dysarthria. Pure dysarthria occurred in 15% of patients, dysarthria + pure motor hemiparesis in 14%, dysarthria + ataxic hemiparesis in 11%, dysarthria + clumsy hand syndrome in 7%, dysarthria + pure sensory stroke in 3%, dysarthria + central facial paresis in 8% and lingual paresis occurred in 2%. The lesions were due to small-artery disease in 41%, large-artery disease in 15%, cardioembolism in 10% and a mixed etiology in 3%. The cause of stroke was not identified in 17 patients. Lesions on DWI were found mainly in the corona radiata (n = 18), middle cerebral artery territory, including the motor cortex and/or insular cortex (n = 13), striatocaudate nuclei (n = 11), primary motor cortex (n = 10), internal capsule (n = 7), pons (n = 25), pontobulbar junction (n = 5) and the thalamomesencephalic junction (n = 4). Isolated cerebellar infarctions (n = 6) or associated brainstem lesions (n = 6) affected mostly the superior cerebellar artery or the posterior inferior cerebellar artery territory.

CONCLUSION

Cortical involvement was more frequent in patients with pure dysarthria than those with dysarthria and additional neurological signs, while the frequency of pontine involvement was higher in patients with additional neurological signs than those with pure dysarthria. One third of the patients with dysarthria had multiple lesions on DWI, and the most common cause of stroke was small-artery disease. Pure dysarthria, dysarthria with lingual paresis, dysarthria with clumsy hand and dysarthria with facial paresis had predictive value for lacunar lesions.

A new model of thromboembolic stroke in the posterior circulation of the rat

The prognosis of vertebrobasilar occlusion is grave and therapeutic options are limited. The aim of the present study was to develop a new model of embolic hindbrain ischemia in the rat that closely resembles the clinical situation and that can be used to study pathophysiology and treatment options. After thoracotomy in 20 male Wistar rats, 15 animals received an injection of in vitro prepared autologous blood clots into the left vertebral artery. Five animals without clot injection served as controls. Neurological deficits were assessed in all animals 2 h after embolism. After 2 h, five animals were sacrificed to measure cerebral blood flow (CBF) by iodo-antipyridine autoradiography, and to calculate early cerebellar swelling by comparison of both hemispheres in brain slices. In these animals, autoradiography revealed ipsilesional brain swelling and significantly reduced blood flow values relative to the contralateral (unaffected) structures. Immunohistology showed the typical pattern of focal cerebral ischemia in the brain stem and/or cerebellum in 7 of 10 animals allowed to recover to 24 h. Hence, successful thromboembolism was achieved in 12 of 15 animals (80%). With this novel model, the pathophysiology and potential treatments of posterior circulation stroke can be investigated.

Bilateral infarcts in the territory of the superior cerebellar artery: Clinical presentation, presumed cause, and outcome

BACKGROUNDS AND PURPOSE

The aim of this study was to document the clinical presentation, vascular topographic patterns, stroke mechanism, and outcome of bilateral infarcts in the territory of the superior cerebellar artery (SCA) based on data collected from a prospective acute stroke registry.

METHODS

We studied the clinical and radiological features of 11 patients with bilateral infarctions in the territory of the SCA diagnosed by brain MRI.

RESULTS

Bilateral SCA infarcts represented 23.4% (11/47) of all SCA territory infarction. Bilateral SCA infarcts mostly associated with brainstem (n = 5), cerebral (n = 5), or non-SCA cerebellar lesions (n = 4). The most common clinical presentation at onset was sudden fall with axial lateropulsion and dysarthria (n = 6). In five patients with a coexisting infarct(s) in the brainstem, limb weakness and/or mental change were prominent and often masked the signs of cerebellar dysfunction. Six patients showed no stenosis or occlusion in the vertebrobasilar system on brain MRA. Five had an obvious cardiac source of emboli. Eight patients showed favorable outcomes with complete recovery or minimal disability, but three patients with additional extensive brainstem infarcts died within 1 week.

CONCLUSIONS

Bilateral SCA territory infarcts show variable clinical, vascular topographic, and prognostic features. They usually result from cardiac emboli.