Gait and bilateral limb ataxia as isolated feature of a lower midbrain tegmental infarction. A clinical-MRI study

Caudal paramedian midbrain infarction: a clinical study of imaging, clinical features and stroke mechanisms

Caudal paramedian midbrain infarction (CPMI) is an extremely rare form of ischemic stroke and related clinical studies are scarce. Our aim is to investigate the clinical features, neuroradiological findings and stroke etiology of CPMI. We conducted a retrospective study of 12 patients with CPMI, confirmed by diffusion-weighted MRI from 6820 cerebral infarction patients at our stroke center from January 2012 to August 2018. Experienced neurologists evaluated the clinical manifestations, neuroimaging findings and stroke mechanisms. Twelve patients (11 men, 1 woman) aged 42-81 years old met the study inclusion criteria. Seven patients had a unilateral infarction (two right-sided, five left-sided) and five had bilateral infarctions. Sagittal image showed a backward oblique sign in the lower level of the midbrain. Significantly, the bilateral CPMIs presented with a characteristic "V-shaped" appearance in the axial MRI. All patients presented with bilateral cerebellar dysfunction which included dysarthric speech, truncal or gait ataxia and four-limb ataxia. In addition, diplopia and internuclear ophthalmoplegia were frequently encountered in CPMI. Five (41.7%) patients were classified with large artery atherosclerosis, four (33.3%) with small vessel disease, two (16.7%) with cardiogenic embolism, and one (8.3%) with undetermined etiology. CPMI is a rare cerebrovascular disease that destroys the Wernekink commissure, medial longitudinal fasciculi and other adjacent structures. It is characterized by bilateral cerebellar ataxia and eye movement disorders, mainly internuclear ophthalmoplegia. A distinct "V-shaped" radiological feature can be seen in bilateral CPMI patients. The primary mechanisms of unilateral CPMI involve small vessel disease. The underlying stroke mechanisms of bilateral CPMI are either large artery atherosclerosis disease or cardiac embolism.

Wernekink commissure syndrome secondary to a rare 'V'-shaped pure midbrain infarction: a case report and review of the literature

Purpose: Wernekink commissure syndrome is a typical but extremely rare mesencephalic syndrome, and generally presents with bilateral cerebellar dysfunction, diverse oculomotor disorders and occasionally delayed-onset palatal myoclonus or tremor. However, it has been reported infrequently.Methods: We report a case of a 55-year-old man who suffered an acute paramedian midbrain infarction presenting with bilateral cerebellar ataxia, bilateral anterior internuclear ophthalmoplegia and unilateral pseudoabducens palsy, which is confirmed as Wernekink commissure syndrome by magnetic resonance imaging (MRI). We summarized the clinical data of this entity and performed a literature review of 20 previous reports of patients with this syndrome.Results: In combination with previous reports, we found that the most common symptom was bilateral cerebellar ataxia (100%) and other frequent symptoms were oculomotor disorders (81%), delayed palatal myoclonus or tremor (33%) and consciousness dysfunction (33%). Lesions on brain MRI of all patients affected the area of caudal paramedian midbrain (CPM).Conclusion: Bilateral cerebellar ataxia and lesions involved in the area of CPM on MRI are the major features of Wernekink commissure syndrome and should be the necessary conditions of diagnostic criteria. The simultaneous occurrence of bilateral cerebellar ataxia and oculomotor disorders is significant for localization diagnosis. Consciousness dysfunction is also a relatively frequent symptom of this syndrome. Moreover, pseudoabducens palsy might be attributed to a midbrain lesion. Clinicians should be familiar with and early to recognize this unique syndrome to avoid misdiagnosis.

Wernekink Commissure Syndrome Secondary to Bilateral Caudal Paramedian Midbrain Infarction Presenting with a Unique "Heart or V" Appearance Sign: Case Report and Review of the Literature

Wernekink commissure syndrome secondary to caudal paramedian midbrain infarction (CPMI) is a rare midbrain syndrome involving the decussation of the superior cerebellar peduncle in the caudal paramedian midbrain tegmentum. The central characteristics are constant bilateral cerebellar dysfunction, variable eye movement disorders, and rare delayed palatal myoclonus. Following is a description of the case of a 60-year-old man who presented with dizziness, slurred speech, and difficulty walking. Neurological examination revealed bilateral cerebellar dysfunction and bilateral internuclear ophthalmoplegia (bilateral INO). Serial magnetic resonance imaging (MRI) revealed a lesion in the caudal paramedian midbrain with a "heart-shaped" sign on fluid-attenuation inversion recovery images and a "V-shaped" appearance on diffusion-weighted imaging (DWI). An acute CPMI with a "heart or V" appearance sign was diagnosed. Upon follow-up evaluation 3 months later, a palatal tremor accompanied by involuntary head tremor was discovered. Hypertrophy and increased signal of the bilateral inferior olivary nucleus, compatible with hypertropic olivary degeneration (HOD) were revealed during a subsequent MRI study.

Hemi- and monoataxia in cerebellar hemispheres and peduncles stroke lesions: topographical correlations

Limb ataxia of sudden onset is due to a vascular lesion in either the cerebellum or the brainstem (posterior circulation, PC, territory). This sign can involve both the upper and the lower limb (hemiataxia) or only one limb (monoataxia). The topographical correlates of limb ataxia have been studied only in brainstem strokes. Therefore, it is not yet known whether this sign is useful to localize the lesion within the entire cerebellar system, both the cerebellar hemisphere and the cerebellar brainstem pathways. Limb ataxia was semi-quantified according to the International Cooperative Ataxia Rating Scale in 92 consecutive patients with acute PC stroke. Limb ataxia was present in 70 patients. Four topographical patterns based on magnetic resonance imaging findings were identified: picaCH pattern (posterior inferior cerebellar artery infarct); scaCH pattern (superior cerebellar artery infarct); CH/CP pattern (infarct involving both the cerebellum and the brainstem cerebellar pathways); and CP pattern (infarct involving the brainstem cerebellar pathways). Hemiataxia was present in (47/70; 67.1%) and monoataxia in (23/70; 32.9%) of patients. Monoataxia involved the upper limb in (19/70; 27.1%) and the lower limb in (4/70; 5.7%) of patients. Limb ataxia usually localized the lesion ipsilaterally (picaCH, scaCH, CH/CP, and CP patterns involving the medulla and sometimes the pons) (53/70; 75.7%), but it might be due also to contralateral (CP pattern involving the pons or midbrain) (16/70; 22.9%) or bilateral lesions (1/70). Limb ataxia usually localizes the lesion ipsilaterally but the infarct might be sometimes contralateral. The occurrence of monoataxia may suggest that the cerebellar system is somatotopically organized.