Clinical aspects of brainstem infarction

Ischemic stroke in the vertebrobasilar arterial territory often presents stunning signs and symptoms, and poses little difficulty in the clinical diagnosis. But in less dramatic cases, it is often difficult to make accurate clinical diagnosis and to document the precise extent of an infarct. The purpose of the present study is to demonstrate clinicotopographic correlations in patients with various brainstem and cerebellar infarctions and to reevaluate the importance of bedside clinical examinations for understanding pathophysiology and planning management of the patient. One hundred forty-three patients with clinical diagnosis of the vertebrobasilar infarction confirmed by MRI were studied. MRI is superior to CT scanning in delineating areas of infarction in the territory of posterior cerebral circulation because of the three dimensional approach and the lack of bone artifact. MRI also allowed very precise clinicotopographic correlations even in patients with good recovery, in whom pathologic verification of the lesion is not possible. There are some restrictions of MRI diagnosis to detect the clinical features which change from hour to hour, because of the mechanical limitation in spatial resolution and of the temporal uncertainty of the lesions such as reversible edema or coincidental asymptomatic old lesions. Clinical importance of ocular signs (eg. skew deviation, gaze limitations, nystagmus, pupillary abnormalities and so on) was discussed. Some eye-movement abnormalities (eg. gaze paresis, MLF syndrome, 'one-and-a-half' syndrome, lateropulsion or contrapulsion of eyes, and vertical nystagmus at the primary position) served as useful localizing signs, and especially their consecutive observations were of importance for clinical local diagnosis. Clinical syndromes, caused by lacunar lesions located either in the supratentorial or in the infratentorial structures, such as pure motor hemiparesis and ataxic hemiparesis were also discussed. In some cases of these syndromes, MRI failed to document the precise lesion responsible for the episode due to the multiplicities of small asymptomatic lesions. Even in such cases, detailed clinical informations (temporal profiles of the episode, past medical histories, neuro-ophthalmic signs and so on) may enable the differential diagnosis. It is concluded that the use of new imaging techniques such as MRI may provide new insights in the diagnosis of cerebrovascular diseases, but the importance of clinical observations can not be overemphasized.