Pure Pontine Infarct

BACKGROUND AND OBJECTIVES: Pure pontine infarct is defined as an infarct limited to the pons without the evidence of any other brainstem infarct. This study was designed to assess the etiology, lesion topography, and clinical characteristics of pure pontine infarcts. METHODS: Sixty-six patients with pure pontine infarcts, shown on magnetic resonance imaging, were divided into three groups(Group I(n=32) : unilateral lesion reaching the ventral surface of the pons(>1.5cm in size), Group II(n=27) : single or multiple lesions, separated from the surface(<1.5cm), Group III(n=7) : bilateral extensive lesion reaching the ventral surface). Clinical characteristics including the risk factors and the symptomotology were evaluated. Conventional or magnetic resonance angiography was performed in 37 patients(Group I ; 18/32, Group II ; 14/27, Group III ; 5/7). RESULTS: Pontine lesions in Group I(number of lesions = 36) were located longitudinally in the upper (8/36, 22.2%), middle(11/36, 30.6%), and lower(17/36, 47.2%) pons. Thirty-seven patients, in whom angiography was performed, were classified etiologically in each groups. In Group I, fourteen patients had basilar artery branch disease and four had large artery disease. In Group II, all had small artery disease. In Group III, three patients had large artery disease and two had basilar artery branch disease. The most frequent risk factor in pure pontine infarct was hypertension in all three groups. CONCLUSION: The lower region of pons is the most vulnerable site of pure pontine infarct. Basilar artery branch disease was the most common cause of the pure pontine infarct(43.2%). Small artery disease occupied 37.8% and large artery disease(18.9%) was less common.

Ocular Torsion and Tilt of Subjective Visual Vertical and Head in Patients with Acute Brainstem Stroke

BACKGROUND & PURPOSE: The ocular torsion (OT) and tilt of the subjective visual vertical (SVV) are sensitive brainstem signs and helps us to localize lesion. We calibrated the degree of OT, SVV tilt and head tilt to investigate their characteristics and temporal profiles in patients with brainstem lesion. METHODS: We selected 15 patients with acute brainstem stroke. We took serial fundus photographs and body pictures in upright position at various times after the stroke. We also determined the deviations of patient's SVV. The data measurement for this investigation ranged from day 2 to day 47. RESULTS: Eight of ten patients with lateral medullay infarction showed ipsiversive tilt of SVV and OT. Among four patients with pontine infarction, one showed ipsiversive tilt and three contraversive. One patient with midbrain hemorrhage showed cotraversive tilt. The resolution of OT and the tilt of SVV in medullary lesions occurred over the periods ranging from 7 days to more than 47 days and was slower in patients with upper brainstem lesion than lower brainstem lesion. The directions of head tilt in our patients, especially with medullary lesions, were rather different from the previous reports. CONCLUSION: The vestibular dysfunction by the brainstem lesions disturbs the eye and head stabilization and also distorts the perception of the subjective vertical in space. The direction of OT and the tilt of SVV is ipsiversive in lower brainstem lesion and contraversive in upper brainstem lesion. But head tilt is contraversive in most lower brainstem lesion as well as upper brainstem lesion. Large-grouped study for the direction of head tilt is thought to be needed. These signs are compensated in the course of clinical recovery.