Body lateropulsion as an isolated or predominant symptom of a pontine infarction.

Background: Lateropulsion of the body--that is, falling to one side--is a well-known clinical feature of stroke in the posterior circulation. Body lateropulsion as an isolated or predominant manifestation of a pontine stroke has not been reported previously.
Objective: To elucidate the possible mechanisms of patients presenting with body lateropulsion as an isolated or predominant symptom of an isolated pontine infarction.
Methods: Between May 2004 and February 2006, out of 134 patients admitted with an isolated pontine stroke, we identified 8 (6%) consecutive patients in the Keimyung University Stroke Registry who had body lateropulsion as the main presenting symptom.
Results: All lesions were localised to the paramedian tegmentum just ventral to the fourth ventricle. All except one showed a uniform pattern of body lateropulsion, in which the direction of falling was away from the side of an infarct. In two patients body lateropulsion was the sole clinical manifestation, whereas the other patients had other neurological signs. All but one patient had contraversive tilting of the subjective visual vertical (SVV). In all cases, the direction of SVV tilt corresponded to the direction of body lateropulsion. The mean net tilt angle was 6.1 degrees.
Conclusions: Based on the known anatomy of ascending vestibular pathways, SVV tilting and MRI findings, it is concluded that body lateropulsion probably results from damage to the graviceptive pathway ascending through the paramedian pontine tegmentum.