Pattern of otolith dysfunction in posterior inferior cerebellar artery territory cerebellar infarction

To document otolith dysfunction in patients with posterior inferior cerebellar artery (PICA) territory cerebellar infarction.

From March to October 2006, 14 consecutive patients with PICA territory cerebellar infarctions (brainstem spared) diagnosed by brain MRI from the acute stroke registry at the Keimyung University Dongsan Medical Center were enrolled within 12 days of onset (mean 4.0 days). Otolith function tests included ocular torsion (OT), skew deviation, and subjective visual vertical (SVV) were performed. The extent of the cerebellar infarction was determined by previously validated MR anatomical templates.

All patients had an abnormal posture as a result of otolithic dysfunction. Eleven patients (79%) had at least one otolith-related test abnormality: abnormal tilt of SVV (79%), abnormal OT (29%), or skew deviation (21%). Two common patterns of otolith dysfunction were identified based on whether or not the nodulus was infarcted: 1) ipsilesional SVV tilt (mean 5.0 degrees at binocular viewing) without accompanying abnormal OT or skew deviation (nodulus spared); 2) contralesional SVV tilt (mean 11.3 degrees at binocular viewing) with concomitant abnormal OT and skew deviation (nodulus infarcted). Patients with type 1 infarcts (i.e., nodulus spared) fell toward the side of lesion while patients with type 2 infarcts (i.e., nodulus infracted) fell toward the opposite side.

Isolated PICA territory cerebellar infarction usually produces two distinct patterns of otolith dysfunction - Ipsilesional SVV tilt and falling without accompanying OT or skew deviation if the nodulus is spared and contralesional SVV tilt and falling with OT and skew deviation if nodulus is infarcted.