Clinical study of medial area infarction in the region of posterior inferior cerebellar artery.

Our objective is to study the neurological characteristics of medial area infarction in the caudal cerebellum. Medial area of the caudal cerebellum is supplied with 2 branches of the posterior inferior cerebellar artery (PICA). The medial hemispheric branch of the PICA distributes to the medial area of the caudal cerebellar hemisphere. The medial branch of the PICA (mPICA) distributes to the inferior vermis. We studied the neurological characteristics of 18 patients with medial area infarction of the caudal cerebellum. The infarction was located in the medial area of the cerebellar hemisphere and vermis (medial ch/vermis) in 11 patients and in the medial area of the cerebellar hemisphere (medial ch) in 7 patients. All the 18 patients showed acute vertigo and disturbance of standing and gait at onset. On admission, the lateropulsion and wide-based gait were present in 13 patients, respectively. Mild ataxia of the extremities was shown in 7 patients. Acute vertigo and unsteadiness were prominent at onset in the 18 patients, although their ataxia of the extremities was mild or none. This result was consistent with the characteristics of medial area infarction of the caudal cerebellum. Comparing the neurological symptoms between the medial ch/vermis group and medial ch group, both lateropulsion and wide-based gait were significantly infrequent in medial ch group. This result indicated that the vermis was spared because the mPICA was not involved in the medial ch group. It is necessary to make a careful diagnosis when we encounter patients who present acute vertigo because truncal and gait ataxia are unremarkable on admission in patients with the medial area infarction of the caudal cerebellum without vermis involvement.