Limb ataxia and proximal intracranial territory brain infarcts: clinical and topographical correlations

Background: Limb ataxia is classically attributed to cerebellar hemispheric lesions, although isolated lesions of the inferior cerebellar peduncle (ICP) in the medulla may also cause this sign. It is still unclear why only some patients with acute cerebellar infarcts in the posterior inferior cerebellar artery ( PICA) territory present with limb ataxia. The proximal intracranial posterior circulation (P-PC) territory includes structures fed by the intracranial vertebral arteries (ICVAs): the medulla, supplied by small ICVAs branches, and posterior inferior portion of the cerebellum, fed by PICA. ICP and PICA territory cerebellar infarcts most often occur independently but occasionally occur together. Objective: To identify structures responsible for limb ataxia in acute P-PC brain infarcts, correlating clinical and topographical findings. Methods: Sixteen patients ( 8 women) were included, aged 30-82 years ( mean 62 years), with isolated acute strokes in the P-PC territory. Results: The cases reported here indicate that limb ataxia in acute P-PC territory infarcts may be associated with damage to the ICP in the dorsolateral medulla, regardless of a hemispheric cerebellar lesion. In fact, among the nine patients with PICA stroke, limb ataxia was observed only in the two patients who also presented damage to the dorsolateral medulla involving the ICP. Of the seven patients with isolated dorsolateral medullary infarct, only five patients with ICP damage had limb ataxia. Conclusions: When correlating limb ataxia and acute P-PC infarcts, it is important to take into account the entire ICVA territory.