Posterior Inferior Cerebellar Artery Infarct Associated With Cervical Dystonia: A Case Report.

Cerebellar infarcts, particularly those involving the posterior inferior cerebellar artery (PICA), can present with diverse and atypical neurological symptoms that complicate timely diagnosis. We present the case of an 84-year-old woman with a history of vascular risk factors who developed sudden-onset dizziness, vomiting, and altered mental status, ultimately found to have a right PICA territory infarct on MRI. Notably, on the second day of admission, she developed transient cervical dystonia (CD) characterized by leftward neck deviation and sternocleidomastoid spasm. This focal motor manifestation, in the absence of classic ataxia or cranial nerve deficits, highlights the rare but significant association between cerebellar stroke and dystonia. Neuroanatomical pathways involving the cerebellum, basal ganglia, and vestibular systems, particularly the Guillain-Mollaret triangle (GMT) and corticocerebellar loops, may underlie such movement disorders. Additionally, ischemia of structures such as the accessory nerve or imbalance in vestibular tone may contribute to cervical posturing. The patient's dystonia improved spontaneously with supportive care and baclofen, supporting the theory of transient post-ischemic hypersensitivity rather than fixed structural damage. This case emphasizes the importance of recognizing central causes of acquired torticollis to avoid misdiagnosis and delays in stroke management, particularly in elderly patients presenting with subtle posterior circulation symptoms.