EXPRESS: Paroxysmal Dyskinesia like movement disorder in a Ragdoll cat following a rostral cerebellar infarct

Case summary A 6-year-8-month-old neutered male Ragdoll cat was investigated for peracute right-sided neurological deficits consistent with a C1–C5 myelopathy. Initial MRI identified an intramedullary lesion at C2, most consistent with ischaemic myelopathy. The cat improved with physiotherapy; however, on day 21, it developed recurrent episodes of abnormal limb posturing and involuntary movements. Episodes comprised segmental dystonia with a spreading pattern, preserved consciousness, and no consistent autonomic signs, supporting a paroxysmal dyskinesia (PD)-like movement disorder rather than epileptic seizures. Brain MRI performed on day 24 identified a focal wedge-shaped lesion in the rostroventral right cerebellar hemisphere within the territory of the rostral cerebellar artery, consistent with a subacute infarct. Additional findings, including renal infarction supported multifocal thromboembolic disease. The temporal association between cerebellar infarction and onset of paroxysmal episodes supported a diagnosis of secondary PD. Clopidogrel was initiated. Further episodes occurred 46 and 87–90 days later; the latter cluster coincided with the presence of two visiting dogs. Two episodes were associated with owner-reported nystagmus alongside PD signs consistent with those observed previously. Relevance and novel information This report describes a novel PD-like movement disorder associated with cerebellar infarction in a cat. Unlike most reported feline PD cases, which are idiopathic or metabolic (hyperthyroidism), it supports a structural cerebrovascular aetiology involving cerebellar motor networks. Although causality cannot be definitively established, the findings support emerging concepts that paroxysmal dyskinesia may arise from dysfunction within distributed motor networks, including cerebellar–thalamo–cortical pathways, rather than being exclusively attributable to basal nuclei circuitry.