A 24-year-old woman presented with a 3.5-year history of paroxysmal dystonia that was precipitated by sudden movement, especially when she started to walk. It was characterised by shrugging of shoulders, flexion of the neck and thoracic spine, and stiffness of the right leg followed by falls. Each attack lasted for less than 5min. Inadequate sleep and stress were exacerbating factors. There was no similar family history. Physical examination and investigations were normal. The following manoeuvres that caused vestibular stimulation precipitated attacks: turning her head from side to side while standing still, sitting still on a rotating chair and an ice-water caloric test. She had partial responses to phenytoin and levodopa, and a good response to haloperidol. Vestibular stimulation as a precipitating factor in paroxysmal kinesigenic choreoathetosis has not been reported previously.
Secondary paroxysmal dyskinesias (PxD) have been previously reported in patients with multiple sclerosis, lacunar infarcts, head trauma, metabolic disorders such as hyperglycaemia, hypocalcaemia, migraine and central nervous system (CNS) infections. The causative lesions typically involve the basal ganglia structures, medulla and rarely the spinal cord. We report two patients who presented with paroxysmal dyskinesias as the only manifestation of subcortical white-matter ischaemia. Patient 1 presented with 3-year history of paroxysmal kinesigenic dyskinesia (PKD) and patient 2 with 6-month history of paroxysmal nonkinesigenic dyskinesia (PNKD). All investigations, including CSF oligoclonal bands were negative, except for a brain MRI which showed multiple, non-enhancing subcortical white matter lacunar infarcts. Therefore, subcortical white matter ischaemia should also be included in the differential diagnosis of PxD.