[Late-onset of idiopathic paroxysmal kinesigenic choreoathetosis: a case report]

A case of late-onset idiopathic paroxysmal kinesigenic choreoathetosis (PKC) is described herein. A 50-year-old right-handed Japanese man with no family history of neurological disease or consanguinity was referred to our neurological unit because of paroxysmal involuntary movement of his right extremities. Physical examination findings were normal. Neurological examination during the interictal period revealed no abnormality. The attacks were triggered by abrupt initiation of voluntary movement and occurred about 30 times a day, lasting 30 to 60 seconds with no disturbance of consciousness. No metabolic abnormalities were found, and brain magnetic resonance imaging showed no abnormality including lacunar infarction. Interictal single photon emission computed tomography (SPECT) showed hypoperfusion of left basal ganglia. Interictal electroencephalography was normal without epileptic discharges. Because the patient did not have any condition that could cause secondary PKC, he was diagnosed as having idiopathic PKC. Treatment with carbamazepine 200 mg once a day resulted in control of the attacks, and 500 mg a day resulted complete resolution. To the best of our knowledge, this case may represent the oldest age reported for idiopathic PKC onset. Although the etiology of PKC remains unknown, late-onset idiopathic PKC is rare. Our SPECT finding leads us to suppose that dysfunction of the basal ganglia is likely involved in the pathogenesis of PKC.