Paroxysmal kinesigenic dyskinesia: a diagnostic challenge

A 10-year-old girl presented with a month long history of episodic limb movements. She had a normal neurological examination and after thorough investigation, she was thought to have possible tics. Anxiety was reported as being a trigger. Unusually, these 'tics' were not directly witnessed during hospital visits. Eighteen months after the initial presentation, the clinician observed dystonic posturing after the child stood up from having been seated during a consultation. Paroxysmal kinesigenic dyskinesia (PKD) was then suspected and confirmed on genetic testing. She was successfully treated with carbamazepine. In hindsight, it became apparent that her anxiety was related to a fear of uncontrolled movements, rather than it being a trigger. The abnormal involuntary movements in PKD are precipitated by sudden voluntary movement. Lack of recognition of this typical feature, normal examination and/or features such as coexisting anxiety can lead to misdiagnosis or delayed diagnosis of this easily treatable condition.