Paroxysmal kinesigenic dystonia mimics focal seizure

Abstract

Dystonia refers to a syndrome of involuntary sustained or spasmodic muscle contractions involving co-contraction of the agonist and the antagonist. Paroxysmal kinesigenic dyskinesia is one of the rare episodic hyperkinetic movement disorders, characterized by brief attacks of abnormal involuntary movements comprising of dystonia, chorea, athetosis, hemiballismus or a combination, usually precipitated by sudden movements. A 16 years old male previously healthy presented with 1 year history of involuntary movement descried as a sudden stiffness of the left arm, sometimes involving the left side of the body after sudden movement of the trunk or while standing up after prolonged physical rest. The spells usually lasted up to 30 to 60 seconds with frequency 3-4/week and were painless. The patient never had a loss of consciousness during spells. He had a normal physical and neurological examination. Brain MRI, routine EEG, laboratory tests including liver functions testes, serum ceruplasmin and copper and 24 hours urine copper were all normal. Simple partial seizure disorder was suspected. As part of workup the patient was admitted in epilepsy monitoring unite and had a long term video EEG. Recoded spells were consistent with a focal dystonic posturing in the left side of the body precipitated by sudden active movement with a normal EEG background, without any epileptiform discharges . Carbamazepine 200 mg /day was initiated as a treatment of kinesigenic dystonia with good clinical response. Paroxysmal kinesigenic dystonia can be frequently misdiagnosed with other medical conditions and required careful clinical assessment and work up.