Title : A rare case of paroxysmal kinesigenic dyskinesia
Abstract:
Introduction: Paroxysmal Kinesigenic Dyskinesia (PKD) is a rare neurologic disorder characterized by transient, episodic, involuntary hyperkinetic movements such as chorea, dystonia, myoclonus, or ballism. It is triggered by sudden voluntary movements, commonly present in young adults with a male predominance. We report a case of a young female with choreiform and ballistic movements lasting over two to three minutes which is an uncommon presentation for PKD.
Case Presentation: A 24-year-old female with a history of asthma was transferred to our facility for evaluation of seizure disorder. The patient was witnessed to have sudden onset, focal, ballistic movements in the right arm that quickly spread to the rest of the body. She would subsequently lose all bodily muscle tone and throw herself from one end of the bed to the other without losing consciousness. Spells were preceded and accompanied by sinus tachycardia and were provoked by voluntary motor activities such as standing, walking, or a change of posture. Her episodes had been ongoing for one month and would recur fifteen to twenty times per day, each lasting two to three minutes. Physical and neurologic examination were otherwise normal in between episodes. She was initially diagnosed as having focal seizures with secondary generalization and treated with levetiracetam but did not experience any improvement. Complete blood count, comprehensive metabolic panel, thyroid panel, vitamin B12, urine drug screen, Treponema pallidum antibody, and HIV screen were all negative. 24-hour electroencephalogram with video monitoring while patient had her episodes did not show any epileptiform activity. MRI brain with and without contrast did not show any abnormality. Cerebrospinal Fluid analysis revealed a normal cell count, protein, and glucose levels, and was negative for Herpes Simplex Virus (HSV)-1, HSV-2, West Nile virus IgG/IgM. CSF culture had no growth. A diagnosis of PKD was considered and the patient was started on Carbamazepine 100mg twice daily. Levetiracetam was discontinued, and she was on no other antiepileptics. Initially, her episodes continued. After two days, the carbamazepine dose was increased from 100mg to 200mg twice daily. After three days on this higher dose, the patient demonstrated dramatic improvement. The frequency of her episodes decreased to only three to five per day, with a duration of less than one minute per episode. By the end of her hospitalization, she walked 400 meters with physical therapy, gained independence in most of her activities of daily living, and had only two spells a day lasting under one minute.
Discussion: PKD is a rare dyskinetic disorder with an estimated prevalence of 1/150,000. It is a diagnosis of exclusion, often misdiagnosed as an epileptic seizure or psychogenic non-epileptic seizure, the latter especially due to the age group of patients affected. Upon literature review, we found a paucity of standardization of diagnostic protocols. Diagnosis requires exhaustive workup ruling out infectious and metabolic causes as in our patient. Studies have demonstrated a dramatic response of PKD to anticonvulsants, particularly sodium channel blockers like Carbamazepine and Phenytoin. This case will prompt the diagnosis and management of this rare entity.
Audience Take Away Notes:
- Recognizing clinical features of Paroxysmal Kinesigenic Dyskinesia
- Establishing a diagnosis while systematically ruling out similar conditions
- Developing treatment plans
