QT interval prolongation in a patient with LQT2 on levetiracetam

Abstract

We report the case of a 24-year old female with a seizure disorder and previously undiagnosed long QT syndrome whose QT interval increased and developed into torsades de pointes after her levetiracetam dose was increased. The patient had been having seizures since age 10. The episodes typically occurred in the early morning and witnesses describe shaking of her entire body, incontinence, and while the patient was not aware of the events at the time when they occurred, she did get tired and confused after the events. She had been started on carbamazepine as a child, with escalating doses as she aged. She presented to the NorthShore epilepsy clinic for the first time after a generalized seizure, and was started on levetiracetam 250 mg twice a day with the plan of increasing the dose over weeks then weaning her carbamazepine (initial random carbamazepine level was 10.1 mg/ml). A brain MRI showed minimal T2 hyperintensities in white matter which were interpreted as non-specific. Her EEG showed intermittent right temporal sharp waves with an electrophysiological maximum at T4 and occasional right temporal polymorphic theta-range slowing suggestive of mild focal cerebral dysfunction. While seizures have not been captured on EEG, the combination of her clinical presentation and focal abnormalities on