Levetiracetam: an unusual cause of delirium.

Levetiracetam is a second-generation anticonvulsant that was approved by the Federal Drug Administration in 1999 for the treatment of epilepsy. Recently, levetiracetam has become more popular for the prevention of posttraumatic seizures. Some of the well-known adverse effects of levetiracetam are somnolence, behavioral abnormalities, and less commonly, psychosis. Delirium is not a well-known adverse effect of levetiracetam. Here, we present the case of a 77-year-old Caucasian male who developed disorientation, agitation, and lethargy after initiation of levetiracetam to prevent posttraumatic seizures. Imaging on admission demonstrated a subacute subdural hematoma in the left frontal lobe without mass effect, and the patient was started on levetiracetam 500 mg intravenously twice daily. Less than 24 hours later, the patient began to display a fluctuating level of consciousness, disorientation, an inability to follow commands, and garbled speech. His symptoms continued for 12 days unabated despite episodic treatment with sedatives and antipsychotics. At one point, the patient progressed to aggressive behavior and required restraints. Laboratory tests during this period did not demonstrate signs of infection or metabolic abnormalities. Delirium from levetiracetam was suspected and the drug was discontinued. The patient's mental status improved dramatically within 24 hours after administration of the last dose of levetiracetam and he was discharged home. Based on the Naranjo scale, the episode of delirium was probably related to levetiracetam. Although the other neuropsychiatric effects of levetiracetam are well known, we highlight the first case of delirium without psychotic features associated with levetiracetam.