Pearls & Oy-sters: Diagnostic challenges in nocturnal frontal lobe epilepsy.

Abstract

A 43-year-old man of normal intelligence consulted our outpatient clinic for nocturnal events that had started at age 32 years. These arise from sleep when he suddenly awakens, experiencing fear and the sensation of falling into a black hole or choking. He recalls raising his body and turning his head but does not recall what happens afterwards. His partner reported the events to be stereotyped, and occurring mostly after 1–2 hours of sleep. After rising, he falls backwards in the bed and jerks his arms and legs. He is unconscious for 3–5 minutes. Afterwards, he is confused and disorientated, and sometimes wanders through the house. These events occur once every 2 months and are debilitating. They affect his relationship and cause daytime sleepiness. Serial EEGs (including sleep deprivation), polysomnography, and MRI of the brain were normal. The individual was referred to our clinic for a 24-hour EEG video recording aiming to record an event. This EEG showed sporadic interictal epileptiform discharges (sharp waves, slow spike wave complexes), predominantly over the left frontotemporal area, but also over the right frontotemporal and frontal areas. During the night, 4 almost identical events occurred during non-REM (NREM) 1 and 2 sleep. In these events, the patient abruptly rose from the bed, looked around with an anxious expression, and went back to sleep after less than 20 seconds. In 2 events, an extension of the right hand was noted. The episodes were not followed by a phase of limb-shaking or by disorientation. He did not call the nursing staff or remember the episodes afterwards. The EEG showed a K-complex at the beginning of each of these events, followed by a diffuse 11–12 Hz rhythm for several seconds, and was once followed by a short delta rhythm over the left frontotemporal region (figure). The episodes were accompanied by an acceleration of heart rate (from 54 to 72 bpm). After the event, when he closed his eyes again, a normal posterior dominant α rhythm was seen. As the events did not clinically resemble a physiologic arousal (due to the abrupt onset, marked stereotypy, and the tonic extension of the right hand), and in combination with the consistent (ictal) EEG findings, these episodes were considered to be of epileptic origin, and a diagnosis of NFLE was made (with paroxysmal arousals, sometimes with secondary generalization). Based on our findings during the EEG video recording, we speculated that the patient probably had more seizures than previously reported, which could also explain the excessive daytime sleepiness (EDS). Treatment was started with levetiracetam 1,000 mg twice daily and he became seizure-free. Moreover, EDS disappeared, confirming our hypothesis.