Nocturnal Frontal Lobe Epilepsy Presenting as Obstructive Type Sleep Apnea
A 20-year-old man visited our sleep center because of snoring and sleep apnoea; the symptoms had started two years prior. He worked for the military, and his apnea and snoring were bothering colleagues in the barracks. His daily life was normal, and he had neither a family history nor a medical history of seizures and had previously been healthy. His Epworth Sleepiness Scale (ESS) score was 14 out of 24, which suggested moderate excessive daytime sleepiness. He especially complained of severe sleepiness in the morning. No parasomnia events or periodic limb movements during sleep had been reported. No tongue biting was reported, but he reported recent occasional enuresis. Physical examination revealed no apparent abnormalities. His body mass index (BMI) was 23.1 kg/m2.\nOvernight polysomnography was performed. Sleep efficiency was 81.9%, wakefulness after sleep onset (WASO) time was 59.2 minutes (17.8%), and his arousal index was 28.7/h. Stage 1 and 2 sleep were increased; however, stage 3 and REM sleep were decreased. He experienced nine apneas and two hypopneas during PSG, each episode lasted 20–40 seconds. His apnea/hypopnea index (AHI) was 2.7/h. These apneic episodes consisted of respiratory cessation accompanied by chest and abdominal movements of the obstructive type. All hypopnea was typical hypopneas. Seven out of nine apneic episodes were accompanied by rhythmic paroxysmal discharges in the bifrontal areas on EEG; clinically, five of the episodes progressed to tonic movement of all four limbs, and two episodes showed apneas only. All that seven episodes occurred during NREM sleep (two in stage 1, four in stage 2, and the others in stage 3). The other apnea and hypopnea did not accompany tonic movement.\nThe next night, a 16-channel video-EEG monitoring was performed to classify these events and to determine the temporal relationship of apnea onset and Ictal discharge. Ten apneic events with ictal discharges preceding the apnoea were recorded throughout the night. Ictal EEG showed paroxysmal rhythmic discharges in the range of 9 to 10Hz in the bifrontal area starting just before onset of the apneic episodes. The interictal EEG was normal, and brain MRI showed no specific abnormality. Ictal SPECT revealed increased cerebral blood perfusion in the right frontal region (). Given these findings, we concluded that these events were epileptic seizures presenting as obstructive sleep apnoea. Carbamazepine therapy was initiated, and the nocturnal episodes were decreased.