Diagnosis Of Nocturnal Frontal Lobe Epilepsy Research Articles

Incidence of sudden unexpected death in nocturnal frontal lobe epilepsy: a cohort study

ObjectiveMost cases of sudden unexpected death in epilepsy (SUDEP) follow a seizure, and most deaths occur while people are in bed, presumably sleeping. Nocturnal seizures are reported to be a risk factor for SUDEP. People with nocturnal frontal lobe epilepsy (NFLE) have seizures predominantly or exclusively during sleep, often many times per night. The present study aimed to assess whether NFLE represents a high-risk condition for SUDEP. MethodsThe present study retrospectively assessed the incidence of SUDEP in a cohort reconstructed from a dedicated database of consecutive patients referred to the Epilepsy and Sleep Centres of the Institute of Neurological Sciences of Bologna from 1980 to 2012 with: (1) a diagnosis of NFLE, (2) at least 90% of seizures during sleep, and (3) at least one-year of follow-up. ResultsOne hundred and three people were included. The median time from seizure onset to last observation was 26 years, equal to a follow-up of 2789 person-years. One person died of SUDEP during the follow-up period. The incidence rate of SUDEP was 0.36 per 1000 person-years (95% CI 0.01 to 2.0). ConclusionsThe incidence of SUDEP in the participant population was not higher than the rates previously reported in prevalent epilepsy populations (0.4 to 2.3 per 1000 person-years). The low prevalence of SUDEP might reflect the low occurrence of generalised tonic-clonic seizures in people with NFLE.

Nocturnal epileptic seizures versus the arousal parasomnias

We review here the clinical features of Nocturnal Frontal Lobe Epilepsy (NFLE) and the arousal parasomnias, to define possible differential diagnostic criteria and their inter-observer reliability, and to determine whether both conditions share a common disturbance of arousal mechanisms. Polysomnographic recordings defined several types of seizures in NFLE: Paroxysmal Arousals (PA), Nocturnal Paroxysmal Dystonia (NPD), Epileptic Nocturnal Wanderings (ENW). There are however several difficulties with the diagnosis of NFLE, not the least being that EEG discharges during the seizures are not universally found. These diagnostic difficulties are highlighted, as well as the fact that studies of the inter-observer reliability of the video polysomnographic features of NFLE were found unsatisfactory, especially for the PA. When NFLE patients and their relatives were matched to control subjects and analysed in regard to personal and family history for the parasomnias, the arousal parasomnias were reported significantly higher by patients with NFLE and their relatives. This higher recurrence of a personal and family history for the parasomnias in NFLE patients suggests that the two conditions share a common underlying mechanism. Based on evidence from Autosomal Dominant NFLE, a genetic disorder with mutations in nicotinic acetylcholine receptors(nAchR), we hypothesise that arousal parasomnias and NFLE both, have abnormal arousal mechanisms in the dorsal cholinergic arousal branch triggering peculiar motor patterns in the medial frontal lobe regions.

Distinguishing Sleep Disorders From Seizures

Abnormal paroxysmal events in sleep may be parasomnias or epileptic seizures. In nocturnal frontal lobe epilepsy (NFLE), the unusual seizure features often lead to diagnostic confusion with nonepileptic parasomnias; video-electroencephalography monitoring is usually required to make the diagnosis. To examine the reliability of the clinical history in diagnosing NFLE, using the Frontal Lobe Epilepsy and Parasomnias (FLEP) scale. The FLEP scale, comprising specific questions reflecting the diagnostic features of NFLE and parasomnias, was developed by an expert panel following review of the literature. It was then validated in a sample of individuals with firmly diagnosed nocturnal events. Patients were recruited after appropriate diagnostic workup in tertiary sleep and epilepsy referral centers in Melbourne, Australia. Sixty-two patients (45 males) [corrected] with paroxysmal nocturnal events. Intervention Two independent interviews were conducted in each case, with the patient and a witness, by researchers blinded to the diagnosis. The diagnosis obtained from scores on the FLEP scale was compared with the confirmed diagnosis in each patient. Nocturnal frontal lobe epilepsy was correctly diagnosed from the FLEP score in 31 of 31 patients, with a sensitivity of 1.0 (95% confidence interval [CI], 0.85-1.00), specificity of 0.90 (95% CI, 0.73-0.97), positive predictive value of 0.91 (95% CI, 0.75-0.97), and negative predictive value of 1.00 (95% CI, 0.85-1.00). A diagnosis of NFLE can be made reliably using the clinical features identified in the FLEP scale. This may reduce the requirement for tertiary referral and extensive inpatient monitoring.

The neurophysiological evaluation of nocturnal frontal lobe epilepsy

The most reliable technique for the diagnosis of nocturnal frontal lobe epilepsy (NFLE) is nocturnal video-polysomnography, which is an expensive procedure and unavailable in many Departments of Neurology and Epileptology around the world. The aim of the present study was to evaluate the role of routine video-EEG and video-EEG after sleep deprivation, during the daytime, in the diagnosis of NFLE. We studied 23 patients complaining of repeated nocturnal motor attacks using a 3-level neurophysiological evaluation, including video-EEG when awake (level 1), video-EEG after sleep deprivation, during the daytime (level 2) and nocturnal video-polysomnography (level 3). All the patients had a normal video-EEG when awake. The video-EEG after sleep deprivation (level 2) allowed a diagnosis of NFLE in 52.2% of the patients, while the nocturnal video-polysomnography (level 3) allowed this diagnosis in 87.0% of the same sample. In the patients complaining of repeated nocturnal motor attacks, a video-EEG after sleep deprivation performed during the daytime, could be useful for diagnosis in about one half of cases. This methodology is routinely performed in many Departments of Neurology and Epileptology, and is much less binding and expensive than nocturnal video-polysomnography and so it could be important economically for the health service.