Unknown but with increasing reports of ADNFLE families.
Age at onset
Markedly variable (2 months to 56 years); peak at 11 years; 90% <20 years.
Males = females.
Neurological and mental state
Autosomal dominant with 70% penetrance. Linkage to chromosomes 20q and 15q. Mutations have been identified in the CHRNA4 gene encoding the neuronal nicotinic acetylcholine receptor (nACHR) alpha 4 subunit protein and CHRNB2 encoding the nACHR beta 2 subunit protein. The clinical phenotypes appear markedly homogeneous.
Hypermotor seizures (identical to those originating from the supplementary somatosensory area) are frequent (nearly every night), occur in clusters, and are brief (20 to 50 sec). Sudden, hyperkinetic movements and dystonic posturing or tonic stiffening of the limbs and the body occur, often with superimposed clonic components. Patients may be thrown out of bed or find themselves prone in a crawling position. Injuries may occur. Sleep is abruptly interrupted but immediately resumes with the end of the seizure. Post-ictal state is normal.
2/3 of patients experience a non-specific aura of somatosensory, sensory, psychic, and autonomic symptoms.
Consciousness is usually preserved.
Secondarily generalized tonic-clonic seizures, occurring in 2/3, are infrequent, mainly in untreated patients.
Nearly exclusive in sleep (hypnagogic state or shortly before awakening).
Brain imaging is normal.
Usually normal but 12% to 65% have frontal lobe epileptiform abnormalities, mainly in sleep.
Usually normal. In 40% to 88%, repetitive frontal sharp waves are intermixed with spikes or rhythmic theta (unilateral frontal or bifrontal).
Seizures are lifelong, with spontaneous remissions and relapses. Attacks become milder after ages 50 to 60. Severity varies from mild (seizures appearing only in brief periods) to severe (frequent and intractable seizures).
Usually misdiagnosed as benign nocturnal parasomnias, night terrors, nightmares, obstructive sleep apnea syndrome, psychiatric and medical disorders. 'Nocturnal paroxysmal dystonia' and 'hypnic tonic postural seizures of frontal lobe origin' are certainly frontal lobe seizures and most patients probably have ADNFLE.
As for focal seizures; 1/3 of patients are resistant to carbamazepine. Newer drugs licensed for focal epilepsies may be effective.
*Expert opinion, please check FDA-approved indications and prescribing information
This page was adapted from:
The educational kit on epilepsies: The epileptic syndromes By C. P. Panayiotopoulos Originally published by MEDICINAE
21 Cave Street, Oxford OX4 1BA
First published 2006 and reprinted in 2007