Autonomic seizures in 18q- syndrome

The 18q- syndrome is due to (terminal) deletion in the long arm of chromosome 18 with variable break points. The phenotype is also variable, with a variety of dysmorphisms, neurological deficits possibly related to haploinsufficiency of the gene for myelin basic protein, and frequent cardiac problems. The diagnosis of paroxysmal events in 18q- syndrome presents difficulties because both epileptic seizures and cardiac syncopes might be expected to occur. Autonomic seizures are epileptic seizures consisting of episodic alterations of autonomic function that are elicited by activation of autonomic cortical centres. In such events confusion with syncope is even more likely. A previous case of autonomic seizures masquerading as syncope in an adult has been reported. The present report is the first to describe autonomic seizures in 18q- syndrome in a child. Very frequent episodes of prolonged apnoea with profound oxygen desaturation was associated with a focal EEG discharge, arising from either the right temporal or left temporal region. As in the adult patient referred to, the seizures ceased on carbamazepine. No systematic studies of incidence have been published, but autonomic epileptic seizures simulating non-epileptic syncopes may be a feature of 18q- syndrome.