Anoxic seizures: self-terminating syncopes.

This review focuses on anoxic seizures induced by self terminating syncopes in the young. Anoxic seizures are nonepileptic events consequent upon abrupt interruption of the energy supply to metabolically active cerebral neurones. Anoxic seizures are the most common paroxysmal events misdiagnosed as epilepsy. Neurally mediated syncopes have numerous appellations, especially in the young. This proliferation of terminology likely results from uncertainty regarding pathophysiology. The most important type of self-limiting syncope from the point of view of diagnostic difficulty has been called neurocardiogenic or vasovagal syncope and reflex anoxic seizure, amongst other names: this review includes a video clip of such a child with prolonged asystole. It also includes a detailed case history emphasising the feelings of a patient with this type of syncope who was misdiagnosed as having epilepsy for many years. The second class of self-terminating syncope discussed and illustrated on video is the so-called breath-holding spell of young children. The third example illustrated is the compulsive Valsalva manoeuvre of individuals with autistic spectrum disorder, in which anoxic seizures - as shown on the video clips - are easily misdiagnosed as epileptic seizures, with unfortunate consequences.