Syncopes and other paroxysmal events

Paroxysmal nonepileptic disorders are very frequent in infants and children and pediatric neurologists need to be as familiar with them as with epileptic seizures. Syncopes are the most important of these episodic disorders and amongst the syncopes the various subtypes of so-called neurally mediated syncopes (vagal, vasovagal, and so forth) predominate. In such syncopes there is almost always a trigger or provoking situation and this is the major clinical clue to the diagnosis. Whatever the mechanism of a syncope it is commonly "convulsive" in that there is a motor element, with tonic extensions and arrhythmic nonepileptic spasms ("jerks"). This everyday situation must be distinguished from the much less common combination of a syncope and a true epileptic seizure. In such anoxic-epileptic seizures the epileptic component is usually clonic, with rhythmic or semi-rhythmic jerks quite different from the arrhythmic spasms of the usual nonepileptic convulsive syncope. Syncope from compulsive Valsalva maneuver may be extremely frequent in affected (usually autistic) children. Diagnosis is easy if one obtains a video recording with audio: the premonitory hyperventilation stops leaving 11 seconds of silence before the tonic extension that signifies the syncope. Syncopes of more serious kind include those in long QT syndrome, hyperekplexia, paroxysmal extreme pain disorder, and congenital myasthenia; each has recognizable characteristics. Other nonsyncopal nonepileptic paroxysmal disorders are described further in the text.