Paediatrics: Paroxysmal episodes: not epilepsy

Paroxysmal episodes: not epilepsy

Up to one-third of children diagnosed with ‘epilepsy’ actually have non-epileptic events. In adolescents presenting to emergency teams in ‘sta-tus epilepticus’, over half turn out to have non-epileptic psychologically induced episodes. Think carefully about other paroxysmal episodes (such as those described below) before diagnosing a form of epilepsy and treat-ing the child with anticonvulsants.

Aetiology

It is best to consider the cause of paroxysmal episodes according to the age of the child.

Neonates and infants

·  Benign neonatal sleep myoclonus: these are single or repetitive episodes of jerking of arms and legs (typically while falling asleep after a feed) and sparing the face.

·  Shuddering attacks.

Older infants and toddlers

·  ‘Breath-holding attacks’ and RAS: history of suddenly going limp (or syncope), which may be followed by clonic jerking (e.g. RAS). On closer questioning at least 1 episode has been triggered by a noxious stimulus (e.g. banging head). Typically, there is a short cry and then the child goes limp, collapses to floor, and may have brief jerking movements. Other episodes are characterized by ‘blue’ breath-holding where the child starts to cry for any reason, the crying builds up, and then the child collapses to the floor at the end of expiration.

·  Masturbation and other gratification phenomena: when the child is bored they indulge in self-stimulation. In girls, the legs are held outstretched, and the eyes are glazed. Sweatiness almost invariably raises the possibility of a tonic seizure and these episodes are commonly mistreated as epilepsy.

·  Febrile myoclonus: short jerks associated with high fever.

·  Benign paroxysmal vertigo of childhood: acute onset of fear, nausea, vertigo, and unsteadiness if forced to walk. Rarely, the child vomits and they may have nystagmus.

·  Benign paroxysmal torticollis: acute episodes of head tilt, similar to the nystagmus seen in benign paroxysmal vertigo.

·  Night terrors: while in deep sleep, about 1–2hr after bed, the child suddenly wakes up and is inconsolable. This lasts some 10–20min and then child ‘wakes’, looks confused, rolls over, and sleeps again.

Childhood

Daydreaming

This episode can appear very similar to an absence seizure. However, the latter will occur at home during activity as well as at school. Classical absences, as part of an idiopathic generalized epilepsy, can be elicited on an EEG (taken during normal and sleep deprived state) in over 95% of cases. They are short, associated with abrupt psychomo-tor arrest and immediate resumption of activity, speech, and thought.

Absences as part of a focal seizure disorder will only very rarely occur without some other suggestive feature such as an automatism, abnormal movement, or postictal state.

Syncope

·Also known as fainting.

·Occurs from age 7mths onwards. There may well be a history of precipitating events (e.g. fright, head bang, sudden standing, hair-brushing).

·Often the child has an aura of loss of vision, tingling, and auditory phenomen, this is followed by loss of consciousness and posture change: falls over if standing. Not all syncopal events result in a loss of tone. In some, the fall is accompanied by increased tone.

·Myoclonic jerks may follow for a few seconds. Useful tools in diagnosis include: a history of a precipitant; jerking lasting less than 20secs; and the movements may not be rhythmic.

·If in doubt assume that it is syncope until there is evidence otherwise (see Psychologically determined paroxysmal events (PDPE)).

Caution If there is a history of sudden death in the family, or of syn-cope induced by sudden physical stress such as exercise or sleep, long QT syndrome should be investigated.

Psychologically determined paroxysmal events (PDPE)

This is a less pejorative term to describe episodes of psychological origin that used to be described as hysteria, and more recently as pseudosei-zures, malingering, factitious or conversion disorders. The episodes are a psychological phenomenon, although identifying or looking for the psy-chological causes at time of diagnosis can be misleading or even counter-productive. There is no single event that will separate them from epilepsy. Some children rarely may even have both.

Features suggestive of, but not diagnostic of PDPE

·  Events triggered by specific situations

·  Events with convulsive movements that are not explained anatomically, e.g. left arm jerking, then lull followed by right leg

·  Thrashing movements that wax and wane, +/– pelvic thrusting

·  Eyes open during the episode

·  Slumping to the floor in a dramatic manner. Falls without injury

·  Violence, rather than violent movements

·  Gain from the situation

·  Generalized movements with rapid return to normal

These features are not diagnostic. There is no never or always. In partic-ular, young people can injure themselves and pass urine in PDPE, which are often misreported as a diagnostic feature of genuine seizures.