Generalized Epilepsy Syndromes in Children

Generalized Epilepsy Syndromes in Children

There are three types of genetic generalized epilepsy syndromes with childhood or juvenile onset which often continue into adulthood. They are Juvenile Myoclonic Epilepsy (JME), Childhood Absence Epilepsy (CAE), and Juvenile Absence Epilepsy (JAE).

Even though each particular syndrome has specific diagnostic criteria, the difference between them may be sometimes pretty obscure; especially at the onset of the symptoms.

There is no single gene responsible for each particular syndrome, so even among the patients with the same syndrome there is a great variability in symptom presentation and prognosis.

All three syndromes may have some or all of the following types of seizures: absence, myoclonus, generalized tonic clonic seizure.

Absence

Absence (spells of spacing out), or transient loss of consciousness without fall or convulsions, is an essential component of childhood and juvenile absence epilepsy syndromes. Absences may occur or may not in JME, and if they do, their onset may precede the rest of the symptoms by a few years.

Absences in each particular syndrome are somewhat different and this difference is one of the keys to the right diagnosis.
In Childhood form of Absence Epilepsy there are hundreds of absences per day, they are brief with rapid loss of consciousness and rapid recovery. Absences are precipitated by hyperventilation. Remit by adolescence.
In Juvenile Absence Epilepsy absences last longer and loss of consciousness may be less profound.  Absences are usually less frequent or may even be occasional. Absences are triggered by hyperventilation and mental and emotional alertness. Remit by adolescence.
In Juvenile Myoclonic Epilepsy absence are infrequent, have variable level of loss of consciousness, may be gradual in onset and recovery, and are triggered by low level of alertness.

Generalized Tonic-clonic Seizures (GTCS)

In Juvenile Absence Epilepsy, GTCS typically start in adolescence and continue through adulthood with variable but usually low frequency.
In Childhood Absence Epilepsy GTCS may occur in some patients later in life but their appearance may put the diagnosis into question.
All patients with Juvenile Myoclonic Epilepsy have at least a single GTCS over a life time.

Myoclonus

Myoclonus is a jerky movement similar to the ones that we all experience while falling asleep.

In Childhood Absence Epilepsy they are limited of eyelids and brows. In Juvenile form Absence Epilepsy they may occur occasionally in other parts of the body.
In Juvenile Myoclonic Epilepsy myoclonus is an essential symptom, which usually affects upper extremities shortly after awakening.

Electroencephalogram is also helpful in differentiation of these epilepsy syndromes. See individual articles about each particular syndrome.