Page 125 - ILAE_Lectures_2015

Juvenile absence epilepsy (JAE)20,28,29 is mainly characterised by TA that are similar to
those in CAE, but much less frequent and probably not as severe. Age at onset of TA is 7-
16 years with a peak at 10–12 years. Random and infrequent myoclonic jerks15,30, as well
as infrequent GTCS, occur in most of the patients. One-fifth of patients also suffer attacks
of absence status epilepticus31.

TA may be frequent, sometimes daily. The interrupted ongoing voluntary activity may be
partly restored during the ictus, and clinical recovery may occur prior to the termination of
the EEG ictal discharge. Automatisms are frequent, usually occurring 6-10 seconds after
the onset of the discharge. The combination of peri-oral or hand automatisms and staring
may lead to misdiagnosis of such TA for complex partial (limbic) seizure and vice versa6.
JAE is usually a life-long disorder, but absences tend to become less severe with age. The
ictal EEG is not fundamentally different than in CAE. Similarly to the latter, ictal features
such as mild impairment of consciousness and brief ictal discharges (less than 4 seconds),
eyelid or perioral myoclonus, rhythmic limb jerking, and single or arrhythmic myoclonic
jerks are thought to be exclusion criteria for JAE. As with CAE, 80% or more of the patients
become seizure free with appropriate treatment, but the risk of relapse following
discontinuation of medication is not clearly defined.

Juvenile myoclonic epilepsy (JME) (Janz syndrome)32 is characterised by myoclonic jerks
on awakening, GTCS, and TA, with the latter occurring in more than one-third of the
patients28,33,34. However, TA are not the predominant seizure type, and are usually very mild
and simple (with no automatisms or localised limb jerks). Seizure precipitating factors
include sleep deprivation and fatigue, alcohol, and mental and psychological arousal, and
up to 40% of patients are photosensitive33. TA, when present, begin between the ages of
five and 16 years, MS usually follow sooner or later, with the GTCS being the last to appear
in most cases. An adult form of this syndrome has also been described35. All seizure types
are probably life-long, although TA may become less severe with age, and MS and GTCS
commonly improve after the fourth decade of life. Prevalence of JME alone is around 9%
of adults with seizures34, and both sexes are equally affected. Generalised spike-wave
discharges at 3–6 Hz have an unstable intradischarge frequency with fragmentations and
multiple spikes.

Myoclonic absence epilepsy (MAE) is a rare generalised cryptogenic or symptomatic
absence epilepsy, although an idiopathic form may also exist. TA occur many times a day
and constitute the predominant seizure type. Ictally, severe bilateral rhythmical clonic jerks
are often associated with a tonic contraction, and some awareness is maintained. Age of
onset is around seven years, and there is a male preponderance. Prognosis is not good
because of resistance to therapy, mental deterioration, and possible evolution to other types
of epilepsy such as Lennox-Gastaut syndrome36,37.

Epilepsy with GTCS on awakening. The term denotes an idiopathic propensity to mainly or
exclusively GTCS that occur mostly within the first two hours after awakening from
sleep3,38,39. They may also occur when the patient is awake at times of relaxation and leisure.
Age at onset is mainly in the mid-teens but may start earlier or much later. Sleep deprivation,
fatigue and excessive alcohol consumption are main precipitating factors. GTCS tend to
increase in frequency with age, and may become unpredictable occurring also during sleep
and alert stages. Avoidance of precipitating factors and adjustment of lifestyle are essential
for the best management of these patients.

There is a considerable overlap with other IGEs that also manifest a similar circadian
distribution and precipitating factors. Idiopathic epilepsy with GTCS on awakening3 is no
longer recognised as a separate syndrome7. Instead, this is now rightly considered as part of
‘IGE with GTCS only’, referring to all patients with GTCS only, irrespective of circadian