ABSTRACT
Juvenile myoclonic epilepsy (JME) is a genetically determined idiopathic generalized epilepsy (IGE), characterized by myoclonic jerks on awakening, generalized tonic-clonic seizures (GTCS) and, in around one third of patients, typical absences (Figure 12B.1).1,2 Janz’s contributions over the last 40 years in all aspects of JME fully justify the eponym Janz syndrome.3-5
The following description, an extract from a patient’s diary, epitomizes the clinical syndrome:6
Myoclonic jerks occurring after awakening are the most prominent and pathognomonic seizure type.3,4,7-10 They are shock-like, irregular and arrhythmic, clonic movements of proximal and distal muscles, mainly of the upper extremities. They are often inconspicuous, restricted to the fingers, making the patient prone to drop things or look clumsy. They may be violent enough to cause falls. One fifth of the patients describe their jerks as unilateral, but video-EEG shows that the jerks affect both sides (Figure 12B.2).4,11
Some patients, less than 10 per cent, with mild forms of JME never develop GTCS.10
