VIDEO-POLYGRAPHIC ANALYSIS OF MYOCLONIC SEIZURES IN JUVENILE MYOCLONIC EPILEPSY

We studied myoclonic seizures (MS) in 5 patients with juvenile myoclon ic epilepsy (JME) using video polygraphic recordings to investigate th e clinical characteristics of MS in this epileptic syndrome. The total number of MS analyzed was 302 (range 27-125, mean 60) seizures per pa tient. MS occurred either singly or repetitively (37 vs. 63%) and corr esponded to generalized bilaterally synchronous single or multispike-a nd-wave complexes at 3-5 Hz. Video analysis of the myoclonic jerks dem onstrated that either distal or proximal muscle involvement predominat ed. In the former, there was mild bilateral flexion and some external rotation of the forearms. In the latter, flexion of both arms at the e lbow, flexion and abduction of the thighs, and extension of the back w as observed. Asymmetry of MS was noted in 4 of 5 patients. Facial invo lvement of MS occurred infre quently in 2 patients. When the patients kept both arms outstretched, the arms dropped or there was sudden inte rruption of ongoing electromyographic (EMG) potentials immediately aft er myoclonic jerks (postmyoclonic inhibition) in all patients. One sho uld inquire about these clinical characteristics of MS in JME when tak ing a thorough history in patients with primary generalized tonic-clon ic seizures (GTC).