Isolated Unilateral EEG Findings in Juvenile Myoclonic Epilepsy: A Case Report

Abstract

Juvenile myoclonic epilepsy (JME) has well-defined clinical and electrophysiological features. On the other hand, large case series have shown that focal and asymmetrical discharges may accompany generalized epileptiform activities in JME. Although it is known that these non-generalized electrophysiological findings do not exclude the diagnosis of this syndrome, some findings may create confusion in the differential diagnosis. In this case report, a case of JME with electroencephalographic findings characterized by isolated unilateral epileptiform activities without typical generalized discharges was discussed. The current case clinically presented with involuntary jerk movements in the bilateral upper extremities. It has been determined that these movements are uni/bilateral myoclonic beats based on home video recordings. Metabolic, toxic and structural problems were excluded in the investigations for the etiology of myoclonus. In the electrophysiological examination performed for epileptic processes, epileptiform discharges localized to the isolated right hemisphere were observed. JME was considered primarily due to clinical findings in the patient, and effective seizure control was achieved in a 4-year follow-up under anti-seizure treatment. The peculiarity of the case is the presence of electrophysiology recordings of isolated unilateral epileptiform activity during the 4-year follow-up period. It should be emphasized that there is no case of JME diagnosed with isolated unilateral epileptiform activity in the absence of generalized spike-slow waves or multiple spike-slow waves in the literature.

Keywords: Electroencephalography; Generalized epilepsy; Juvenile myoclonic epilepsy.

Figure 1

Non-contrast cranial MRI examination within normal limits. Sections (A) axial T2/FLAIR-weighted, (B) axial T2-weighted, (C) coronal T2-weighted, and (D) sagittal T1-weighted. MRI, magnetic resonance imaging; FLAIR, fluid attenuated inversion recovery.

Figure 2

Isolated unilateral EEG findings of the patient. (A) Asymmetric slowing of the ground activity in the right hemisphere in wakefulness EEG. (B) Right hemisphere spike-slow wave paroxysms during hyperventilation. (C) Right hemisphere spike-slow wave paroxysms during sleep. EEG, electroencephalography.