The Effectiveness of Perampanel for Myoclonic Seizures in Down Syndrome with Isodicentric Chromosome 21

Abstract

Epileptic seizures are common in the elderly Down syndrome population. We encountered a patient with Down syndrome in whom karyotyping showed the rare isodicentric chromosome 21 and who suffered from myoclonic seizures. A 52-year-old woman with Down syndrome experienced sudden onset of drowsiness and frequent myoclonic jerks in the upper body. Video-EEG recordings demonstrated generalized polyspike-wave discharges consistent with myoclonic jerks, which were exacerbated by photo-stimulation. Her myoclonus completely resolved with perampanel administration. Perampanel was effective for myoclonic seizures in our patient. We suggest that perampanel is an option as first-line therapy for epilepsy and myoclonus in elderly Down syndrome patients.

Keywords: Down syndrome; Epilepsy; Isodicentric chromosome 21; Myoclonus; Perampanel.

Fig. 1

a Video-EEG taken at the referral day shows generalized polyspike-wave complexes (arrows) consistent with myoclonic jerks on the monitor. b Intermittent photo-stimulation at 12 Hz induces polyspike-wave complexes and myoclonic jerks.

Fig. 2

a Brain MRI shows severe cortical atrophy and ventricle enlargement. b On diffusion-weighted image, no high-intensity lesion is found. c Single-photon emission computed tomography reveals a significant hypoperfusion around the Sylvian fissure, parietal region, and cingulate gyrus. d Chromosome analysis detects a female karyotype denoted by 46, XX, idic(21)(q22.3) with a normal chromosome 21 and an isodicentric chromosome 21. idic, isodicentric chromosome.