Assessing the diagnostic performance of investigations in pediatric myoclonic epilepsies: A retrospective cohort study.

OBJECTIVE

The primary purpose was to assess the diagnostic performance of investigations in children with myoclonic epilepsy. The secondary objectives were to examine the definitive syndromic diagnoses and report the outcomes of pediatric myoclonic epilepsies.

METHODS

We conducted a retrospective monocentric study from a pediatric center for rare epilepsies. We included pediatric patients investigated for myoclonic epilepsy at our center from 2009 to 2022. Data were collected from their medical records.

RESULTS

Forty-one children were included; 32 (78%) underwent untargeted etiological investigations, including brain magnetic resonance imaging and diverse laboratory tests to rule out an underlying etiology for progressive myoclonus epilepsy (PME). These investigations led to an etiological diagnosis of epilepsy for two patients, exclusively based on genetic investigations. At the final follow-up, an underlying etiology for epilepsy was established for nine patients (22%). The definitive syndromic diagnoses were diverse, comprising myoclonic epilepsy in infancy, epilepsy with myoclonic absences, Rasmussen syndrome, and PME. Some patients were diagnosed with nonsyndromic developmental and epileptic encephalopathy or unclassified nonsyndromic myoclonic epilepsy. Developmental delay or regression at the initial evaluation was found to be significantly associated with an unfavorable neurological outcome, the total number of antiseizure medications (ASMs) prescribed, and the unlikelihood of achieving ASM freedom. No patients with an abnormal head circumference or born of a consanguineous union were in the favorable neurological outcome group, although this finding did not reach statistical significance.

SIGNIFICANCE: Except for the need to promptly identify diseases for which precision medicine treatments are available, a first-line genetic approach seems reasonable to investigate children diagnosed with epileptic myoclonus.