Repetitive EEG recordings are necessary for the diagnosis of early myoclonic encephalopathy

Abstract

Early myoclonic encephalopathy (EME) is a rare malignant epileptic syndrome. The erratic myoclonus with or without focal motor seizures, time of onset before 3 months of age, and suppression-burst (SB) pattern in EEG are accepted as the diagnostic criteria for EME. We report a 40-day-old infant with the diagnosis of non-ketotic hyperglycinemia (NKHG). The infant developed myoclonic and focal tonic seizures on the first day of life. His first sleep EEG recorded after onset of seizure was normal. Because of the diagnosis of NKHG and early developed myoclonic seizure, we thought the infant might be EME, and repeated sleep EEG on admission in which asymmetrical SB pattern was seen. We concluded that the absence of SB pattern in the first EEG recording does not exclude the diagnosis of EME, but repetition of EEG is necessary to demonstrate the presence of SB pattern to meet the diagnostic criteria for EME.

The role of EEG in the diagnosis and classification of the epilepsy syndromes: a tool for clinical practice by the ILAE Neurophysiology Task Force (Part 2)

“…Background In EME, EEG can be normal at the onset of the seizures, and repetitive EEGs may be necessary for the diagnosis (Ozyurek et al, 2005). When the presentation is complete, there is no spatial or temporal organization (background rhythms are not different between cerebral areas and do not cycle/change with time and state of vigilance), and there are no physiological features in either wakefulness or sleep.…”

Sepsis-associated encephalopathy: A review of literature

“…These malignant wave forms indicate disturbances in the deeper brain structures such as basal ganglia and diencephalon, which makes differential diagnoses for distinct CNS disturbances such as myoclonic encephalopathy possible. [111] The estimated mortality of septic patients without pathological EEG signs is 0%, 19% when theta waves are present, 36% with delta waves, 50% with triphasic waves, and even worse, could be as high as 67% if the clinical picture is associated with more malignant EEG results. [10] The administration of sedative agents often heavily affects EEG findings.…”

Nonketotic Hyperglycinaemia (Glycine Encephalopathy)

“…In the early hours of myoclonic activity the EEG may be normal [4], although in most instances before the first ictal events it shows a burst suppression (BS) pattern consisting of periods of high-amplitude activity lasting 1-3 Hz that arise periodically from a hypoactive background (⊡ Fig. 24.2) and without spatio-temporal differentiation.…”