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Epileptic encephalopathies in early infancy
1Department of Child Neurology, Okayama University Medical School, Japan.
Insights
Early myoclonic encephalopathy (EME) and Ohtahara syndrome (OS) are distinct infantile epileptic syndromes. Key differences lie in seizure types, EEG suppression-burst patterns, and etiology, aiding differential diagnosis.
Area of Science:
- Neurology
- Pediatric Neurology
- Epileptology
Background:
- Early infantile epileptic encephalopathies pose diagnostic challenges.
- Distinguishing between early myoclonic encephalopathy (EME) and Ohtahara syndrome (OS) is crucial for appropriate management.
Purpose of the Study:
- To delineate the clinical and electroencephalographic (EEG) characteristics of EME and OS.
- To provide differential diagnostic criteria between EME and OS based on a review of literature and case studies.
Main Methods:
- Review of existing literature on EME and OS.
- Analysis of clinical seizure types and EEG findings in 6 cases of EME and 15 cases of OS.
- Comparison of the suppression-burst (S-B) pattern characteristics and age-related evolution between the two syndromes.
Main Results:
- Ohtahara syndrome (OS) typically presents with tonic spasms, while EME is characterized by myoclonias and partial seizures.
- Both syndromes feature suppression-burst (S-B) EEG patterns, but OS patterns are consistent across wakefulness/sleep, whereas EME patterns are enhanced during sleep.
- OS exhibits age-dependent epileptic encephalopathy with EEG changes and often associated brain lesions, unlike EME, which shows familial occurrences suggesting metabolic disorders.
Conclusions:
- EME and OS are distinct epileptic syndromes with differing clinical presentations, EEG characteristics, and likely etiologies.
- Specific features of seizure types, S-B pattern evolution, and associated findings aid in differentiating EME from OS.
- Understanding these distinctions is vital for accurate diagnosis and potential etiological investigation in infantile epilepsy.
Abstract:
Of the epileptic syndromes beginning in early infancy, we described the clinical and electrical characteristics of early myoclonic encephalopathy (EME) and Ohtahara syndrome (OS), and the differential diagnosis between the two syndromes, reviewing previous articles and our own study of 6 cases with EME and 15 cases with OS. With regard to the clinical seizure types, the main seizure type was tonic spasms in OS while myoclonias, especially erratic myoclonias, and frequent partial seizures were predominant in EME. The suppression-burst (S-B) pattern was a common feature of both syndromes, although their form, time of appearance, and duration of appearance differed considerably. The S-B pattern in OS was characterized by periodic and consistent appearances during both waking and sleeping states, whereas in EME, the S-B pattern was enhanced by sleep and often not manifested in the awake states. OS showed a specific pattern of evolution as age-dependent epileptic encephalopathy with concomitant EEG change while EME had no specific evolution with age. In OS, obvious brain lesions such as brain malformations were often seen. In contrast, frequent occurrence of familial cases suggested some kind of congenital metabolic disorder as the etiological factor in EME.