Myoclonus epilepsy with ragged-red fibers
Jun. 10, 2021
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Benign neonatal seizure (nonfamilial) is a syndrome characterized by clonic seizures that begin around the fifth day of life and may recur during the following 2 to 3 days. It is a benign syndrome, but its diagnosis requires a workup to eliminate other potentially more serious epileptic syndromes during this period. In the following article, the authors discuss many issues related to this syndrome, including etiology, pathogenesis and pathophysiology, epidemiology, and differential diagnosis.
This syndrome was first described by Dehan and colleagues in 1977. They reported a neonatal convulsive disorder of unknown etiology that occurs around the fifth day of life and is associated with a favorable outcome (04). In 1989, the Commission on Classification and Terminology of the International League Against Epilepsy proposed the term "benign neonatal seizures" (02). Currently, it is classified under the idiopathic generalized epilepsies, although partial seizures are common. Indeed, Watanabe and colleagues reported only partial seizures in 16 infants with the syndrome (30), raising questions about the accuracy of the inclusion of benign neonatal seizures under the rubric of idiopathic generalized epilepsies.
This issue may be resolved with the proposed diagnostic scheme of the ILAE commission report of 2001 (05). One paper reviewed 94 cases of neonatal seizures and showed some of the advantages of using the proposed classification (14). Specifically, benign neonatal seizures would be classified as an Axis 3 syndrome separate from seizure semiology, relieving the problem of classifying it as an idiopathic generalized epilepsy. The extent to which we will be able to diagnose any additional cases of benign neonatal seizures based on the proposed classifications is yet to be seen. Three de novo mutations in KCNQ2 were found in 4 patients with benign neonatal seizures without a family history (03). Another de novo mutation was reported in a neonate with benign neonatal seizures and no family history of seizures (12). Because mutations in KCNQ2 have been described in patients with benign familial neonatal seizures, these data suggest an overlap between the 2 syndromes.
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