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Benign nonfamilial neonatal seizures
Benign neonatal seizure (nonfamilial) is a benign syndrome characterized by clonic seizures that begin around the fifth day of life and may recur during the following 2 to 3 days.
History & terminology
- Dehan et al 1977[1] first reported a neonatal convulsive disorder of unknown etiology that occurs around the fifth day of life and associated with a favorable outcome.
- Prior & Macourt (1981)[2] described the features in 90 infants with the condition and coined the term “fifth day fits”
- In 1989, the ILAE Commission on Classification and Terminology proposed the term “benign neonatal seizures”
- The updated ILAE 2017 classification categorizes it under Conditions with epileptic seizures that are traditionally not diagnosed as a form of epilepsy per se.
Genetics
- Claes et al 2004 reported three de novo mutations in KCNQ2 in 4 patients with benign neonatal seizures without a family history (Claes et al 2004).
- Ishii et al 2009 also reported another de novo mutation was reported in a neonate with benign neonatal seizures and no family history of seizures.
- KCNQ2 variants have been described in patients with benign familial neonatal seizures suggesting an overlap between the 2 syndromes.
Clinical features
- seizures are mainly clonic
- median duration is around 20hrs (status epilepticus)[3]
- onset is around fifth day of life
EEG
- ictal EEG usually shows localised spikes
- interictal EEG usually shows theta pointu alternant. It may also show focal or multifocal, non-specific abnormalities or a discontinuous pattern or it may be normal in ~10%.
Pathophysiology
- probably environmental
Differential diagnosis
Prognosis
- excellent with risk of subsequent seizures practically nil(0.5%)[3]
- normal neurodevelopmental outcome
Discussion