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Benign familial neonatal epilepsy
Benign familial neonatal epilepsy is a rare autosomal dominant epileptic syndrome characterised by frequent brief seizures within the first days of life.
Clinical features
- Seizures mainly occur in full-term normal neonates following a normal pregnancy and delivery and without precipitating factors. Seizures are brief, of 1–2 min and may be as frequent as 20–30 per day.
- The tonic phase is followed by a clonic component which is usually asymmetrical and unilateral
- The post-ictal state is brief
- The neonate is asymptomatic interictally
- Pure clonic or focal seizures are rarely seen[4]
Electroencephalography
- The inter-ictal EEG may be normal, discontinuous, have focal or multifocal abnormalities or have a theta pointu alternant pattern[5] have suggested that BFNC cannot be produced by KCNQ-channel dysfunction alone but by reciprocal action between impaired KCNQ channel and other conditions which results in either an increase in excitation or decrease in inhibition.
- Potassium channels shown differential expression at different stages of maturation which might be another explanation for the pathogenesis of BFNS[6]
Differential diagnosis
Benign (non-familial) neonatal seizures | Benign familial neonatal seizures | |
---|---|---|
Main seizures | Mostly clonic | Tonic-clonic |
Onset | Fifth day of life | Second or third day of life |
Duration of seizures | Status epilepticus (median 20 hours) | Repetitive isolated seizures |
Main causes | Unknown, probably environmental | Autosomal dominant |
Subsequent seizures | Practically nil (0.5%) | Relatively high (11%) |
Psychomotor deficits | Minor | Practically non-existent |
Ictal EEG | Usually localised spikes | Usually generalised flattening |
Interictal EEG | Usually theta pointu alternant | Normal or focal abnormalities |
Source: The Epilepsies: Seizures, Syndromes and Management. Panayiotopoulos CP. Oxfordshire (UK): Bladon Medical Publishing; 2005. |
Prognosis
- Seizures remit between 1 and 6 months from onset, majority during the first 6 weeks[4].
- 10–14% may later develop other types of febrile (5%) or afebrile seizures including idiopathic generalised seizures. Rolandic seizures have also been reported.
- Although an exception deaths during neonatal seizures have also been reported
- the prevalence of learning disabilities is reported to be around 2.5% which is not significantly different to that in the general population[9]
Management
- seizures usually remit spontaneously without medication
- The use of anti-seizure medications does not influence the eventual outcome
- if the seizures are prolonged benzodiazepines or phenytoin may be used to terminate them
- counselling parents about this familial condition with generally good prognosis is important
References
4.
a,
b
Panayiotopoulos CP. (2005). The Epilepsies: Seizures, Syndromes and Management. Oxfordshire (UK): Bladon Medical Publishing.
Discussion