Prevalence
7% of neonatal seizures, but this has declined significantly in recent years.

Age at onset
First week of life, mainly (90%) in between the fourth and sixth days, for which the synonym 'fifth day fits' was coined.

Sex
Males (62%) slightly more than females.

Neurological and mental state
Normal.

Etiology
Unknown but probably environmental.

Clinical manifestations
There is a one-off event of a repetitive lengthy seizure that constitutes clonic status epilepticus, which occurs in otherwise normal full-term neonates. This consists of successive unilateral clonic convulsions affecting the face and the limbs. Convulsions may change sides and may also be less often bilateral. Apnea is a common concomitant in one third of these clonic seizures. Each seizure lasts from 1 to 3 min, repeating at frequent intervals and cumulating to discontinuous or continuous clonic status epilepticus. The whole seizure-status event lasts from 2 hours to 3 days, with a median of ~20 hours. It does not recur again. Tonic seizures are incompatible with this syndrome.

Diagnostic procedures
All relevant tests applied for neonatal seizures are normal.

Inter-ictal EEG
'Theta pointu alternant' pattern occurs in 1/2 of cases. In the others, the EEG may show focal or multifocal, non-specific abnormalities or a discontinuous pattern or it may be normal in ~10%.

Ictal EEG
Rhythmic spikes or slow waves, mainly in the Rolandic regions. The ictal paroxysms may be unilateral, generalized, or first localized and then generalized. Duration is 1 to 3 min and this may be followed by subclinical discharges for many hours.

Prognosis
Usually excellent, with normal development and no recurrence of seizures. Minor psychomotor deficits and occasional febrile or non-febrile seizures (0.5%) have been reported.

Differential diagnosis
The diagnosis can be made only after other causes of neonatal seizures have been excluded. Neonatal seizures with favorable outcomes include late hypocalcemia, subarachnoid hemorrhage, and certain meningitides.

They are entirely different from benign familial neonatal seizures.

Management options*
Prophylactic anti-epileptic drug (AED) treatment is generally not needed. Benzodiazepines or phenytoin can be used to terminate the prolonged seizure.

*Expert opinion, please check FDA-approved indications and prescribing information

This section was adapted from: The educational kit on epilepsies, The epileptic syndromes By C. P. Panayiotopoulos Originally published by MEDICINAE 21 Cave Street, Oxford OX4 1BA First published 2006 and reprinted in 2007

Authored by: C. P. Panayiotopoulos MD PhD FRCP on 1/2005
Reviewed by: Steven C. Schachter MD on 6/2008
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