The neonatal period is the most vulnerable period of life for developing seizures. Neonatal epileptic seizures often constitute a neurological emergency demanding urgent diagnosis and management. Neonatal seizures are paroxysmal, repetitive, and stereotyped events. They are usually clinically subtle. There is no recognizable post-ictal state. Generalized tonic-clonic seizures probably do not occur.
There are 5 main types of neonatal seizures:
- Subtle seizures (50%)
- Tonic seizures (5%)
- Clonic seizures (25%)
- Myoclonic seizures (20%)
- Non-paroxysmal repetitive behaviors
The prevalence of neonatal seizures is approximately 1.5%. The overall incidence is 3 per 1,000 live births (57 to 132 per 1,000 live births in pre-term infants). Eighty percent occur in the first 1 to 2 days to the first week of life. The etiology of neonatal seizures is extensive and diverse. Severe causes predominate. Hypoxic-ischemic encephalopathy is the most common cause (80% of all seizures in the first 2 days of life). Previously common acute metabolic disturbances such as electrolyte and glucose abnormalities are now unusual causes.
Prognosis is cause dependent because the main factor that determines outcome is the underlying cause and not the seizures themselves. Despite high mortality (approximately 15%) and morbidity (approximately 30%), one half of neonates with seizures achieve a normal or near-normal state. One third of the survivors develop epilepsy. Neonatal seizures often impose significant difficulties in their differentiation from normal or abnormal behaviors of neonates. As a rule, any suspicious repetitive and stereotyped events should be considered as possible seizures requiring video-electroencephalogram (video-EEG) confirmation.
Neonatal syndromes: Despite the high prevalence of neonatal seizures, epileptic syndromes in neonates are rare and infrequent. These are:
- Benign familial neonatal seizures
- Benign neonatal seizures (non-familial)
- Early myoclonic encephalopathy
- Ohtahara syndrome
The epileptic syndromes and their significance
A major advance in recent epileptology is the recognition of epileptic syndromes that allows an accurate diagnosis and management of seizure disorders.[1-3]
Medical diagnosis is the identification of a disease by investigation of its symptoms and history, which provides a solid basis for the treatment and prognosis of the individual patient. An accurate diagnosis is the golden rule in medicine, and epilepsies should not be an exception to this. Like in any other disease, the recognition of non-fortuitous clustering of symptoms and signs in epilepsies requires the study of detailed clinical and laboratory data.[1-3] However, often in current practice, the diagnosis is limited to either epilepsy or seizures, which is unsatisfactory because this cannot provide guidance on important items such as severity of the disease, prognosis, short- and long-term therapeutic decisions, and genetics (research and counselling), which are all factors that crucially affect personal, family, and social life; education; and career choices of patients. Defining the type of epilepsy should now be considered mandatory as it offers the best guide to both management and prognosis. Most epileptic syndromes and diseases are well defined and easy to diagnose. The benefits of syndromic diagnosis over seizure/symptom diagnosis or an inclusive diagnosis such as epilepsy far outweigh any morbidity from incorrect categorization that may arise in difficult cases.
Important clinical features of a syndrome include the type of seizures, their localization, frequency, sequence of events, circadian distribution, precipitating factors, age at onset, mode of inheritance, physical or mental symptoms and signs, prognosis, and response to treatment.
Epilepsies or epilepsy?
The clinical and practical significance of the syndromic diagnosis of epilepsies is well illustrated by 3 common epileptic disorders. Benign childhood focal epilepsies, juvenile myoclonic epilepsy (JME), and hippocampal epilepsy have nothing in common other than the fact that they may all be complicated by generalized tonic-clonic seizures (GTCS), which are primarily GTCS in JME and secondarily GTCS in benign childhood focal epilepsies and hippocampal epilepsy.
Furthermore, the short-and long-term treatment strategies are entirely different for each disorder: benign childhood focal epilepsies may or may not require medication for a few years, appropriate anti-epileptic drug (AED) treatment is lifelong in JME while neurosurgery may be life-saving for patients with hippocampal epilepsy. What may be a life-saving drug such as carbamazepine for hippocampal epilepsy may be ill-advised for JME.
It should not be difficult to distinguish an intelligent child with benign focal seizures or childhood absence epilepsy from a child with Kozhevnikov-Rasmussen, Lennox-Gastaut, Down, or Sturge-Weber syndrome or a child with severe post-traumatic cerebral damage, brain anoxia, or catastrophic progressive myoclonic epilepsy. Describing all these children as simply having epilepsy just because they have seizures offers no more benefit than a diagnosis of febrile illness irrespective of cause, which may be a mild viral illness, a life-threatening acute bacterial meningitis, or a malignancy. Inappropriate generalizations with regard to terminology, diagnosis, and treatment are the single most important factor of mismanagement in epilepsies.
- Engel J Jr. A proposed diagnostic scheme for people with epileptic seizures and with epilepsy: Report of the ILAE Task Force on Classification and Terminology. Epilepsia 2001;42:796-803.
- Commission on Classification and Terminology of the International League Against Epilepsy. Proposal for revised classification of epilepsies and epileptic syndromes. Epilepsia 1989;30:389-99.
- Blume WT, Luders HO, Mizrahi E, Tassinari C, van Emde BW, Engel J Jr. Glossary of descriptive terminology for ictal semiology: report of the ILAE task force on classification and terminology. Epilepsia 2001;42:1212-8.
- Panayiotopoulos CP. A clinical guide to epileptic syndromes and their treatment. Second edition. London:Springer; 2007.
For details and bibliography for these syndromes see the reference book: Panayiotopoulos CP. A clinical guide to epileptic syndromes and their treatment. Second edition. London:Springer; 2007.
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