Educationals

The main epileptic syndromes of childhood and adolescence

Neonatal Period

Benign neonatal convulsions (5th day fits)

Benign familial neonatal convulsions

Myoclonic epilepsy - severe (malignant)

Benign neonatal seizures are repetitive seizures between 4-6 days of life which continue for a few days and then remit. The prognosis is good.

Benign familial neonatal seizures are rare and autosomal dominant inheritance. Convulsions start in the first week of life and remit within a few months.

Early myoclonic encephalopathy : The seizures are fragmentary or massive myoclonia, partial, motor or tonic. EEG shows the classic features of suppression which alternate with complex bursts of spike, sharp and slow wave activity. It is associated with severe neurological abnormality and early death. Non-ketotic hyperglycinaemia has been identified some patients.

Infancy

Myoclonic epilepsy	-benign -severe
West syndrome

Benign Myoclonic Epilepsy of Infants

Age of occurrence 1 to 2 years of life.

In previously normal children characterised by brief episodes of generalised myoclonic seizures of duration of 1-3 seconds with on loss of consciousness, affects axis of body and limbs and does not occur in sleep.

EEG in the inter ictal period is normal and generalised spike and wave discharges seen ictally. Seizures are easily controlled with sodium valproate, may persist if untreated and later develop generalised tonic seizures.

Severe myoclonic epilepsy in infancy

In a previously normal child, usually starts with unilateral or bilateral clonic seizures usually with fever. Later myoclonic jerks supervene associated with partial seizures with autonomic or atonic features and automatisms may occur. EEG shows generalised spike wave and polyspike activity, photosensitivity and focal abnormalities. Refractory to treatment and developmental arrest are common.

West Syndrome

Age of onset : 3 to 12 months (peak 3-7).
The full syndrome comprises :

• Infantile spasms (flexor, extensor, clonic or myoclonic seizures) occurring singly or in clusters more on awakening.
• Hypsarrythmia or modified hypsarrythmia on EEG.
• Mental deterioration.

Seizures are sudden, brief, bilateral, symmetrical contraction of neck, trunk and extremities. Seen as flexor spasms in 34%, extensor in 22% and mixed in 42%.

Occur in series or clusters, repetitive, more on awakening, less frequently in sleep Brief momentary head nods may be missed by parents and misdiagnosed by physician

Two types of West syndrome :

• Symptomatic - Following known insult such as hypoxic - ischaemic encephalopathy or perinatal insult, cerebral malformation such as tuberous sclerosis, infections (pre and postnatal) and metabolic disorders. They account for 70-80% of West syndrome.
• The remaining 20-30% are cryptogenic with no obvious cause.

EEG : Slow waves of high voltage intermixed with diffuse asynchronous spikes over both hemispheres, basal rhythm not discernible, REM sleep causes dimunition or disappearance of the abnormality. Neuroimaging has brought a decrease in number of cryptogenic cases.

Prognosis is poorer in symptomatic spasms and also if diagnosis is delayed.

Steroids (ACTH, prednisone), soldium valproate, benzodiazepines and more recently vigabatrin are the treatment of choice.

Early childhood (1-5 years)

Febrile seizures
Lennox - Gastaut syndrome

Febrile convulsion

Age 3 months -5 yrs (1-2yrs)
With no evidence of intracranial infection or defined cause.
Incidence 2-5% before age of 5 years. A family history is present in 10% of cases. Simple febrile convulsions are brief, single, bilateral, tonic clonic in a child with normal development.

Complex febrile convulsions lasting more than 15-20 minutes, repeated within in 24 hours, unilateral seizures, followed by Todd's palsy.

The recurrence rate is 33%, more often seen in children presenting at less than 1 year of age, with a positive family history, and with complex febrile features.

Risk of epilepsy - 3% (0.5% in general population) Regular treatment with phenobarbitone and valproate will reduce the risk of recurrence. However the risk is small and in most cases outweighs the effects of hyperkinesis, cognitive dysfunction with phenobarbitone and liver toxicity with valproate. Diazepam given orally or rectally is also effective in reducing further febrile seizures. More recently oral clobazam has been used effectively for febrile convulsions.