Paediatrics: Epilepsies: infantile

2021-03-02 12:00 AM

Infantile epilepsies are challenging and expert advice should be sought.

Epilepsies: infantile

Infantile epilepsies are challenging and expert advice should be sought.

Benign myoclonic epilepsy of infancy

This form of epilepsy requires no further investigation or therapy provid-ing that what is observed meets the following criteria.

  • Myoclonic seizures only.
  • No other seizure type.
  • Normal interictal EEG.
  • Normal development.

West’s syndrome

The diagnosis of this condition is based on a classic triad.

  • Infantile spasms: short tonic contraction of trunk with upwardelevation of arms; may be confused with gastro-oesophageal reflux or colic.
  • Developmental: delay or regression.
  • Hypsarrhythmia: on the EEG.

Often children have only some of these or the EEG is reported as being chaotic, with high voltage sharp and slow waves, but not ‘classical hypsarrhythmia’.

Investigations

Take a thorough history and examination and make sure that you have excluded tuberous sclerosis. Then, use the series of investigations on the previous page for epileptic encephalopathy.

Treatment

Children with West’s Syndrome are best cared for at home.

Prednisolone therapy

  • Step 1:15mg* oral/tds for the first week
  • Step 2: Continuing seizures. Increase oral dose to 20mg*, qds
  • Step 3: at 14 days. Withdraw—in four steps over 15 days
  • This is the complete dose, NOT per kg

Note: The child will be immunosuppressed whilst and for 2wks after therapy. Many will develop hypertension, it is useful to let the GP know the dose of nifedipine should the child become hypertensive. Some authors prefer ACTH IM injections, but evidence of its superiority is poor, and administration is more difficult

Second line therapy is with oral vigabatrin First 24hr: 25mg/kg bd, Next 2 days: 50mg/kg bd, Day 4—if there are continuing seizures— 75mg/kg, twice daily for no more than 20wks, due to the risk of visual field damage.

Severe myoclonic epilepsy of infancy

Seizures occur from the first year onwards, and include:

  • prolonged (>1hr) febrile and shorter afebrile seizures;
  • focal seizures;
  • atypical absences;
  • segmental myoclonia.

Investigations

  • EEG: may be normal initially, but may develop photosensitivity (i.e.within 12mths in 50%) and generalized discharges once the seizures are frequent.
  • Genetics: over 70% have a mutation in the SCN1a gene. However,if negative and the clinical picture is atypical, then use the screening investigations for epileptic encephalopathy.

Treatment

The treatment should follow a sequence, adding anticonvulsants if there is no response. Lamotrigine should be avoided. The sequence is as follows:

  • Start with sodium valproate.
  • Add clobazam.
  • Consider stiripentol if resistant to therapy (needs expert supervision).

Myoclonic astatic epilepsy

A condition with:

  • myoclonic astatic seizures;
  • myoclonic jerks;
  • generalized tonic–clonic seizures.

The EEG demonstrates predominantly generalized discharges once sei-zures are established. Seek advice about further investigation and treat as for idiopathic generalized epilepsy. Seizures in this condition are likely to be unresponsive, so consider using the ketogenic diet early in refractory cases.

Lennox–Gastaut syndrome

A condition with:

  • Tonic seizures with trunk flexion (often evolving out of infantile spasms).
  • Atonic seizures, myoclonic jerks, atypical absences.

Invariably there is developmental delay once the seizures are established. This condition rarely responds to drugs. Seek advice about further investigation and treat as for an idiopathic generalized epilepsy, initially, then getting expert help