Infantile spasms (West syndrome)

 

Presentation

Severe form of epileptic encephalopathy with forceful ‘spasms’ in first few months of life, arising from range of underlying etiology that affect the outcome.

There may be an underlying structural brain abnormaly (HIE, perinatal stroke, neuronal migration disorder etc), genetic disorder (Downs synd, Tuberous Sclerosis, gene mutations) or other metabolic disorder.

 

Seizures manifest as bilateral spasms lasting 1 – 2 seconds, mostly causing tonic flexion of limbs, trunk and bending head forwards; or sometimes extension spasms with arms and legs ‘flung’ outwards. Flexor head spasms are sometimes referred as ‘salaam’ attacks.

 

There could be brief flexor, followed by extensor spasms. Spasms are infrequent initially, so can be missed, but later increase in frequency or come in clusters causing distressful crying.

 

Spasms often occur upon awakening from sleep, but can affect behaviour when awake, feeding and sleep; also causing developmental arrest or regression unless recognized and treated promptly. Measure head circumference, full examination including wood’s lamp, BP and detailed ophthalmology assessment.

 

Investigation

Description and video of episodes are helpful to recognize seizure type.

Arrange urgent EEG – will show ‘chaotic’ or disorganised waves referred as hypsarrhythmia. If inconclusive, repeat EEG during sleep. If EEG still normal, but suspecting IS- repeat in 7 to 10 days.

 

Test for underlying causes- consider MRI Brain, chromosomal microarray & metabolic tests (incl Lactate, Ammonia, S-AA, U-OA) in discussion with tertiary neurology. 2^nd line investigations done by tertiary neurology.

 

Management

If suspecting IS, urgently discuss with neurology to start treatment promptly.

The UKISS and ICISS trials randomized infants to receive either hormonal treatment (usually Prednisolone, but also Hydrocortisone or ACTH) or Vigabatrin. It is common to offer either Prednisolone only / Preg with VBG, but for Tuberous Sclerosis offer Vigabatrin monotherapy. Assess response in 2^nd week clinically & with repeat EEG between day 12 – 15.

 

Other recommended AEDs include Valproate, Nitrazepam, Pyridoxine, Levetiracetam or Zonisamide; or Ketogenic diet under tertiary neurology.

 

Once spasms are controlled and EEG no longer has hypsarrhythmia, conventional antiepileptic may be beneficial for 2 – 3 years as some cases evolve in to other seizure types.

 

Most children with infantile spams will be left with range of developmental disabilities, particularly if delay in diagnosis and treatment.

Prognosis for seizure control, later epilepsy and neurodevelopmental outcome also depends on underlying cause.

 

There is overlap either between those who initially manifest as Ohtahara syndrome; or many with IS who later evolve in to Lennox-Gestaut type features.