West syndrome (infantile spasms)
The usual age of onset of West syndrome (infantile spasms) is 4 to 12 months. The spasms are sudden brief contractions of the head, neck and trunk, usually in flexion but sometimes in extension. Characteristically, the spasms occur in runs lasting several minutes. Hypsarrhythmia is typical on electroencephalogram but is not essential to diagnosis. When spasms occur, use:
1 prednisolone (or prednisone) 10 mg orally, 4 times daily for 2 weeks (or increase to 20 mg orally 3 times daily after the first week if spasms continue), then taper dose over 2 to 3 weeks and stop West syndrome (infantile spasms) prednis ol one
OR
1 tetracosactide (tetracosactrin) (depot) 0.5 mg intramuscularly, on alternate days for 2 weeks (or increase to 0.75 mg on alternate days after the first week if spasms continue), then stop West syndrome (infantile spasms) tetracosactide (tetracosactrin) tetracosactide (tetracostactrin) tetracosactide (tetracostactrin)
OR
2 vigabatrin 50 mg/kg orally, twice daily (or increase to 75 mg/kg twice daily after 4 days if spasms continue) for 3 months, then taper over 1 month and stop West syndrome (infantile spasms) vigabatrin
OR
3 clonazepam 0.005 to 0.015 mg/kg orally, twice daily. Increase dose gradually to 0.05 to 0.1 mg/kg twice daily. After 3 months, taper over 3 months and stop West syndrome (infantile spasms) clonazepam
OR
3 nitrazepam 0.3 to 1 mg/kg orally, daily for 3 months, then taper over 3 months and stop. West syndrome (infantile spasms) nitrazepam
Results of studies comparing the effectiveness of these drugs are inconsistent, and no drug has been proved superior. Prednisolone controls spasms better than vigabatrin initially but not at 12 to 14 months of age. In infantile spasms with no identified cause, a 2010 trial showed that better initial spasm control with prednisolone or tetracosactide (tetracosactrin), compared with vigabatrin, led to an improved developmental outcome after 4 years1. A trial published in 2017 showed that initial treatment combining vigabatrin with either prednisolone or tetracosactide (tetracosactrin) had a better outcome after 4 weeks than prednisolone or tetracosactide (tetracosactrin) alone2.
Vigabatrin commonly causes permanent visual field defects that are usually asymptomatic and may not be detected by confrontation testing. Perform formal visual field testing before starting therapy and at intervals during therapy. When visual field testing is not possible (eg in a young child or a person with a developmental disability), use ocular coherence tomography (OCT) to detect early retinal changes caused by vigabatrin.
Sodium valproate can also be used but the risk of liver toxicity is higher in young children. Rare cases of infantile spasms that respond to pyridoxine have been reported.