Neurofibromatosis type 1 and infantile spasms

There is no agreement on the prevalence, natural history and outcome of infantile spasms (IS) in neurofibromatosis type 1 (NF1). By contrast, its prevalence and outcome are well characterised in the setting of other neurocutaneous disorders (e.g. tuberous sclerosis).

The aim of the present study was to try to establish a genotype-phenotype correlation in IS in the setting of NF1. A retrospective (years 1990-2000) and prospective (years 2000-2006) study in three paediatric centres in Italy were taken as referral populations for: (1) children with NF1 and (2) neurological problems in childhood.

Ten NF1 patients have had IS. The calculated population-based: (1) prevalence of IS in NF1 (0.76%) was higher than the reported frequency of IS in the general population (0.02-0.05%) and (2) frequency of NF1 in the IS series in two out of three centres (0.62-0.90%) was lower than the estimated frequencies in the literature (1.5-3.0%). Patients had psychomotor delay preceding the spasms (50%), symmetrical spasms (50%), typical (80%) and modified (20%) hypsarrhythmia and foci of spikes and waves and a good response to corticosteroid treatment (50%). Outcome was good in 30%. Imaging revealed high-signal foci in atypical locations (sub-cortical and central brain regions). Deoxyribonucleic acid analysis revealed three novel NF1 gene mutations without genotype-phenotype correlation.

Even though the combination of IS and NF1 does not seem to be coincidental, it is certainly an unusual event in NF1--rarer than in other neurocutaneous disorders. Spasms in NF1 are not associated with specific genetic defects.