Beckwith-Wiedemann syndrome and Chiari I malformation--a case-based review of central nervous system involvement in hemihypertrophy syndromes.

BACKGROUND: Beckwith-Wiedemann syndrome (BWS) is an unusual complex of abnormalities that includes mainly omphalocele, macroglossia, gigantism, visceromegaly, and neonatal hypoglycemia. Type I Chiari malformation, on the other hand, is defined as ectopia of the cerebellar tonsils below the plane of the foramen magnum. Only one case of association of BWS with Chiari I malformation has been previously reported in the literature. DISCUSSION: Several conditions involving congenital hemihypertrophy have been previously reported in association with Type I Chiari malformation. The pathophysiological mechanism for most of these associations is thought to be quite complex and still remains unclear. However, the presence of tonsillar herniation in BWS has been explained by Tubbs and Oakes in the only one existing case report of BWS with Type I Chiari malformation in the literature, to be due to associated hemihypertrophy of the skull base. We additionally suggest that cerebellar hypertrophy may also contribute to the tonsillar herniation and fourth ventricular outlet obstruction. ILLUSTRATIVE CASE: We now report our recent experience on this association following a review of the literature on association of other hemihypertrophy syndromes with the central nervous system anomalies.
CONCLUSION: We believe that a common pathogenesis of Type I Chiari malformation occurs in conditions of hemihypertrophy including BWS, probably secondary to dysmorphology involving the posterior cranial fossa, and is not just an associated finding.