Surgical management of cerebellar tonsillar herniation in three patients with macrocephaly-cutis marmorata telangiectatica congenita. Report of three cases.

The authors report on three patients with a congenital brain overgrowth syndrome, macrocephaly-cutis marmorata telangiectatica congenita (M-CMTC), who experienced neurological sequelae associated with herniation of the cerebellar tonsils through the foramen magnum. In two of these patients, the authors document postnatal brain overgrowth that contributed to recurrent descent of the cerebellar tonsils and complicated the surgical treatment in one of the patients. The authors address the neurosurgical concerns related to this syndrome with special attention to acquired tonsillar ectopia and postulate that some patients may be at risk for progressive tonsillar herniation and consequent neurological symptoms due to cerebellar overgrowth. Ectopic cerebellar tonsils have been reported previously in cases of M-CMTC, and this phenomenon may be a secondary event associated with brain overgrowth rather than due to a congenitally small posterior fossa.