A Case of Symptomatic Neurocutaneous Melanosis Associated with the Dandy Walker Complex and Excellent Response of Seizures to Topiramate

Abstract

Neurocutaneous melanosis is a rare non-familial congenital neurocutaneous syndrome characterized by the presence of large or multiple congenital melanocytic nevi in association with benign or malignant proliferation of melanocytes in the leptomeninges. It is believed to be an embryonic neuroectodermal dysplasia. The Dandy Walker complex is an uncommon disorder of the CNS, also. refers to a condition with a broad posterior fossa and high tentorium insertion, hypoplasia or aplasia of the cerebellar vermis and cystic dilation of the fourth ventricle communication with the posterior fossa. We report a patient with NCM associated with the DWC that was diagnosed by MRI. The patient had multiple, small to medium-sized melanocytic nevi on the scalp and back, presenting at birth. At 6 months of age, frequent daily attacks of partial seizures were noted. T1 weighted MR images showed multiple high signal lesions in the amygdala, cerebellar folia, deep nuclei, and basis pontis, compatible with intraparenchymal melanin deposits. In addition, hypoplasia of the inferior vermis and a broad posterior fossa were identified. The patient failed to respond to oxcarbazepine. The seizure frequency did not decrease for the first three months. Vomiting and mild elevation of the liver enzymes were observed after adding valproic acid. However, after topiramate was started the frequency of the seizures decreased, and the oxcarbazepine and valproic acid were discontinued. With 5 mg/kg of topiramate treatment, the patient became seizure free for 20 months; however, infrequent seizures recurred thereafter. The dosage of topiramate was increased to 13 mg/kg, and for the following 15 months, there have been no seizures. Seizures were well controlled by topiramate for four years.