Review of Neurocutaneous Disorders Related to the Neurosurgical Patient Neurocutaneous Disorders

Background: The neurocutaneous disorders, also known as the phakomatoses, are a group of hereditary conditions that have neurological manifestations as well as benign cutaneous lesions; both tissue types share a common embryologic origin. Neurofibromatosis: Neurofibromatosis (NF) is the most common neurocutaneous disorder. Although there are as many as 8 distinct forms of NF, the term is most commonly used to refer to the 2 most common subtypes: NF1 and NF2. While the 2 disorders share a common name, they are distinct hereditary conditions that arise as a result of different genetic mutations. The NF1 gene is located on chromosome 17q and encodes neurofibromin, a tumor suppressor gene that plays a role in the negative regulation of the ras proto-oncogene. NF2 is inherited in an autosomal dominant fashion. The disorder is due to a mutation on chromosome 22q, which encodes for the protein merlin (or schwannomin), which is a membrane-related protein thought to function as a tumor suppressor. Tuberous Sclerosis Complex: Tuberous sclerosis complex is the second most common neurocutaneous disorder following NF. It is characterized by hamartomas of several organs, including the skin, brain, eyes, and kidneys. Tuberous sclerosis complex was first described by Bourneville in 1880, and is also known as Bourneville disease. The annual incidence is approximately 1 in 5800 individuals. Von Hippel-Lindau Disease: von Hippel-Lindau disease (VHL) is characterized by the presence of both benign and malignant tumors in multiple systems, including hemangioblastomas of the cerebellum and spinal cord, retinal angiomas, and renal cell carcinomas. Eugen von Hippel first recognized the hereditary nature of retinal angiomas in 1904, and Arvid Lindau first reported their connection with cerebellar hemangioblastomas in 1927. VHL has an incidence of 1 in 36,000 individuals. Sturge-Weber Syndrome: Sturge-Weber Syndrome is a neurocutaneous syndrome characterized by a leptomeningeal angioma, with an ipsilateral cutaneous vascular malformation (port-wine stain), often in the ophthalmic distribution of the trigeminal nerve. The condition, first described by William Sturge in 1879, is also referred to as encephalotrigeminal angiomatosis, and has an estimated incidence of 1 in 50,000 individuals.