Neurofibromatosis type 1 (CNS manifestations)

Central nervous system manifestations of Neurofibromatosis type 1 (NF1), or von Recklinghausen disease, are relatively common among these patients and has a variety of expressions.

For a general discussion of the underlying condition, please refer to the article NF1.

Clinical presentation

NF1 is a complex multi-systemic disease with a broad range of expression and unpredictable behavior.

Cognitive disability is the commonest neurological symptom described in children with this disease, and it does not improve in adulthood . A broad spectrum of neurological symptoms may be related to cerebrovascular conditions, malformations, and CNS tumors related to NF1.

The gliomas occur in all parts of the brain, with a predilection for the optic pathways, brainstem, and cerebellum. Many tumors are asymptomatic, but visual disturbances,  precocious puberty, acute hemiplegia or focal neurological deficits may manifest.

Multiple sclerosis and epilepsy have also been described in association with NF1 .

Neoplasms

In result of the inactivation of a tumor suppressor gene, NF1 is also associated with increased incidence of numerous tumors, particularly for the CNS :

• malignant peripheral nerve sheath tumor (MPNST)
  • previously known as neurofibrosarcoma
  • the overall risk of developing MPNST is ~10%
• glioma
  • juvenile pilocytic astrocytoma
  • optic nerve glioma: most common in children younger than age six years.
  • diffuse brainstem glioma
  • spinal astrocytoma and spinal pilocytic astrocytoma
• ganglioglioma

Radiographic features

• FASI: focal areas of signal intensity in deep white matter and basal ganglia or corpus callosum , i.e. areas of T2/FLAIR hyperintensity with no contrast enhancement
• optic nerve glioma or optic pathway glioma (may manifest as enlarged optic foramen)
• progressive sphenoid wing dysplasia
• lambdoid suture defects
• dural calcification at the vertex
• dural ectasia
• moya-moya phenomenon (rare)
• buphthalmos