Neurological Disorders: Neurofibromatosis

Introduction

Neurofibromatosis is an AD (autosomal dominant) type of inherited disorder involving the nervous system.

There are an extensive number of manifestations associated with this disease. It is also called as a neurocutaneous syndrome since in this condition there are both skin & neurological manifestations.

In NF, tumorous growth of the nervous tissue takes place along the peripheral nerves as well structures within the central nervous system (brain & spinal cord).

Types of NF

There are two types; NF1 & NF2

NF1:

The following features are characteristic for type 1;

1) Café au lait pigmented spots over the skin

2) Skin tumors called as neurfibromas

3) Plexiform neurofibroma

3) Frecklings in the axilary or groin area

4) Bone abnormalities like dysplasis of sphenoid bone or thinning of the cortex of the long bones

5) Iris hemartomas called as Lisch nodules

6) Glioma of the optic nerve (1st cranial nerve or nerve of vision)

NF2:

A tumor of the 8th cranial nerve named as acoutsic shwannoma occurs on both sides.

Tumors like gliomas, meningiomas, pheochromocytoams occur with a higher frequency in patients with NF especially the type 1. Other findings may include cataracts (opacity of the eye lens), large head (macrocephaly), epileptic seizures etc.

The skin tumors are generally benign however sometimes malignant (cancerous) transformation can take place. Also intracranial malignant tumors can occur.

Diagnosis

NF1 is a mainly a clinical diagnosis while NF2 requires radiological studies like a CT or MRI of the brain to confirm the diagnosis. Even in NF1 such investigations are required to look for intracranial tumors, and also to provide more diagnostic features as mentioned below.

As per the criteria put forward by NIH (national institute of health) at least 2 of the following are required for NF1 diagnosis;

1) 6 or more café au lait pigmented spots on the skin of the size of 5 millimeter or more if the affected individual is before puberty; > 15 millimeter if after puberty
2) At least 2 neurofibromas or 1 plexiform neurofibromatosis
3) Optic nerve glioma
4) Axillary or inguinal region freckling
5) Lisch nodules – 2 or more
6) The bone changes as mentioned above
7) A 1st degree family relative with confirmed NF
8) Mutation of the NF gene on chromosome 17

Treatment

There is no curative treatment for NF. The treatment is symptomatic & supportive. A neurologist is frequently involved in the care of these patients.



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