Neurofibromatosis type 2

What it is

Neurofibromatosis type 2 is inherited in an autosomal dominant pattern, and the NF2 gene sits on chromosome 22. The most common type of tumor in NF2 is the schwannoma, and the cranial nerve most often affected by schwannomas is CN VIII, the vestibulocochlear nerve. It is best known for the bilateral vestibular schwannoma, also called acoustic neuroma: a benign slow-growing tumor of the vestibular portion of CN VIII, and the most common CPA tumor. Café-au-lait macules can be seen but are much less frequent in NF2, and NF2 is not associated with the cognitive impairment that is often seen with NF1.

How it presents

The tumors of NF2 are what present:

• Bilateral vestibular schwannoma, giving tinnitus and hearing loss.
• Meningiomas.
• Spinal tumors, for example ependymomas.
• Skin nodules, for example schwannomas.
• Early-onset bilateral cataract, which is typically the first manifestation to appear.

The hearing picture of a vestibular schwannoma is chronic unilateral gradual SNHL or unilateral ringing, that is tinnitus, with unsteadiness and loss of balance; facial nerve palsy and trigeminal (V1) sensory deficit with a reduced corneal reflex are late signs. In NF2 the signs are bilateral. In the elderly, unilateral tinnitus or SNHL is acoustic neuroma until proven otherwise.

Vertigo is the one point on which the pages do not say the same thing. The bilateral vestibular schwannoma of NF2 is listed with tinnitus, hearing loss and vertigo in one source; a second source gives dizziness and unsteadiness but no vertigo; a third lists dizziness (vertigo) among the clinical features.