Brief overview
- Course and prognosis: Depends on the size and development of the tumors, average life expectancy 60 years
- Symptoms: Neurological impairment, hearing loss, tinnitus, glaucoma, impaired sense of balance, facial paralysis
- Causes and risk factors: Hereditary due to mutation of the NF2 gene. This does not slow down tumor growth
- Diagnosis: Based on clinical criteria, imaging procedures (CT, MRI), hearing test
- Treatment: No causal therapy available, surgical removal of tumors, pain treatment
What is neurofibromatosis type 2?
Neurofibromatosis type 2 (NF2) is a rare hereditary disease. In contrast to neurofibromatosis type 1 (NF1, Recklinghausen’s disease), in which the changes occur along the peripheral nervous system and on the skin, NF2 primarily affects the central nervous system, i.e. the brain and spinal cord.
Neurofibromatosis type 2 is characterized by the formation of benign tumours that are localized in the brain and spinal cord. They develop particularly frequently on the eighth cranial nerve, the auditory and vestibular nerve. In addition to tumor formation, there is often a pathological change in the lens of the eye (posterior subcapsular cataract).
What is the life expectancy?
In developed countries, the average life expectancy for people with NF2 is over 60 years. The problem is that neurofibromatosis type 2 is often only discovered in adulthood, as the symptoms appear relatively late. For close relatives, for example the children of those affected, regular check-ups are advisable. They have an increased risk of developing the disease. The earlier possible tumors in the brain and spinal cord are discovered, the better the treatment of neurofibromatosis type 2 can be planned.
How does neurofibromatosis type 2 manifest itself?
Neurofibromatosis type 2 causes a variety of symptoms. The symptoms depend primarily on the size and location of the respective tumors. In the majority of patients, bilateral tumors form along the auditory nerves (acoustic neuromas), which often impairs hearing and the sense of balance and is accompanied by tinnitus (ringing in the ears).
In neurofibromatosis type 2, tumors also develop on other cranial nerves and cause neurological deficits such as vocal cord paralysis. Most people affected also develop cataracts, a clouding of the lens of the eye, at a young age.
Skin tumors also sometimes occur. However, other typical skin symptoms of neurofibromatosis type 1 (such as café-au-lait spots or freckling) are absent.
Complications
- Hearing impairment up to deafness
- Facial nerve paralysis (facial nerve palsy)
- Swallowing disorders (dysphagia)
- Vocal cord paralysis (recurrent paresis)
The complications of neurofibromatosis type 2 depend on which cranial nerves are affected. While the frequent involvement of the eighth cranial nerve primarily affects hearing and balance, swallowing disorders are usually caused by a tumor on the ninth cranial nerve. In many cases, however, it is possible to prevent the complications of neurofibromatosis type 2 if the tumors in question are detected and removed at an early stage.
What causes neurofibromatosis type 2?
Neurofibromatosis type 2 is a hereditary disease. It is caused by a change (mutation) in a specific gene, the NF2 gene, which in humans is located on chromosome 22. This gene contains the “blueprint” for a special protein: schwannomin, often referred to as “merlin” (moesin-ezrin-radixin-like protein).
Schwannomin is a so-called tumor suppressor protein. Among other things, it regulates the growth of Schwann cells, which have the function of enveloping and insulating nerve fibers. If the NF2 gene is damaged, there is a risk that the Schwann cells will multiply uncontrollably and grow into tumors. Tumors form on the nerves – so-called schwannomas.
How is neurofibromatosis type 2 diagnosed?
Neurofibromatosis type 2 is diagnosed on the basis of various clinical criteria. If one of these two criteria applies, it is referred to as NF2:
- Bilateral tumors on the auditory and vestibular nerves
- A parent or brother/sister with NF2 and either a) a unilateral tumor on the auditory nerve or b) a neurofibroma, meningioma, glioma, schwannoma or c) a cataract (clouding of the lens of the eye)
Another combination of different criteria – such as a single tumor on the auditory nerve, a clouding of the lens or several typical tumors before the age of 30 – also increase the probability of neurofibromatosis type 2.
The diagnosis begins with a medical history: the doctor asks about existing symptoms (such as dizziness, hearing impairment or blurred vision) and any family history of the disease. If neurofibromatosis type 2 is suspected, the doctor will examine the eyes, skin and ears and, if necessary, carry out a neurological examination. If hearing problems, sudden hearing loss or tinnitus are the first symptom, a hearing test (audiogram) is carried out to assess hearing disorders more precisely.
How is neurofibromatosis type 2 treated?
Neurofibromatosis type 2 is a hereditary disease for which there is no causal therapy. The treatment options are limited to detecting tumors in good time and operating on them. Some symptoms can also be treated – for example, cataracts, which are often associated with neurofibromatosis type 2, can be treated by ophthalmologic surgery.
In addition, painkillers, so-called analgesics, are used for existing pain, with active substances such as amitriptyline, gabapentin or pregabalin.
