Neurofibromatosis type 2

Neurofibromatosis type 2: description

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 involves the central nervous system, ie the brain and spinal cord.

Characteristic of the neurofibromatosis type 2 is the formation of benign tumors, which are located in the brain and in the area of ​​the spinal cord. Most frequently, they develop on the eighth cranial nerve, the auditory and equilibrium nerve. In addition to tumor formation, there is often a pathological change in the lens of the eye (posterior subcapsular cataract).

Neurofibromatosis type 2 is a rare disease: one in 40,000 people is affected. Thus, it is also much less common than NF1, in which one of 3,000 people suffers. However, neurofibromatosis type 2 is often only discovered in adulthood, as the symptoms are relatively late.

Neurofibromatosis type 2: symptoms

Neurofibromatosis type 2 causes many symptoms. The symptoms depend mainly on the size and location of the respective tumors. Unlike neurofibromatosis type 1, whose onset often begins before or during puberty, the first symptoms of neurofibromatosis type 2 often do not appear until adulthood.

In the majority of patients, bilateral tumors form along the auditory nerves (acoustic neuromas), which may affect hearing and sense of balance, often accompanied by tinnitus (ear noise).

Neurofibromatosis type 2 tumors can also develop on other cerebral nerves and trigger neurological deficits (for example vocal cord paralysis). Most people also develop a cataract when they are young, a clouding of the lens of the eye. Even small skin tumors may occur; however, other typical skin symptoms of neurofibromatosis type 1 (such as café-au-lait spots or freckling) are lacking.

complications

The tumors characteristic of neurofibromatosis type 2 destroy long-term different nerve structures in the area of ​​the brain and the spinal cord. Thus, depending on the location of the tumors, various complications and consequential damages may arise:

• Hearing damage to the point of deafness
• Facial nerve paralysis (facial paralysis)
• Dysphagia (dysphagia)
• Vocal cord paralysis (recurrent paralysis)

The complications of type 2 neurofibromatosis depend on which brain nerves are affected. While the frequent involvement of the eighth cerebral nerve mainly affects hearing and balance, dysphagia is usually caused by a tumor on the ninth cerebral nerve. In many cases, however, these complications of neurofibromatosis type 2 can be anticipated if the tumors in question are detected and removed in good time.

Neurofibromatosis type 2: causes and risk factors

Neurofibromatosis type 2 is a hereditary disease. The cause is a mutation of a particular gene, the NF2 gene, which is located on chromosome 22 in humans. 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 the so-called Schwann cells, which have the function of enveloping and isolating nerve fibers. If the NF2 gene is damaged, the Schwann cells can multiply uncontrollably and grow into tumors. Tumors form on the nerves – so-called schwannomas.

Most tumors of NF2, including akusitcus neuromas, are schwannomas. Other types of tumors – such as the NF1-typical neurofibromas and meningiomas (tumors of the meninges) – may occur but are less common.

Neurofibromatosis type 2: examinations and diagnosis

The diagnosis of neurofibromatosis type 2 is based on various clinical criteria. If one of these two criteria applies, one speaks of NF2:

• bilateral tumors on the auditory and equilibrium nerves
• a parent or brother / sister with a NF2 and either a) a unilateral tumor on the auditory nerve or b) a neurofibroma, meningioma, glioma, schwannoma or c) a cataract (opacity of the eye lens)

Another combination of different criteria – such as a single tumor on the auditory nerve, a lens opacification or several typical tumors before the age of 30 – increase the likelihood of neurofibromatosis type 2.

At the beginning of the diagnosis is the history: The doctor asks for existing symptoms (such as dizziness, hearing impairment or cloudy vision) and for corresponding diseases in the family. If neurofibromatosis type 2 is suspected, it examines the eyes, the skin, the ears and, if necessary, carries out a neurological examination. If hearing problems, a sudden hearing loss or tinnitus are the first symptom, a hearing test (audiogram) will be performed – this will help the doctor to assess hearing impairment more accurately.

In order to visualize the tumors occurring in the area of ​​the brain and spinal cord in neurofibromatosis type 2, various imaging techniques are suitable, in particular computer tomography (CT) and magnetic resonance imaging (MRI). With these examinations, for example, sectional images of the head area can be prepared and – possibly supported by contrast medium – represent changes such as schwannomas and neurofibromas.

Neurofibromatosis type 2: treatment

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 to operate. Also, some symptoms can be treated – for example, can be treated by an ophthalmological surgery, the cataract, which is often associated with neurofibromatosis type 2.

The treatment options thus depend on the individual expression of the disease. There are also a number of self-help groups that can help those affected deal with any consequences such as numbness or facial nerve paralysis.

Neurofibromatosis type 2: Disease course and prognosis

Prognosis strongly depends on the course of neurofibromatosis type 2. In many cases it is possible to remove the typical tumors such as the acoustic neuroma and avert serious consequences, but this is not always successful. It can not be ruled out that operated tumors recur (recurrences).

For close relatives, such as the children of those affected, regular check-ups are useful. You have an increased risk of disease. The sooner possible tumors in the brain and spinal cord are discovered, the better the therapy of theNeurofibromatosis type 2 to plan.