Neurofibromatosis type 2

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Neurofibromatosis type 2 (NF2) is a hereditary disease in which tumors form in the central nervous system (brain and spinal cord). The auditory nerve is particularly often affected. Like neurofibromatosis type 1, NF2 is one of the so-called phacomatoses - diseases that primarily affect the skin and nervous system.

ICD codes for this disease: ICD codes are internationally recognized codes for medical diagnoses. They can be found, for example, in doctor's letters or on certificates of incapacity for work. Q85C47D33

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, in NF2 the central nervous system, i.e. the brain and spinal cord, is primarily involved.

Type 2 neurofibromatosis is characterized by the formation of benign tumors that are located in the brain and in the area of the spinal cord. They develop particularly often on the eighth cranial nerve, the auditory and equilibrium nerves. 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. This means that it is also significantly rarer than NF1, which affects one in 3,000 people. However, neurofibromatosis type 2 is often only discovered in adulthood because the symptoms appear relatively late.

Neurofibromatosis type 2: symptoms

Type 2 neurofibromatosis causes a variety of symptoms. The symptoms depend primarily on the size and location of the respective tumors. In contrast to neurofibromatosis type 1, the onset of which is often before or during puberty, the first symptoms of neurofibromatosis type 2 often only appear in adulthood.

In the majority of patients bilateral tumors form along the auditory nerve (acoustic neuroma), which can impair hearing and balance and is often associated with tinnitus (noise in the ear).

In neurofibromatosis type 2 tumors can also develop on other cranial nerves and trigger neurological deficits (for example vocal cord paralysis). Most of those affected also develop cataracts, a clouding of the lens of the eye, as young people. Small skin tumors can also occur; however, other typical skin symptoms of neurofibromatosis type 1 (such as café-au-lait spots or freckling) are absent.

Complications

The tumors characteristic of neurofibromatosis type 2 destroy various nerve structures in the area of the brain and spinal cord in the long term. Depending on the location of the tumors, various complications and consequential damage can arise:

Hearing damage up to deafness
Facial nerve paralysis
Difficulty swallowing (dysphagia)
Vocal cord paralysis (recurrent palsy)

The complications of type 2 neurofibromatosis depend on which cranial nerves are affected. While the frequent involvement of the eighth cranial nerve primarily affects hearing and balance, swallowing disorders are mostly caused by a tumor on the ninth cranial nerve. In many cases, however, these complications of type 2 neurofibromatosis can be anticipated if the tumors in question are identified and removed in good time.

Neurofibromatosis type 2: causes and risk factors

Type 2 neurofibromatosis is a hereditary disease. The cause is a change (mutation) of a certain gene, the NF2 gene, which is located on chromosome 22 in humans. This gene contains the “blueprint” for a special protein: Schwannomin, often also 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 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 in an uncontrolled manner and grow into tumors. Tumors form on the nerves - so-called schwannomas.

Most NF2 tumors, including acoustic neuromas, are schwannomas. Other types of tumors - such as the neurofibromas typical of NF1 and meningiomas (tumors of the meninges) - can 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 an 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)

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

The diagnosis starts with the anamnesis: The doctor asks about existing symptoms (such as dizziness, hearing impairment or clouded vision) and about related illnesses in the family. If type 2 neurofibromatosis is suspected, he will examine the eyes, skin, and ears and, if necessary, perform a neurological examination. If hearing problems, sudden hearing loss or tinnitus are the first symptom, a hearing test (audiogram) is carried out - this allows the doctor to assess the hearing impairment more precisely.

Various imaging methods, especially computed tomography (CT) and magnetic resonance imaging (MRT), are suitable for making the tumors in the brain and spinal cord that occur in neurofibromatosis type 2 visible. With these examinations, for example, sectional images of the head area can be made and - possibly supported by contrast media - changes such as schwannomas and neurofibromas can be shown.

Neurofibromatosis type 2: treatment

Neurofibromatosis type 2 is a hereditary disease for which there is no causal therapy. The treatment options are limited to identifying tumors in good time and operating them. Some symptoms can also be treated - for example, cataracts, which are often associated with neurofibromatosis type 2, can be treated by an ophthalmologist.

The treatment options are therefore based on the individual characteristics of the disease. There are also a number of self-help groups that can help people deal with possible consequences such as numbness or facial nerve paralysis.

Neurofibromatosis type 2: disease course and prognosis

The 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 to avert serious consequences, but this is not always successful. It cannot be ruled out that tumors that have been operated on may recur (recurrence).

For close relatives, for example the children of those affected, it makes sense to have regular preventive examinations. You have an increased risk of illness. The earlier possible tumors in the brain and spinal cord are discovered, the easier it is to plan a therapy for neurofibromatosis type 2.

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