The clinical presentation of neurofibromatosis type 2 is comprised of several crucial elements [1] [2] [3] [4] [5] [6]:

• Nervous system tumors - Schwannomas are the most common tumor type identified in patients suffering from this condition and they predominantly develop in vestibular nerves [1] [2] [3]. For this reason, early-onset bilateral hearing loss and possible deafness in adolescents (accompanied by tinnitus and deficits in maintaining balance) is a cardinal characteristic of neurofibromatosis type 2 [2] [3]. Schwannomas, but also meningiomas, ependymomas, and astrocytomas, may also be seen in other parts of the nervous system, such as the spinal cord, the cranial nerves, and the peripheral nervous system [1] [2] [3]. In rare cases, vestibular tumors can compress the brain stem and induce hydrocephalus [1]. One of the additional traits of neurofibromatosis related to the nervous system are neuropathies that often develop (without a connection to the tumors), mainly manifesting as palsies of the facial or oculomotor nerve, whereas peripheral signs of a foot drop or wrist drop are encountered as well [1] [6].
• Ocular deficits - Although findings related to the vestibular system are a very important feature of neurofibromatosis, eye symptoms often precede hearing loss and are often the first sign of this rare condition [1] [3]. Subcapsular lens opacities that may progress into cataracts, retinal hamartomas, and epiretinal membranes can be noticed in the affected population [1].
• Skin lesions - Schwannomas can also develop on the skin, either subcutaneously or intradermally [3]. In addition, the appearance of slightly raised and well-circumscribed hyperpigmented plaques commonly indicates neurofibromatosis [3].

The diagnostic workup of patients must include a thorough patient history and a detailed physical examination. The physician should obtain as much information as possible regarding the onset of complaints, their progression, as well as severity, while a complete neurological and skin examination is crucial for raising clinical suspicion [2] [3]. The findings of bilateral hearing loss in adolescence with cutaneous lesions and neuropathy can be sufficient to make a presumptive diagnosis based on clinical grounds. Despite the fact that autosomal dominant pattern of inheritance is established (meaning that a proper family history is of great benefit) [4], up to 50% of cases develop de novo mutations [2] [3]. For this reason, the presence of a bilateral vestibular schwannoma (regardless of the family history) is considered to be the main criteria for neurofibromatosis type 2 [3] [5]. Alternatively, a clinical diagnosis is reached when unilateral vestibular tumors or two lesions typically associated with this condition are supported by either a positive family history or the appearance of multiple meningiomas [3] [4]. To confirm central nervous system tumors, magnetic resonance imaging (MRI) is the cornerstone and high-resolution T1 weighted, contrast-enhanced images are optimal for visualizing vestibular schwannomas [3]. By using mutational analysis of the NF2 gene located on chromosome 22, genetic studies can be employed to make a definitive diagnosis [1].

Treatment for NF2 focuses on managing symptoms and preventing complications. Surgical removal of tumors may be necessary if they cause significant symptoms or threaten vital functions. Stereotactic radiosurgery, a non-invasive procedure, can be used to treat smaller tumors. Hearing aids or cochlear implants may help manage hearing loss. Regular monitoring through MRI and audiometric tests is crucial to track the progression of the disease. Supportive therapies, such as physical therapy, can help maintain mobility and balance.

The prognosis for individuals with NF2 varies depending on the severity and location of the tumors. Early diagnosis and intervention can improve outcomes and quality of life. While NF2 is a lifelong condition, advancements in treatment have improved the management of symptoms and extended life expectancy. Regular follow-up with healthcare providers is essential to monitor the disease and adjust treatment plans as needed.

NF2 is caused by mutations in the NF2 gene, which provides instructions for making a protein called merlin or schwannomin. This protein acts as a tumor suppressor, helping to control cell growth. Mutations in the NF2 gene lead to uncontrolled cell growth and the formation of tumors. NF2 is inherited in an autosomal dominant pattern, meaning a single copy of the altered gene is sufficient to cause the disorder. However, some cases result from new mutations with no family history.

NF2 is a rare disorder, affecting approximately 1 in 25,000 to 1 in 40,000 individuals worldwide. It affects both males and females equally and can occur in any ethnic group. Most individuals with NF2 develop symptoms in their late teens or early adulthood, although the age of onset can vary widely.

The pathophysiology of NF2 involves the loss of function of the merlin protein due to mutations in the NF2 gene. Merlin is crucial for regulating cell growth and maintaining the stability of the cytoskeleton, the structure that helps cells maintain their shape. Without functional merlin, cells can grow uncontrollably, leading to the formation of tumors, particularly schwannomas, meningiomas, and ependymomas, in the nervous system.

Currently, there is no known way to prevent NF2, as it is a genetic condition. Genetic counseling is recommended for individuals with a family history of NF2 to understand their risk of passing the condition to their children. Prenatal testing and preimplantation genetic diagnosis are options for families who wish to prevent the transmission of NF2 to future generations.

Neurofibromatosis Type 2 is a genetic disorder characterized by the growth of benign tumors in the nervous system, primarily affecting hearing and balance. Early diagnosis and regular monitoring are crucial for managing symptoms and improving quality of life. While there is no cure, various treatment options are available to address the complications associated with the disease. Genetic counseling can help families understand the risks and implications of NF2.

If you or a loved one has been diagnosed with NF2, it's important to work closely with a healthcare team to manage the condition. Regular check-ups and imaging tests are essential to monitor tumor growth and address any symptoms that arise. Hearing aids, physical therapy, and surgical interventions may be part of your treatment plan. Understanding the genetic nature of NF2 can help you make informed decisions about family planning and future care.

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5. Evans DGR, Sainio M, Baser ME. Neurofibromatosis type 2. J Med Genet. 2000;37:897–904.
6. Evans DGR, Birch JM, Ramsden RT. Paediatric presentation of type 2 neurofibromatosis. Arch Dis Child. 1999;81:496–99.