User:Ramirezxn/sandbox

...and causes benign tumors of the brain, spinal cord and peripheral nerves. The types of tumors frequently associated with NF2 include vestibular schwannomas, meningiomas, and ependymomas.

Cause
The hearing loss caused by NF2 is gradual and results from the presences of bilateral cochleovestibular schwannomas, also known as acoustic neuromas, which damage to cochlear nerve causes hearing loss. Hearing loss may also result from benign tumors that grow on the vestibular and auditory nerves, which lead to the inner ear.

Type/Degree
Typically, patients diagnosed with NF2 generally present with a mild to moderate hearing loss that is commonly bilateral, and may become profound. Patients may benefit from the use of hearing aids; however, in many instances, their hearing loss will eventually surpass the level at which this would be considered an effective treatment.

Treatment
As hearing loss in individuals with NF2 is generally gradual, eventually profound and sensorineural, the best options for treatment for hearing loss are cochlear implants and auditory brainstem implants (ABIs), as well as supplementing hearing with lip-reading and sign language.

Cochlear Implants
A cochlear implant is an electronic device that is surgically implants to stimulate the cochlear nerve. Cochlear implants will work only when the cochleovestibular nerve (8th nerve) and the cochlea are still functioning. In a study done with open-set speech perception testing and closed-set speech perception testing by Neff et al., they discovered that the use of cochlear implants with NF2 patients allowed significant improvement of hearing abilities. In testing of recognition of sentences of everyday speech, five out of six patients scored within the 90%-100% range, and in testing of hearing in noise setting, four of six of the patients scored within the 83%-96%. Additionally, all testing was done without lip-reading.

Auditory Brainstem Implants (ABIs)
Auditory Brainstem Implants, or ABIs, are used when the cochlea or any portion of the cochleovestibular nerve are not functioning due to damage to those areas or anatomic abnormalities. The procedure is done by implanting a device that send an electrical signal directly to the cochlear nucleus, allowing sound to bypass the peripheral auditory system and straight into the brain stem.

Symptoms
Symptoms can occur at any age, typically in adolescence and early adulthood and rarely seen in children, and severity depend on the location of the tumors. Symptoms include but are not limited to:


 * Tinnitus
 * Loss/problems of balance
 * Glaucoma
 * Seizures
 * Hearing loss
 * Vision impairment
 * Numbness or weakness in arms and legs

Diagnosis
NF2 is a genetically transmitted condition. Diagnosis is most common in early adulthood (20 - 30 years); however, it can be diagnosis earlier. NF2 can be diagnosed due to the presence of a bilateral vestibular schwannoma, or an acoustic neuroma, which causes a hearing loss that may begin unilaterally. If a patient does not meet this criterion of diagnosis, they must have a family history of NF2, and present with a unilateral vestibular schwannoma and other associated tumors (cranial meningioma, cranial nerve schwannoma, spinal meningioma, spinal ependymomas, peripheral nerve tumor, spinal schwannoma, subcutaneous tumor, skin plaque). This being said, it should be noted that more than half of all patients diagnosed with NF2 do not have a family history of the condition. Although it has yet to be included into clinical classification, peripheral neuropathy, or damage to the peripheral nerves, which often causes weakness, numbness and pain in the hands and feet, may also lead to a diagnosis of NF2. In children, NF2 can present with similar symptoms, but generally causes "visual disturbances (cataracts, hamartomas), skin tumors, and mononeuropathy (facial paresis, drop foot), symptomatic spinal cord tumors, or non-vestibular intracranial tumors".

Prognosis
NF2, NF2, is a life limiting condition. It is a rare genetic disorder that involves noncancerous tumors of the nerves that transmit balance and sound impulses from the inner ear to the brain. The prognosis is affected by early age onset, a higher number of meningiomas and schwannomas and having a decrease in mutation.

An early diagnosis is the best way to ensure improvement in management. Although, even with an early diagnosis, some patients still die very young.

Meningiomas and schwannomas occur in around half of patients with NF2. Meningiomas are tumors that are both intracranial and intraspinal. Schwannomas are tumors that are often centered on the internal auditory canal. Patients with NF2 who have meningiomas have a higher risk of mortality, and the treatment can be very challenging. Individuals who develop schwannomas frequently develop hearing loss and deafness. These individuals may also develop tinnitus after being presented with unilateral hearing loss. The first symptom that individuals may encounter is dizziness or imbalance.

Truncating mutations lead to smaller and non-functional protein products. Studies have shown that missense mutations and large deletions can both cause predominantly mild phenotypes. Phenotype is more variable in patients with splice-site mutations, and a milder disease in patients with mutations in exons 9-15. Patients with a missense mutation have a greater survival rate than nonsense and frameshift mutations.