In most cases, the cause of acoustic neuromas is unknown. The only statistically significant risk factor for developing an acoustic neuroma is having a rare genetic condition called neurofibromatosis type 2 (NF2). There are no confirmed environmental risk factors for acoustic neuroma. There are conflicting studies on the association between acoustic neuromas and cellular phone use and repeated exposure to loud noise. In 2011, an arm of the World Health Organization released a statement listing cell phone use as a low grade cancer risk. The Acoustic Neuroma Association recommends that cell phone users use a hands-free device.

Meningiomas are significantly more common in women than in men; they are most common in middle-aged women. Two predisposing factors associated with meningiomas for which at least some evidence exists are exposure to ionizing radiation (cancer treatment of brain tumors) and hormone replacement therapy.

The overall complication rate following surgery is around 20%; cerebrospinal fluid leak is the most common.

A nerve sheath tumor is a type of tumor of the nervous system (nervous system neoplasm) which is made up primarily of the myelin surrounding nerves.

A peripheral nerve sheath tumor (PNST) is a nerve sheath tumor in the peripheral nervous system. Benign peripheral nerve sheath tumors include schwannomas and neurofibromas.

A malignant peripheral nerve sheath tumor (MPNST) is a cancerous peripheral nerve sheath tumor.

The cause of acoustic neuromas is usually unknown; however there is a growing body of evidence that sporadic defects in tumor suppressor genes may give rise to these tumors in some individuals. In particular, loss or mutation of a tumor suppressor gene on the long arm of chromosome 22 is strongly associated with vestibular schwannomas. Other studies have hinted at exposure to loud noise on a consistent basis. One study has shown a relationship between acoustic neuromas and prior exposure to head and neck radiation, and a concomitant history of having had a parathyroid adenoma (tumor found in proximity to the thyroid gland controlling calcium metabolism). There are even controversies on hand held cellular phones. Whether or not the radiofrequency radiation has anything to do with acoustic neuroma formation, remains to be seen. To date, no environmental factor (such as cell phones or diet) has been scientifically proven to cause these tumors. The Acoustic Neuroma Association (ANA) does recommend that frequent cellular phone users use a hands free device to enable separation of the device from the head.

Although there is an inheritable condition called Neurofibromatosis Type 2 (NF2) which can lead to acoustic neuroma formation in some people, most acoustic neuromas occur spontaneously without any evidence of family history (95%). NF2 occurs with a frequency of 1 in 30,000 to 1 in 50,000 births. The hallmark of this disorder is bilateral acoustic neuromas (an acoustic neuroma on both sides) usually developing in late childhood or early adulthood, frequently associated with other brain and spinal chord tumors.

The median survival time of patients without treatment is four to six weeks. The best prognosis are seen from NM due to breast cancer with the median overall survival of no more than six months after diagnosis of NM. Death are generally due to progressive neurological dysfunction. Treatment is meant to stabilize neurological function and prolong survival. Neurological dysfunction usually cannot be fixed but progressive dysfunction can be halted and survival may be increased to four to six months.

Factors that lower survival:

Much of prognosis can be determined from the damage due to primary cancer. Negative hormone receptor status, poor performance status, more than 3 chemotherapy regimes, and high Cyfra 21-1 level at diagnosis, all indicates lower survival period of patients with NM. Cyfra 21-1 is a fragment of the cytokeratin 19 and may reflect the tumor burden within the CSF.

A schwannoma is a usually-benign nerve sheath tumor composed of Schwann cells, which normally produce the insulating myelin sheath covering peripheral nerves.

A nervous system neoplasm is a tumor affecting the nervous system. Types include:

- Nerve sheath tumor

- Brain tumor

- Arachnoid cyst

- Optic nerve glioma

Schwannomas are homogeneous tumors, consisting only of Schwann cells. The tumor cells always stay on the outside of the nerve, but the tumor itself may either push the nerve aside and/or up against a bony structure (thereby possibly causing damage). Schwannomas are relatively slow-growing. For reasons not yet understood, schwannomas are mostly benign and less than 1% become malignant, degenerating into a form of cancer known as neurofibrosarcoma. These masses are generally contained within a capsule, and so surgical removal is often successful.

Schwannomas can be associated with neurofibromatosis type II, which may be due to a loss-of-function mutation in the protein merlin. They are universally S-100 positive, which is a marker for cells of neural crest cell origin.

Schwannomas of the head and neck are a fairly common occurrence and can be found incidentally in 3–4% of patients at autopsy. Most common of these is a vestibular schwannoma, a tumor of the vestibulocochlear nerve that may lead to tinnitus and hearing loss on the affected side. Outside the cranial nerves, schwannomas may present on the flexor surfaces of the limbs. Rare occurrences of these tumors in the penis have been documented in the literature.

Verocay bodies are seen histologically in schwannomas.

Other causes may include:

- Diabetes mellitus

- Facial nerve paralysis, sometimes bilateral, is a common manifestation of sarcoidosis of the nervous system, neurosarcoidosis.

- Bilateral facial nerve paralysis may occur in Guillain–Barré syndrome, an autoimmune condition of the peripheral nervous system.

- Moebius syndrome is a bilateral facial paralysis resulting from the underdevelopment of the VII cranial nerve (facial nerve), which is present at birth. The VI cranial nerve, which controls lateral eye movement, is also affected, so people with Moebius syndrome cannot form facial expression or move their eyes from side to side. Moebius syndrome is extremely rare, and its cause or causes are not known.

A vestibular schwannoma (VS) is a benign primary intracranial tumor of the myelin-forming cells of the vestibulocochlear nerve (8th cranial nerve). A type of schwannoma, this tumor arises from the Schwann cells responsible for the myelin sheath that helps keep peripheral nerves insulated. Although it is also called an acoustic neuroma, this a misnomer for two reasons. First, the tumor usually arises from the vestibular division of the vestibulocochlear nerve, rather than the cochlear division. Second, it is derived from the Schwann cells of the associated nerve, rather than the actual neurons (neuromas).

Approximately 2,000 to 3,000 cases are diagnosed each year in the United States (6 to 9 per million persons). Comprehensive studies from Denmark published in 2012 showed an annual incidence of 19-23 per million from 2002 to 2008, over the last 30 years the reported incidence have been increasing, until the last decade in which an approximation of the true incidence may have been found. Most recent publications suggest that the incidence of vestibular schwannomas have been rising because of advances in MRI scanning.

Most cases are diagnosed in people between the ages of 30 and 60, and men and women appear to be affected equally. Most vestibular schwannomas occur spontaneously in those without a family history. One confirmed risk factor is a rare genetic mutation called NF2.

The primary symptoms of vestibular schwannoma are unexplained progressive unilateral hearing loss and tinnitus, and vestibular (disequilibrium) symptoms. Treatment of the condition is by surgery or radiation, and often results in substantial or complete hearing loss in the affected ear. Observation (non-treatment) over time also usually results in hearing loss in the affected ear.

In reported cases of the tumor over the last 25 years, the number of affected females with astroblastoma is significantly higher than the number of affected males. Sughrue et al. confirmed this trend, stating that 70% of the cases with clearly stated gender were female (100 cases total). While several publications support a genetic predisposition to females, the underlying reasons are still unknown.

The clinical spectrum of the condition is broad. In other words, people with NF II may develop a wide range of distinct problems.

1. Acoustic nerve: 90% of the patients show bilateral acoustic schwannomas on magnetic resonance imaging (MRI).

2. Other cranial nerves and meninges: About 50% of patients develop tumours in other cranial nerves or meningiomas.

3. Spinal cord: About 50% of the patients develop spinal lesions. Only 40% of the spinal lesions are symptomatic. The spinal tumours in NF II are separated in two groups. Intramedullary lesions are located within the spinal tissue and usually belong to the so-called spinal astrocytomas or ependymomas. The extramedullary lesions are located within the small space between the surface of the spinal cord and the bony wall of the spinal canal. These tumours belong to the schwannomas and meningiomas.

4. Skin: If children show neurofibromas, a diagnostic procedure should be performed to decide which form of neurofibromatosis causes the alterations.

5. Eyes: Studies on patients with NF II show that more than 90% of the affected persons suffer eye lesions. The most common alteration in NF II is the juvenile subcapsular cataract (opacity of the lens) in young people.

"Presenting symptoms" (initial concern that brings a patient to a doctor) of a lesion of the nervus vestibulocochlearis due to a tumour in the region of the cerebello-pontine angle are the following: hearing loss (98%), tinnitus (70%), dysequilibrium (67%), headache (32%), facial numbness and weakness (29% and 10% respectively).

"Clinical signs" (alterations that are not regarded by the patient and that can be detected by the doctor in a clinical examination) of the lesion in discussion are: abnormal corneal reflex (33%), nystagmus (26%), facial hypesthesia (26%).

Evaluation (study of the patient with technical methods) shows the enlargement of the porus acousticus internus in the CT scan, enhancing tumours in the region of the cerebello-pontine angle in gadolinium-enhanced MRI scans, hearing loss in audiometric studies and perhaps pathological findings in electronystagmography. Some times there are elevated levels of protein in liquor study.

In NF II, acoustic neuromas usually affect young people, whereas in sporadic forms of acoustic neuromas, the appearance of the tumour is limited to the elderly.

There are two forms of the NF II:

- The "Wishart-Phenotype" is characterized by multiple cerebral and spinal lesions in patients younger than 20 years and with rapid progression of the tumours.

- Patients that develop single central tumours with slow progression after age of 20 are thought to have the "Feiling-Gardner-Phenotype".

A lateral pontine syndrome is a lesion which is similar to the lateral medullary syndrome, but because it occurs in the pons, it also involves the cranial nerve nuclei of the pons.

Because hearing loss in those with NF-2 almost always occurs after acquisition of verbal language skills, patients do not always integrate well into the Deaf culture and are more likely to resort to auditory assistive technology.

The most sophisticated of these devices is the cochlear implant, which can sometimes restore a high level of auditory function even when natural hearing is totally lost. However, the amount of destruction to the cochlear nerve caused by the typical NF2 schwannoma often precludes the use of such an implant. In these cases, an auditory brainstem implant (ABI) can restore a primitive level of hearing, which, when supplemented by lip reading, can restore a functional understanding of spoken language.

THS is uncommon in both the United States and internationally. In New Zealand, there is only one recorded case, there is also one recorded case in New South Wales, Australia. Both genders, male and female, are affected equally, and it typically occurs around the age of 60.

Damage to the following areas produces symptoms (from medial to lateral):

Central facial palsy can be caused by a lacunar infarct affecting fibers in the internal capsule going to the nucleus. The facial nucleus itself can be affected by infarcts of the pontine arteries.

Jacod Syndrome is commonly associated with a tumor of the middle cranial fossa (near the apex of the orbit); but it can have several other causes.

In terms of the prognosis of ulnar neuropathy early decompression of the nerve sees a return to normal ability (function). which should be immediate.Severe cubital tunnel syndrome tends to have a faster recovery process in individuals below the age of 70, as opposed to those above such an age. Finally, revisional surgery for cubital tunnel syndrome does not result well for those individuals over 50 years of age.

At this point, no literature has indicated whether environmental factors increase the likelihood of astroblastoma. Although cancer in general is caused by a variety of external factors, including carcinogens, dangerous chemicals, and viral infections, astroblastoma research has not even attempted to classify incidence in this regard. The next few decades will aid in this understanding.

The facial nerve is the seventh of 12 cranial nerves. This cranial nerve controls the muscles in the face. Facial nerve palsy is more abundant in older adults than in children and is said to affect 15-40 out of 100,000 people per year. This disease comes in many forms which include congenital, infectious, traumatic, neoplastic, or idiopathic. The most common cause of this cranial nerve damage is Bell's palsy (idiopathic facial palsy) which is a paralysis of the facial nerve. Although Bell's palsy is more prominent in adults it seems to be found in those younger than 20 or older than 60 years of age. Bell's Palsy is thought to occur by an infection of the herpes virus which may cause demyelination and has been found in patients with facial nerve palsy. Symptoms include flattening of the forehead, sagging of the eyebrow, and difficulty closing the eye and the mouth on the side of the face that is affected. The inability to close the mouth causes problems in feeding and speech. It also causes lack of taste, acrimation, and sialorrhea.

The use of steroids can help in the treatment of Bell's Palsy. If in the early stages, steroids can increase the likelihood of a full recovery. This treatment is used mainly in adults. The use of steroids in children has not been proven to work because they seem to recover completely with or without them. Children also tend to have better recovery rates than older adults. Recovery rate also depends on the cause of the facial nerve palsy (e.g. infections, perinatal injury, congenital dysplastic). If the palsy is more severe patients should seek steroids or surgical procedures. Facial nerve palsy may be the indication of a severe condition and when diagnosed a full clinical history and examination are recommended.

Although rare, facial nerve palsy has also been found in patients with HIV seroconversion. Symptoms found include headaches (bitemporal or occipital), the inability to close the eyes or mouth, and may cause the reduction of taste. Few cases of bilateral facial nerve palsy have been reported and is said to only effect 1 in every 5 million per year.

The prognosis of THS is usually considered good. Patients usually respond to corticosteroids, and spontaneous remission can occur, although movement of ocular muscles may remain damaged. Roughly 30–40% of patients who are treated for THS experience a relapse.

Neoplastic or malignant meningitis, also called meningitis carcinomatosa and leptomeningeal carcinomatosis, is the development of meningitis due to infiltration of the subarachnoid space by cancerous cells. Malignant cells come from primary cancer such as breast cancer or from a primary brain tumor like medulloblastoma. Neoplastic Meningitis (NM) was first reported in the 1870s with the most common cause being breast cancer, lung cancer, and malignant melanoma.

The most common finding is oculomotor nerve dysfunction leading to ophthalmoplegia. This is often accompanied by ophthalmic nerve dysfunction, leading to hypoesthesia of the upper face. The optic nerve may eventually be involved, with resulting visual impairment.

Papillary tumors of pineal region are extremely rare, constituting 0.4-1% of all central nervous system tumors. These tumors most commonly occur in adults with the mean age being 31.5. There have been cases reported for people between the ages 5 to 66 years. There is a slight predominance of females who have these tumors.