What are the other Names for this Condition? (Also known as/Synonyms)

• Cranial Nerve 7 Schwannoma
• FNS (Facial Nerve Schwannoma)
• Seventh Cranial Nerve Schwannoma

What is Facial Nerve Schwannoma? (Definition/Background Information)

• Schwannomas are mostly benign tumors that arise from the Schwann cells around the nerves; these tumors are nerve sheath tumors. Schwannomas involving the central nervous system (CNS) are classified as grade I tumors of the cranial and paraspinal nerves, according to the World Health Organization (WHO)
• WHO grade I brain tumors are the most benign of the brain tumors that are slow-growing and are not known to infiltrate into surrounding tissues. They offer a very high chance for surgery to be curative, and thus, have the best prognosis amongst all brain tumors; long-term survivals are usually noted
• A majority of schwannomas involve the cranial nerve, particularly cranial nerve VIII (in nearly 90% of the cases) causing vestibular schwannomas. Cranial nerves are 12 pairs of sensory and/or motor nerves having specific functions that connect parts of the head and neck region to the brain. Ten of these pairs originate from the brainstem; two pairs originate from the cerebrum
• Facial Nerve Schwannomas (FNSs) are uncommon schwannomas that involve the cranial nerve VII (CN VII), or the facial nerve. It is a highly complex bundle of nerves with both sensory and motor function. This cranial nerve is responsible for a wide variety of facial expressions such as frowning, wrinkling of the brow, puffing the cheeks, showing anger, closing the eyes tight, etc.
• The seventh cranial nerve is also involved in regulating the lacrimal (tear) glands and salivary glands, including providing special taste sensation and communicating sensory information from some parts of the ear. The course of the nerve is both intracranial, arising from the pons near the brainstem and running through the cranium, and extracranial, moving to parts of the ear and neck regions
• Currently, no causative factors have been identified for Facial Nerve Schwannoma, although certain genetic, environmental, and occupational factors have been implicated. The risk factors for the tumor may include the presence of neurofibromatosis type 2 (NF2) and a positive family history of schwannoma
• Facial Nerve Schwannomas may cause facial nerve palsy, including facial drop, facial twitching and spasms. In some cases, the involvement of multiple cranial nerves is noted. Many individuals may experience symptoms associated with vestibular schwannoma, such as hearing impairment, ringing in the ears, vertigo, and balance issues. In rare cases, the presence of malignant schwannomas may worsen the symptoms and outcomes
• Occasionally, the healthcare provider may undertake a ‘wait and watch’ approach for small-sized and slow-growing tumors. In many cases, depending on the tumor size, a complete excision by surgery or treatment through Gamma Knife radiosurgery can be curative. The prognosis of Facial Nerve Schwannoma is typically good with appropriate management and follow-up care

Who gets Facial Nerve Schwannoma? (Age and Sex Distribution)

• Facial Nerve Schwannoma (FNS) is an uncommon tumor that is mostly observed in adults; some cases are reported in children too. The age range of presentation is between 10 and 70 years (according to one particular study); the mean age of diagnosis being 39 years
• After vestibular and trigeminal schwannoma, it is the third most common intracranial nerve schwannoma. However, FNS is the most common tumor involving the facial nerve
• Both males and females are affected, and no gender preference is noted
• There is no known geographical bias and racial/ethnic preference observed

What are the Risk Factors for Facial Nerve Schwannoma? (Predisposing Factors)

Based on the available reports, a majority of Facial Nerve Schwannomas may be sporadic in nature with no well-established predisposing factors.

• Very rarely, the presence of neurofibromatosis type 2 (NF2) may be noted. NF2 is a genetic condition characterized by the formation of non-cancerous tumors affecting the nervous system
• In general, for schwannomas the risk factors may include:
  • A family history of the tumor
  • Frequent exposure to ionizing and non-ionizing radiation

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases one’s chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Facial Nerve Schwannoma? (Etiology)

The exact cause and mechanism of Facial Nerve Schwannoma formation is unknown; in most cases, they are believed to be the result of sporadic mutations. It is researched that certain genetic, environmental, and occupational factors may contribute towards the development of cranial nerve schwannomas.

Overall, the following factors have been identified as playing a role in schwannoma development:

• Abnormalities in chromosome 22
• Multiple schwannomas are known to occur in a background of genetic disorders, such as NF2 and Gorlin-Koutlas syndrome, or a positive family history
• The tumor is believed to be caused by the overproduction of Schwann cells that wrap around the nerve

In general, it is known that tumors form when normal, healthy cells begin transforming into abnormal cells - these cancer cells grow and divide uncontrollably (and lose their ability to die), resulting in the formation of a mass or a tumor.

What are the Signs and Symptoms of Facial Nerve Schwannoma?

The signs and symptoms of Facial Nerve Schwannoma (FNS) may differ from one individual to another. It may be mild or severe, depending on several factors. The onset and speed of progression of the tumor can vary. In some individuals, the tumors are known to remain asymptomatic and are only diagnosed during certain radiological imaging studies of the head and neck region, performed for unrelated health conditions.

Facial Nerve Schwannoma is known to develop and progress along a least resistance path. Thus, it can remain asymptomatic and undetected for many years, until the onset of significant symptoms due to facial nerve dysfunction from large-sized tumors is noted. But, the signs and symptoms are largely dependent on the location of the tumor; FNS can arise from anywhere in the facial nerve. In some cases, FNS is observed to involve other cranial nerves, especially the vestibulocochlear nerve. Depending on the nerve involved, associated signs and symptoms are also noted.

In general, the signs and symptoms include:

• The tumors are mostly slow-growing and solitary; they normally appear as a firm but painless mass
• Schwannomas affecting cranial nerve VII usually arise in the temporal bone region of brain, particularly from near the perigeniculate area and tympanic segment 
• Schwannomas may involve the parotid gland (a major salivary gland) in 20-25% of the cases. Such tumors are known as intraparotid Facial Nerve Schwannomas
• Injury to the facial nerve by the tumor can gradually result in (one-sided) facial nerve paralysis
• Facial neuropathy, in nearly 45% cases, leading to facial muscle weakness, twitching, and spasms on one side of the face
• Facial drop and altered touch sensation on the face (facial paresthesia)
• Facial numbness or tingling sensation
• About 50% of the tumors affect the auditory canal (presence of mass in the ear canal), and there are overlapping symptoms of vestibular schwannomas including:
  • One-sided hearing impairment
  • Ringing in the ears (tinnitus)
  • Vertigo
  • Loss of balance
  • Dizziness, in some individuals
  • Pain in or around the ear
• Sensorineural hearing loss (observed in nearly 30% of the individuals): A type of hearing loss that results from a problem in the inner ear. Often, one-sided hearing loss is observed (depending on which ear is affected)
• Conductive hearing loss, in some cases: It is a type of hearing loss that results from a problem in the outer ear or middle ear
• The tumors may affect one side (unilateral), or rarely, both sides (bilateral) of the face
• Malignant tumors grow far more rapidly and present pronounced symptoms, including pain
• Multiple schwannomas are known to occur in a background of genetic disorders, such as neurofibromatosis type 2 or Gorlin-Koutlas syndrome

Large tumors can cause significant signs and symptoms. Also, associated symptoms of the underlying condition, if any, may be noted.

How is Facial Nerve Schwannoma Diagnosed?

A majority of Facial Nerve Schwannomas (FNSs) may remain undiagnosed for prolonged periods, because many are asymptomatic and slow-growing. The slow development of symptoms may contribute to a delayed detection and diagnosis of these tumors. The tumors are detected when there is a sudden worsening of symptoms prompting the healthcare provider to perform radiological studies of the brain.

In general, it is difficult to diagnose FNS due to their wide-ranging presentations and close resemblance to tumors that exhibit similar symptoms. The tumor may be misdiagnosed as vestibular schwannoma, meningioma, or parotid gland tumor. A diagnosis may involve the following tests and examinations:

• Complete physical examination with thorough evaluation of the individual’s medical history (including family history of NF2 or schwannoma)
• Assessment of the presenting signs and symptoms
• Hearing and audiometric tests, including:
  • Otoscopy: Examination using an instrument that allows the physician to look inside the ear
  • Weber and Rinne test, where a vibrating tuning fork is used to assess one’s hearing ability
  • Tympanometry: A test using air pressure in the ear canal to move the eardrum, and measure eardrum mobility (movement)
  • Acoustic reflex: A test that stimulates the stapedius (a tiny ear muscle) to move, in response to a loud sound
  • Static acoustic measures: A test to measure the amount of air in the ear canal
  • Auditory brainstem response: In this test, electrodes are placed on the scalp, to measure the electrical response of the brain to sounds
  • Otoacoustic emissions: A test in which a tiny microphone is placed in the ear to play sounds, and measures the signals produced by the inner ear
• Neurological, motor skills, and cognitive assessment:
  • Checking intellectual ability, memory, mental health and function, language skills, judgment and reasoning, coordination and balance, reflexes, and sensory perceptions (space, sight, hearing, touch, etc.)
  • The healthcare provider/neurologist may use the Karnofsky Performance Scale in order to assess the neurological functioning of the individual’s central nervous system (CNS)
• Cranial nerve examination
• Electroencephalography (EEG)
• Electromyography with nerve conductivity tests
• Imaging studies that may be performed include:
  • X-ray of head and neck and/or vertebral column
  • Computerized tomography (CT) scan of the head and neck region; CT with contrast
  • Magnetic resonance imaging (MRI) scan of the central nervous system; MRI with contrast agents such as gadolinium
  • Cerebral angiographic studies or MR angiography: An angiogram involves injecting dye into the bloodstream, which makes the blood vessels to appear visually on X-rays
  • Positron emission tomography (PET scan): A PET scan is a nuclear medicine imaging technique that uses three-dimensional images to show how tissue and organs are functioning. It may be performed to detect any malignancy, and if there is a metastasis (spread) of the tumor to other regions
• Cerebrospinal fluid analysis, where a spinal tap or lumbar puncture procedure may be performed: This diagnostic test is used to remove a sample of cerebrospinal fluid (CSF) from the spaces in and around the brain and spinal cord. The sample is removed from the lower spinal cord using a thin needle, and it is then checked for the presence of cancer cells
• Magnetic resonance spectroscopy: This radiological technique is used to study the chemical profile of the tumor. It is often performed with and compared to corresponding MRI scan images of the affected region

Tissue biopsy: A biopsy of the affected region (brain) is performed and sent to a laboratory for a pathological examination. A pathologist examines the biopsy sample under a microscope. After putting together clinical findings, special studies on tissues (if needed) and with microscope findings, the pathologist arrives at a definitive diagnosis. Examination of the biopsy sample under a microscope by a pathologist is considered to be gold standard in arriving at a conclusive diagnosis.

There are two ways to perform a biopsy:

• First, a biopsy can be performed as part of a surgical procedure to remove the brain tumor
• Second, a stereotactic needle biopsy can be performed when the tumor is deep within the brain or located in a sensitive area. In this procedure, the surgeon drills a small hole (called a burr hole) into the skull. A thin needle, guided by CT or MRI scanning, is then inserted through the hole to help in the removal of tissue

A differential diagnosis to eliminate other conditions or tumor types may be considered, before arriving at a definitive diagnosis. This may include the exclusion of:

• Cholesteatoma
• Facial nerve hemangioma
• Meningioma
• Parotid gland tumors
• Perineural parotid malignancy
• Vestibular schwannoma

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Facial Nerve Schwannoma?

The complications from Facial Nerve Schwannoma (FNS) could include:

• Emotional and mental stress for both the patient and the caretakers, due to the diagnosis and during treatment of a brain tumor
• Permanent damage to the facial nerve or other involved cranial nerves, causing permanent hearing loss (on one side or both sides) and facial drop/paralysis
• Irreversible hearing loss and severe vertigo/dizziness is observed in individuals with longstanding and undetected FNS tumors due to formation of labyrinthine fistula (abnormal connection between the inner ear and surrounding structures) from bone erosion
• Large undetected tumors can severely affect brain function and be disabling or even life-threatening
• Very rarely, the presence of malignant schwannomas can result in tumor metastasis and severe complications
• Complications due to an underlying genetic disorder, if any present, may be observed

Complications may arise from surgery, radiation therapy, chemotherapy, or any other treatment measures.

Surgery:

• Damage to the muscles, vital nerves, and blood vessels, during surgery to remove the tumor; injury to unaffected brain tissue during surgery
• Post-surgical infection at the wound site is a potential complication
• Sometimes, removing the tumor can worsen the signs and symptoms in some individuals
• In some cases, post-operative facial nerve palsy is observed that may not resolve for a long time
• Infrequently, recurrence of the tumor after surgery, if the tumor is incompletely removed

Chemotherapy side effects depend on the type of chemotherapy medication used and may include:

• Nausea and vomiting
• Hair loss
• Mouth sores
• Loss of appetite
• Diarrhea
• Fatigue
• Increased risk for infections
• Easy bruising

Radiation therapy can cause short-term side effects. It depends on the type used and may include:

• Nausea and vomiting
• Hair loss
• Dryness of mouth; loss of taste
• Headaches
• Fatigue
• Skin color changes; usually darkening of skin on the face and neck may be noted
• Speech and hearing difficulties
• Memory issues
• Seizures
• Long-term side effects (seen after 6 months or beyond) may include loss of memory, impaired brain function, and appearance of symptoms that mimic stroke

How is Facial Nerve Schwannoma Treated?

In general, the treatment modality for a benign brain tumor is chosen depending on the size, location, and stage of the tumor, tumor growth rate, age and health status of the individual. Tumors that are small and slow-growing usually may be observed and no treatment necessitated, based on the healthcare provider’s specific case-by-case assessment. Often, a multidisciplinary team of specialists including ophthalmologists, otolaryngologists, neurologists, oncologists, surgeons, radiation therapy experts, and other healthcare professionals may be involved in managing the condition.

The treatment measures for benign Facial Nerve Schwannoma (FNS) may include:

• Wait and watch approach by the healthcare provider may be rarely considered for small tumors that are not associated with any underlying genetic disorders such as neurofibromatosis
• Symptomatic treatment may involve the use of antiseizure medications, painkillers, steroids (to reduce inflammation), and administration of anti-depressants

Conservative approaches are preferred initially in treating FNS, unless vital regions of the brain are getting compromised, such as the brainstem. Hence, the healthcare provider may consider the use of stereotactic radiosurgery initially, depending on the size and other characteristics of the tumor.

A surgery may be undertaken if the tumor is large, the symptoms are severe, and/or to aid in its diagnosis. However, when surgical excision and tumor removal is recommended, the preservation of cranial nerve function that is affected by the tumor, is an extremely important consideration. The invasive procedures and surgical approach evaluated are based on tumor sizes and anatomical locations, including the extent of hearing impairment in the individual.

Surgical treatment options may include the following:

• Microsurgery: The surgery is performed using microsurgical techniques, which can help minimize damage to the accompanying nerve. Since the tumor mostly affects the covering around the nerves, it can be completely removed without affecting the nerve in most cases. The following techniques may be employed:
  • Subtotal removal; when the tumor is incompletely removed
  • Near total removal; when most of the tumor is removed and there is very little tumor remnants
  • Total tumor removal; when the tumor is removed completely
• Craniotomy: It is a surgical procedure wherein a tiny hole is created in the cranium to remove the tumor
• Post-operative care is important: One must maintain minimum activity levels, until the surgical wound heals

Surgical procedures to remove brain tumors carry risks, including infection, possible damage to healthy brain tissue, swelling, or possible fluid build-up in the brain.

In case of malignancy, additional treatment options, such as chemotherapy and/or radiation therapy, may be considered.

• Chemotherapy may be used to destroy the tumor cells:
  • It is not reportedly a very useful method to treat the condition
  • The response of the tumor to chemotherapy is an important consideration while using this treatment modality
  • Whether to use chemotherapy as a treatment modality is determined by healthcare provider on case-by-case basis
• Radiation therapy may be useful in individuals who are not candidates for surgery. Such cases include:
  • Individuals with overall poor health status
  • The presence of bilateral schwannomas
  • Individuals with minimal symptoms
• Stereotactic radiosurgery is a relatively new treatment method that can be helpful in some individuals. It is a radiation therapy technique and not an invasive surgical procedure. It can be administered using a Gamma Knife (Gamma Knife radiosurgery). This method has known to be beneficial in some cases
• Treatment of the underlying neurofibromatosis type 2 or any other genetic condition, if present

Clinical trials: In advanced stages of tumor progression, there may be some newer treatment options, currently on clinical trials, which can be considered for some patients depending on their respective risk factors.

Regular observation and periodic checkups to monitor the condition is recommended following treatment. In order to avoid a relapse, or be prepared for a recurrence, the entire diagnosis, treatment process, drugs administered, healthcare recommendations post-treatment, etc. should be well-documented and follow-up measures initiated accordingly.

How can Facial Nerve Schwannoma be Prevented?

Presently, there are no specific methods or guidelines to prevent the formation of Facial Nerve Schwannoma. However, if it is associated with a genetic disorder, the following points may be considered:

• Genetic counseling and testing: If there is a family history of the condition, then genetic counseling will help assess risks, before planning for a child
• Regular health check-ups might help those individuals with a history of the condition in the immediate family, in order to help diagnose the tumor early

In general, the factors that may help reduce the incidence of schwannomas and other brain tumor include:

• Reducing exposure to ionizing radiation
• Avoiding high noise areas; using suitable earmuffs when working in noisy environment
• Avoiding cigarette smoke inhalation
• Weight loss, in case one is obese or overweight; maintaining a good BMI
• Availing early treatment for infections
• Using safety gear including wearing helmets when playing sports or while riding two-wheelers
• Wearing seatbelts while driving automobiles to minimize the risk for head/body injury

Regular medical screening at periodic intervals with blood tests, scans, and physical examinations are mandatory. Often several years of active vigilance are crucial and necessary.

What is the Prognosis of Facial Nerve Schwannoma? (Outcomes/Resolutions)

The prognosis of Facial Nerve Schwannoma (benign tumor) is usually good, particularly if the tumor can be removed without damaging the underlying nerve. Some individuals may present post-surgical complications that may require long-term follow-up.

• Asymptomatic tumors may not be treated for a period of time as determined by the healthcare provider; or, unless they start causing discomfort, affect the quality of life, and/or affect the functioning of the underlying nerve. In such cases, a close monitoring of the schwannoma is considered
• Bilateral tumors and the presence of neurofibromatosis type 2 can adversely influence outcomes
• If malignant schwannomas are noted (rarely), then the prognosis may depend upon a variety of factors such as the stage of the tumor, overall health of the individual, and one’s response to therapy

In general, the prognosis of brain tumors (both benign and malignant) may vary considerably from one individual to another and is dependent on a set of factors, which include:

• Tumor histology or grade of the tumor: The lower the grade, the better is the prognosis. Benign schwannomas are grade I tumors
• Stage of tumor: With lower-stage tumors, when the tumor is confined to site of origin, the prognosis is usually excellent with appropriate therapy. In higher-stage tumors, such as tumors with metastasis, the prognosis is poor
• Age of the individual: Older individuals generally have poorer prognosis than younger individuals
• Overall health of the individual: Individuals with overall excellent health have better prognosis compared with those with poor health
• The size of the tumor: Individuals with small-sized tumors fare better than those with large-sized tumors
• Location of the tumor is an important prognostic factor: Tumors at certain sites involving the central nervous system are more difficult to surgically excise and remove. They can also cause considerable neurological damage at certain sites in the brain and/or spinal cord. Tumors located near vital structures of the brain have poor prognosis
• Tumors that are slow-growing have better prognosis than rapidly-growing tumors
• Presence of certain genetic abnormalities may result in a rapid progression of tumor growth and development
• Sporadic tumors have generally better prognosis than syndromic tumors; tumors in a background of genetic disorders/syndromes may have additional complications
• The ease of accessibility and surgical resectability of the tumor (meaning, if the primary tumor can be removed completely). This is an important prognostic factor, since it may determine if the tumor can be completely resected or not
• Extent of residual tumor in the body following a surgical resection: A complete surgical excision with entire tumor removal presents the best outcome. In some cases, large portions of the tumor may be removed; or, only a small portion for tissue biopsy
• Individuals with bulky disease may have a poorer prognosis
• Involvement of other vital organs may complicate the condition
• Metastatic spread: Spread of the malignancy to other body sites portrays a poorer prognosis
• Whether the tumor is occurring for the first time or is a recurrent tumor. Recurring tumors have worse prognosis compared to tumors that do not recur 
• Response to treatment and absence of post-operative complications: Tumors that respond to treatment have better prognosis compared to tumors that do not respond to treatment
• Functional neurologic status based on neurological evaluation of the patient: A higher score on the Karnofsky Performance Scale may indicate a more favorable outcome

An early diagnosis and prompt treatment of the tumor generally yields better outcomes than a late diagnosis and delayed treatment.

Additional and Relevant Useful Information for Facial Nerve Schwannoma:

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