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

• Cranial Nerve 11 Schwannoma
• Eleventh Cranial Nerve Schwannoma
• Spinal Accessory Nerve Neurinoma

What is Accessory 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 nerves, particularly cranial nerve VIII (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
• Accessory Nerve Schwannoma is a very rare form of schwannoma that involves the cranial nerve XI (CN XI), or the accessory nerve. The nerve is traditionally subdivided into two parts - the cranial part and the spinal part. The former originates in the medulla oblongata, while the latter in the upper spinal cord in the neck
• The cranial part of the nerve is involved in control of muscles in the mouth and throat (soft palate, larynx, and pharynx). The spinal component controls the sternocleidomastoid muscle and trapezius muscle, two main muscles that help in neck and shoulder movement, including rotating, extending, or flexing of the neck and shoulders
• Currently, no causative factors have been identified for Accessory Nerve Schwannoma, although certain genetic, environmental, and occupational factors have been implicated in schwannoma development. It is reported that in a majority, the tumor is not seen in the presence of neurofibromatosis (NF), which is a rare genetic disorder
• The signs and symptoms of Accessory Nerve Schwannomas depend on the location of the tumor along the accessory nerve, and the involvement of other cranial nerves. Most individuals present mild headaches, walking difficulties, nausea and vomiting, and lightheadedness. Many also report head, neck, and shoulder pain of varying degrees
• Occasionally, the healthcare provider may undertake a ‘wait and watch’ approach for small-sized and slow-growing tumors. In many cases, a complete excision by surgery can be curative for benign tumors. The prognosis of Accessory Nerve Schwannoma is typically good with appropriate management and follow-up care

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

• Accessory Nerve Schwannomas are very rare tumors reported worldwide with around 60 cases recorded in the medical literature. They constitute about 6.7% of the non-vestibular intracranial schwannomas
• The tumors are observed in both children and adults (mostly); most cases are recorded in the 21-60 years’ age category. The age range of presentation is 10 to 76 years with average age of diagnosis being 43 years
• Both males and females are affected, and a slight female gender preference is noted
• There is no known geographical bias and racial/ethnic preference observed

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

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

• The schwannomas may be observed in the presence of neurofibromatosis, which 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 Accessory Nerve Schwannoma? (Etiology)

The exact cause and mechanism of Accessory 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 neurofibromatosis type 2 (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 Accessory Nerve Schwannoma?

The signs and symptoms of Accessory Nerve Schwannoma may differ from one individual to another and depends on several factors. The speed of progression of the tumor can vary. The onset of significant symptoms are from large-sized tumors. However, in many 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.

Accessory Nerve Schwannomas have been observed to simultaneously involve several other cranial nerves, such as cranial nerves II, VII, VIII, IX, and X, based on the location of the tumor; frequently, the eighth cranial nerve is affected. Depending on the nerve involved, a set of associated signs and symptoms may be noted.

• The tumors are mostly slow-growing and solitary; they may appear as a gradually enlarging painless mass
• Tumors may arise anywhere along the accessory nerve, including:
  • Cisternal segment (50% of the cases), mostly at cerebellopontine angle, and some tumors are seen at the cerebellomedullary cistern. There are the most common site of Accessory Nerve Schwannomas
  • Jugular foramen (29% of the cases)
  • Extracranial sites (14% of the cases); extracranial tumors appear as painless lump on the neck
  • Cervical spinal canal (about 7% of the cases), which is the least common site

Some tumors remain asymptomatic, although mostly signs and symptoms that are noted depend on the region of tumor involvement.

• Common symptoms include headaches (in nearly 50% individuals), nausea and vomiting, and neck and shoulder pain
• Pain in the occipital region may run into the neck and shoulder region may be observed in nearly 45% of the individuals
• Arm and shoulder pain may cause difficulty lifting one’s arms or shrugging one’s shoulders
• Some individuals present hoarse voice, swallowing difficulties, blurred vision, ringing in the ears, and thickening of the tongue
• Dizziness and gait disturbances may be noted in some individuals
• Dysfunction of the eighth cranial nerve with associated symptoms is observed in many
• When the cerebellar region is affected, it can cause walking difficulties and nausea and vomiting
• Compression of the brainstem and spinal cord including of the nerve roots, may result in a painful set of related symptoms
• Tumors in the spinal canal may lead to neck pain and stiffness, breathing difficulties, numbness of the extremities, and upper and lower limb weakness
• Usually due to solitary tumors, only one side of the head, neck, and shoulder is affected
• Multiple schwannomas are known to occur in a background of neurofibromatosis
• Malignancy is usually observed when there is underlying neurofibromatosis; but, this is very infrequent

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

How is Accessory Nerve Schwannoma Diagnosed?

Accessory Nerve Schwannomas may remain undiagnosed if they 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.

A diagnosis of Accessory Nerve Schwannoma 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
• Oral and ear, nose, and throat (ENT) examination
• Cranial nerve examination
• Hearing and audiometric tests
• 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)
• Electroencephalography (EEG)
• 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. The following tumors may be excluded (radiological differential diagnosis):

• Chondrosarcoma
• Meningioma
• Metastatic tumors to the central nervous system
• Paraganglioma

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 Accessory Nerve Schwannoma?

The complications from Accessory Nerve Schwannoma could include:

• Vocal cord paralysis is observed in some individuals
• Permanent damage to the accessory nerve or other involved cranial nerves
• Severe vestibulocochlear nerve dysfunction
• Emotional and mental stress for both the patient and the caretakers, due to the diagnosis and during treatment of a brain tumor
• 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 cranial 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 Accessory 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 Accessory Nerve Schwannoma 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

Surgical excision and tumor removal may be recommended for treating Accessory Nerve Schwannoma. The surgical approach is based on the tumor size and location. An important criterion for surgery is preservation of the cranial nerve and minimizing post-operative symptoms such as cranial nerve dysfunction.

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
• Laminectomy: An invasive procedure that is performed to relieve compression on the spinal cord or spinal nerves by widening the spinal canal through removal of the laminae (part of the vertebra)
• Nerve grafts may be necessary in some cases, particularly if the nerve is injured during surgery
• Post-operative care is important: One must maintain minimum activity levels, until the surgical wound heals
• Thyroplasty to improve voice may be considered
• Physiotherapy may be recommended in some individuals

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
• External beam radiation therapy using a linear accelerator is helpful in preserving neurological function, especially when tumors are smaller
• 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 Accessory Nerve Schwannoma be Prevented?

Presently, there are no specific methods or guidelines to prevent the formation of Accessory 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 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 Accessory Nerve Schwannoma? (Outcomes/Resolutions)

The prognosis of Accessory Nerve Schwannoma (benign tumor) is usually good, particularly if the tumor can be removed without damaging the underlying nerve.

• According to case study reports, in a majority of cases (over 85%), a complete removal of the schwannoma is achieved. A combination of surgery and adjuvant radiosurgery has ensured very low recurrence rates and excellent outcomes in benign tumors
• Even though post-operative complications, such as cranial nerve palsy, vocal cord paralysis, and swallowing difficulties may be noted; in a vast majority of cases, most of the neurological signs and symptoms improve over a short duration and the prognosis is good
• 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 can adversely influence outcomes
• If malignant schwannomas are noted (very rare), 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 Accessory Nerve Schwannoma:

Please visit our Cancer & Benign Tumor Health Center for more physician-approved health information:

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