Vestibular Schwannoma

Overview

Vestibular schwannoma is a benign, slow-growing tumor that forms on the major (vestibular) nerve that connects your inner ear to your brain. This nerve's branches have a direct impact on your balance and hearing, and pressure from an vestibular schwannoma can cause hearing loss, ringing in your ear, and unsteadiness. Vestibular schwannoma is often formed by the Schwann cells that surround this nerve and develops slowly or not at all. It may develop quickly and become large enough to push against the brain and interfere with key processes in rare cases.

What is Vestibular Schwannoma?

A vestibular schwannoma (also known as an acoustic neuroma, an acoustic neuroma, or an acoustic neurilemoma) is a benign, slow-growing tumor that arises from the balance and hearing nerves that feed the inner ear. The tumor is caused by an overproduction of Schwann cells, which ordinarily wrap around nerve fibers like onion skin to support and insulate them. The vestibular schwannoma affects the hearing and balance nerves as it develops, resulting in unilateral (one-sided) or asymmetric hearing loss, tinnitus (ringing in the ear), and dizziness/loss of balance. As the tumor develops, it can cause facial numbness by interfering with the face sensory nerve (the trigeminal nerve). Vestibular schwannomas can also damage the facial nerve (which controls facial muscles), producing facial weakness or paralysis on the tumor's side If the tumor becomes large enough, it will press against surrounding brain areas (such as the brainstem and cerebellum), potentially causing death.

Vestibular schwannoma tumors arise in cells known as Schwann cells. These cells produce myelin, which is the substance that insulates and protects your body's nerves. The vestibular nerve, which helps you maintain your balance, is where most vestibular schwannomas originate. Hearing loss and balance problems are caused by tumor development. Vestibular schwannomas can begin in the cochlear nerve, which transmits sound from the inner ear to the brain.

The majority of auditory neuromas develop slowly. As growth occurs, the tumor presses against adjacent nerves, blood vessels, and the surface of the brainstem and cerebellum (the base of the brain). The pressure from a developing auditory neuroma is what causes symptoms to develop. Over 5,000 persons in the United States are diagnosed with an vestibular schwannoma each year. They often range in age from 30 to 60.

What are the common signs and symptoms of vestibular schwannoma?

Vestibular schwannoma symptoms and signs are frequently overlooked and can develop over time. They are often caused by the tumor's impact on the hearing and balance nerves. Pressure from the tumor may also produce issues on neighboring nerves regulating face muscles and sensation (facial and trigeminal nerves), surrounding blood vessels, or brain structures. As the tumor develops, the signs and symptoms may become more obvious or severe.

Vestibular schwannoma is characterized by the following signs and symptoms:

• Hearing loss that normally worsens over months to years, but can be rapid in rare situations, and occurs on only one side or is more severe on one side
• Tinnitus (ringing in the afflicted ear)
• Uncertainty or loss of equilibrium
• Dizziness (vertigo) (vertigo)
• Facial numbness and muscular weakness or lack of mobility

An auditory neuroma can develop large enough to compress the brainstem and become life-threatening in rare situations.

Consult your doctor if you develop hearing loss in one ear, ringing in your ear, or difficulty balancing. Early detection of an Vestibular schwannoma may help prevent the tumor from developing large enough to cause major complications, such as total hearing loss.

What causes Vestibular Schwannoma?

Vestibular schwannoma are caused by a malfunction with a gene on chromosome 22. This gene normally generates a tumor suppressor protein that aids in the regulation of the proliferation of Schwann cells that coat the nerves. Experts are unsure what is causing the gene issue. The majority of vestibular schwannomas have no recognized etiology. This defective gene is also inherited in neurofibromatosis type 2, an uncommon illness characterized by the development of tumors on both sides of your head's hearing and balance nerves (bilateral vestibular schwannomas).

Having a parent with the uncommon genetic illness neurofibromatosis type 2 is the only known risk factor for auditory neuroma. However, only around 5% of vestibular schwannoma cases are caused by neurofibromatosis type 2. The growth of noncancerous tumors on the hearing and balance nerves on both sides of the head, as well as other nerves, is a defining feature of neurofibromatosis type 2. Neurofibromatosis type 2 (NF2) is an autosomal dominant condition, which means that the mutation may be handed down from just one parent (dominant gene). Each afflicted parent's kid has a 50/50 chance of acquiring it.

How is a Vestibular Schwannoma Diagnosed?

Early symptoms of a vestibular schwannoma include unilateral/asymmetric hearing loss and/or tinnitus, as well as loss of balance/dizziness. Unfortunately, early diagnosis of the tumor can be challenging since symptoms might be modest and may not show in the early phases of development. Hearing loss, dizziness, and tinnitus are also frequent symptoms of many middle and inner ear disorders (the important point here is that unilateral or asymmetric symptoms are the worrisome ones). Once symptoms occur, a comprehensive ear examination as well as hearing and balance testing (audiogram, electronystagmography, auditory brainstem responses) are required for accurate diagnosis. MRI scans are crucial in the early discovery of a vestibular schwannoma and are useful in detecting the location and size of a tumor as well as in planning its microsurgical excision.

Vestibular schwannoma diagnosis might be difficult (vestibular schwannoma). This is due in part to the fact that the signs and symptoms of an vestibular schwannoma, such as hearing loss, ringing in the ears, and dizziness, can be confused with those of other disorders.

Your doctor has most likely already done the following:

• Your ears were examined
• Performed an MRI imaging test to examine your hearing

What is the treatment for Vestibular Schwannoma?

Early detection of a vestibular schwannoma is critical for avoiding significant effects. A vestibular schwannoma can be treated in three ways: surgical excision, radiotherapy, or observation. The tumor is sometimes surgically removed (excised). The type of procedure performed is determined by the size of the tumor and the level of hearing in the afflicted ear. If the tumor is tiny, removing it to avoid its eventual influence on the hearing nerve may save hearing and reduce concomitant symptoms. As the tumor increases in size, surgical removal becomes more difficult since the tumor may have injured the nerves that regulate face movement, hearing, and balance, as well as other nerves and brain structures. Tumor removal that affects the hearing, balance, or face nerves can potentially aggravate the patient's symptoms since these nerves may be harmed during tumor removal.

Radiosurgery (radiation therapy—the "gamma knife" or LINAC) may be used as an alternative to traditional surgical approaches to reduce the size or limit the development of the tumor. Radiation therapy is sometimes the recommended treatment choice for elderly patients, patients in poor medical condition, patients with bilateral vestibular schwannoma (tumor affecting both ears), or patients whose tumor affects only one of their hearing ears. When the tumor is tiny and not developing, it may be appropriate to "monitor" its development. MRI scans are used to closely monitor the tumor for any signs of growth.

Is there a difference between Unilateral and Bilateral Vestibular Schwannomas?

Only one ear is affected by unilateral vestibular schwannomas. They account for around 8% of all tumors inside the skull; one in every 100,000 people develops a vestibular schwannoma each year. Symptoms can appear at any age, although they are most common between the ages of 30 and 60. Most unilateral vestibular schwannomas are spontaneous and not inherited.

Bilateral vestibular schwannomas impact both hearing nerves and are commonly linked with neurofibromatosis type 2. (NF2). Half of affected individuals have inherited the condition from an affected parent and half seem to have a mutation for the first time in their family. Each kid of a parent with the condition has a 50% chance of acquiring it. Individuals with NF2 typically develop symptoms in their teens or early adulthood, as opposed to those with unilateral vestibular schwannoma. Furthermore, individuals with NF2 frequently develop numerous brain and spinal cord tumors. They can also develop nerve tumors that affect swallowing, speech, eye and face movement, and facial sensibility. Determining the optimal management strategy for vestibular schwannomas as well as other nerve, brain, and spinal cord tumors is more difficult than deciding how to treat a unilateral vestibular schwannoma. More study is required to find the optimal therapy for people with NF2. Scientists think that unilateral and bilateral vestibular schwannomas develop as a result of the loss of function of a gene on chromosome 22. (A gene is a tiny segment of DNA that is responsible for a certain feature such as hair color or skin tone.) Scientists think that this gene on chromosome 22 codes for a protein that regulates the formation of Schwann cells. When this gene fails, Schwann cell proliferation becomes uncontrollable, resulting in a tumor. Scientists believe that this gene may potentially aid in the regulation of the growth of other types of cancers. The defective gene on chromosome 22 is inherited in NF2 sufferers. Some experts believe that in people with unilateral vestibular schwannoma, this gene loses its capacity to operate normally.

What steps are being taken to treat Vestibular Schwannoma? 

A vestibular schwannoma can be treated in three ways:

1. Surgical excision
2. Radiotherapy 
3. Observation.

Scientists are continuing to investigate the molecular processes that regulate normal Schwann cell formation in order to better identify gene mutations that cause vestibular schwannomas. Scientists are trying to figure out how the gene works so that they may start developing novel medicines to reduce the overproduction of Schwann cells in people with vestibular schwannoma. Understanding how genes govern Schwann cell formation may aid in the prevention of other brain cancers. Furthermore, scientists are working on robotic technology to help physicians in vestibular schwannoma surgery.

Vestibular Schwannoma Surgery

Specialists may propose surgery based on your vestibular schwannoma (vestibular schwannoma) symptoms, size and location, and other relevant variables. The goal of surgery is to remove as much of the tumor as possible while protecting vital nerves, particularly the nerve that controls movement in the face. If we are afraid that surgery would harm these nerves, we may not be able to remove the entire tumor.

Vestibular schwannoma Surgery Methods

Surgical methods for removing an auditory tumor include:

• The retrosigmoid method (also known as the retromastoid approach or the suboccipital approach). An incision behind the ear is made, and bone is removed to reveal the tumor. It may be used for any size tumor and can occasionally retain hearing in people with tiny tumors.
• Translabyrinthine strategy An incision behind the ear is made, and bone, including a portion of the inner ear structures, is removed. This method provides the surgeon with exceptional access to the tumor. It causes total deafness, but many vestibular schwannoma patients have already lost their hearing.
• Approach from the middle fossa (also known as the subtemporal approach). This procedure is meant for tiny tumors in people who have normal hearing. To reach the tumor, an incision above the ear is made and bone is removed.

Surgeons utilize advanced monitoring techniques to limit the danger to the nerves in the area and the brain during an auditory neuroma removal procedure.

Vestibular schwannoma surgery requires the collaboration of neurosurgeons and neurotologists (skull-base surgeons who specialize in the inner ear, the bones of the side and back of the skull, and the lower cranial nerves and brainstem). Advances in imaging technology and skull-base surgical procedures have made vestibular schwannoma surgery safer and more successful than ever before.

Vestibular schwannoma radiation therapy 

Vestibular schwannoma (vestibular schwannoma) cells can be shrunk or killed with radiation therapy. Radiation may be recommended based on your symptoms, the size or shape of your tumor, your age, and other health issues. Radiation may also be recommended if your tumor is in a location that makes it difficult to remove with surgery, or if we are not able to remove the entire tumor with surgery.

We use three types of radiation for vestibular schwannoma:

• Stereotactic radiosurgery is a highly precise, minimally invasive way of delivering radiation directly to a tumor with little or no impact on surrounding structures. It can be given with a linear accelerator like the Varian TrueBeam System, which is used at MSK. Gamma Knife is a device used by other institutions. Both systems have the same impact on the tumor.
• Intensity-modulated radiation treatment (IMRT) focuses high doses of radiation directly on your tumor using sophisticated algorithms and 3-D pictures from CT scans. The intensity of these pencil-thin beams varies and conforms to the unique shape and size of the tumor. This narrowly targeted technique decreases exposure to healthy brain tissue. Radiation side effects can be reduced using IMRT.
• Image-guided radiation therapy (IGRT) is a type of radiation therapy that employs real-time imaging with CT scans or x-rays to help ensure perfect posture and absence of motion during treatment. With IGRT, your treatment team can administer radiation with pinpoint accuracy.

Observation of an Vestibular Schwannoma

Vestibular schwannoma are benign tumors that may typically be monitored without therapy. Unless the tumor is already extremely big or producing substantial symptoms, doctors may recommend a second MRI six to twelve months following the first diagnosis. This enables you and your doctor to evaluate whether or not the tumor is expanding. Tumors that are tiny, cause mild or no symptoms, and are not growing can frequently be monitored with routine MRI. If imaging reveals that a tumor is developing, or if the tumor begins to produce substantial symptoms, therapy may be indicated.

Are Vestibular Schwannomas harmful?

Many vestibular schwannoma do not develop, and those that do grow tend to expand slowly. They do not normally penetrate and damage tissue in the same way as malignant tumors do. They can, however, produce symptoms when they expand and press against essential surrounding structures. A developing vestibular schwannoma can compress the nerves that allow for face feeling and muscular movement. Compression of nerves vital for eating, speaking, and eye movement can occur with bigger tumors. Even if the vestibular schwannoma does not expand, it might deteriorate hearing and balance function. Untreated vestibular schwannoma can create a hazardous accumulation of fluid in the brain or compress the cerebellum and brainstem, both of which can be fatal. This is uncommon in people whose cancers have been adequately detected and treated.

Conclusion 

Vestibular schwannoma affects both men and women equally and often develops in adults in their 40s or 50s. These tumors are far less prevalent in children, but when they do occur, they are frequently connected with a genetic condition known as neurofibromatosis type 2. (NF2). Hearing loss on the side of the vestibular schwannoma is the most prevalent symptom of vestibular schwannoma, occurring in 90% of patients. A hearing test (audiogram) and imaging are used to identify vestibular schwannoma (MRI). Observation (watching and waiting), surgery, or radiation are all options for treatment. Vestibular schwannoma is also known as acoustic schwannoma, vestibular neuroma, auditory neuroma, and inner ear tumor.