Schwannoma

• Schwannoma is a benign tumor arising from Schwann cells, which insulate nerve fibers.
• The most common type is the vestibular schwannoma (acoustic neuroma), affecting the nerve connecting the ear to the brain.
• Symptoms vary widely depending on the tumor’s location, often including pain, numbness, weakness, or hearing loss.
• Diagnosis typically involves neurological examination and advanced imaging like MRI.
• Treatment options range from observation to surgical removal or radiation therapy, tailored to the individual case.

What is Schwannoma: Definition and Types

A Schwannoma is a generally slow-growing, non-malignant tumor that develops from Schwann cells. These cells are crucial for the proper functioning of the nervous system, as they produce myelin, the insulating sheath that surrounds nerve fibers and helps transmit electrical impulses efficiently. When a schwannoma forms, it typically pushes the nerve aside rather than invading it, but its growth can still compress the nerve or adjacent structures, leading to various symptoms.

While schwannomas can occur anywhere in the body where Schwann cells are present, certain locations are more common. Understanding the types of schwannoma often relates to their anatomical site:

• Vestibular Schwannoma: Also known as an acoustic neuroma, this is the most common type, accounting for approximately 8% of all intracranial tumors. It develops on the eighth cranial nerve, which connects the inner ear to the brain and is responsible for hearing and balance.
• Spinal Schwannoma: These tumors grow along the spinal cord, often within the spinal canal, and can compress the spinal cord or nerve roots.
• Peripheral Schwannoma: Occurring on nerves in the arms, legs, or other parts of the body, these may present as a palpable lump under the skin.
• Trigeminal Schwannoma: Affecting the fifth cranial nerve, which controls sensation in the face and motor functions like chewing.

Schwannoma Symptoms and Causes

The schwannoma symptoms and causes are diverse, largely depending on the tumor’s size and exact location. Because schwannomas grow slowly, symptoms may develop gradually over months or even years. Common symptoms associated with vestibular schwannomas include progressive hearing loss in one ear, tinnitus (ringing in the ear), and balance problems or dizziness. If the tumor grows large, it can also affect facial nerves, leading to numbness or weakness on one side of the face.

For spinal schwannomas, symptoms often involve localized pain, numbness, tingling, or weakness in the limbs, depending on which nerve roots or spinal cord segments are compressed. Peripheral schwannomas may manifest as a noticeable lump, sometimes accompanied by pain, numbness, or weakness in the affected limb. The exact causes of most schwannomas are unknown. However, some cases are linked to genetic conditions, most notably Neurofibromatosis type 2 (NF2), an inherited disorder that predisposes individuals to develop multiple schwannomas and other nervous system tumors.

Diagnosing and Treating Schwannoma

The process of schwannoma diagnosis and treatment begins with a thorough neurological examination, which may include tests of hearing, balance, facial sensation, and motor function. If a schwannoma is suspected, imaging studies are crucial for confirmation. Magnetic Resonance Imaging (MRI) with contrast is the most effective diagnostic tool, providing detailed images of the tumor’s size, location, and relationship to surrounding nerves and brain structures. Computed Tomography (CT) scans may also be used, particularly if MRI is contraindicated.

Treatment strategies for schwannomas are highly individualized, taking into account the tumor’s size, location, growth rate, the patient’s age, overall health, and the severity of symptoms. The primary treatment options include:

• Observation (Watch and Wait): For small, asymptomatic, or slow-growing tumors, especially in older patients, regular MRI scans are performed to monitor tumor growth.
• Surgical Removal: This is often recommended for larger tumors or those causing significant symptoms. The goal is to remove as much of the tumor as safely possible while preserving nerve function.
• Radiation Therapy: Stereotactic radiosurgery (SRS) or fractionated stereotactic radiotherapy (FSRT) uses highly focused radiation beams to target the tumor, aiming to stop its growth or shrink it. This is often an option for smaller tumors, those in challenging surgical locations, or for patients who are not candidates for surgery.

The choice of treatment is made in consultation with a multidisciplinary team of specialists, including neurosurgeons, otolaryngologists, radiation oncologists, and neurologists, to ensure the best possible outcome for the patient.