Vestibular schwannoma

Vestibular schwannoma
Synonyms	Acoustic neuroma
Pronounce
Field	Neuro-oncology
Symptoms	Gradual hearing loss, dizziness, tinnitus
Complications	Brain tumor growth; unilateral facial paralysis, single-sided hearing loss
Onset
Duration
Types	Sporadic vestibular schwannoma (VS); Neurofibromatosis type II (NF2)
Causes
Risks
Diagnosis	Hearing exam, MRI exam
Differential diagnosis
Prevention	Tumor management
Treatment	Radiosurgery and radiotherapy
Medication
Prognosis	Variable, based on size of tumor
Frequency	Very rare
Deaths

Vestibular schwannoma (VS), commonly referred to as acoustic neuroma, is a noncancerous tumor that manifests on the vestibulocochlear nerve (8th cranial nerve). This nerve is a bridge connecting the inner ear to the brain, playing a crucial role in both hearing and balance.

MRI of a Vestibular Schwannoma.

Origin and Development

The tumor arises from malfunctioning Schwann cells, which usually form the protective myelin sheath covering the nerve. Under healthy conditions, these cells serve the essential purpose of ensuring the efficient transmission of sound and balance information to the brain. However, certain genetic mutations can trigger the cells to behave abnormally.

The Role of the NF2 Gene

Research indicates that mutations in the tumor suppressor gene named NF2—located on chromosome 22—are major contributors to the onset of vestibular schwannoma. This mutation hampers the normal production of a cell protein called Merlin, leading to an abnormal multiplication of Schwann cells that ultimately forms a tumor.

Localization and Effects

Although the tumor's name might suggest an association with the cochlear division of the nerve, which is involved in hearing, the tumor predominantly originates in the vestibular division related to balance. Nevertheless, its growth can adversely impact both hearing and balance, given the intertwined roles of these two divisions of the vestibulocochlear nerve.

Symptoms and Diagnosis

Patients with vestibular schwannoma may experience:

• Gradual hearing loss
• Tinnitus (ringing in the ears)
• Dizziness or loss of balance
• Facial numbness or tingling

Magnetic Resonance Imaging (MRI) is the primary tool used to diagnose vestibular schwannoma, as it provides detailed images of the brain and the inner ear.

Treatment Options

While vestibular schwannomas are benign and may not always necessitate immediate treatment, their growth can lead to severe complications. Treatment options include:

• Surgery to remove the tumor
• Radiotherapy or stereotactic radiosurgery to halt the tumor's growth
• Monitoring through regular MRIs if the tumor is small and not causing significant symptoms