Acoustic neuroma: The most silent brain tumor

Dr. Nopasin Thekingdech,

Neurosurgeon

     While hearing loss is not typically caused by brain tumors, a specific type of brain tumor called an acoustic neuroma, or vestibular schwannoma, can lead to this symptom. This is a non-cancerous, slow-growing tumor (WHO grade I).

Common Symptoms

• Hearing loss: 95% of patients experience single-sided hearing loss.
• Tinnitus: 63% experience ringing or buzzing in the ear.
• Unsteadiness: 61% report feeling unsteady or wobbly without leg weakness.

Causes and Risk Factors

     Acoustic neuromas originate from the sheath of the eighth cranial nerve, which is responsible for hearing and balance. Research has explored whether factors like prolonged exposure to loud noise or extensive mobile phone use can be a cause, but a clear link has not been established. The only confirmed risk factor is a genetic disorder called Neurofibromatosis (NF2), which is associated with tumors on both auditory nerves.

Diagnosis

     The primary diagnostic tool is an MRI, which can detect very small tumors. If an MRI is not possible, a CT scan can be used. An audiogram is also essential to assess the level of hearing loss and guide treatment.

Treatment Options

Treatment depends on the tumor's size and the patient's symptoms.

1.  Watch and Wait

     Recommended for small tumors. The tumor's growth and the patient's symptoms are monitored with regular MRIs and audiograms. If the tumor grows more than 2.5 mm per year, other treatments are considered.

2.  Surgery

     This is a viable option for tumors larger than 3 cm. The goal is to remove the tumor while preserving facial and auditory nerve function. Potential complications include facial palsy and permanent hearing loss.

3.  Radiation Therapy

     Used for tumors smaller than 3 cm. Techniques like Gamma Knife or CyberKnife can effectively shrink the tumor. However, there is a small risk that the tumor may continue to grow or that the radiation could damage the nerve.

Why Early Detection Matters

     Acoustic neuromas are typically slow-growing, and for many patients, observation is a safe and effective approach. Only 20% of patients who are initially monitored will eventually need surgery or radiation. However, it is important not to ignore symptoms like hearing loss, unsteadiness, or dizziness, as they could be early signs of this tumor.