I. Read and translate the text. Answer the questions. What does the term “acoustic neuroma” imply?
Give the symptoms of the disease.
How are most acoustic neuromas treated?
What are advantages and disadvantages of different methods of treatment acoustic neuroma?
A vestibular schwannoma, often called an acoustic neuroma, is a benign primary intracranial tumour of the myelin-forming cells of the vestibulocochlear nerve. The term “vestibular schwannoma” involves the vestibular portion of the 8th cranial nerve and arises from Schwann cells, which are responsible for the myelin sheath in the peripheral nervous system.
The earliest symptoms of acoustic neuromas include ipsilateral sensorineural hearing loss/deafness, disturbed sense of balance and altered gait, vertigo with associated nausea and vomiting, and pressure in the ear, all of which can be attributed to the disruption of normal vestibulocochlear nerve function. Additionally more than 80% of patients have reported tinnitus (most often a unilateral high-pitched ringing, sometimes a machinery-like roaring or hissing sound, like a steam kettle).
Patients with a severe or profound unilateral hearing loss following the removal of an acoustic neuroma tumour are significantly disabled in a number of situations such as hearing sounds from the deaf side, hearing in the presence of background noise (both in quiet and noisy surroundings) and localising sounds.
The perceived hearing handicap may even be greater in unilateral losses than in bilateral. It has also been reported that patients with unilateral hearing loss experience difficulties in group discussions and dynamic listening situations where there is limited possibility to compensate for the handicap by changing listening position.
Indicated treatments for acoustic neuroma include surgical removal and radiotherapy. About 25% of all acoustic neuromas are treated with medical management consisting of a periodic monitoring of the patient’s neurological status, serial imaging studies, and the use of hearing aids when appropriate. Because these neuromata grow so slowly, a physician may opt for conservative treatment beginning with an observation period. In such a case, the tumour is monitored by annual MRI to monitor growth. This route is common among patients over 70 years old. Records suggest that about 45% of acoustic neuromata do not grow detectably over the 3–5 years of observation. In rare cases, acoustical neuromata have been known to shrink spontaneously. Since the growth rate of an acoustic neuroma rarely accelerates, annual observation is sufficient. Acoustic neuromata may cause either gradual or – less commonly – sudden hearing loss and tinnitus.
Removal of acoustic neuromas may be performed using several approaches. Each approach has its advantages and disadvantages. Radiation treatment (discussed in another section) does not remove the tumour, but has the potential to slow or stop its growth. Surgery is the only treatment that will definitively treat balance symptoms associated with tumour growth, as the vestibular nerves are removed at surgery.
Surgery cannot repair damage that has already occurred to the facial or hearing nerves. Even after surgery, there is a small chance that the neuroma will grow back and follow-up MRI scans are necessary. Choice of surgical approach is based on the patient’s age, medical condition, size of tumour, and preoperative hearing thresholds and speech discrimination, as well as other tests such as electronystagmography, imaging, and auditory brainstem response testing.