Vestibular schwannoma
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Definition
A vestibular schwannoma (also known as acoustic neuroma, acoustic neurinoma, or acoustic neurilemoma) is a benign, usually slow-growing cerebellopontine angle tumor that develops from the balance and hearing nerves supplying the inner ear. The tumor comes from an overproduction of Schwann cells.
They usually originate in the internal acoustic meatus, and gradually extend into the cerebellopontine cistern. Invasive growth into the petrous bone is extremely rare. This may have arisen because of an unusually peripheral site of origin on the vestibular nerve 1).
In the narrow confines of neurosurgery, neurology, and neuroradiology, changes in nomenclature have been motivated by improved understanding of disease states reflected in precision of the newly adopted appellation. Numerous examples of novel nomenclature demonstrate the potential benefit, including paradigm shifts in understanding as well as treatments for disease. For example, acoustic neuromas no longer exists, replaced with the more accurate vestibular schwannoma 2).
Epidemiology
Etiology
Classification
Natural history
Pathology
Tumors are composed of Antoni A fibers (narrow elongated bipolar cells) and Antoni B fibers (loose reticulated). Verocay bodies are also seen, and consist of acellular eosinophilic areas surrounded by parallel arrangement of spindle shaped schwann cells (they are not a cell type).
Clinical Features
Diagnosis
Scores
Differential diagnosis
Guidelines
Treatment
Outcome
Meta-analysis
Observational cohort studies
One hundred seventy-three patients diagnosed with unilateral vestibular schwannoma operated via the retrosigmoid approach were included in a study from the People's Liberation Army General Hospital Beijing. All patients underwent relevant examinations and completed the Tinnitus Handicap Inventory scale before surgery and 6 months after surgery. The prognosis of tinnitus was evaluated according to the changes in THI.
Of the 129 preoperative tinnitus patients, postoperative tinnitus resolved in 12.4%, improved in 29.5%, remained unchanged in 28.6%, and worsened in 29.5%. 18.2% of 44 patients without preoperative tinnitus appeared new-onset tinnitus postoperatively. Thirty-six patients never had tinnitus. Patients with smaller tumor sizes (≤ 3 cm) were more likely to experience preoperative tinnitus. Younger patients and those with serviceable hearing preoperatively were more likely to report their tinnitus unchanged or worsened. A new onset of postoperative tinnitus in the preoperative non-tinnitus group was found in better preoperative hearing function.
70% of patients had persistent tinnitus after vestibular schwannoma resection. The tinnitus prognosis was influenced by age and preoperative hearing function. Tinnitus is a bothersome symptom and is often underestimated by doctors. Assessment of tinnitus is mandatory during the vestibular schwannoma management 3)