A vestibular schwannoma (VS), also called acoustic neuroma, is a benign tumor that develops on the vestibulocochlear nerve that passes from the inner ear to the brain.

Initial hearing loss is usually subtle and may be attributed mistakenly to aging, earwax buildup, or perhaps exposure to some loud environmental noise.

IAC tumors that grow beyond 1.5 cm in diameter expand into the relatively empty space of the cerebellopontine angle, taking on the characteristic 'ice-cream-cone' appearance seen on MRIs.

Bilateralism is considered to be the hallmark and main diagnostic criterion of Neurofibromatosis Type II (NF2), a genetic disorder that is heritable, progressive, difficult to manage, and has a 1 in 2 chance of being passed on to each offspring.

[6][7][8] Patient surveys in the U.S. by the national Acoustic Neuroma Association (1998, 2007–08, 2012, 2014) showed that the percentage of diagnosed tumors 1.5 cm or less increased significantly from 23% to 47%.

(Note: 1 inch = 2.54 cm) Radiologists reporting on MRI scans use the Koos Grading Scale which relates tumor size to its proximity to the brainstem and nearby cranial nerves.

Today, hearing preservation, facial nerve function, and tumor control remain the primary benchmarks used to evaluate treatment effectiveness and compare outcomes."

Adjunctive use of the endoscope for enhanced visualization during surgery for IAC tumors has gained attention as an emerging technique with advancing technology.

For small to medium size tumors, the appropriateness of so-called 'hearing preservation surgery' via either the Middle Fossa or Retrosigmoid approach remained controversial.

Stangerup et al. reported (2010) that most patients with 100% speech discrimination at diagnosis had the best chance of maintaining good hearing after ten years of observation.

Generally, single-session Gamma Knife radiosurgery is limited in use to VSs less than 3 cm in diameter to avoid possible complications with facial nerves, brainstem and the cochlea apparatus.

The use of MRI with contrast enhancement has resulted in the identification of patients with very small, relatively asymptomatic vestibular schwannomas for whom the natural history is unknown.

In 2006, a landmark study from Denmark, entitled "The Natural History of Vestibular Schwannoma,"[3] initiated a significant trend toward observation for managing small VS.

The 2006 study by Stangerup et al. looked at the data for 1,818 patients (1976–2004) comparing intrameatal VS (in the auditory canal) and extrameatal VS (into the cerebellopontine angle).

However, long-term observational studies are desperately needed to guide the development of evidence-based surveillance algorithms designed to detect late tumor progression."

"[36][3][37][38][39] In 2015, researchers at the Cleveland Clinic in Ohio used population-based data of the Central Brain Tumor Registry of the U.S. to calculate an incidence of 10.9 per million of population, or about 3,300 cases of VS per year.

In 1895, Thomas Annandale, a general surgeon at the Royal Infirmary in Edinburgh, Scotland, was the first to successfully localize and surgically remove a VS.[43] Finger dissection of VS to 'shell out' the tumor was typical.

Harvey Cushing (1869–1939) is known as 'the father of neurosurgery for VS.' His basic study published in 1917 was entitled Tumors of the Nervus Acusticus and the Syndrome of the Cerebellopontine Angle.

An equally famous specialist for VS at Johns Hopkins in Baltimore was Walter E. Dandy (1886–1946), a former pupil of Cushing who advocated total tumor removals.

Treating tumors that grew overly large in the cerebellopontine angle resulted in poor outcomes for the goals of facial nerve and hearing preservation.

In 1986, at a meeting for neurosurgeons in San Francisco, the House group endorsed a guideline for the surgical treatment of VS: "The best opportunity for successful removal of an acoustic neuroma is when it is small: when first diagnosed.

The consensus conference's panel of experts reported: "Currently, the ideal treatment for symptomatic patients with vestibular schwannoma is the total excision of the tumor in a single stage with minimal morbidity and mortality and with preservation of neurological function.

And long-term observation management was deemed appropriate as MRI scans began to reveal more and more small tumors with stable neurological symptoms.

Departments of radiation oncology at major medical centers began to modify X-ray linear accelerators (linacs) to do single-session radiosurgery and multiple-session radiotherapy.

In 1991, the U.S. National Institutes of Health convened a Consensus Development Conference (December 11–13, 1991) for Acoustic Neuroma (Vestibular Schwannoma) to evaluate management of the disorder and recommend areas for future activity and research.

A key step forward in 1993 was the identification of the NF2 gene and its protein product Merlin, which modulates the complex molecular signaling pathways that control cell proliferation.

A second important field of study in molecular biology investigates ways to stop the formation (angiogenesis) of the new blood vessels that are needed to support tumor growth by supplying nutrients and oxygen.

[53][54][55][56][57][58][59][60] American actor, director, humanitarian, social activist and film producer Mark Ruffalo was diagnosed with vestibular schwannoma in 2001 which resulted in a period of partial facial paralysis.

[64] Tionne Watkins, better known by her stage name T-Boz, R&B singer from the R&B/hip-hop group TLC, was diagnosed with a strawberry-sized acoustic neuroma on her vestibular nerve in 2006.

[66] English comedian, artist, surrealist, musician, actor, and television presenter Vic Reeves revealed that he was diagnosed with a grape-sized vestibular schwannoma at age 62.