Molecular Biology and Etiopathogenesis of Vestibular Schwannomas

It is well established that the NF2 gene, a tumor suppressor gene located on chromosome 22, plays an essential role in controlling the proliferation of Schwann cells. Mutations in both alleles of the NF2 gene disrupt the normal regulation of Schwann cell proliferation, leading to uncontrolled proliferation of these Schwann cells and the development of a Schwannoma. Acoustic neuroma is a vestibular schwannoma. In 1915, Henschen observed that the tumor originates from the vestibular nerve, specifically the inferior vestibular nerve, which was lost within the tumor. In 1929, Skinne observed that the cochleovestibular nerve exhibits a distinctive histological structure: the fibrous cone of this nerve is located more than 10 mm from its emergence in 56% of cases and further into the internal auditory canal in the remaining 44%. Pirsig et al. observed the presence of clusters of Schwann-like cells, known as "Pirsig clusters." These formations exist only in the vestibular nerve and its ganglion, in the immediate vicinity of the falciform crest, where most vestibular schwannomas appear to originate.