Intracranial Schwannomas

Vestibular Schwannomas are slow-growing tumors benign tumors derived from the vestibular division of the eight cranial nerve, and they represent approximately 8% of intracranial tumors in adults and 80–90% of tumors of the cerebellopontine angle. They are unilateral in 95% of cases, while bilateral tumors usually develop in context of tumor genetic syndrome such as neurofibromatosis type 2 (NF2). The most common presenting symptoms include ipsilateral sensorineural hearing loss, dizziness or imbalance and tinnitus. Large tumors can be associated with trigeminal hypoesthesia or neuralgia, cerebellar syndrome or hydrocephalus-related symptoms. The management of these tumors can include observation, surgery, radiosurgery or a combination of them. Asymptomatic small tumors may be considered for a wait-and-scan approach. Surgical removal is the treatment of choice for large tumors causing brainstem compression, hydrocephalus, trigeminal neuralgia or other cranial neuropathies. The main microsurgical approach is the most commonly used; however, the trans-labyrinthine and middle fossa approaches can be adopted. Radiosurgery is recommended as primary treatment for tumors without significant brain stem compression, for residual tumor after subtotal surgical removal and for recurrences. Single-fraction radiosurgery with Gamma Knife using a marginal dose of 12–13 Gy is considered the treatment of choice, although hypofractionation using Linac, Cyber Knife or Gamma Knife potentially allows for the treatment of larger tumors, in patients not eligible for surgery.