Vestibular and acoustic dysfunction in patients with early stages of vestibular schwannoma

Abstract

Introduction: Vestibular schwannoma (VS) is known to be a benign tumor. It develops from the Schwann cells in the vestibular portion of the VIII nerve. The causes of tumor development are not fully defined. VS is diagnosed more often in people of active age (30-60 years), mostly in women.   Aim: The aim is to study the state of vestibular and acoustic dysfunctions in patients with VS at an early stage. Materials and Methods: A total of 71 patients with MRI-verified VS at an early stage were analyzed. The 1st group consisted of 34 patients with intracanal VS, and the 2nd group included 37 patients with stage one VS. Vestibular dysfunction, including the registration of three pathological vestibular reactions vestibulo-somatic, vestibulo-sensory and vestibulo-vegetative, was studied. Acoustic dysfunction was studied using tonal, speech and suprathreshold speech audiometry, and auditory brainstem responses (ABR). Results: Unilateral or asymmetric bilateral vestibular dysfunctions have been established in all patients at the early stages of VS, which forms phantom phenomena of sensory and motor memory in the cortical structures of the brain in the form of pathological vestibulo-somatic, vestibulo-sensory and vestibulo-vegetative reactions, which are to be considered during rehabilitation. Acoustic dysfunction of different manifestations—from normal symmetrical hearing to socially adequate unilateral or asymmetric sensorineural hearing loss  of degree I-II, and significant socially inadequate sensorineural hearing loss  of degree III-IV, deafness, and also mixed hearing loss, was determined in these patients. ABR registration indicated unilateral or asymmetric delays of sound signals transferring in the brainstem structures at the early stages of VS with both normal hearing and socially adequately impaired hearing. Conclusion: Various manifestations of vestibular and acoustic dysfunctions with development of excitatory and inhibitory processes in the peripheral, brainstem, and cortical structures of the vestibular and acoustic systems were defined in all patients at the early stages of VS.