術前検査—神経耳科学的検査とその意義

Preoperative Examination:Neuro-Otological Examination and Its Significance

Point

・神経耳科学では，各種検査を用いて聴覚障害や平衡覚障害の病態を解明し，診断・治療にあたる．

・聴性脳幹反応は聴力レベルや障害部位の推定に，聴性定常反応は周波数別の聴力レベルの推定に有用である．

・電気眼振図下の視刺激検査は脳幹や小脳の機能評価に，vHIT（video head impulse test）や前庭誘発筋電位は前庭（耳石器，半規管）機能の個別評価に有用である．

　Neuro-otologic examinations are essential to identify lesion sites in patients with hearing and balance disorders. These tests assess the functions from the peripheral sensory organs to the central auditory and vestibular pathways. They are valuable for evaluating inner ear function and detecting central nervous system involvement.

　Auditory tests, such as pure-tone audiometry and auditory brainstem response, help localize lesions along the auditory neural pathway. Vestibular function can be assessed using the caloric test, video head impulse test, and vestibular evoked myogenic potentials, which individually evaluate the semicircular canals and otolith organs. Additionally, eye movement recordings using the ENG or VOG during visual stimulation aid in the detection of central vestibular dysfunction.

　Cerebellopontine angle (CPA) tumors vary in size and extent, from small lesions within the internal auditory canal to large masses compressing the brainstem and cerebellum. Preoperative neuro-otologic assessment provides insight into the extent of the tumor and affected functional areas. This is valuable for understanding the pathophysiology of CPA tumors and contributes to surgical planning and prognosis.