Audiologic Changes in Vestibular Schwannoma

Primary Audiologic Findings

Vestibular schwannomas typically present with progressive unilateral sensorineural hearing loss, with approximately 50% of patients losing functional hearing within 3-4 years of diagnosis, according to the American Academy of Neurology 1
Approximately 50% of patients with vestibular schwannoma will lose functional hearing during a 3-4 year observation period, as reported by the American Academy of Neurology 1
Full speech discrimination score at initial diagnosis is considered a good predictor for preservation of functional hearing, as stated by the American Academy of Neurology 1
All types of audiometric patterns can be found in patients with vestibular schwannoma, although low-frequency hearing loss patterns are less commonly associated with tumors, according to the American Academy of Otolaryngology-Head and Neck Surgery 2

Serial audiometry is an important component of monitoring for vestibular schwannoma, though less sensitive than MRI, as noted by the American Academy of Otolaryngology-Head and Neck Surgery 3
Progressive hearing loss of greater than 10 dB (HL) in 2 or more frequencies or a drop in word recognition scores of greater than 10% should trigger evaluation with ABR or MRI, according to the American Academy of Otolaryngology-Head and Neck Surgery 4
Auditory Brainstem Response (ABR) testing may be used for initial evaluation but has limitations, including missing 8-42% of intracanalicular vestibular schwannoma tumors, as reported by the American Academy of Otolaryngology-Head and Neck Surgery 4
ABR is highly sensitive for tumors >1 cm in size but less reliable for smaller tumors, as stated by the American Academy of Otolaryngology-Head and Neck Surgery 4
ABR testing is not possible when hearing loss exceeds 80 dB in the 2000-4000 Hz range, according to the American Academy of Otolaryngology-Head and Neck Surgery 4
The sensitivity of ABR is proportional to the degree of hearing loss; milder losses are more likely to yield false-negative results, as noted by the American Academy of Otolaryngology-Head and Neck Surgery 4

Vestibular schwannomas arise from Schwann cells along the eighth cranial nerve, with approximately 80% found in the vestibular portion and 20% in the cochlear portion, as reported by the American Academy of Neurology 5

Audiological monitoring is recommended as part of the observational management of vestibular schwannoma, according to the American Academy of Neurology 1
Annual follow-up with audiometry is recommended for conservatively treated, radiated, and incompletely resected vestibular schwannoma for 5 years, as stated by the American Academy of Neurology 6
If tumor size remains stable for 5 years, follow-up intervals can be doubled thereafter, according to the American Academy of Neurology 6
MRI with gadolinium enhancement remains the gold standard for diagnosis and monitoring of vestibular schwannoma, with audiometry serving as a complementary assessment, as noted by the American Academy of Otolaryngology-Head and Neck Surgery 7 and 4

No clinical features can reliably distinguish sudden sensorineural hearing loss caused by vestibular schwannoma from idiopathic varieties, as reported by the American Academy of Otolaryngology-Head and Neck Surgery 2
Hearing recovery does not predict whether a patient's sudden hearing loss is the result of a tumor, according to the American Academy of Otolaryngology-Head and Neck Surgery 2
Associated events or diseases (e.g., barotrauma or recent viral infection) that were presumed to cause sudden hearing loss are present in approximately one-third of patients with vestibular schwannoma, as stated by the American Academy of Otolaryngology-Head and Neck Surgery 2
Tinnitus in the affected ear prior to hearing loss onset, associated otalgia, or paresthesias are more common in patients with vestibular schwannoma but are too rare for their absence to reliably rule out a retrocochlear lesion, according to the American Academy of Otolaryngology-Head and Neck Surgery 2