Asymmetric Sensorineural Hearing Loss Causes and Diagnostic Approaches

Primary Retrocochlear Causes

Vestibular schwannoma is the leading retrocochlear cause that must be ruled out with MRI in every patient presenting with asymmetric sensorineural hearing loss, according to the American Academy of Otolaryngology-Head and Neck Surgery 1, 2, 3, 4
Meningioma represents another important intracranial tumor that can present with asymmetric hearing loss, as noted by the American Academy of Otolaryngology-Head and Neck Surgery 1, 3, 4

Idiopathic sudden sensorineural hearing loss is an otologic emergency requiring immediate steroid therapy, as recommended by the American Academy of Otolaryngology-Head and Neck Surgery 1, 2
Autoimmune inner ear disease can cause rapid unilateral or bilateral hearing loss, according to the American Academy of Otolaryngology-Head and Neck Surgery 2, 3
Infections including Lyme disease, syphilis, and HIV can produce asymmetric patterns, as noted by the American Academy of Otolaryngology-Head and Neck Surgery 1, 2, 3

Temporal bone fractures should be evaluated with CT imaging when head trauma precedes the hearing loss, as recommended by the American Academy of Otolaryngology-Head and Neck Surgery 2, 3, 4
Inner ear anatomic abnormalities including superior canal dehiscence or other third window lesions can cause asymmetric sensorineural hearing loss, according to the American Academy of Otolaryngology-Head and Neck Surgery 1, 2

Noise-induced hearing loss can be asymmetric, particularly with unilateral occupational or recreational noise exposure, as noted by the American Academy of Otolaryngology-Head and Neck Surgery 1, 2
Ototoxic medications including aminoglycosides, cisplatin, loop diuretics, and phosphodiesterase-5 inhibitors can cause hearing loss, although they more commonly cause bilateral loss, according to the American Academy of Otolaryngology-Head and Neck Surgery 5

Asymmetric sensorineural hearing loss is variably defined but commonly includes a ≥15 dB difference at 2 or more frequencies between ears, as defined by the American Academy of Otolaryngology-Head and Neck Surgery 1, 2
A ≥15% difference in speech recognition scores or a ≥20 dB difference at 2 contiguous frequencies can also indicate asymmetric sensorineural hearing loss, according to the American Academy of Otolaryngology-Head and Neck Surgery 2, 3