Auditory profile in superficial siderosis of the central nervous system: a prospective study.

Objective: To identify auditory pathology resulting from superficial siderosis of the central nervous system (SSCN), auditory site of lesion, and a clinical profile for differential diagnosis and development of recommendations.

Study Design: Prospective study.

Setting: Academic clinical center.

Patients: Ten participants with SSCN (the largest prospective evaluation of audiologic status reported to date).

Intervention(s): Demographics, clinical characteristics and history, audiometric evaluation, and Tinnitus Handicap Inventory (THI).

Main Outcome Measure(s): Type and degree of hearing loss, relationship to clinical course of SSCN, and expected results based on age and sex.

Results: Sensorineural hearing loss (SNHL) is the most common symptom in SSCN (100%). Tinnitus (100%), imbalance (80%), and gait disorder (80%) were also frequently reported. Hearing loss is typically bilateral, asymmetric, progressive, sloping, and exceeds expected hearing loss related to age and sex. Hearing loss may be cochlear and/or retrocochlear in origin. Decreased word recognition is possible, and traditional amplification may offer limited benefit.

Conclusion: We observed significant audiometric findings in all participants. SSCN variably and pathologically targets the auditory system without regard for duration of disorder. A long asymptomatic phase and lack of predictive relationship between duration and severity of hearing loss makes suspicion of SSCN based solely on audiometric battery difficult; however, asymmetric hearing loss exceeding expectations, particularly with history of head trauma or previous neurosurgical procedure, should raise a red flag and trigger further medical evaluation including MRI. Diagnosis of SSCN may alter expectations for audiologic prognosis and is a critical component for comprehensive management of SSCN patients.