Systematic review of outcome of cochlear implantation in superficial siderosis.
BACKGROUND
Superficial siderosis is a progressive disease of the central nervous system associated with chronic subarachnoid hemorrhage. Sensorineural hearing loss occurs early in the disease typically progressing to a profound hearing loss during several years and ultimately affecting 95% of patients.


OBJECTIVE
There are published reports of variable outcomes regarding auditory performance for cochlear implantation in cases of superficial siderosis: the objective of this article was to systematically review this evidence.


METHODS
A systematic search of NHS Evidence electronic journal databases AMED (1985 to present), BNI (1985 to present), CINAHL (1981 to present), EMBASE (1980 to present), HEALTH BUSINESS ELITE, HMIC, MEDLINE (1950 to present), and PsycINFO (1806 to present) was performed. Further research using personal communication, Google Scholar, hand searching Otology & Neurotology (2008-2011), and assessment of reference lists identified in other relevant articles yielded additional articles.


METHODS
A total of 24 articles were short-listed based on relevance; no studies were excluded on a basis of quality. Of these 24 articles, 11 were excluded.


METHODS
The 13 articles included in this review report 15 cases of cochlear implantation in superficial siderosis. Of these 15 individual cases, 7 (47%) showed clear sustained benefit from cochlear implantation, 6 showed limited/no benefit from the onset, and the remaining 2 patients' initial benefit was not maintained.


CONCLUSIONS
Outcomes will depend on the site of lesion and the degree of cochlear nerve functionality, as well as ongoing neural deterioration. Comprehensive assessment of the auditory pathway including electrical auditory brainstem response and magnetic resonance imaging as well as pre/postimplantation counseling is indicated, but these preoperative measures are imperfect predictors of outcomes. There are indications that, where the underlying disease is stable, cochlear implant performance may be sustained, and where there is disease progression (specifically regarding involvement of auditory brainstem nuclei), cochlear implant performance may deteriorate. Further data are needed in this regard; however, results suggest that earlier implantation would provide benefit for a longer period and increase cost-effectiveness.
Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK. gemma.tyler@addenbrookes.nhs.uk
Gemma K
GK
Tyler
Thomas P C
TP
Martin
David M
DM
Baguley
D000293:Adolescent; D000328:Adult; D001309:Auditory Threshold; D002648:Child; D002675:Child, Preschool; D019929:Cochlear Implantation; D003054:Cochlear Implants; D003362:Cost-Benefit Analysis; D003627:Data Interpretation, Statistical; D005260:Female; D006309:Hearing / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D012181:Retrocochlear Diseases / Q000601:surgery / Q000628:therapy; D012806:Siderosis / Q000601:surgery*; D013069:Speech Reception Threshold Test; D016896:Treatment Outcome; D055815:Young Adult