Cochlear implantation in a patient with superficial siderosis: an update

A Case of Cochlear Implantation in a Patient with Superficial Siderosis

Superficial siderosis is a disease in which iron from hemoglobin is deposited in the central nervous system, resulting in conditions such as progressive sensorineural hearing loss, cerebellar ataxia, dementia, and pyramidal signs. A 30-year-old man with superficial siderosis received a cochlear implant in the left ear, which had shown complete hearing loss. Good auditory responses were obtained at 14 days after implantation. The postoperative average hearing level with the cochlear implant was 56.7 dB at 3 months and 55.0 dB at 6 months. However, the patient showed gradual hearing loss, and the dynamic range changed each time the electrode parameters were adjusted. To assess residual hearing ability, single-photon emission computed tomography was performed together with an assessment of electrical auditory brainstem response, which showed a good response and increased blood flow in both the temporal lobes. Based on this result, we asked the patient to continue using the cochlear implant to see whether a perception of speech response would be obtained. However, the patient discontinued using the cochlear implant because he could not hear satisfactorily. Hearing outcomes after cochlear implant surgery for patients with superficial siderosis are not necessarily good. Therefore, the possibility of unsatisfactory results should be fully explained before recommending this surgery to patients.

Outcomes of Cochlear Implantation in Patients with Superficial Siderosis: A Systematic Review and Narrative Synthesis

This study aimed to establish outcomes following cochlear implantation (CI) in patients with superficial siderosis (SS). MEDLINE, Embase, Web of Science, Cochrane, and ClinicalTrials.gov databases were searched for this systematic review. No limits were placed on the language or the year of publication. The review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. Of a total of 46 studies, 19 studies met the inclusion criteria reporting outcomes in 38 patients. Of the 44 implants, 23 implants (52.27%) had good hearing outcomes at the last follow-up, 9 (20.45%) were initially beneficial for the patient, but then the performance deteriorated (4 of which were re-implanted), and 12 (27.27%) were not beneficial for the patient. All studies were classified as grade 4 studies using the Oxford Centre for Evidence-Based Medicine (OCEBM) grading system, being retrospective in nature and consisting of case reports and noncontrolled case series with a small number of patients. Of the 44 implants, 32 (72.73%) showed improved hearing outcomes following CI for SS at some point in time, of which 23 (52.2%) implants showed sustained benefit at the last follow-up (average follow-up time was 21.97 months). It is difficult to predict the longevity of benefit owing to the progressive nature of the disease or the patients in whom it may be beneficial, as the preoperative investigations inadequately predict benefit. Preimplantation and postimplantation counseling with the patient and their family regarding the potential limited benefit and eventual parallel decline with the neurological disease are crucial, along with thorough clinical investigations.

Cochlear implantation is a therapeutic option for superficial siderosis patients with sensorineural hearing loss

Background:

Superficial siderosis is a rare disease that results from chronic bleeding in the subarachnoid space. Haemosiderin deposits throughout the subpial layers of the brain and spinal cord lead to progressive sensorineural hearing loss, which is seen in 95 per cent of patients with superficial siderosis. The impact of cochlear implantation on the quality of life of superficial siderosis patients is under debate.

Case report:

A 38-year-old male with superficial siderosis presented with bilateral progressive sensorineural hearing loss. The patient underwent cochlear implantation and his quality of life was improved as evaluated by the Abbreviated Profile of Hearing Aid Benefit inventory.

Conclusion:

The remarkable improvement in Abbreviated Profile of Hearing Aid Benefit scores shown in this study indicates that cochlear implantation leads to a better quality of life in superficial siderosis patients.

Vestibular function in superficial siderosis

BACKGROUND

Superficial siderosis (SS) is caused by repeated or continuous bleeding into the subarachnoid space that results in iron from hemoglobin (hemosiderin) being deposited on the surface of the brain. Clinically, the condition is characterized by sensorineural deafness, ataxia, and pyramidal signs. However the mechanism of peripheral vestibular disturbance was not revealed. We show the vestibular function of SS patients, and shed light on saccule-inferior vestibular nerve.

METHODS

Over the past 9 years, 5 patients were definitively diagnosed with SS by MRI in our department. These patients were subjected to balance testing.

RESULTS

Vestibular evoked myogenic potential (VEMP) was observed in patients who had suffered from SS for a short period but tended to be diminished or absent in patients who had suffered from the condition for a longer period.

CONCLUSIONS

These findings in SS patients suggest that saccule-inferior vestibular function is maintained at early stages of the disorder. Our study may help to clarify the mechanism of SS.

Programming peculiarities in two cochlear implant users with superficial siderosis of the central nervous system

OBJECTIVE

To report the audiological outcomes of cochlear implantation in two patients with severe to profound sensorineural hearing loss secondary to superficial siderosis of the CNS and discuss some programming peculiarities that were found in these cases.

METHOD

Retrospective review. Data concerning clinical presentation, diagnosis and audiological assessment pre- and post-implantation were collected of two patients with superficial siderosis of the CNS.

RESULTS

Both patients showed good hearing thresholds but variable speech perception outcomes. One patient did not achieve open-set speech recognition, but the other achieved 70% speech recognition in quiet. Electrical compound action potentials could not be elicited in either patient. Map parameters showed the need for increased charge. Electrode impedances showed high longitudinal variability.

CONCLUSION

The implants were fairly beneficial in restoring hearing and improving communication abilities although many reprogramming sessions have been required. The hurdle in programming was the need of frequent adjustments due to the physiologic variations in electrical discharges and neural conduction, besides the changes in the impedances. Patients diagnosed with superficial siderosis may achieve limited results in speech perception scores due to both cochlear and retrocochlear reasons. Careful counseling about the results must be given to the patients and their families before the cochlear implantation indication.

Cochlear implantation in a patient with superficial siderosis

Superficial siderosis is a rare disease characterized by accumulation of hemosiderin in the leptomeninges, subpial tissue, spinal cord, and cranial nerves. The first clinicopathological description was reported in 1908. Most patients (95%) experience progressive bilateral hearing loss that begins early in the course of disease. The initial management of a patient with hearing loss secondary to superficial siderosis involves sound amplification using hearing aids. However, cochlear implants can be considered in cases where the patient can no longer gain significant benefit from hearing aids. Only 10 studies have described the use of cochlear implants in superficial siderosis and results have been variable. We report the case of a 65-year-old woman with bilateral progressive sensorineural hearing loss caused by superficial siderosis who benefited significantly from cochlear implantation.