Does Residual Spiral Ganglion Cell Count Predict Performance in Patients with Bilateral Multichannel Cochlear Implants?

Although the parameters that are most important for postoperative speech perception in cochlear implantation have not been identified, it is assumed that the numbers of remaining cochlear neurons and spiral ganglion cells in the implanted deaf ears are critical. In this study, we evaluated the correlation of the maximum diameter of the cochlear and vestibular nerve trunks with the number of spiral ganglion cells in horizontal sections of the temporal bone of 42 patients who were profoundly deaf during life, and in 5 patients with normal hearing. The maximum diameters of the cochlear, vestibular, and eighth cranial nerves were significantly smaller in the deaf population as compared to normal-hearing controls. In addition, the counts of the remaining spiral ganglion cells were significantly correlated with the maximum diameter of the cochlear (p = .0006), vestibular (p = .001), and eighth cranial nerves (p = .0003). The regression equation estimated that 25% of the variance of the spiral ganglion cell count was predicted by the maximum diameter of the eighth nerve. Although the results of this study suggest that preoperative radiographic imaging of the diameter of the eighth nerve may be helpful in predicting the residual spiral ganglion cell count, the wide variability of diameters of the eighth nerve in hearing and deaf subjects militates against this theoretic usefulness.

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Survival of Spiral Ganglion Cells in Profound Sensorineural Hearing Loss: Implications for Cochlear Implantation

Annals of Otology Rhinology & Laryngology ◽

10.1177/000348948909800602 ◽

1989 ◽

Vol 98 (6) ◽

pp. 411-416 ◽

Cited By ~ 260

Author(s):

Joseph B. Nadol ◽

Yi-Shyang Young ◽

Robert J. Glynn

Keyword(s):

Hearing Loss ◽

Ganglion Cell ◽

Cell Count ◽

Ganglion Cells ◽

Spiral Ganglion ◽

Bivariate Analysis ◽

Spiral Ganglion Cell ◽

Cell Counts ◽

Profound Deafness ◽

Temporal Bones

Ninety-three temporal bones from 66 patients who were profoundly deaf during life were reconstructed by analysis of serial light microscopic sections. The correlations of total and segmental spiral ganglion cell counts with age, duration of hearing loss and profound deafness, and cause of hearing loss were evaluated. Bivariate analysis demonstrated that total spiral ganglion cell count tended to be lower in older than in younger deaf individuals and lower with longer duration of hearing loss and total deafness. However, multiple regression analysis demonstrated that the cause of hearing loss was the single most significant determinant of total spiral ganglion cell count. Patients with deafness due to aminoglycoside toxicity or sudden idiopathic deafness had the highest residual spiral ganglion cell count and patients with deafness due to presumptive postnatal viral labyrinthitis, bacterial labyrinthitis, and congenital or genetic causes had the lowest numbers of residual spiral ganglion cells.

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Within-Subject Comparison of Word Recognition and Spiral Ganglion Cell Count in Bilateral Cochlear Implant Recipients

Otology & Neurotology ◽

10.1097/mao.0000000000000443 ◽

2014 ◽

pp. 1 ◽

Cited By ~ 18

Author(s):

Mohammad Seyyedi ◽

Lucas M. Viana ◽

Joseph B. Nadol

Keyword(s):

Word Recognition ◽

Cochlear Implant ◽

Ganglion Cell ◽

Cell Count ◽

Spiral Ganglion ◽

Spiral Ganglion Cell ◽

Bilateral Cochlear Implant ◽

Subject Comparison

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Effect of Cochlear Implantation on Residual Spiral Ganglion Cell Count as Determined by Comparison with the Contralateral Nonimplanted Inner Ear in Humans

Annals of Otology Rhinology & Laryngology ◽

10.1177/000348940511400508 ◽

2005 ◽

Vol 114 (5) ◽

pp. 381-385 ◽

Cited By ~ 33

Author(s):

Aayesha M. Khan ◽

Ophir Handzel ◽

Donald K. Eddington ◽

Doris Damian ◽

Joseph B. Nadol

Keyword(s):

Cochlear Implant ◽

Ganglion Cell ◽

Cell Count ◽

Ganglion Cells ◽

Spiral Ganglion ◽

Apical Segment ◽

Spiral Ganglion Cell ◽

Cell Counts ◽

The Mean ◽

Temporal Bones

It is generally assumed that at least a minimal number of spiral ganglion cells is essential for successful speech perception with a cochlear implant. Although the insertion of a multichannel cochlear implant frequently results in loss of residual hearing in the implanted ear, this outcome does not imply that significant damage to residual populations of spiral ganglion cells has occurred. The purpose of the current study was to compare spiral ganglion cell counts in implanted and nonimplanted cochleas in 11 patients for whom both temporal bones were available and in whom a multichannel cochlear implant had been placed unilaterally. The temporal bones were processed for light microscopy by standard techniques. The cochleas were reconstructed by 2-dimensional methods. Spiral ganglion cell counts of the implanted and nonimplanted sides were compared by a paired t-test (2-tailed). The mean spiral ganglion cell counts for implanted and nonimplanted ears were not statistically different in the most basal three segments of the cochlea. However, the mean spiral ganglion cell count in segment 4 (apical segment) and the mean total spiral ganglion cell count were lower in the implanted cochleas than in the nonimplanted cochleas (p < .01). The results of this study suggest a modest decrease in the total spiral ganglion cell count in the implanted ears as compared to the nonimplanted ears, principally in the apical segment. Possible interpretations of this finding are discussed.

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