Patterns of degeneration in the human cochlear nerve

• Published in: Hearing research 1995-10, Vol.90 (1), p.192-201
• Main Authors: Zimmermann, Corinna E., Burgess, Barbara J., Nadol, Joseph B.
• Format: Article
• Language: English
• Subjects: Aged; Aged, 80 and over; Aging - pathology; Analysis of Variance; Biological and medical sciences; Cell Survival; Cochlea - pathology; Deafness - pathology; Ear, auditive nerve, cochleovestibular tract, facial nerve: diseases, semeiology; Female; Hair Cells, Auditory, Inner - cytology; Hair Cells, Auditory, Inner - pathology; Hair Cells, Auditory, Outer - cytology; Hair Cells, Auditory, Outer - pathology; Hearing Loss, Sensorineural - pathology; Humans; Male; Medical sciences; Middle Aged; Nerve Degeneration; Neural degeneration; Non tumoral diseases; Organ of Corti - pathology; Otorhinolaryngology. Stomatology; Sensorineural hearing loss; Sex Factors; Spiral ganglion; Spiral Ganglion - cytology; Spiral Ganglion - pathology; Staining and Labeling; Tissue Fixation; Vestibulocochlear Nerve - pathology; Vestibulocochlear Nerve - physiology
• ISSN: 0378-5955; 1878-5891
• DOI: 10.1016/0378-5955(95)00165-1

The patterns of neural degeneration of the spiral ganglion were studied in 12 human pathologic specimens and 2 normal neonatal specimens. Morphometric analysis of spiral ganglion cells included the maximum cross-sectional areas of both large (type 1) and small (type II) spiral ganglion cells. The organ of Corti in segments corresponding to the spiral ganglion, was evaluated for the presence or absence of inner (IHC) and outer (OHC) hair cells and supporting cells. The relationship between degeneration of spiral ganglion cells and degeneration in the organ of Corti, the age, sex, duration of deafness, cochlear location and delay between death and fixation was evaluated statistically. Both primary and secondary degeneration of the spiral ganglion were more severe in the basal than apical half of the cochlea. Degeneration of the spiral ganglion was most severe when both IHCs and OHCs were absent in the organ of Corti. No survival advantage was identified for type II ganglion cells as has been previously reported. That is, there was no correlation between the degree of degeneration of the spiral ganglion and the prevalence of type II ganglion cells. In fact, there was more severe degeneration of type II cells when the corresponding organ of Corti was severely degenerated. These findings in the human were compared with animal models of degeneration of the spiral ganglion, and the implications for cochlear implantation were discussed.