Histopathology of nonsyndromic autosomal dominant midfrequency sensorineural hearing loss.
BACKGROUND
Autosomal dominant, nonsyndromic, midfrequency sensorineural hearing loss (SNHL) is a well-known clinical entity. There are no reported histopathologic studies of temporal bones from individuals with such a hearing loss.


OBJECTIVE
To describe the otopathology in 2 affected individuals from 2 different kindreds with nonsyndromic, dominant, midfrequency SNHL.


METHODS
Both subjects belonged to multigenerational families with nonsyndromic, autosomal dominant SNHL showing a cookie-bite pattern. Temporal bones were removed at autopsy and studied by light microscopy. Cytocochleograms were constructed for hair cells, stria vascularis, and cochlear neuronal cells.


RESULTS
Subject 1 (a 77-yr-old man) from Kindred A was diagnosed in early childhood with an SNHL that was progressive, reaching profound levels by adulthood. Both cochleae showed complete loss of inner and outer hair cells, moderate to severe diffuse atrophy of the stria vascularis, and severe loss of cochlear neurons, including the peripheral dendrites. The hearing loss in Subject 2 (an 82-yr-old man from Kindred B) began in late childhood, was slowly progressive, and involved the higher frequencies later in life. Histopathology showed loss of outer and inner hair cells in the basal turn of the cochlea, moderate to severe loss of stria vascularis, but relative preservation of peripheral dendrites and cochlear neurons.


CONCLUSIONS
The main histopathologic abnormalities were loss of hair cells, stria vascularis, and cochlear neurons in 1 case and loss of hair cells and stria vascularis in the second case. Our results are consistent with the hypothesis that dysfunction and loss of hair cells may have been the primary histopathologic correlate for the midfrequency hearing losses in these 2 subjects.
Bahmad
Fayez
F
Department of Otolaryngology, Massachusetts Eye and Ear Infirmary, Boston, Massachusetts 02114-3096, USA.
O'Malley
Jennifer
J
Tranebjaerg
Lisbeth
L
Merchant
Saumil N
SN
D000328:Adult; D000368:Aged; D001301:Audiometry, Pure-Tone; D001309:Auditory Threshold / Q000502:physiology; D016326:Extracellular Matrix Proteins / Q000235:genetics; D005260:Female; D058851:GPI-Linked Proteins; D006198:Hair Cells, Auditory / Q000473:pathology; D006312:Hearing Loss, Bilateral / Q000175:diagnosis / Q000235:genetics; D006319:Hearing Loss, Sensorineural / Q000175:diagnosis* / Q000235:genetics*; D006801:Humans; D008297:Male; D008562:Membrane Glycoproteins / Q000235:genetics; D008875:Middle Aged; D010375:Pedigree; D017354:Point Mutation / Q000235:genetics; D012720:Severity of Illness Index; D013067:Speech Perception; D013701:Temporal Bone / Q000473:pathology
D016326:Extracellular Matrix Proteins; D058851:GPI-Linked Proteins; D008562:Membrane Glycoproteins; C491350:TECTA protein, human