Objective-To demonstrate that sudden sensorineural hearing loss is possibly of viral origin rather than vascular.Study Design-The histopathologic morphology in 7 temporal bones with known vascular impairment due to surgical interventions was compared with that of 11 bones with a history of idiopathic sudden sensorineural hearing loss (ISSNHL). Attention was paid to the spiral ligament, stria vascularis, organ of Corti hair cells, tectorial membrane, ganglion cell population, and degree of perilymph fibrosis and the auditory nerve.Setting-A temporal bone laboratory that has been in operation for more than 50 years and includes a database consisting of clinical and histopathological information that facilitates quantitative and qualitative analysis.Subjects-Eight hundred forty-nine individuals who pledged their temporal bones for scientific study, of which 18 were selected for this study by means of the database criteria of sudden sensorineural hearing loss and postmiddle fossa and retro sigmoid sinus tumor removal or vestibular nerve section.Results-Sudden sensorineural hearing loss bones exhibited no perilymph fibrosis compared with 6 of 7 vascular cases with fibrosis (P ≤ .001), exhibited less loss of ganglion cells (P ≤ .026), exhibited greater survival of spiral ligament (P ≤ .029), and averaged twice the survival of hair cells and more widespread tectorial membrane abnormalities.Conclusion-Analysis of human temporal bones from patients with a sudden sensorineural hearing loss does not support a vascular insufficiency but is more suggestive of a viral etiology.
Materials and MethodsThe temporal bone laboratory of our institution contains 840 pairs of temporal bones with accompanying complete clinical records. This study is in compliance with regulations of the institutional review board of St. Vincent Medical Center #06-030, October 4, 2012. Most bones are from patients in our own pledge program, but a few are from the National Temporal Bone Registry From the database containing information on these bones, a total of 7 bones from 6 patients were found that had undergone middle fossa, suboccipital, or retrolabyrinthine surgery for the removal of vestibular nerve schwannomas or vestibular nerve lysis for the relief of the vertigo of Ménière's disease. These approaches were used to preserve the patient's serviceable hearing. In all cases, the auditory nerve was left intact. The postoperative hearing loss could be attributed only to an inadvertent interruption of the blood supply. These cases were designated the postoperative vascular group. A total of 11 cases in the database were identified with ISSNHL. The bones had been fixed with buffered formalin, decalcified with ethylenediaminotetraacedic acid until shown by xray to be free of calcium, embedded in celloidin, and cut into 20-μm sections on a sliding microtome. Every 10th section was stained with hematoxylin and eosin and mounted on glass slides and cover slipped. The percentages of normal spiral ligament, stria vascularis, hair cells, and peripher...