Idiopathic sudden sensorineural hearing loss: vascular or viral?

Abstract

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.

Keywords: sudden sensorineural; vascular; viral.

Figure 1

Fibrosis (arrows) with some neo-ossification spicules in the cochlear basal segment in a case of vascular insufficiency following a middle fossa vestibular nerve schwannoma removal. rwm indicates round window membrane. Hematoxylin and eosin 40X.

Figure 2

Abnormal tectorial membrane (arrow) characteristic of idiopathic sudden sensorineural hearing loss. Hematoxylin and eosin 200X.

Figure 3

Spiral ganglion in Rosenthal’s canal with a low normal number of neurons of 23,971 (normal for age 79 years, 26,200 ± 4491) in the case of idiopathic sudden sensorineural hearing loss. Hematoxylin and eosin 200X.

Figure 4

Rosenthal’s canal with a subnormal population of neurons of 12,789 (normal for age 72 years, 26,200 ± 4491) in a case of vascular insufficiency. Hematoxylin and eosin 200X.