Sudden Sensorineural Hearing Loss: Subclinical Viral and Toxoplasmosis Infections as Aetiology and How They Alter the Clinical Course

Abstract

Aim: To explore in a prospective study the evidence of certain viral and toxoplasmosis infections in sudden sensorineural hearing loss (SSHL). Methods: 84 consecutive patients with SSHL meeting certain criteria. All patients were assessed for specific IgM antibodies against cytomegalovirus, herpes simplex virus, toxoplasma and Epstein-Barr virus. All were treated with intravenous steroids and assigned to two groups: 76 IgM negative (NV group) and 8 IgM positive (no history of acute infection – V group). Results: The mean hearing level at presentation was 86.5 dB HL (median, 100) in the V group and 60.7 dB HL (median, 61) in the NV group. The difference was statistically significant (p = 0.003). The mean hearing level following treatment was 81.8 dB HL (median, 88) in the V group and 48.7 dB HL (median, 39) in the NV group. The difference was statistically significant (p = 0.004). There was a considerable improvement in hearing after treatment only in the NV group (p < 0.000001). Conclusions: Recent subclinical viral or toxoplasmosis infections may be involved in the pathogenesis of SSHL (in approx. 10% of cases), suggesting that SSHL is not a single disease. When certain viruses or toxoplasmoses are involved, the hearing is much worse in comparison to patients with no such indication of infection. An alteration in treatment dosage or method of steroid administration may be needed in such cases.

Higher Risk of Developing Sudden Sensorineural Hearing Loss in Patients With Chronic Otitis Media

“…Diagnoses of certain types of chronic infection have been significantly associated with subsequent SSNHL. 15,16 However, the mechanism underlying the association between COM and subsequent SSNHL remains unclear. The risk factors for chronic sensorineural hearing loss are middle ear infections, which are also important in the development and progression of labyrinthitis.…”

GRHL2 genetic polymorphisms may confer a protective effect against sudden sensorineural hearing loss

“…As a transcription factor, GRHL2 is important in embryonic development and otic epithelial tissue differentiation by promoting apical junction maturation (14,26,27). GRHL2 could also be involved in apical barrier formation and activate adult antimicrobial defense, which may be associated with SSHL observed in viral infections (28,29). GRHL2 could Table IV.…”

Genetic Polymorphisms and Susceptibility to Sudden Sensorineural Hearing Loss: A Systematic Review

“…GRHL2 is important in embryonic development and otic epithelial tissue differentiation by promoting apical junction maturation. Research has shown that GRHL2 plays an important role in apical barrier formation and adult antimicrobial defense, which may be associated with SSNHL observed in viral infections [Kikidis et al, 2011]. A great number of previous studies have reported that genetic polymorphisms in GRHL2 are the cause of autosomal dominant sensorineural hearing loss and are correlated with the development of age-related hearing impairment [Fransen et al, 2008;Konings et al, 2009;Li et al, 2013].…”