Bone Conduction Improvement After Surgery for Conductive Hearing Loss

Abstract

The objective is to evaluate change in postoperative bone conduction in patients who underwent surgery for conductive/mixed hearing loss due to various reasons. The study design is of retrospective case review and tertiary referral center setting. Five-hundred patients with unilateral conductive/mixed hearing loss were divided into five equal groups (each representing different causes for pre-operative hearing loss), who underwent appropriate surgical correction and had a follow-up audiogram available. The intervention comprises surgery (like myringoplasty and ossiculoplasty with closed or open cavity mastoidectomy for chronic otitis media, stapes mobilization for tympanosclerosis and stapedotomy for otosclerosis) for conductive/mixed hearing loss. Significant improvement or worsening in bone conduction was defined as 15 dB or more improvement or worsening of bone conduction threshold at least in two frequencies between 500 and 4000 Hz. All the other groups also showed a consistent preoperative bone conduction reduction with an equally consistent improvement in post-operative bone conduction improvement to a varying degree with otosclerosis group having maximum percentage of patients with post-operative bone conduction improvement (60%). The measurement of bone conduction is not necessarily a true reflection of the function of the inner ear. Middle ear makes a contribution to bone conduction and correction of a middle ear conductive lesion causes an apparent improvement in inner ear function. The apparent inner ear hearing loss caused in this way may be reversible to some extent.

The effect of preserved stapedial superstructure on hearing improvement

“…The results observed in subsets 1 and 2 unequivocally confirm that severe damage to the ossicular chain with only stapes bone (or only It is believed that hearing improvement may not be achieved in approximately 60% of patients with damaged stapedial superstructure [18][19].…”

Hearing treshold before and after middle ear surgery in chronic suppurative otitis media (CSOM)

“…11,13 Other factors that may result in decreased bone conduction in patients with CSOM are influenced by: 1) sealed or obliterated round window by middle ear granulation tissue that affects the loss of phase difference between round window and oval window, 2) stiffness of hearing bone as a result of granulation tissue and cholesteatomas that envelop the hearing bones, 3) perforation and discontinuities of the hearing bone. 4 The difference between the air-bone conductivity range in each groups of both canal wall up and canal wall down tympanoplasty is statistically significant, especially at 2000 Hz (p=0.005). The diagnosis and management of each group sample has been adjusted for clinical indications and considerations for the selection of surgical procedures.…”

“…The management of CSOM is different depending on the type. 3,4 The CSOM is a common worldwide disease especially in developing countries with low socioeconomic status with the prevalence varies from 0.5 to 30%. 5 Prevalence of CSOM surveys worldwide showed the global burden of illness from CSOM involved 65-330 million people with otorrhoea, 60% of whom (39-200 million) suffered from significant hearing loss.…”

Does bilateral otosclerosis make pre-operative bone conduction more inaccurate?

“…It is widely accepted that fixation of the stapes footplate in otosclerosis, although manifesting mainly as a conductive hearing loss, also has a deleterious effect on the bone conduction pathway which is partially reliant on middle ear transmission. ( Tondorf, 1972 ) Bone conduction has been shown in many studies to improve after successful stapes surgery with published figures for average improvement ranging from 4.5 dB to 15.6 dB ( Mokhtarinejad et al., 2013 ; Awengen, 1993 ; Vijayendra and Parikh, 2011 ; García-Iza et al., 2016 ).…”