Mild hearing loss is common among people with ankylosing spondylitis, particularly in older patients regardless of disease severity, researchers have found.
Ankylosing spondylitis is a chronic inflammatory disease that mainly affects the joints that connect the end of the spine to the hip bones, as well as the head and trunk bones.
It is not uncommon for rheumatic diseases to affect a person’s hearing. This is often because of impaired function of the small bones and ligaments involved in the hearing process. However, to date, there is still limited information regarding hearing loss among patients with ankylosing spondylitis.
To shed light on this matter, Indian researchers evaluated 100 patients diagnosed with ankylosing spondylitis. Participants had a median age of 33 and a mean disease duration of 8.2 years.
Upon audio assessment, the team found that 48 participants had impaired hearing; 28 of those had bilateral (both ears) hearing loss. Hearing loss was mild in 38 of the affected patients, and moderate to severe in 10 patients.
Hearing loss was associated with older age.
A total of 29 patients were found to have problems only with the process of transferring sound waves within the ear’s structures (conductive components), while three patients had exclusively sensory impairment (a problem within the inner ear or sound sensory organ). The other 16 participants showed mixed hearing loss, involving both sensory and conductive components.
Approximately 70% of cases of conductive impairment had more problems detecting low frequency (0.25, 0.5, 1 kHz) sounds. In contrast, 75% of sensory impairment cases were less sensitive to high- frequency (4, 8 kHz) sounds.
Patients who had conductive hearing loss also had nine times the chance of developing sensorineural hearing loss.
Despite the high incidence of hearing loss in this population, the team did not find any significant association between hearing loss — either conductive or sensorineural — and disease severity parameters, nor with use of non-steroidal anti-inflammatory drugs (NSAIDs).
A detailed analysis of the ear components revealed that patients with hearing loss had limited mobility of the small bones (ossicles) that need to vibrate to translate sound waves into nervous stimuli.
“The possible mechanism of conductive hearing loss could be arthritis of joints between the ossicles [in the middle ear], defect in the supporting ligaments or the fixation of stapes footplate (otosclerosis),” researchers suggested.
Additional studies are still necessary to better understand the involvement of joints and ligaments of the middle ear in patients with ankylosing spondylitis.