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Elderly patients who attend an audiology department for hearing loss are commonly found to have a treatable cause.1
A retired army quartermaster aged 72 sought advice because of hearing loss and tinnitus reminiscent of Morse code. He also reported an increase in regimental beret size from 6¾ inches to 7½ inches. This classic detail of the history prompted measurement of serum alkaline phosphatase, which was high at 562 u/L (corrected calcium 2.35 mmol/L). The diagnosis of Paget's disease was confirmed by isotope bone scan.
MRI of his brain and internal acoustic meati confirmed skull vault thickening and showed no evidence of compression of the 8th cranial nerve on either side. The cochleas appeared normal. His audiogram showed the moderate mixed high-frequency sensorineural and low-frequency conductive hearing loss typical of Paget's disease. Tympanograms were normal, and loudness discomfort levels suggested a non-recruiting loss. He was treated with six intravenous pamidronate infusions at one-week intervals and was provided with a hearing aid. At reassessment six months later the conductive component of his hearing loss had completely resolved and in consequence air conduction thresholds had improved (Figure 1). He no longer required the hearing aid. His tinnitus had greatly improved, and the alkaline phosphatase was now 198 u/L.
In the UK, about 5% of the population over 55 have Paget's disease. A quarter have skull involvement, and in half of these the temporal bones are affected, usually bilaterally. Of those with temporal bone involvement about half have hearing loss, a quarter have tinnitus and a quarter have vertigo. These figures suggest that, in a randomly selected population of a thousand over-55s, three would have hearing loss from temporal bone Paget's disease.
Several case reports and one retrospective study record improvement or slowing of hearing loss in Paget's disease. A recent prospective uncontrolled study did not show improvements in hearing with such agents, but about half the patients who reported tinnitus or vertigo said that these symptoms had improved.6
There is no unifying explanation of the mechanism by which Paget's disease causes hearing loss.7 Ossicular involvement is by no means universal even in those with a purely conductive loss. The sensorineural component has been thought to result from compression of the 8th cranial nerve as it passes through the internal auditory canal but, as in the present case, the auditory nerve is intact in a large proportion of patients with Paget's disease and hearing loss.7
In view of the evidence of benefit from medical treatment, conductive hearing loss or other audiological symptoms in a patient of mature years should prompt consideration of Paget's disease.