Otologic manifestations of malignant osteopetrosis

Abstract

Objective: To determine the incidence of hearing loss and describe the neurotologic manifestations over time in a large series of patients with malignant osteopetrosis.

Study design: Longitudinal study.

Setting: Tertiary care referral center.

Patients: Thirty-two patients, including 19 infants (< 1 yr of age at initial visit) and 13 children (aged 1-7.6 yr at initial visit), with autosomal recessive osteopetrosis were followed-up during a 10-year period from 1991 to 2001. The average length of follow-up was 2.5 years (range, 0-9.1 yr).

Interventions: Patients underwent annual otologic evaluations including clinical examination, audiologic evaluation (auditory brainstem response, pure-tone thresholds, speech discrimination scores, and tympanograms), and high-resolution computed tomography of the temporal bone.

Main outcome measures: Incidence of hearing loss, otitis media, and facial paralysis. Serial changes in temporal bone anatomy by computed tomographic scan.

Results: Twenty-six percent of infants' ears demonstrated hearing loss during the first year of life, and 78% of children's ears demonstrated hearing loss during the study period. Of the children's ears with hearing loss, 100% had a conductive component and 26% had an additional sensorineural component (mixed hearing loss); VIIIth nerve conduction was normal in 100% of infants and 78% of children. Five patients (16%) had unilateral facial nerve palsy. Common temporal bone findings included thickening and sclerosis of the calvarium; poor pneumatization of the mastoid bone; and narrowing of the external auditory canal, eustachian tube, and internal auditory canal.

Conclusion: Otologic manifestations are common in malignant osteopetrosis secondary to the formation of dense, brittle bone. Frequent findings include external auditory canal stenosis, otitis media, conductive and sensorineural hearing loss, and facial nerve paralysis.