Characteristic temporal bone changes have recently been defined by high 
resolution CT in nine patients with achondroplasia (Cobb et al., Am J 
Neuroradiol 9:1195, 1988). These included narrowing of the skull base and 
"towering" petrous ridges resulting in abnormal orientation of the inner and 
middle ear structures. In order to determine whether these morphologic changes 
are the cause of the hearing deficit in achondroplasia, audiometric studies and 
ENT evaluation were performed in eight of the nine patients. All had a history 
of frequent otitis media and four had experienced tympanic membrane tube 
insertion. Three patients had significant sensorineural hearing loss, two had 
conductive hearing loss and one patient had combined hearing loss. None of the 
temporal bone morphologic changes were found to be correlated with the degree of 
either sensorineural or conductive hearing loss. Fusion of the ossicular chain 
was not present in any of our cases. Appropriate treatment of frequent acute 
otitis media and early awareness of middle ear effusions and conductive hearing 
loss in children with achondroplasia may be of great importance in preventing 
permanent hearing loss.