Bela purohit affiliated with department of radiology, university hospitals leuven email author . Robert hermans affiliated with department of radiology, university hospitals leuven . Katya op de beeck affiliated with department of radiology, university hospitals leuven otosclerosis is an otodystrophy of the otic capsule and is a cause of conductive, mixed or sensorineural hearing loss in the 2nd to 4th decades of life. High resolution ct hrct of the temporal bone using 1 mm or less thick sections is the modality of choice for assessment of the labyrinthine windows and cochlear capsules. Mri has limited application in the evaluation of the labyrinthine capsules but is useful for assessment of the cochlear lumen prior to cochlear implantation in patients with profound hearing loss. The treatment of fenestral otosclerosis is primarily surgical with stapedectomy and prosthesis insertion. Patients with retrofenestral otosclerosis and profound hearing loss are treated medically using fluorides, but may derive significant benefit from cochlear implantation.

This pictorial review aims to acquaint the reader with the pathology and clinical features of otosclerosis, the classical imaging appearances on ct and mri, a radiological checklist for preoperative ct evaluation of otosclerosis, imaging mimics and a few examples of post stapedectomy imaging and complications. People who have otosclerosis have an abnormal sponge like bone growing in the middle ear. Otosclerosis is the most common cause of middle ear hearing loss in young adults. Otosclerosis is an otodystrophy of the otic capsule and is a cause of conductive, mixed or sensorineural hearing loss in the 2nd to 4th decades of life.

X02022 fluorides and cochlear implantation are used to treat retrofenestral otosclerosis. It is also called x02018 otospongiosis x02019 as it is characterised by replacement of the normal ivory like enchondral bone by spongy vascular bone. Patients typically present in the 2nd 4th decades of life with conductive hearing loss chl , sensorineural hearing loss snhl or mixed hearing loss mhl and/or tinnitus. Otosclerosis is commoner in caucasians as compared to blacks, native americans and asians. Otosclerosis is categorised into two types, fenestral and retrofenestral/cochlear. Retrofenestral otosclerosis rarely occurs without fenestral involvement hence these manifestations are considered to be a continuum rather than two separate entities 1 x02013 4 .

Otosclerosis is a common condition affecting the bone of the otic capsule in 7.3% of caucasian males and 10.3% of caucasian females. The condition is rare in non caucasians, except east indians, in whom the incidence is approximately the same as persons of northern or central european origin. The stapes appears fixed in only 12.3% of temporal bones with histopathologic evidence of otosclerosis. Otosclerosis often starts in an area anterior to the stapes footplate called the fistula ante fenestrum but can occur in any part of the otic capsule. Histologically, otosclerosis is characterized by 2 phases: 1 otospongiosis and, 2 otosclerosis. In otospongiosis, affected bone becomes hypervascular and osteoclasts and osteolytic osteocytes cause enlargement of the vascular spaces of the bone.

The term cochlear otosclerosis is used to describe the sensorineural hearing loss seen in some patients with otosclerosis. Photo two shows the temporal bone ct of a woman with bilateral profound sensorineural hearing loss due to otosclerosis. The patient eventually underwent cochlear implantation with satisfactory results. During surgery it was noted that otosclerosis had filled the basal turn of the cochlea and obliterated the round window. Photo one: normal cochlea the progression of otosclerosis can be retarded, but not reversed. Florical can cause fetal problems and therefore should be used with caution in women of childbearing age.

while the etiology of otosclerosis remains unknown, there are two main theories regarding its origin genetic and viral.

genetic. otosclerosis seems inherited in approximately 50% of cases. It may be inherited as an autosomal dominant trait with 25 40 percent penetrance and is more common in females 1. Hearing loss associated with otosclerosis has long been noted to accelerate during pregnancy in some women.