PhiliPPine Journal of otolaryngology-head and neck Surgery  35

PhiliPPine Journal of otolaryngology-head and neck Surgery                                                         Vol. 24 no. 1 January – June 2009

FROM THE VIEWBOX

A 34-year-old Filipina presents with bilateral progressive hearing loss and 
tinnitus of three years’ duration. Otologic examination reveals normal external 
auditory canals and tympanic membranes, with good tympanic membrane 
mobility on pneumatic otoscopy. Standard audiometric examination shows 
a bilateral moderate conductive hearing loss. Temporal bone CT imaging 
reveals the presence of a focal region of bone demineralization involving the 
dense bone of the otic capsule surrounding the cochlear lumen (Figure 1), a 
finding consistent with a diagnosis of active otospongiosis.  The diagnosis was 
confirmed by visualization of an otosclerotic focus during transcanal middle 
ear exploration where stapedectomy with placement of a stainless steel stapes 
prosthesis was performed.

Demineralization of the Otic Capsule in 
Otosclerosis (Otospongiosis)

Nathaniel W. Yang, MD1,2

1Department of Otorhinolaryngology
College of Medicine – Philippine General Hospital
University of the Philippines Manila

2Philippine National Ear Institute
National Institutes of Health
University of the Philippines Manila

Correspondence: Nathaniel W. Yang, MD
Department of Otorhinolaryngology
Ward 10, Philippine General Hospital
Taft Avenue, Ermita, Manila 1000
Philippines
Phone: (632) 526 4360
Fax: (632) 525 5444
Email: nwyang@gmx.net 
Reprints will not be available from the author. Philipp J Otolaryngol Head Neck Surg 2009; 24 (1): 35-36 c  Philippine Society of Otolaryngology – Head and Neck Surgery, Inc.

Figure 1. The white arrow is pointing to the area of focal demineralization surrounding the cochlea, a 
finding described as the “halo effect.”1



                                PhiliPPine Journal of otolaryngology-head and neck Surgery                                                          Vol. 24 no. 1 January – June 2009   

36  PhiliPPine Journal of otolaryngology-head and neck Surgery

FROM THE VIEWBOX

Otosclerosis is a condition unique to the temporal bone 
characterized by abnormal resorption and deposition 
of bone in the otic capsule and ossicles. Although it 
occurs more rarely in Asiatic populations compared to 
Europeans, Americans of Caucasian origin and Indians, it 
must be considered in patients presenting with primarily 
conductive hearing loss, especially if there is bilateral 
involvement. CT imaging of the temporal bone may 
help to differentiate this condition from other causes of 
conductive hearing loss such as tympanosclerosis and 
bony epitympanic fixation of the ossicular chain from 
chronic infection and inflammation of the middle ear. 
One must be cognizant of the fact that a normal temporal 
bone CT scan does not rule out a diagnosis of otosclerosis 
because an inactive, highly sclerotic focus that appears as 
a uniform hyperdense mass may be difficult to distinguish 
from the normal compact labyrinth capsule.1 Other causes 
of otic capsule demineralization include osteogenesis 
imperfecta, Paget disease, otosyphilis and Camurati-
Engelmann disease. These may be differentiated by their 
individually characteristic patterns of bone involvement 
and evidence of disease in other organ systems.2

Figure 2. A normal temporal bone for comparison showing the dense bone surrounding 
the cochlear lumen

REFERENCES 
1. Häusler R. Advances in stapes surgery. In : Jahnke K, editor. Middle ear surgery recent 

advances and future directions. Stuttgart: Thieme; 2004. p. 96-133.
2. Alkadhi H, Rissmann D, Kollias SS. Osteogenesis imperfecta of the temporal bone: CT 

and MR imaging in Van der Hoeve-de Kleyn syndrome. Am J Neuroradiol 2004 Jun/Jul; 
25:1106-1109.