Single photon emission computed tomography in otosclerosis: diagnostic accuracy and correlation with age, sex, and sensorineural involvement.

OBJECTIVE

To evaluate the accuracy of single photon emission computed tomography (SPECT) in detecting otospongiotic foci of the labyrinthine capsule in otosclerotic patients and to correlate the metabolic patterns detected by SPECT with age, sex, and sensorineural hearing loss.

PATIENTS AND

METHODS

Thirty-six patients with surgically confirmed otosclerosis and a control group of 12 subjects with normal hearing; each subject underwent SPECT study of the skull with (99m)technetium-diphosphonate ((99m)Tc-medronate). Statistical analysis of the results was performed by use of the Mann-Whitney U test.

RESULTS

SPECT seemed to be very sensitive in differentiating otospongiotic bone from normal bone; in the affected group, only 2 of 72 ears yielded false-negative results (sensitivity 97.2%). Moreover, in the otosclerotic patients, the mean petrosa uptake value was higher than in the control group, a difference that was statistically significant (p < 0.0001).

MAIN OUTCOME MEASURES: Regarding uptake in relation to patient age, an inverse relationship was observed between increased metabolic activity and age: the mean uptake index in the younger patients was significantly higher than that in the older patients (p < 0.0001). By contrast, no statistically significant differences were found between men and women (p = 0.1519). Comparison of SPECT alterations with bone conduction thresholds revealed a statistically significant correlation (p = 0.0002 and p = 0.0010) between increased metabolic bone activity and sensorineural involvement only in the younger group of otosclerotic patients.

CONCLUSIONS

Diphosphonate bone SPECT is the only functional method that allows in vivo evaluation of disease activity, and it was highly sensitive in detecting otosclerosis. SPECT can be considered useful in the diagnosis of otosclerosis that is difficult to recognize, such as cochlear otosclerosis and far-advanced otosclerosis, and it could also find a place in evaluating the efficacy of medical therapy for otosclerosis.