An assessment of the value of the preoperative computed tomography scans prior to otoendoscopic 'second look' in intact canal wall mastoid surgery

'Second look' surgery following primary intact canal wail mastoid surgery F or cholesteatoma is considered mandatory for most cases in modern otologica l practice. The morbidity of the second look can be reduced by the use of t he rigid otoendoscope. Forty-three patients undergoing 'second look' surger y were studied with an average age of 24.7 years. Prior to surgery a comput ed tomography (CT) scan was performed to assess the anatomy and pneumatisat ion of the cavity. The mean interval between primary and secondary surgery was 16 months and in all cases CT scans were performed within 6 months of ' second look' surgery. The presence of an opaque mastoid did not correlate w ith residual or recurrent cholesteatoma. The sensitivity of CT in diagnosin g residual or recurrent cholesteatoma was 42.9% with a specificity of 48.3% and a predictive value of 28.6%. These results are explained by the fact t hat it is radiologically impossible to differentiate between recurrence, sc ar tissue or fluid with a CT scan. Nevertheless it was possible to inspect the cavity with the otoendoscope even in the presence of an opaque mastoid whether due to scar tissue or residual/recurrent cholesteatoma.