CT OF THE NORMAL SUSPENSORY LIGAMENTS OF THE OSSICLES IN THE MIDDLE-EAR

PURPOSE: To establish the range of normal variation in the CT appearan ce of the middle ear ligaments and the stapedius tendon as an aid in d etecting abnormal changes in these structures. METHODS: CT scans of th e temporal bone in 75 normal middle ears, obtained with l-mm-thick sec tions, were reviewed by two observers, who rated the visibility of the structures of interest on a scale of 1 to 5. RESULTS: The anterior, s uperior, and lateral malleal ligaments and the medial and lateral part s of the posterior incudal ligament were seen in 68%, 46%, 95%, 26%, a nd 34% of the ears, respectively. The stapedius tendon was seen in 27% of the cases, When visible, the ligaments were judged to be complete in 90% to 100% of the ears and the stapedius tendon was complete in 65 % of cases, Their width varied considerably. Interobserver variability was high for most observations. CONCLUSION: CT scans are more likely to show the malleal than the incudal ligaments. Although the interobse rver agreement was statistically significant for most study parameters , the percentage of agreement above that expected by chance was low. W hen seen, the ligaments usually appeared complete. Understanding the n ormal range of appearance may help identify abnormalities of the ligam ents and tendons of the middle ear.