Traumatic dislocation of middle ear ossicles: A new computed tomography classification predicting hearing outcome

Area of Science:

• Radiology
• Otolaryngology
• Medical Imaging

Background:

• Temporal bone fractures can cause ossicular joint dislocation, potentially leading to hearing loss.
• Accurate prediction of hearing outcomes is crucial for managing patients with traumatic ossicular dislocation.

Purpose of the Study:

• To evaluate the feasibility of radiologic measurements on CT scans for predicting hearing outcomes in patients with temporal bone fractures and suspected ossicular joint dislocation.
• To determine if CT scan evaluations can predict hearing outcomes.

Main Methods:

• Analyzed 4002 temporal bone CT scans, identifying 34 patients with traumatic ossicular joint dislocation.
• Measured malleus-incus axis distance, angle, and joint space; used contralateral side as control.
• Performed logistic regression to predict conductive hearing loss based on radiologic measurements.

Main Results:

• Excellent inter-rater agreement (ICC 0.81) for measuring malleus-incus axis deviation.
• Larger axis deviation correlated with higher probability of poor hearing outcome (OR 2.67 per 0.1mm, p = .006).
• Axis deviation cutoff of 0.25mm showed high sensitivity (0.778) and specificity (0.94) for predicting conductive hearing loss.

Conclusions:

• High-resolution CT scans are feasible for assessing traumatic ossicular chain dislocation.
• Malleus-incus axis deviation is a strong predictor of poor hearing outcome 1-3 months post-trauma.
• A 3-level classification system for hearing outcome prediction based on radiologic measures is proposed.