Contralateral Occlusion Test (COT): Predicting the degree of conductive hearing loss by the effect of external ear canal occlusion
Bedside testing may decrease turnaround time and improve decision making for a quick qualitative assessment of hearing loss. It was designed a bedside test with tuning forks that can allow the quantitative evaluation of hearing loss in the presence of unilateral conductive hearing loss. COT showed a better association between hearing loss and the lateralization response using the 512 Hz tuning fork (p = 0.001). The sensitivity of the 512 Hz fork in detecting a PTA of at least 35.6 dB was 94.6% and the specificity was 75.0% for a positive predictive value of 89.7% and a negative predictive value of 85.7%, assuming a pretest prevalence of 69.8%. The overall accuracy of the COT in predicting the degree of unilateral conductive hearing loss was significant. The COT had significant power in one direction: if lateralization to the affected ear occurred, it was almost certain evidence of a moderate or severe conductive hearing loss.
Steps to reproduce
Perform the following sequential steps: 1. Weber test to confirm the lateralization of sound to the affected ear. We considered lateralization positive when it occurred at three or more tuning fork frequencies. 2. Total occlusion of the EAC of the contralateral ear (the non-affected ear). 3. The base of a vibrating tuning fork was placed in the middle of the forehead, equidistant from both ears, with the tines in the coronal plane and facing forward. 4. The COT was sequentially and randomly performed in a soundproof test room. 5. The sound of a vibrating tuning fork placed in the middle of the forehead will lateralize to the ear with the greater hearing loss or will not lateralize to either of the ears.