Cause of AAD in one ear & TTD in other ear

1) Difference in pneumatisation of mastoid on 2 sides

2) Retraction of TM & breakdown à TTD on that side

        3) Central pathology affecting more on AAD side e.g. severe DNS, adenoid hypertrophy covering ET opening on one side

        4) Initial ET dysfunction in both ears, one side ET function improved later or has intermittent dysfunction