Dr Srinivas (Bangalore)
Dr. Prahlada N.B(Bangalore)
Dr. Rishi Gautam Aggarwal (Ambala)
Dr. Deepak Dalmia(Mumbai)
In some patients, an outwardly bulging, thin atrophic area or "herniation" of the tympanic membrane will be encountered. These “pulsion hernias” are asymptomatic and do not seem to interfere in any way with normal epithelial migration along the surface of the tympanic membrane.
There appear to be two prerequisites necessary for the development of a pulsion hernia.
The first is a preexisting defect in the fibrous middle layer of the pars tensa of the tympanic membrane.
The second is the presence of positive pressure within the middle ear, which forces the thinned portion of the tympanic membrane laterally into the canal (the pulsion).
If the fibrous middle layer of the pars tensa were intact, the tympanic membrane would be unable to herniated laterally to any significant extent.
The thinness of the pars tensa of the tympanic membrane over the pulsion pocket suggests that the herniation of the tympanic membrane occurred in an area where the fibrous middle layer of membrane has disappeared (e.g., the site of a previous, healed perforation or retraction pocket), leaving an area where the membrane consists of only two layers (a dimeric membrane).