Retraction pockets involving the pars tensa portion of the ear drum is caused by atrophy of that portion of the ear drum. This thinning of the ear drum occurs due to loss of middle collagenous fibrous layer. This condition is commonly associated with chronic middle ear pathology. In rare cases atrophy of the pars tensa portion of the ear drum could be caused by intense sniffing on the part of the patient.. Sniffing reduces the middle ear pressure causing retraction of the pars tensa portion of the ear drum.
Retraction pockets are more common in the postero superior part of the pars tensa of the ear drum. Two reasons have been attributed to this feature:
1. This area is more vascular than other areas of ear drum, hence could be subjected to intense inflammatory reaction.
2. The middle fibrous layer in this area is incomplete, lacking the circular fibers.
Otoendoscopic picture of retracted ear drum
Long term effects of pars tensa retraction:
1. Progressive retraction of pars tensa may even cause fixation of the atrophic segmentto the bony walls of the middle ear cavity.
2. Progressive retraction of pars tensa may cause erosion of ossicles. Commonest ossicle eroded being the long process of incus
3. A small protion of these retraction pockets may progress and become cholesteatoma.
Classification of pars tensa retraction pockets:
Initially Sade classified these retractions under two heads:
1. Atelectasis: This is defined as diffuse retraction of the tympanic membrane towards the promontory.
2. Retraction pocket: This is defined as focal retraction of pars tensa towards the attic.
Recent classification proposed by Sade:
|1||Retracted ear||Slight retraction of ear drum|
|2||Severe retraction||Retracted drum touching the incus or stapes|
|3||Atelectasis||Tympanic membrane touching the promontory|
|4||Adhesive otitis||Tympanic membrane adherent to the promontory|
1. Variable hearing loss due to chronic infection of middle ear cavity or due to middle ear effusion.
2. Persistent hearing loss is a possibility if the long process of incus is eroded. In pure tone audiometry the hearing loss exceeds 60 dB.
3. Episodic or recurrent otalgia or otorrhoea may occur due to episodes of acute otitis media
4. Variable levels of eustachean tube patency may cause varying levels of deafness
1. Ear drum appears retracted.
2. Handle of malleus appear prominent
3. There is apparant shortening of the handle of malleus
4. The ear drum mobility is restricted / absent on siegalisation
5. Cone of light appear distorted
1. Eustachean tube insufflation: May be useful in early cases.
2. Grommet insertion
3. Reinforcement tympanoplasty: In this surgical procedure, the retraction pocket is excised and grafting of the deficient ear drum is performed using temporalis fasica graft.