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What is Schwartz operation is also called as - and explain in detail?
Mastoidectomy is defined as a surgical procedure which opens up the mastoid cavity, cleans up the infected air cells, improves middle ear ventilation by widening of the aditus.
There are several types of mastoidectomy.

Cortical mastoidectomy (simple mastoidectomy or schwartz operation)

The mastoid air-cell system is exenterated, including epitympanum.
But the posterior meatal wall (canal wall) is left intact.