Fistula of labyrinth Including bone erosion, exposure of the endosteal membrane and a true fistula into the fluid compartment of the inner ear It occurs in 5-10% of cases with cholesteatoma Lateral semicircular canal is the most common location (90%) Mechanism of bone erosion LSC 1 Osteolysis I resorptive osteitisFistula of labyrinth ◼ Including bone erosion, exposure of the endosteal membrane and a true fistula into the fluid compartment of the inner ear. ◼ It occurs in 5-10% of cases with cholesteatoma ◼ Lateral semicircular canal is the most common location (90%) ◼ Mechanism of bone erosion ◼ Osteolysis ◼ resorptive osteitis