In traummatic disruption of the ossicular chain the most common affected ossicles is

a. Malleus.
b.incus
c.stpes.
d.All are equally affected.


Ans: B

Violent, closed-head injuries, especially if associated with a temporal bone fracture, are common causes of ossicular chain disruption.

A major conductive hearing loss (30-60dB) may result which does not improve after tympanic membrane repair.

The most common traumatic ossicular chain lesion is a incudostapedial joint dislocation with or without a fracture of the long process of the incus.

However, just about any imaginable fracture or displacement can be found. Ossicular dislocation interrupts the normal transmission of sound energy from the tympanic membrane to the fluid of the middle ear.

Hence, under these conditions the impedance matching mechanism, which alone overcomes the nearly 30 dB loss of energy when sound waves in air meet a fluid boundary, is lost. Coupled with the mechanisms surround a tear in the tympanic membrane (see above), the hearing loss is substantial and disabling.