Bony sheathed chorda tympani: a unique case of incudomalleolar fixation.

OBJECTIVE

To describe a unilateral conductive hearing loss caused by restriction of the movements of malleus and incus due to chorda tympani in a bony sheath.

PATIENT: A 23-year-old man with a stable mild conductive hearing loss in the left ear and mild sensorineural hearing loss in the right ear.

INTERVENTION: An exploratory tympanotomy was performed.

MAIN OUTCOME MEASURE: Immobility of the ossicles due to a bony structure, which was found to be chorda tympani encircled in a bony sheath. Ossicular system regained its mobility with the severance of the chorda tympani.

RESULTS

Hearing was improved both subjectively and audiographically.

CONCLUSION

This is the second case of chorda tympani with a bony sheath and the first case of this pathologic finding affecting both malleus and incus. Bony sheathed chorda tympani is considered to be a congenital anomaly of the chorda tympani that causes incudomalleolar fixation and behaves as posterior bony bars.