Effects of sectioning chorda tympani nerve during middle ear surgery
Tuesday, March 15 2011 @ 02:11 AM IST
Contributed by: Admin
surgical procedures. Initially studies have demonstrated that unilateral injury to this nerve just caused
transient taste disturbances in the anterior 2/3 of the tongue. Progressively the alternate pathways of
of taste take over and the sensation returns to normal. House and Rice in their study demonstrated
that sectioning of chorda tympani during middle ear surgical procedures caused earlier return of the
taste sensation when compared to that of a severely traumatized nerve during the surgical procedure.
The chorda tympani nerve is a branch of facial nerve. It derives all its fibers from the nervous intermedius of wrisberg. The chorda tympani
nerve contains gustatory fibers from the anterior two thirds of the tongue and parasympathetic fibers to all the salivary glands excepting the parotid.
Sectioning the chorda tympani nerve not only affects the taste but also reduces the basal secretion of salivary glands causing xerostomia.
The sublingual and submandibular salivary glands are responsible for about two thirds of the basal saliva production. The parotid gland contributes
to just a third of the basal salivary production. Destruction / trauma to chorda tympani nerve on both sides can definitly cause dryness
of mouth due to a reduction in the amount of saliva secreted by sublingual and submandibular salivary glands.
Usually sectioning of one chorda tympani nerve will go unnoticed. When middle ear surgery is contemplated on both ears then the patient should be warned of the realistic risks of xerostomia.
Caution should be exercised in operating on the opposite ear of patients who have already undergone middle ear surgery in the ipsilateral ear.
Hence all otologists should take extra care to preserve this nerve during middle ear Surgical procedures.