Injury to the chorda tympani during middle ear surgery will affect which side?

Correct answer: A. The same (ipsilateral) side as the injury

• A. Correct. The chorda tympani is a peripheral branch of CN VII and carries taste from the anterior two-thirds of the tongue plus secretomotor fibres to the submandibular and sublingual glands. Peripheral cranial nerve lesions produce IPSILATERAL deficits — the patient loses taste on the SAME side of the anterior tongue and has reduced submandibular/sublingual salivary flow on that side. Decussation occurs centrally in the brainstem, well proximal to this branch.
• B. Incorrect. The deficit involves both taste AND secretomotor function, and it is strictly unilateral.
• C. Incorrect. Contralateral deficits arise from lesions ABOVE the decussation — i.e. supranuclear/cortical lesions, not peripheral nerve branches.
• D. Incorrect. A unilateral peripheral injury produces a unilateral deficit; the intact contralateral chorda tympani is unaffected.

Note: Patients often do not notice unilateral taste loss because the intact side compensates — the more common complaint after chorda tympani injury is a persistent metallic taste or dry mouth sensation.