What is the primary cause of Frey's syndrome after parotidectomy?

Frey's syndrome, also known as gustatory sweating, occurs following surgery to the parotid gland, typically a parotidectomy. The primary mechanism involves the aberrant regeneration of the auriculotemporal nerve after surgical trauma.

During the surgery, the auriculotemporal nerve, which normally innervates the skin near the temple and stimulates sweating, can be inadvertently damaged. If the nerve is severed or traumatized during the procedure, it may heal incorrectly and sprout fibers that become connected to the sweat glands in the skin over the parotid area. Consequently, when a person eats (when the parotid gland normally produces saliva), the nerve signals erroneously lead to sweating in the preauricular region, producing the phenomenon characteristic of Frey's syndrome.

This aberrant regeneration is distinct from other options such as damage to the facial nerve, which would primarily impact motor function and could lead to facial weakness rather than the sympathetic response observed in Frey's syndrome. Infection and excessive scarring may complicate post-operative recovery but they do not directly establish the development of the syndrome. Thus, the relationship between auriculotemporal nerve damage and subsequent gustatory sweating is the primary cause of Frey's syndrome after parotidectomy