NBDE Quiz # 69

74. The correct answer is A. This 40-year-old woman has Frey syndrome, which occurs as a result of peripheral autonomic dysfunction because of surgical injury. In patients who de¬velop Frey syndrome following parotidectomy, the most likely cause is injury to branches of the auriculotemporal nerve, which is a branch of the mandibular division of the trigemi¬nal nerve. The auriculotemporal nerve links the parasympathetic secretory fibers to the parotid gland. The preganglionic parasympa¬thetic fibers course down the tympanic branch of the glossopharyngeal nerve and the lesser petrosal nerve to the otic ganglion; from there,the postganglionic fibers travel via the auricu-lotemporal nerve to the parotid gland.
Following parotidectomy, the dermal sweat glands may be reinnervated abnormally by the parasympathetic fibers, resulting in innervation of the skin in the preauricular or temporal area. Patients with this abnormal innervation may have localized erythema and diapho¬resis instead of saliva production from the parotid gland. Appropriate management for pa¬tients who develop this condition includes re¬elevating the skin flap and using interposition grafts and flaps.
Frey syndrome does not develop following injury to motor nerves. Therefore, the facial (VII) nerve, which provides innervation for most of the facial muscles, cannot be injured in this patient.
The great auricular nerve arises from the sec¬ond and third cervical nerves and emerges from the posterior border of the sternocleidomastoid muscle, then travels anterosuperiorly between the sternocleidomastoid and platysma muscles and divides into auricular, facial, and mastoid branches. The auricular branch provides sen¬sation to the earlobe and posterior two-thirds of the ear and is prone to injury during surgery of the upper lateral neck.
The posterior auricular nerve arises from the facial nerve at the stylomastoid foramen, re¬ceives a contribution from the auricular branch of the vagus nerve, and supplies two nerve branches, one of which joins with the mas¬toid branch of the great auricular nerve and an¬other that joins with the lesser occipital nerve. Both branches provide sensibility to the pos¬terior side of the pinna and the concha. The posterior auricular nerve supplies motor inner¬vation to the posterior auricular and occipitalis muscles.
The auricular branch of the vagus (X) nerve, also known as Arnold’s nerve, arises from the su¬perior ganglion, receives a contribution from the glossopharyngeal nerve, and travels along the temporal bone, emerging through the au¬ricular fissure between the mastoid process and external auditory meatus. It supplies sensation to the posterior aspect of the ear and external auditory meatus.