Michael D. Chambers and William Chung
Frey syndrome, also known as gustatory sweating or auriculotemporal syndrome, consists of sweating and flushing of the skin in the preauricular area during mastication. Occasionally, a patient may also experience pain in the region. The onset of symptoms is quite variable. Duphenix first described the syndrome in literature in 1757, followed by Baillarger in 1853, and again by Weber in 1897; however, the pathophysiology of the syndrome remained uncertain until 1923 [1-3]. The syndrome itself was named after a Polish neurologist at the University of Warsaw, Lucja Frey, who correctly identified the autonomic innervation of the parotid gland via the auriculotemporal nerve while caring for a patient who sustained a traumatic gunshot wound to the parotid region and exhibited symptoms of gustatory sweating while eating .
The auriculotemporal nerve, a branch of the trigeminal nerve, is a mixed nerve that carries general somatosensory fibers as well as parasympathetic and sympathetic fibers. In a normal patient, the parasympathetic fibers stimulate parotid gland salivary secretion, vasodilation, and the erector pilae of the overlying skin. Sympathetic fibers stimulate vasoconstriction of the vessels in the gland, the skin of the preauricular region, and the cutaneous sweat glands. The neurotransmitter released by the parasympathetic nerves at the effector organ is acetylcholine, while that of the sympathetic nerves is norepinephrine.
The pathophysiology of Frey syndrome describes an aberrant process in which the postganglionic parasympathetic nerve fibers innervate the sweat glands and
M.D. Chambers, DMD, MD • W. Chung, DDS, MD (*)
© Springer International Publishing AG 2017
G.F. Bouloux (ed.), Complications of Temporomandibular Joint Surgery, DOI 10.1007/978-3-319-51241-9_6
subcutaneous vascular plexus rather than the secretomotor cells of the parotid gland. This is typically a result of surgery involving the parotid gland such as a parotidectomy or incision and drainage of a parotid abscess. However, there are reports of gustatory sweating associated with blunt trauma to the region, mandibular condyle fractures, temporomandibular joint surgery, and rare congenital abnormalities such as a bifid or trifid condyle [5, 6]. While congenital abnormalities of the condylar head are rare, Blackwood introduced the developmental theory in 1957 which states that a bifid condyle is the result of the fetal vascular fiber septum in the condylar cartilage and its lack of normal involution around 9 weeks of life after birth. The mechanism by which Frey syndrome develops in such a congenital abnormality is unclear . The close anatomical relationship between the auriculotemporal nerve and the temporomandibular joint capsule is of significant importance when operating in the region and results in frequent injury to the nerve with resulting paresthesia and the potential to develop Frey syndrome.