Frey's syndrome (gustatory sweating) is due to lesion of
Auriculotemporal nerve carries parasympathetic secreto-motor fibres to parotid gland. After parotidectomy, sometimes there may be regeneration of secretomotor fibres in Auriculotemporal N This regeneration is misdirected into sweat glands. Thus, whenever the patient thinks of food/smells /chews food there would be stimulation of sweat glands & hyperaemia resulting in redness & sweating in front of ear on cheek. This clinical entity is called 'FREY SYNDROME'/AURICULOTEMPORAL SYNDROME/GUSTATORY SWEATING. Image showing Starch-iodine test:
Glossopharyngeal nerve
Chorda tympani nerve
Trigeminal nerve
Auriculo-temporal nerve
Neck Triangles and parotid gland