Teaching neuro-image: a case of gustatory hyperhidrosis

A 49-year-old man presented with left facial and scalp hyperhidrosis during eating, especially with spicy or sour foods, severe enough to cause social avoidance (Fig. 1). This hyperhidrosis started 6 months after surgery on the left parotid gland to remove an abscess, and symptoms are still ongoing 8 years later. Neurological examination was unremarkable. Frey’s syndrome results from damage to the auriculotemporal nerve, a branch of the trigeminal nerve at the parotid region. The aberrant regeneration with cross innervation between parasympathetic fibres that induce salivation and sympathetic fibres that induce perspiration of the face and scalp, results in increased perspiration in the preauricular area after gustatory stimulation [1, 2]. To the authors’ knowledge, there is no paper that describes this large territory of focal hyperhidrosis, as observed in this patient. The diagnosis of Frey’s syndrome is based on clinical history. Other symptoms include flushing, neuralgia, pruritus, and burning sensation [3]. Confirmatory testing can be done with a starch and iodine test, also called Minor’s test, by applying iodine to the post-surgical affected area. Once dry, starch is applied to the same area and a gustatory stimulus is given to stimulate sweat causing blue and brown discoloration of the starch in the presence of iodine and sweat. Medical treatments include antiperspirants and the most widely used injections of botulinum toxin A [4]. Surgical management is reserved for severe and refractory cases, consisting of the sternocleidomastoid muscle and temporalis fascia transposition. Prognosis can be refractory in a large population with Frey’s syndrome [5].

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