Painful sweating.

OBJECTIVE: The authors report a case of spontaneous and gustatory facial pain and sweating. METHODS: The patient had frequent episodes of pain, sweating, and flushing bilaterally in the hairless skin of the ophthalmic and maxillary distributions of the trigeminal nerve. Gustatory stimuli (e.g., orange juice, pickled onions) reliably evoked episodes, but episodes also frequently came on spontaneously. The problem had begun during adolescence, about the time of topical treatment and then electrocauteries for facial warts. The patient reported benefit from tricyclic antidepressants, guanethidine, and trospium chloride (an anti-cholinergic quaternary amine used in Europe for urinary urgency). There was no pain or excessive sweating in other body areas, nor pain with exercise. RESULTS: Administration of edrophonium IV evoked pain and sweating, and ganglion blockade by IV trimethaphan eliminated pain and sweating and markedly attenuated responses to edrophonium. Trospium chloride also prevented edrophonium-induced pain and sweating. Bicycle exercise produced the same increment in forehead humidity as in a spontaneous episode but did not evoke pain. Tyramine infusion did not bring on pain or sweating, whereas iontophoretic acetylcholine administration to one cheek evoked pain and sweating bilaterally. Topical glycopyrrolate cream eliminated spontaneous, gustatory, and edrophonium-induced episodes. CONCLUSIONS: The findings indicate that facial pain and sweating can result from occupation of muscarinic cholinergic receptors after acetylcholine release from local nerves. The authors propose that after destruction of cutaneous nerves, aberrant regenerant sprouting innervates sweat glands, producing gustatory sweating as in auriculotemporal syndrome (Frey syndrome), and innervates nociceptors, producing pain.

The role of gustatory flushing in Frey's syndrome and its treatment with botulinum toxin type A.

After parotid surgery, gustatory sweating and flushing occur more frequently, the former reportedly in 15-100% of cases, while no reliable data are available for the latter. Although botulinum toxin (BoNT) is effective in controlling sweating, little is known about its effect on flushing. In 17 patients suffering from Frey's syndrome after parotid surgery, we studied the gustatory flushing phenomenon as compared to gustatory sweating, analyzing their frequency, area, type of stimulus and response to BoNT administration. Cutaneous blood flow (CBF) was monitored by laser Doppler flowmetry (LDF) on affected and unaffected areas of the cheek in basal conditions and after meals, before and then 1 month after starting the BoNT injections. The Minor test was used to identify the sweating area. Flushing was observed in 7 of 17 patients after masticatory activity, spicy meals or citrus fruits. No clinical data correlated with any presence of flushing. Flushing regressed completely after BoNT administration and CBF reached similar values in the affected and unaffected sites. No adverse effects were observed. BoNT administration proved an effective and safe treatment for gustatory sweating and flushing in patients with Frey's syndrome.