Indications

Gustatory sweating can be seen after superficial parotidectomy. These patients notice mild to profuse sweating of the cheek during meals.

Anatomic Considerations

Acetylcholine, the neurotransmitter blocked by botulinum toxin, is released when eating, and it stimulates secretion of saliva by the salivary glands. When the gland has been partially resected, such as in superficial parotidectomy, the acetylcholine is released and diffuses to the skin, where it stimulates the sweat glands. These patients notice sweating of the cheek skin overlying the parotid bed.

The starch-iodine test is useful when first treating these patients because the pattern of sweating may not be predictable. On subsequent treatments, once the injector has developed an idea of the affected sites, further treatments may be performed without repeating the starch-iodine test. It can also be utilized for touch-up treatments in order to identify areas that require re-treatment.

If the starch-iodine test can be performed prior to injection, then povidone iodine (Betadine) is painted over the cheek on the side of the parotidectomy and is left for a few minutes to air dry. The Betadine application should extend over the mandible into the neck, onto the ear, and into the temporal hairline. Corn starch (available from a grocery store) is sprinkled lightly onto the cheek; a large makeup brush works well for this application. The patient may need to suck on a piece of sour candy to stimulate the salivary glands. The areas of sweating will cause the cornstarch to turn black, and a grid is drawn in the area of the sweating. The area is marked with a surgical marker, then the starch and iodine are cleaned prior to injection.