ATLANTA – The use of a threading technique, rather than the standard depot injection technique, when using botulinum toxin A to treat perioral and glabellar rhytides provides a more uniform and natural cosmetic result, according to Dr. H. William Higgins II.
Threading involves injecting the muscle along its normal anatomic course to paralyze the related muscle more evenly, he explained at the annual meeting of the American Society for Dermatologic Surgery.
For upper and lower lip treatment, for example, injections are made at a 20- to 30-degree angle, entering the skin at a location just lateral to the targeted rhytid. The toxin is dispensed while withdrawing, thereby threading the injection along the length of the orbicularis oris. This differs from the typical approach, which often involves a depot injection at an angle more perpendicular to the skin, said Dr. Higgins of Brown University in Providence, R.I.
For the glabellar lines, the threading technique involves four symmetrical injection points, with two points targeting each corrugator. Injections at the more medial points are made directly above the inner canthus, with intramuscular injections made perpendicularly to the skin in the traditional depot manner.
At the two lateral injection points, however, the needle is inserted in most cases just medial to the mid-pupillary lines, thereby targeting the "tail" of the corrugators, he explained.
"Similar to our approach at the orbicularis oris, rather than injecting at an angle more perpendicular to the skin, we inject at an angle of roughly 20-30 degrees, entering the skin at a location just medial to the glabellar rhytid we intend to treat. The needle is then directed laterally and slightly superiorly in order to follow the anatomy of the corrugator supercilii, and the injection is threaded along the muscle’s length while withdrawing," he explained.
This approach corrects for the inadequate responses sometimes seen when using the typical method of placing subepidermal blebs to produce localized microparesis of the targeted muscle, and could reduce the need for touch-up injections.
Cosmetic outcomes have been excellent and patient satisfaction high with the use of this technique, he said. In his experience, the technique has dramatically reduced the incidence of adverse effects.
"It has been documented that, even with conservative dosing, neuromodulator treatment of perioral rhytides can affect mouth function by weakening the lip sphincter, but this has not been the case in our patient population when using this technique," he said.
Similarly, when treating glabellar rhytides, the injection of the toxin at a more precise depth – and more evenly along the tail of the corrugators, has resulted in a reduced incidence of brow ptosis as well as more natural smoothing.
"This approach helps prevent the undesirable appearance of a 'forehead freeze,' " he said.
The threading technique also results in fewer needle sticks, which means less pain and bruising for the patients.
The use of a longer 1- or 1.5-inch needle could potentially allow for even fewer injections without compromising the result, Dr. Higgins noted.
"Furthermore, this technique could conceivably be applied on other areas of the face. Crow's feet, for example, could be treated with fewer threading injections rather than with multiple depot injections," he said.
Dr. Higgins reported having no relevant financial disclosures.