Neuromodulator threading: revisiting an approach to neurotoxin delivery

Neuromodulator toxins are traditionally delivered to facial muscles via a depot technique using a 32g needle. This article revisits the threading technique, which was used more commonly in the 1990s and early 2000s prior to the introduction of the 32g x ½" gamma ray sterilized needle. A description of the threading technique, illustrated by diagrams and patient photos, is presented for the orbicularis oris and corrugator supercilii injection sites. In contrast to the depot technique in which the needle enters the skin at a 90-degree angle, the threading technique enters the skin at a 20- to 30-degree angle. Specifically, for the orbicularis oris, onabotulinum toxin A injections are performed 2 to 5mm beyond the "white roll" of the vermillion border. After the needle punctures the skin, the toxin is injected while withdrawing in a threading manner parallel to the vermillion border. This method is repeated along the entire length of the orbicularis oris muscle. For the corrugator supercilii muscles, the injection technique differs slightly. A depot injection is given at the most medial point of the muscle, targeting the body of the muscle. The tail of the corrugator supercilii is injected using the threading technique as described for the orbicularis oris, in which the needle inserts at a 20- to 30-degree angle. This paper revisits the threading injection technique for neurotoxin treatment of the orbicularis and corrugator supercilii sites.