Botox Mechanism of Action
To understand the details of exactly how Botox works requires a small amount of basic anatomy and physiology knowledge. Muscles that are used for facial expression (examples of skeletal muscles) contract when there is an innervation by a nerve, meaning that the nerve sends a signal to the muscle telling it to contract. This occurs at a point called the neuromuscular junction, the attachment of the nerve to the muscle. The nerve releases a neurotransmitter called acetylcholine into the space between the nerve and muscle called the synaptic cleft. The acetylcholine then binds to the membrane of the muscle. This binding triggers the muscle to contract. Botox prevents release of acetylcholine from the end of the nerve into the synaptic cleft. This prevents the signal from being passed to the muscle and it prevents the muscle from contracting, thereby relaxing the muscle.
Common Areas of Treatment with Botox
The most common areas of treatment with Botox are in the upper face. These include the horizontal lines seen on the upper forehead when one raises the brows, the vertical lines seen between the brows when one frowns, and the crow's feet seen around the eyes when one smiles.
Patient Assessment for Botox Treatments
A full assessment for a Botox treatment requires a formal exam in the office where the skin can be viewed in multiple angles and with and without facial expressions. In our office, we take standardized photographs to monitor our patients’ progress. The photographs are taken with a clean face, consistent lighting, consistent background, with jewelry and makeup removed, and with clothing covered. These are taken in five different angles, one straight on, two profile photographs, and two oblique photographs. These five photographs are taken of patients with a neutral expression. Additionally, multiple sets of photographs are taken depending on the area to be treated. For example, if the frown lines are being treated five more photographs are taken in the same positions, but with the patient frowning. This allows for monitoring of the patient’s progress. It helps a person remember what someone looked like prior to a treatment and to observe the improvement from a treatment. It can also be used if correction is necessary as it will show the areas that require additional units of Botox.