Recent Updates in Botulinum Toxin
Gary D. Monheit, M.D.
Associate Professor
Department of Dermatology
University of Alabama at Birmingham
Birmingham, Alabama

The upper face is a visual portal for human communication. In our society where first impressions are important in forming relationships, when one is in contact with a new individual, our first assessment are facial expressions and most particularly around the eyes. Upon greeting, one looks directly into another’s eyes for an initial meeting that will relate to an individual an early message of the encounter to be expected. The periorbital structures and skin gives non-verbal messages as to one’s expectations of the encounter. For example, an open-eyed, smooth glabella and raised brow most commonly indicates receptivity, friendship, friendliness, while a lower brow and scowl can indicate lack of interest, anger, hostility, haughtiness or aloofness. The hanging medial brow, wrinkles and scowl can also indicate disinterest and fatigue. In our rough society with brief meetings, we depend heavily upon visual contact and many times, miscued messages are given by overused and aging muscle structures.

The glabella, forehead and brow control the periorbital units of expression in the upper face. Due to repeated contracture, the photoaging brow ptosis, and concentration lines, a shown or dropped brow may become a permanent fixture giving miscues.

Lucrative brow muscles will cause the skin to crease and repeated movement of specific muscles over time creates visible lines and wrinkles in areas of muscle movement. In particular, the corrugator, the procerus and orbicularis muscles have a major effect for frowning and brow placement.

The orbicularis oculi orbitalis is the “sphincter of the eye” responsible for squinting and blinking. The superior fibers along the brow and above are responsible for brow movement involved in this complex voluntary eyelid closure. The corrugator muscle extends from the base of the nose to the medial brow and forehead area; its function to draw the brow medial and downward and is responsible for the vertical lines in the glabellar area. The procerus muscle, which begins at the nasal base and extends upward to the forehead, wrinkles the nose and pulls the forehead downward. The procerus supercilli ocularis is a smaller muscle in the medial canthus and side of the nose to the infrabrow area medially. It compresses the medial brow, hooding the orbital area. It also is responsible for the wrinkle and frown lines through the glabella. The frontalis muscle which laterally extend upward to the galea from the brow on both sides, have an indirect influence on the glabella but also control brow position and create horizontal wrinkle lines across the brow itself.

In treating the glabella, the muscle sites for Botox treatment are the orbicularis, the corrugator and the procerus. Each should be entered superficially by direct skin injection near the sites of origin. It is best to inject the orbicularis 1 cm. above the supraorbital notch in the suprabrow area. The corrugator is located above the medial-most point of the brow approximately 1 cm. above. The procerus is located midline between the brows and extending down on it. Each muscle may respond to a different dosage of botulinum toxin based on muscle size and strength of movement. These are categorized into mild, moderate and severe frowning forms. Proper doses of each of these have been worked out in dose ranging studies. A 2002 Dose Ranging Study performed by Carruthers, et.al. demonstrated the effectiveness of botulinum toxin A in doses of 10 units to 40 units. The ideal dose range was between 25-40 with an onset within the first week, a peak value at 2 weeks, and longevity between 3-4 months. The mild glabellar wrinkle profile will need approximately 25 units botulinum toxin divided within the 3 muscle groups with 5 injection sites. This can be divided equally but can also be nitrated as to muscle size. Many times, the procerus will need the larger dosage because of its mass and action. This should be evaluated individually on each patient. The moderate glabellar frown has greater muscle bulge and more medial deviation from both the corrugator and orbicularis. A secondary orbicularis injection can be given near the primary to hit bulging fibers. Similarly, a heavier dose to the corrugator can be given, upping the dose to 30 units. The severe form, which has multiple bulges in the glabella, corrugator and orbicularis, may not fully respond due to concomitant photoaging skin and prominent sebaceous skin. Thirty-five to 40 units should be used in controlling the over activity of these muscle groups.

Thus, individual factors affect the Botox dosage in the upper face. These include:
1. Muscle size and location – the clinical should watch carefully the movement of frown in each of their patients pre-treatment. This will tell him which muscle strength is being used for each of the components of frown. These include vertical movement, oblique movement and horizontal brow movement with brow depression. Thus, the dosage can be judged by the action and by the muscle size. In addition, males usually require more of a dosage than females because of muscle size and muscle contracture. The older patient requires a larger dosage than the younger patients and one must also take into account skin quality.