San Francisco ? Dermatologists require an extensive understanding of the superficial anatomy and key principles of surgical reconstruction when they operate on the head and neck, according to a dermatologist presenting here at the 64th Annual Meeting of the American Academy of Dermatology.
"Nearly every dermatologist does some surgery on the head and neck," says Christopher J. Miller, M.D., an assistant professor of dermatology and a Mohs micrographic surgeon in the department of dermatology at the University of Pennsylvania in Philadelphia.
"The goal is to improve your technique, so that you maximize patient safety and optimize cosmetic and functional outcomes. There are some areas that are potentially more dangerous than other areas, such as the lateral face and the posterior triangle of the neck."
Dr. Miller tells Dermatology Times that dermatologic surgeons must exercise caution when operating in these areas, since motor nerves course more superficially and are at increased risk of being cut.
"Motor nerves are critical structures that we all want to avoid because they can lead to permanent cosmetic and functional problems for the patient," Dr. Miller says.
Dermatologists operating over the temple, mandible and posterior triangle of the neck must have intimate knowledge of the course and function of three motor nerves, specifically the temporal branch of the facial nerve, the marginal mandibular branch of the facial nerve and the spinal accessory nerve.
"Dermatologists can gain confidence operating in those areas by familiarizing themselves with the regional anatomy," Dr. Miller says. "To protect patients from inadvertent nerve damage, dermatologists operating on the head and neck must know how to map the course of these three nerves."
Navigating the nerves
Specifically, dermatologists can use topographic landmarks of the surface anatomy to predict the course of the underlying nerves and should have a solid grasp of the relationship of the nerves to the fascial layers of the head and neck.
Dr. Miller says, "When operating over these high-risk areas of the face, the critical question is not, 'How wide can I cut safely?' Intraoperatively, the critical question becomes, 'How deep can I cut without putting the nerve at risk?' If you operate in an area where you can't answer this question confidently, you'll tend to be overly aggressive or timid."
One of the physical patient characteristics that a surgeon should watch for is the amount of subcutaneous fat with which the patient presents.
"The subcutaneous fat is a safe plane in which to operate," Dr. Miller explains. "When you are faced with an older patient who has temporal wasting or a very thin patient with minimal subcutaneous fat, you might cut through the safety layer with your scalpel before realizing it. You need to anticipate the amount of subcutaneous fat that is present prior to making your incisions."
Cosmetic, functional outcomes
Dermatologists operating on the head and neck must also adhere to key principles of reconstruction to optimize cosmetic and functional outcomes. Avoiding distortion of free margins, such as the eyebrows, eyelids, lips and the rim of the nose is critical, according to Dr. Miller.
"You don't want to disrupt the free margins, and you want to avoid creating tension in the wrong direction," Dr. Miller says.
Whenever possible, dermatologists should place incisions within cosmetic subunit junctions or relaxed skin tension lines. But if such a closure threatens free margin distortion, a dermatologist should consider alternative reconstruction designs.
Dr. Miller cites as a common example how a vertically oriented ellipse on the forehead is frequently preferable if a horizontal closure along the relaxed skin tension lines of the forehead would result in an asymmetric lift of an eyebrow.