“SMAS” stands for sub muscular aponeurotic system. The fancy name is just a way to describe the layer found immediately beneath facial skin and fat. Closer to the ear this layer is a thin fibrous sheath, further in toward the nose it transitions to the muscles that move your face, mouth, nose, eyes, etc. and are essentially responsible for your facial expressions. Into the neck, the layer becomes a thin coat of muscle that can tent neck skin. Using this layer for suspension could potentially provide a more substantial lift, both in terms of result and longevity. The reasons some surgeons shy away from this type of lift is that it requires dissection under this layer. The problem with this is that the nerve that supplies the facial musculature, the facial nerve, with its many branches is at a considerably higher chance for injury. This can happen, albeit temporarily, even if the nerve is not cut, but only stretched or tugged. The result is paralysis of some of the muscles of facial expression, which could range from a purely cosmetic, temporary deficit, to more serious problems like oral incontinence, or the inability to close the eyes. A more limited dissection exposing only enough edge to sew without risking a deeper dissection can achieve similar results to a full SMAS lift. In conclusion, the full submuscular aponeurotic system (SMAS) lift should be reserved lift for smokers, while a variation of this deeper lift involving more limited dissection should be reserved for patients without and risk of devascularizing a thin muscular flap.
Jacob Gerzenshtein, MD, FACS,
A Board Certified Plastic Surgeon
