Methodologic and physiologic considerations for liposuction of the face and neck

There are many different techniques to achieve the basic goal of liposuction. Techniques used on the face and neck, although very similar in technique to those used on the body, must be differentiated because of the anatomy and physiology of these areas. When performing liposuction on the face and neck, the surgeon must be aware of the thinner skin of the face, the proximity of motor and sensory nerves (especially the mandibular branch of the facial nerve system), the depth of fat requiring aspiration, and the natural effects of aging on facial fat deposits.

The liposuction technique, introduced in the 1970s, uses a rigid cannula and a suction device. The cannula is quickly advanced back and forth through the fat deposits through subcutaneous tunnels. The fat cells are ruptured, drawn into the perforated cannula by the negative pressure created by the suction. If the suction pressure is high enough, the fat cells are lysed and destroyed. This technique consistently produces good results.

The addition of hypotonic infiltration (injection of hypotonic saline with local anesthetic) to the liposuction technique has found wide application in body contouring. It allows liposuction to be performed over a large area under intravenous sedation, and the infiltration of physiological saline solution promotes rupture of cell membranes and facilitates aspiration of large volumes of fat. Hypotonic infiltration involves the injection of a vasoconstrictor solution into the entire bed intended for liposuction. Waiting 15 minutes before the procedure allows the adrenaline to take effect and significantly reduces bleeding. Some surgeons use hypotonic infiltration in facial plastic surgery not only for aspiration but, in smaller volumes, also for tissue dissection. Hypotonic infiltration can be harmful in small areas such as the face and neck because of the distortion it causes. This can make symmetrical fat removal difficult. For the body undergoing large volume surgeries, the advantages of hypotonic infiltration are to facilitate fat removal and dissipate the heat generated, especially when using ultrasound energy. The main disadvantage of using a hypotonic solution is the problem of fluid migration into the third space.

The need for liposuction of the body and the ongoing search for ways to improve results with minimal complications have led to the development of another, relatively new technique. It involves the application of ultrasound to the fat tissue either internally or externally, which causes the fat cells to break up and facilitate aspiration. Although ultrasound has been used for tissue aspiration since the late 1960s, it has only recently been adapted for liposuction purposes. Many of the most common areas of fat deposition on the body are highly fibrous, and advancing the liposuction cannula with an internal or external ultrasound device not only requires less effort, but is significantly more effective at aspirating fat. Some studies of ultrasound-assisted liposuction of the body also report less swelling and signs of tissue contusion after surgery.

Physiologically, ultrasound energy is converted into mechanical vibrations that create a "micromechanical effect - the cavitation effect (cycles of expansion and compression of adipose tissue elements), which leads to an explosion, destruction of cells, i.e., liquefaction of fat and temperature effects on fat cells." Numerous studies have identified problems associated with the subcutaneous use of ultrasound energy, such as the formation of excess heat at the site of the skin incision, as well as possible complications caused by this in remote areas of the subcutaneous space. In modern literature, the use of external ultrasound devices for liposuction is less often discussed. At the same time, it is noted that such devices have similar advantages, simplifying surgical intervention and shortening the postoperative period, but still require serious research. Recent publications devoted to this technique do not contain information on the methods of using external devices, but discuss issues of their safety. Plastic surgeons should exercise caution when considering the use of internal ultrasound-assisted liposuction on the face and neck due to the proximity of neural structures, both sensory and motor, and the thinner dermis and epidermis. Animal studies have evaluated the effects of ultrasound energy on neural tissue and have shown that low-amplitude ultrasound energy applied directly to a nerve causes visible damage. However, no functional impairment of nerve conduction occurs unless the ultrasound amplitude is increased. Most literature on ultrasound-assisted liposuction advises following the manufacturers' recommendations for power settings and considers these settings to be reasonably safe. A Medline search found no controlled studies demonstrating the safety or additional benefit of ultrasound-assisted liposuction on the face and neck over standard microcannula mechanical liposuction.

The latest advance in liposuction is the liposhaver, recommended by Gross and Becker for direct lipectomy or for closed lipectomy of the face and neck. A similar device has made significant advances in endoscopic sinus surgery; some experts also recommend it for use in rhinoplasty. The liposhaver is a protected, motorized blade that cuts away fat either under direct vision or in the subcutaneous space. The procedure is reported to be less invasive than the standard technique because the fat is cut away rather than torn away. Interestingly, however, Schudde's original liposuction used a sharp curette-type instrument that cut away rather than tore away the fat. The technique has fallen into disfavor after reports of tissue loss and even limb loss due to vascular injury.

Fat shaving differs from traditional techniques, hypotonic infiltration techniques and ultrasound liposuction in that it does not require high vacuum during suction, actively excising rather than tearing off fat deposits. This method, although based on a principle similar to sharp curettage, differs from it in that the network of tunnels created by the liposhaver cannula is very similar to that of traditional methods. Its creation preserves vascular and nerve structures. Comparative multicenter studies have demonstrated the successful use of this device and have suggested it as a simple alternative to traditional liposuction, possibly with less trauma and more complete lipolysis, in experienced hands. When using this device, one must be sure that only subcutaneous fat is excised and suctioned, without contact with the dermis. In a closed procedure, uniform fat removal and preservation of vessels and nerves is ensured by contouring the cannula and the surgeon pulling the skin upward with the non-dominant hand. Compared to traditional liposuction, the use of liposhaver may be associated with a slight increase in the incidence of seromas and hematomas.

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