Russell W. H. Kridel and Peyman Soliemanzadeh
The SMAS suspension facelift is a highly effective operation. With appropriate case selection and planning, both patient and surgeon can expect a technically sound surgery to produce very satisfactory results. However, cosmetic surgeons and their patients are very demanding groups. Therefore, innovative surgeons have continued to attempt to improve the SMAS plication facelift by doing deep plane/ sub- SMAS facelifts (2,4-6).
The primary areas of patient and surgeon dissatisfaction with generally accepted facelift techniques have been the nasolabial fold, the inconsistency in achieving long term results, and the occurrence of perioperative complications. The family of deep-dissection rhytidectomies are aimed primarily at improving the nasolabial fold to a greater extent than is possible using widely accepted SMAS suspension techniques. Of the various techniques that have been reported (4-6), the deep plane or, more recently, composite rhytidectomy of Hamra has attracted the most interest. The key distinctions of deep plane rhytidectomy relative to the SMAS plication procedure described in detail already will be discussed and the theoretical advantages and disadvantages noted.
The deep plane rhytidectomy is in fact carried out at three different planes, depending on the area of the face and neck being dissected (2,5). The dissection of the neck (inferior to the jawline) is preplatysmal and is connected subcutaneously with the contralateral dissection. A platysmaplasty with submental lipectomy is performed. In this area, the operation is similar to that already described.
Dissection of the lower face is carried out in a subSMAS plane, in contradistinction to the subcutaneous plane described previously but similar to most SMAS imbrication techniques. One significant point of difference with established techniques is that the sub-SMAS dissection is carried out anterior to the parotid, where the buccal and marginal branches of the facial nerve may be encountered. A second distinction is that the subcutaneous plane is developed only minimally so that the bulk of the elevated flap contains SMAS along with the skin and subcutaneous fat.
Finally, dissection in the midface is carried out over the malar eminences into the central face. This dissection is much more extensive than in other SMAS suspension techniques. The subcutaneous plane is maintained initially for 2 to 3 cm anterior to the tragus, presumably to avoid injury to the frontal branch of the facial nerve. A thick flap then is developed anteriorly, with dissection immediately superficial to the orbicularis and zygomaticus muscles. No other motor-nerve branches should be encountered in this plane, as they enter the muscles from their deep surface (7). The two facial dissection planes are bluntly connected to create a large, thick flap. Excess skin is excised after the flap is resuspended at the SMAS level under tension (5).
The major theoretical advantage of this and similar procedures is that the malar fat and skin can be elevated and resuspended, and the nasolabial fold can be undermined, allowing for its effacement. Additionally, the facelift flap is maintained as a “myocutaneous” flap (5) consisting of platysma, SMAS, and the superficial tissues, purportedly allowing increased viability and closure under greater tension than is possible with standard procedures. Further possible advantages include a decrease in hematomas because of a more avascular dissection plane and a decrease in skin slough due to the theoretically increased viability. The major theoretical disadvantage of the deep plane dissections is the increased exposure to the facial nerve in the lower face with the concomitant possibility of injury. Moreover, patients with deep rhytids or acne scarring may also find improved results from SMAS suspension with an extended skin flap which may stretch the skin itself more directly. Because of the widespread interest in this procedure, it is important to evaluate these potential advantages and disadvantages critically.
If ptotic subcutaneous fat in the malar region is a significant contributor to a prominent nasolabial fold, one could predict improvement in the nasolabial fold with infra-zygomatic undermining, as described by Hamra and others (4,5,8). This fat is not to be confused with the buccal fat pad (of Bichat), which gives the cheek most of its fullness but lies at a deeper plane, in intimate association with the facial nerve. On the other hand, anatomic studies of the nasolabial fold demonstrate that it usually consists of little more than skin excess (1,9). In this case, it would seem that only skin resection, and not deep tissue repositioning, is capable of attaining significant improvement in this area. Because the current SMAS suspension procedures usually do not involve undermining medial to the malar eminence, the deep-plane procedures as described should obtain some advantage in malar skin redraping and resection.
As for theoretically improved viability with the deeper plane of dissection, this depends on the vascular anatomy of the flap. For the deep-plane facelift flap to be a true fasciocutaneous flap of the SMAS based on the facial artery, as asserted, there must be multiple small perforators from the SMAS to the overlying skin, with only the distal few centimeters immediately anterior to the pinna left random, as this area is undermined subcutaneously. At least one recent study of the vascular anatomy of the face calls this interpretation into question (8). The authors observe vast numbers of small perforators from the facial system in the medial face but only sparse perforators in the transverse facial and posterior auricular distributions. Abundant small perforators from the facial system via the SMAS fascia are not described. Indeed subcutaneous facelift dissection results in little bleeding above the jawline and in front of the ear, except for the transsection of the transverse facial perforators, which are divided in the deep-plane dissection as well. These observations suggest the possibility that both the classic and deep-plane facelift flaps are similarly viable large random flaps. As skin slough is a relatively rare complication, extensive experience with deep-plane lifting will be required before reliable empiric judgments can be made.
A much lower incidence of hematoma (about 1%) relative to the classic procedure (8%) is reported for the deep plane procedure (5), providing some indirect evidence that the dissection is more avascular. Given that dissection in the neck for both procedures is in a similar plane, only the facial hematoma incidence is likely to be lower. It may be, however, that neck hematomas can be reduced as well by remaining strictly in the preplatysmal plane as recommended by Hamra (5) rather than hugging the subcutaneous tissues as described above, regardless of whether a deep plane or a more standard SMAS suspension procedure is performed.
In most SMAS suspension procedures practiced today, the facial nerve is well protected. As long as SMAS undermining is not carried forward of the anterior margin of the parotid, the nerve is shielded by the gland parenchyma. Anterior to the gland, the nerve courses within the buccal fat pad deep to the SMAS and therefore is exposed to injury by SMAS undermining in this area. In a similar vein, dissection that remains meticulously superficial to the zygomaticus will protect its innervation; however, the branches to the lower orbicularis are more superficial (the orbicularis lies in a plane superficial to the zygomaticus) and may be vulnerable to injury by dissection over the malar eminence if care is not exercised to remain strictly superficial to the orbicularis as well (7). Both areas are manipulated by the deep plane lifting techniques, which therefore carry theoretically greater risks of nerve injury. A working estimate of the incidence of temporary weakness in deep-plane facelift can be obtained by combining cases from several recent reports (5,10, 11). These authors report a total of 23 cases of temporary paralysis in 638 deep-plane rhytidectomies, for an estimated incidence of 3.6%. By contrast, a classic review of facial nerve injury in more standard rhytidectomy revealed 50 cases of paralysis in 6,500 rhytidectomies, for an incidence of 0.8%. Seven of these cases were permanent (3). Although no cases of permanent paralysis have yet been reported for deep plane rhytidectomy, it would seem reasonable that the incidence would be correspondingly higher.
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