-------------------------------------------------------------------------------- TITLE: TISSUE EXPANDERS IN HEAD AND NECK SURGERY SOURCE: Dept. of Otolaryngology, UTMB, Grand Rounds DATE: April 27, 1994 RESIDENT PHYSICIAN: Denise V. Guendert, M.D. FACULTY: Karen Calhoun, M.D. DATABASE ADMINISTRATOR: Melinda McCracken, M.S. -------------------------------------------------------------------------------- "This material was prepared by resident physicians in partial fulfillment of educational requirements established for the Postgraduate Training Program of the UTMB Department of Otolaryngology/Head and Neck Surgery and was not intended for clinical use in its present form. It was prepared for the purpose of stimulating group discussion in a conference setting. No warranties, either express or implied, are made with respect to its accuracy, completeness, or timeliness. The material does not necessarily reflect the current or past opinions of members of the UTMB faculty and should not be used for purposes of diagnosis or treatment without consulting appropriate literature sources and informed professional opinion." I. History of Tissue Expansion -Used cosmetically by women of the Territory of Chad in Africa for lip stretching and by the Paduang women of Burma for neck elongation. -Neumann, in 1956, was the first to apply tissue expansion clinically. He inflated a rubber balloon with air subcutaneously for auricular reconstruction and presented it to the American Society of Plastic and Reconstructive Surgeons 10/56. -Little else in literature until Radovan's work in 1976 which was met with skepticism. -In 1979, Radovan presented his clinical experience and his evaluation of histological changes associated with expansion at the meeting of the American Society of Plastic and Reconstructive Surgeons in Toronto. By demonstrating the efficacy and safety of expansion, Radovan gave credence to the technique, and won first place. -Radovan's work led the way for others, and in 1981 the first national symposium on tissue expansion took place in Ann Arbor. II. Expander Variables A.Shape and Size -Three most often-used shapes are round, rectangular and crescent. -Most important to match shape of expander with shape of region to be expanded, not shape of defect -Most effective surface area gain is with the use of a rectangular expander-38% of the calculated surface increase of the expander is actually gained in tissue area in vivo. -Round expanders gain 25% of calculated surface increase. -Crescent expanders gain 32% of calculated surface increase. -Expander base should be roughly 2.5 times as large as the defect to be closed when using rectangular or crescentic expanders. For round expanders, this correction factor is found to be true for the diameter of the expander rather than the area of the base. -When defect is irregular many recommend custom fitted expanders, this allows more surface area gain. B. Volume -Used to recommend filling to volume as stated by manufacturer. -Hallock overinflated implants until rupture or leakage occurred and found that one could overinflate with twice the recommended volume safely. -Nordstrom described leakage of expanders and domes up to 50% of the injected volume C. Number of expanders -Larger custom fitted implants are more efficient than several small expanders. -In some instances it is not possible to find enough acceptable matching tissue beside the defect to cover one large expander and several small expanders should be placed instead. D. Types of Expanders 1. Self-inflating expander that is osmotically powered and expands slowly at a constant rate 2. Expander with distant filling valve -most common in use today -sizes range from 1cc to 1000cc -shapes include round, crescent, U-shaped, rectangular, hemispheric -the silicone expander is connected to a silicone tube with a self-sealing inflation reservoir that is inserted subQ away from the expander -Filling is safe because port is easy to localize -additional surgical tunnel needs to be created for reservoir -more possible sites for disconnection and leakage present -second place for skin breakdown (over filling port) 3. Expander with Incorporated filling valve -Injection dome contains a self-sealing membrane, usually located at the highest point of the expander . -a silicone palpation ring surrounds the injection site and allows for localization. -Steel plate at base of dome prevents puncture by injection needle -Some companies have magnetic location system -available in hemispheric, rectangular, crescent, and teardrop -sizes range from 50cc to 1000cc -main advantage is no need for separate tunnel and therefore reduced tissue trauma and less time consuming -disadvantages include: no mini expanders are available because of the volume of the injection port, the injection port is stiff and increases the risk of skin erosion especially if placed over bone 4. Directional or Differential Expander -obtains more expansion at one end than the other by using different physiomechanical properties within the envelope. -mostly used in breast reconstruction to obtain a more normal looking breast. -More recently used for treatment of male pattern baldness III. Types of Expansion A. Prolonged Tissue Expansion (PTE) 1. advantages -supplies adequate area of tissue from adjacent areas with excellent color match, texture, sensation, and retained adnexal structures. -Actual increase in tissue volume achieved -Allows donor site closure without tension 2. disadvantages -requires at least two separate procedures -takes several weeks to gain adequate tissue and is therefore limited, for the most part, to elective reconstructive problems. -There is usually a significant cosmetic deformity associated with expansion -inherent risks of infection and exposure of the expander B. Rapid Intraoperative Tissue Expansion 1. advantages -tissue for reconstruction is obtained in a matter of minutes via stretching and recruitment by expansion. -will gain an additional 1-3 cm of tissue depending on site, patient, local tissue factors -because of the thicker and less elastic properties of skin from the scalp, nasal tip, and back, the average tissue gain is less in these areas -allows closure of small defects without tension -single procedure and no cosmetic deformity outside OR -a recent study has shown that when combined with prolonged tissue expansion (performed in OR after placement of expander), patients have less pain with subsequent expansion and expansion time decreased -can be used to stretch unyielding tissue that restricts placement of alloplastic implants in aesthetic procedures. It is theorized that the incidence of implant exposure and migration is lessened 2. disadvantages -no true tissue gain -no great advantage over undermining as tissue obtained mostly by recruitment -skin may appear bruised but this usually resolves in 3 weeks -edge ischemia is more common than with prolonged expansion, as is retraction of the wound edges as changes of rapid expansion are reversible. IV. Physiology of Expansion A. Rapid Intraoperative Expansion -the ability of skin to stretch is based on its viscoelastic properties which results from two properties; mechanical creep and stress relaxation -rapid skin expansion is accomplished by cyclic loading of temporary expanders -expansion secondary to property of mechanical creep as named by Gibson -Mechanical creep occurs when load applied to skin is kept constant and consists of 1)dehydration of tissue by displacement of fluids and mucopolysaccharide ground substances, 2) paralleled realignment of the random positions of collagen fibers, 3) microfragmentation of the elastic fibers, though this has not been demonstrated in recent histologic studies, 4) migration of tissue into the field by the stretching force. -stress relaxation refers to the finding that with time , the load required to maintain the skin in a stretched position decreases -with load-cycling, maximum expansion is not obtained with the first cycle. with the first expansion, the amount of stretch is dependent on the displacement of fluid and ground substance. After serial expansion the collagen and elastic fibers realign B. Prolonged Tissue Expansion -Tissue expanded by mechanical creep as well as element of biological creep -Biological creep refers to a proliferation of epithelial cells and connective tissue secondary to increased mitotic activity. Also see expansion of subdermal vascular network and increased fibroblastic synthesis of collagen precursors 1. Epidermis -On histologic studies see an increase in thickness of epidermis -thickening occurs in the stratum spinosum. -rete pegs become flattened -shrinking of intercellular spaces is seen as well as increased mitosis which returns to normal 4 weeks after expansion 2. Dermis -See thinning of dermis ~20% -thinning is significantly dependent on rate of expansion -The more acute the expansion, the more the normal angle of cross-linkage of collagen fibers diminishes (normal 70 degrees) -Increase in fibroblast activity seen 3. Dermal appendages -Distance between hair follicles becomes greater and no new follicles seen -Sebaceous and sweat glands are insensitive to expansion, some blockage of excretory ducts may be seen 4. Subcutaneous Fat -The subcutaneous layer of fat is intolerant to stretching with its thickness decreasing by 50%. -With faster expansion, necrosis of fat can be seen 5. Muscle Layer -Muscle layer in pig which is similar to the platysmal layer in humans tends to atrophy with maximum expansion at times resulting in hyalinization and calcification 6. Capsule -A capsule develops around expanders as with most foreign body reactions. -Maximum thickness at 8-10 weeks. -Within 7 days there is a 2 layer capsule consisting of an inner layer of macrophages and an outer layer of fibroblasts and some lymphocytes -Over time the outer layer becomes more rich in collagen fibers -The bordering layer around the capsule becomes richly vascularized. It is because of this very vascular capsule that Cherry et al (1983) determined that expanded skin flaps had 117% greater survival length than acutely raised, random skin flaps. 7. Vasculature -Studies are contrary on whether there is an increase in vascularization seen with expansion, though most studies state there is. -as stated above, there is definitely increased vasculature secondary to the capsule. -Vessels will elongate with expansion without reduction in vessel wall diameter. Elongation has been documented ranging from 30% to 140% 8. Neural tissue -Neural tissue is very tolerant to expansion, there may be a slight condensation of the perineurium. No evidence of reactive sprouting noted V. Patient Selection -Patient must be willing to subject him/herself to protracted treatment course with potentially embarrassing temporary physical deformity -avoid in patients with major psychiatric disorders -avoid in non-compliant patient -avoid in patients who are smokers VI. Technique of Expansion -Donor site selected where tissues are most like those to be replaced, and in close proximity to defect -Incision for placement should be in site well hidden and/or incorporated into incisions planned for reconstruction, and if possible, perpendicular to long axis of expander -placement is usually beneath the subQ fat in the face and neck though can be under the platysma in the neck -In the scalp, placement is underneath the galea -dissect large enough pocket so that expander fits without any folding -place reservoir about 4-6 cm away from expander in a separate pocket -after wounds are closed instill enough saline into expander such that dead space is obliterated -usually drain wound -begin expansion with saline 2 weeks post-op by introducing a 23 gauge or smaller needle into reservoir -instill saline until overlying skin is tense or patient c/o discomfort -should blanch with pressure on skin over expander but capillary refill should return to normal after adequate pressure withdrawn -24 hours of perioperative antibiotics recommended by most -usually inject every seven days, but this can vary -on occasion a very rigid capsule may form around a scalp expander requiring a capsulotomy during expansion in order to proceed -Azzolini recommends removal of capsule at time of expander removal to thin flap and therefore further lengthen flap. -Good idea to leave superficial layer of capsule especially in children to prevent flap from becoming to thin secondary to reduction of dermis and subQ fat. Also potential for damage to hair follicles with complete removal of capsule -In rapid intraoperative expansion, expand with progressively increasing volumes of saline in repetitive cycles of 3 minutes of expansion and 3 minutes of relaxation. Usually requires 3-4 cycles -cyclic hyperinflation and deflation with each filling session decreases the time of expansion by allowing 50% increase in inflation volume, but may lead to a greater incidence of flap necrosis and discomfort VII. Applications of Tissue Expansion in the Head and Neck A. Scalp 1. Alopecia a. traumatic -usually secondary to burns -custom shaped expanders are usually preferred. Many recommend the use of several expanders -allows coverage with hair bearing tissue as opposed to skin grafts -very large flaps based on axial vessels can be performed -expander should be placed under galea -Often partial excision performed and is followed by further expansion and excision but this serial expansion is very well tolerated in the scalp. -Though no new hair follicles develop, hair density is usually sufficient to be unnoticeable -important to expand greatest area of hair bearing scalp as possible to distribute thinning of hair as much as possible -Good to excellent results with up to 50% loss -there are some who believe expansion of scalp in children may result in cranial deformity, Iconomou has not found this to be the case in 19 children over 3 years 2. Male pattern baldness a. -Possible to achieve excellent results in patients with frontal balding with flaps alone. Tissue expansion is not needed for single flap in patient with flexible scalp. Delay of Juri flaps whether expanded or not recommended by many. -In patients with extensive balding including the crown area it is not possible to cover with flaps alone -Punch grafting usually will not achieve the density of hair that is desired especially in the frontal region -scalp excisions result in least density of hair on top of scalp where greater density is desirable -Above problems can be averted with the procedure described by Nordstrom, which is valuable for patients with Norwood types IVa to Va and moderate type VI. i. Nordstrom places custom horseshoe expanders in hair bearing region of scalp through a sagittal midline incision ii.a temporoparietooccipital flap is transposed. this is based on parietal branch of the superficial temporal artery. Maximal width of flap is 5cm, pedicle is 2 cm. Tail end of flap includes occipital artery. This is not a delayed flap, many do recommend as delayed flap since the distal one third of this flap is likely to have a random pattern blood supply especially if taken to the contralateral occipital protuberance iii.lax scalp is then used to advance hair-bearing scalp from the contralateral side. iv.transposed flap is used to reconstruct the frontal hairline v. dogear can be excised ~4 weeks later vi.At time of transposition, another expander is placed under occipital scalp. Wait 3 weeks for expansion vii.expanded occipital scalp is used to cover top of scalp. One expansion will usually allow excision of 5 by 10 cm of scalp. Can repeat as many as three times ix.lasts a minimum of 8 months, but unlike punch grafting hair does not fall out x. no sagittal midline scar, good frontal hairline which is stable with time b. Scalp Extension -avoids deformity associated with expansion -allows hairbearing skin to be stretched secondary to constant tension -<1mm thick rectangular or T-shaped silastic sheet with a row of titanium hooks on either side is placed below galea -hooks are first inserted into galea on one side and the extender is stretched and hooked to other side -extenders are left in place 30-40 days -allows removal of wider portion of scalp than undermining, prevents widening of midline scar, and places greater hair density on vertex -can do repeat extensions B. Auricular reconstruction -Tissue expansion is often required as there is not a lot of non-hairbearing skin in this region. -one of the goals of using expansion for microtia is to achieve enough skin to create the auriculocephalic sulcus in the same procedure as placement of cartilage -Use crescent or custom shaped expander -for microtia use 65cc to 100 cc expander -place incision in hairbearing scalp -ablate dead space it initial surgery -inflation begins 2 weeks after placement and injections are initially biweekly than weekly -average inflation period is 8 weeks -once adequate soft tissue available, cartilage framework can be placed and reconstruction performed -capsule needs to be excised to allow for adequate thinning of skin and definition of framework -third stage usually necessary for creation of conchal bowl and tragus other minor revisions can be performed as well -potential complication is that of necrosis of skin over mastoid as this tends to be fairly thin and is over pressure point, extrusion can also be a problem as can infection C. Nasal Reconstruction -Pre-expanded forehead flaps facilitates total or near total nasal reconstruction, including formation of vestibular lining and columella, with closure of forehead defect -prosthesis placed through incision behind hairline in submuscular plane. pocket should be larger than expander base by 1 cm in vertical and horizontal planes -use 100 to 250cc rectangular prosthesis depending on whether defect subtotal or total. Again, inflate to ablate deadspace at initial surgery -160cc expander will cover forehead completely making expansion slightly less conspicuous -inflate weekly over 6 to 8 weeks. Flap for total reconstruction requires 8 cm in vertical dimension and 7 cm in greatest horizontal dimension. Usually paramedian flap needed to obtain this length -expansion additionally thins the tissue allowing for better contouring to create ala, though thinning of distal flap important for pliability in this area. -Capsulotomies often needed for adequate lengthening for insetting -some use intraoperative miniexpanders for flap reconstruction of lower third nasal defects. Many would argue tissue gain not greater than with extensive undermining -the expanded forehead flap can also be used for nonnasal, midfacial defects D. Lower Face and Neck Defects -Expansion of neck skin good for resurfacing defects of lower face -place expander beneath platysma in most cases -deep anchoring stitches are required when flap advanced to prevent retraction -best to avoid in radiated skin -it is recommended that these not be placed in midline or over aerodigestive tract structures, or great vessels, though there are no reports of vessel compromise in such cases -when the defect involves advancement over mandible, it is best to use caudal advancement of cheek skin in addition to cephalad advancement of neck skin, especially in children, as they are more prone to scar widening and hypertrophy -for total resurfacing of neck, the expanded trapezius fasciocutaneous flap is excellent and can be reexpanded to better resurface lower face E. Facial Resurfacing -good results with expanded full thickness skin grafts have been demonstrated -allows one to close donor site (usually upper chest, arm) primarily as opposed to with STSG -best results when facial aesthetic subunits are covered separately F. Musculocutaneous Flaps -Trapezius, pectoralis, and latissimus all tolerate expansion well -place expander beneath muscle and expand for 6-8 weeks prior to flap elevation and transfer -when this method used with reconstruction of defects secondary to tumors, often requires that tumor be excised and initially covered by less cosmetic means (can not wait to excise malignancy during expansion) G. Micrognathia -adequate projection of micrognathic mandible with osteotomies is limited by the tension of the overlying soft tissues -subperiosteal expansion creates a pocket for advanced bony structures -there is adequate blood supply to bone from capsule VIII. Complications A. Major Complications -rate of 3-10% -require implant removal or additional procedures -rate reduced with appropriate patient selection and surgical experience 1. Implant Infection -skin over expander often becomes erythematous as expansion proceeds when no infection is present. This can be differentiated by aspirating subQ fluid to assess for pus -if immediate infection, remove implant and treat with IV Abxs -If later in the course of expansion, treat with IV Abxs, partially deflate expander and observe closely. If no improvement remove expander 2. Implant or Valve Exposure -may be secondary to infection, erosion of flap due to folds in expander, overly aggressive expansion, placement of valve over bony prominence -manifest as thinning of overlying skin often with visible implant fold below -often happens ear;y in course of expansion -can attempt salvage by either holding off on further inflation, deflating or inflating in attempt to remove implant folds -with valve exposure, can attempt to use valve as external device, though with continued expansion, implant is at greater risk of exposure 3. Implant Failure -it is surgeons responsibility that implant is intact and functional before placement -a small quantity of methylene blue can be placed into the implant through the valve to assess for leaks prior to placement -One can assume that valves and implants will leak slightly -unless the implant is unable to retain any significant volume, expansion should proceed 4. Flap Ischemia -usually secondary to overfilling expander, ie filling to or past point at which capillary perfusion ceases -pain and blanching are indicators that overfilling has occurred -a study comparing laser doppler flowmetry and transcutaneous oxygen monitoring revealed that pain and capillary refill should be sufficient for monitoring except in anesthetic regions where laser doppler flowmetry was more sensitive -more common in smokers, patients S/P radiation, and those with vascular disease -if flap appears to be compromised, the implant should be partially deflated -expand beneath muscle in radiated areas 5. Hematoma -if expanding or immediately post-op, return to OR and explore -hemostasis at time of initial procedure is key to prevention 6. Seroma -aspirate collection and apply light compressive dressing -do not inflate expander when compression dressing in place IX. Future of Tissue Expansion A. Continuous Expansion -success has been reported with this method of expansion where the expander is connected to an IVAC machine and expanded continuously for 4-5 days. Inflation is shut off when a certain pressure is reached. Allows shorter expansion time B. Pharmacologic Agents -topical application and incorporation into expander membrane have both been suggested -these are agents that enhance expansion by increasing rate of angiogenesis and tissue mitosis -agents include; Dimethylsulfoxide (DMSO), D- penicillamine, betaaminopropiometrile C. Elongation of Nerves and Vessels -proven in the laboratory, clinical applications in progress D. Expansion of Free Flaps -for improved closure of donor site -greater soft-tissue for reconstruction --------------------------------------------------------------------------- BIBLIOGRAPHY Apesos, J. and Perofsky, H.J.: The Expanded Forehead Flap for Nasal Reconstruction, Annals of Plastic Surgery, Vol. 30, May 1993, pgs. 411-416 Azzolini, A., etal: Skin Expansion in Head and Neck Reconstructive Surgery, Plastic and Reconstructive Surgery, Vol. 90, Nov. 1992, pgs. 799-807 Denny, A.D.: Expanded Midline Forehead Flap for Coverage of Nonnasal Facial Defects, Annals of Plastic Surgery, Vol. 29, Dec. 1992, pgs. 576-578 Edmond, J.A., Padilla, J.F.: "Off-the-Shelf" Techniques for Continuous Tissue Expansion, Annals of Plastic Surgery, Vol. 30, June 1993, pgs 552-555 Frechet, P.: Scalp Extension, Journal of Dermatologic Surgery and Oncology, Vol 19, July 1993, pgs 616-622 Fukuta, K., etal: Efficacy of Cycled Hyperinflation for Rapid Tissue Expansion, Plastic and Reconstructive Surgery, Vol. 91, April 1993, pgs. 846-852 Hallock, G. G., etal: Increased Sensitivity in Objective Monitoring of Tissue Expansion, Plastic and Reconstructive Surgery, Vol. 91, Feb. 1993, pgs. 217-222 Holt, G.R.: Tissue Expansion in Reconstruction, In: Bailey,B.J. ed. Head and Neck Surgery-Otolaryngology, Vol. 2, J.B. Lippincott Co., Philadelphia, 1993 Iconomou, T.G., etal: Tissue Expansion in the Pediatric Patient, Annals of Plastic Surgery, Vol. 31, August 1993, pgs. 134-140 Neale, H.W., etal: Tissue Expanders in the Lower Face and Anterior Neck in Pediatric Burn Patients: Limitations and Pitfalls, Plastic and Reconstructive Surgery, Vol. 91, April 1993, pgs. 624-631 Nordstrom, R.E.: Tissue Expansion, International Quarterly Monographs of Facial Plastic Surgery, Vol. 5, July 1988 Olenius, M., etal: Mitotic Activity in Expanded Human Skin, Plastic and Reconstructive Surgery, Vol. 91, Feb. 1993, pgs. 213-216 Petty, P., etal: Panniculus Morbidus, Annals of Plastic Surgery, Vol. 28, May 1992, pgs. 444-445 Spence, R.J.: Experience with Novel Uses of Tissue Expanders in Burn Reconstruction of the Face and Neck, Annals of Plastic Surgery, Vol. 28, May 1992, pgs. 453-464 Vergnes, P., etal: Repeated Skin Expansion for Excision of Congenital Giant Nevi in Infancy and Childhood, Plastic and Reconstructive Surgery, Vol. 91, March 1993, pgs. 450-455 Wee, S.S., etal: Continuous Verses Intraoperative Expansion in the Pig Model, Plastic and Reconstructive Surgery, Vol. 90, Nov. 1992, pgs. 808-814 -----------------------------END-------------------------------------------