Phonation time (s)
Airflow (17s x 10)
Fig. 8.3.1. Preoperative and postoperative (at 1 and 3 months) acoustic parameters and voice handicap index data. Jitter and shimmer are reported in percent, phonation time in seconds, airflow in 1/sec x 10, and the Voice Handicap Index as the total score divided by 10, so that it fits the graph's y axis scale. (From )
studies in this area, along with comparisons of paresis and paralysis injections, may help clarify the role of micronized acellular dermis in injection laryngoplasty.
There are few reports regarding complications specific to this material. While the expected concerns for airway, hemorrhage, and exacerbation of dysphonia can accompany any injection laryngoplasty, none appear to be unique to micronized acellular dermis. Zapanta and Bielamowicz  did present a case of laryngeal abscess 4 days after trans-oral injection under general anesthesia. The patient recovered and maintained glottic closure following intensive treatment with intravenous steroids and antibiotics. To date, there are no reports of infection or abscess following percutaneous injection.
The package insert for Cymetra, the commercially available form of micronized acellular dermis, comes with step-by-step instructions for preparation and use. The technical aspects of injection laryngoplasty, either in the awake setting or under general anesthesia, are presented elsewhere in this book. Some key points in the reconstitution of the micronized dermis include the following:
1. It is imperative that the syringe containing the powdered dermis be "declumped" and separated within the provided 5-cc syringe prior to mixing.
2. The most error-prone step is in the initial mix. The user must assure that the liquid, be it lidocaine or sterile saline, blend thoroughly with the micronized dermis prior to pushing the mix back and forth across the syringe adaptor. If a clump of product is not in the mix, the administered solution will be relatively thin, and theoretically more transient. Several experienced laryn-gologists have advocated retrograde manipulation of the "clump" with a sterile needle through the distal end of the syringe so that it can blend better.
3. It is possible to intentionally use more liquid for reconstitution, thus making a more easily injected material. For the 2-cc syringe of micronized dermis, it is possible to use 1.9 cc instead of 1.7 cc.
4. Care must be taken to expel air pockets from the syringes prior to transfer to the final syringe. Air mixed into the final product may be responsible for what appears to be "rapid absorption", i.e., a technically well-injected vocal fold may appear nearly empty within a matter of days if the volume of injectate contained air.
5. Use a Luer-Lok style syringe/needle for percutaneous injections to prevent the needle from becoming a projectile due to the force occasionally necessary to pass the material through a small lumen.
Micronized acellular dermis (Cymetra) is an important material for all practitioners managing glottic insufficiency because of its overall safety and availability for immediate use. This latter point is a key advantage over bovine collagen. With the advent of other materials, such as non-donor human collagen protein (Cos-moplast, Inamed Corp., Santa Barbara, Calif.), this feature may no longer be unique. There are several technical issues with preparation that must be mastered to have predictable results. When used for vocal augmentation, the duration of clinical benefit from micronized acellular dermis is not well established scientifically. While it appears last about 3 months, this may not be true in all cases.
1. Pearl AW, Woo P, Ostrowski R, Mojica J, Mandell DL, Costantino P (2002) A preliminary report on micronized AlloDerm injection laryngoplasty. Laryngoscope 112:990-996
Technical Aspects for Using Micronized Acellular Human Dermis
2. LifeCell Corporation package insert from Companywebsite, accessed 10 January 2005. www.life-cell.com
3. Morgan AS, Mclff T, Park DL, Tsue TT, Kriet JD (2004) Biomechanical properties of materials used in static facial suspension. Arch Facial Plast Surg. 6:308-310
4. Buinewicz B, Rosen B (2004) Acellular cadaveric dermis (AlloDerm): a new alternative for abdominal hernia repair. Ann Plast Surg 52:188-194
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6. Menon NG, Rodriguez ED, Byrnes CK, Girotto JA, Goldberg NH, Silverman RP (2003) Revascularization of human acellular dermis in full-thickness abdominal wall reconstruction in the rabbit model. Ann Plast Surg 50:523-527
7. Scalfani AP, Romo T III, Jacomo AA (2002) Rejuvenation of the aging lip with an injectable acellular dermal graft (Cymetra). Arch Facial Plast Surg. 4:252-257
8. Courey MS (2001) Homologous collagen substances for vocal fold augmentation. Laryngoscope
9. Klemuk SA, Titze IR (2004) Viscoelastic properties of three vocal-fold injectable biomaterials at low audio frequencies. Laryngoscope 114:15971603
10. Karpenko AN, Dworkin JP, Meleca RJ, Stachler RJ (2003) Cymetra injection for unilateral vocal fold paralysis. Ann Otol Rhinol Laryngol 112:927-934
11. Milstein CF, Akst LM, Hicks MD, Abelson TI, Strom M (2005) Long-term effects of micronized alloderm injection for unilateral vocal fold paralysis. Laryngoscope. Sep; ii5(9):i68i-6
12. Woo P (2004) Presented at the 2004 annual meeting ofthe American Broncho-Esophagological Association, Scottsdale, Arizona, 1 May
13. Zapanta PE, Bielamowicz SA (2004) Laryngeal abscess after injection laryngoplasty with micronized AlloDerm. Laryngoscope 114:1522-1524
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