PLATYSMA MYOCUTANEOUS FLAP FOR HEAD AND NECK RECONSTRUCTION IN CATS Mark M. Smith, VMD, Stacey Shults, DVM, Don R. Waldron, DVM, and Martha L. Moon, DVM, MS

Squamous cell carcinoma is the fourth most common neoplasm in cats. As in man, local resective surgery of stage 111 and IV carcinoma often results in recurrence related to compromised margins. Radical resective procedures may be perlormed when reconstructive techniques are available to restore comesis and function. A platysma rnyocutaneous flap that was based on a cutaneous branch of the caudal auricular artery and vein was developed to fulfill this requirement. Control flaps, which in- cluded ligation and division of the caudal auricular artery and vein, were similarly developed on the contralateral aspect of the neck. Mean survival of all platysma myocutaneous flaps (86.7%), compared with control flaps (62.9%), was significantly different (p < .05). Flaps grouped in lengths of 6, 9, and 12 cm had mean survival lengths of 93.8%, 81.9%, and 84.4%, respec- tively. The mean survival length of flaps measuring 12 cm in length was significantly different (p < .05) compared with flaps measuring 6 and 9 cm. On the basis of the results of this study, the platysma myocutaneous flap based on a cutaneous branch of the caudal auricular artery and vein may be a source of tissue for reconstructive procedures of the head and neck in cats.

0 1993 John Wiley & Sons, Inc. HEAD & NECK 1993;15:433-439

From the Department of Sniall Animal Clinical Sciences, Virginia-Mary- land Regional College of Veterinary Medicine. Virginia Polytechnic Insti- tute and State University, Blacksburg, Virginia.

Acknowledgments: Fundecl by the Virginia Veterinary Memorial Fund and Virginia Division of the American Cancer Society.

Address reprint requests to Dr. Smith, Department of Small Animal Clin- ical Sciences, Virginia- Maryland Regional College of Veterinary Medi- cine, Virginia Polytechnic lristitute and State University, Blacksburg, VA 24061

Accepted for publication October 9, 1992.

CCC 0148-64031931050433 -07 0 1993 John Wiley & Sons, Inc.

Head and neck neoplasms in cats are often ma- lignant, with guarded or poor prognosis for long- term remission or palliation, regardless of treat- ment.'-* Squamous cell carcinoma (SCC) and fibrosarcoma are neoplasms which have a statis- tically significant increased incidence in these anatomic location^.^ Unfortunately, detection of these malignant neoplasms is often late in the disease process because their location may not be readily observed by the owner or veterinarian. The most common oral neoplasm in humans is SCC, and, as in the feline, advanced primary site disease is often present at the time of diagnosis related to the hesitancy of people to consult their phy~ ic i an .~ ,~

The concept of complete local excision of all visible tumor followed by, or concurrent with, chemotherapy or radiation therapy for treatment of presumed micrometastasis has achieved marked acceptance in human oncologic therapy and is being applied in veterinary medicine.' This multimodality treatment plan includes sur- gery as an integral component especially for large, aggressive neopla~ms.~~~- ' ' The goals of the operative plan for neoplasms of the head and neck in cats is most commonly curative resection or p a l l i a t i ~ n . ~ , ~

A surgical procedure which offers the great- est possibility of cure, restores or maintains function, and has an acceptable cosmetic result is often required in veterinary medicine. Re- gional myocutaneous flaps may serve as a

Platysma Myocutaneous Flap HEAD & NECK September/October 1993 433

compromise between local and free flaps by pro- viding durable, tumor-free tissue for wound re- construction. The availability of a cervical myo- cutaneous flap with direct cutaneous blood supply for head and neck reconstruction might allow radical resective surgery, avoiding func- tional disturbances while providing a cosmetic result.

Development and application of an axial pat- tern flap which included the platysma muscle for oral and maxillofacial reconstruction in the dog has been described.12"3 Investigations have been performed to determine guidelines for caudal su- perficial epigastric and thoracodorsal axial pat- tern flap development in cats.14 The purpose of this study was to assess the caudal auricular ar- tery and vein in cats as a source of direct cutane- ous vascular supply to the lateral cervical area and determine surgical guidelines and surviv- ability of a myocutaneous flap based on these vessels.

MATERIALS AND METHODS

Cadaver Studies. Cervical vascular supply was studied in six cat cadaver specimens following intravascular injection of latex (Latex Injection Medium, Carolina Biological Supply Co, Bur- lington, NC)' Observations were made Of the Ori-

gin ofblood supply to cervical skin and platysma muscle with potential for facial reconstruction after ~ 1 8 0 " of rotation.

FIGURE l . Angiogram of the cranial cervical area, showing cu- taneous vascular supply from a branch (arrow) of the caudal au- ricular artery.

Vascular Studies. Three mature adult cats were evaluated. Carotid artery catheterization was performed under aseptic surgical conditions. The catheter was advanced to the origin of the maxil- lary and caudal auricular arteries. Radiopaque contrast solution (Renografin-76, ER Squibb & Sons, Inc., Princeton, NJ) was injected by hand to visualize branches of the caudal auricular ar- tery and their spatial relation to anatomic land- marks (Figure 1).

Surgical Studies. Twelve mature cats, six fe- males and six males, with a mean weight of 4.2 2 1.2 kg were used. Anesthesia was induced and maintained, and supportive fluid therapy ad- ministered. Guidelines for flap location were based on results of cadaver and vascular studies (Figure 2). The flap base was centered over the lateral aspect of the wing of the atlas. The flap was positioned in the center of the neck within ventral and dorsal lines paralleling the mea- sured flap base and the same width measure-

ment centered on the spine of the scapula. Flap dimensions were 3 x 6 cm ( n = 4 ) , 3 x 9 cm ( n = 41, and 3 x 12 cm ( n = 4) . Flap length varied by group and did not necessarily extend to the spine of the scapula. Group assignment of cats was performed randomly.

Flaps were developed and elevated bilater- ally. The platysma muscle was intimately associ- ated with the subcutis of the flap. Flaps were completely elevated to their base allowing iden- tification of cutaneous arterial supply, which was avoided (Figure 3). One flap was randomly assigned as the control by ligation and di- vision of the caudal auricular artery and vein af- ter proximal digastricus myotomy. Flaps were placed orthotopically and sutured with nonab- sorbable suture in a simple continuous pattern. Butorphanol tartrate (0.2 mg/kg) (Torbugesic in- jection, Bristol Laboratories, Syracuse, NY) was administered subcutaneously immediately fol- lowing surgery and twice daily during the entire evaluation period.

434 Platysma Myocutaneous Flap HEAD & NECK SeptemberiOctober 1993

FIGURE 2. Diagram showing location of the platysma myocutaneous flap (broken lines) based on a cutaneous branch of the caudal auricular artery (arrowhead) in relation to the wing of the atlas (a) and the scapula (b).

Flap viability was determined on the basis of skin temperature and color between 5 and 8 days following surgery (Figure 4). Cardboard tem- plates made during the surgical procedure were used to outline contralateral flaps and record ar- eas of flap necrosis, compared with total flap area. The length of skin viability was deter- mined as described previou~ly. '~ Data were ana-

FIGURE 3. Intraoperative photograph of the platysma myocuta- neous flap base showing the thin platysma muscle and vascular supply from the caudal auricular artery (arrows).

lyzed by use of the paired t-test and analysis of variance with p < .05 considered significant. The study was conducted in accordance with federal and university guidelines with approval by the Animal Care and Use Committee of the Vir- ginia- Maryland Regional College of Veterinary Medicine.

A platysma myocutaneous flap based on the caudal auricular artery and vein was used in two cats for head and neck reconstruction following radical resective surgery for periocular (T,N,M,J and aural (T,N,M,) SCC. Flap dimensions were 4 x 10 cm and 5 x 12 cm, respectively.

RESULTS

Results of cadaver and vascular studies showed one cutaneous branch of the caudal auricular ar- tery and vein contributing blood supply to the cranial aspect of the cervical skin and platysma muscle. Angiography revealed dorsal and caudal vessel orientation, which paralleled the central cervical region. The cutaneous branch of the cau- dal auricular artery observed during surgery was intimately associated with the platysma muscle and divided near its origin located in the area between the lateral aspect of the wing of

Platysma Myocutaneous Flap HEAD & NECK SepternberIOctober 1993 435

the atlas and the vertical ear canal (Figure 3). Mean length of experimental and control flaps was 9.0 _t 2.6 cm (Table 1). Mean survival length of experimental and control flaps was 7.7 -+ 2.0 cm and 5.4 ? 1.5 cm, respectively. Necrosis oc- curred in 10 of 12 control flaps, resulting in mean survival length of 62.9%, compared with mean survival length of 87.6% in flaps incorpo- rating vascular supply from the caudal auricular artery and vein. Survival length was signifi- cantly different. Flaps grouped in lengths of 6, 9, and 12 cm had mean survival lengths of 93.8 * 12.5%, 81.9 * 12.4%, and 84.4 2 4.0%, respec- tively. The mean survival of flaps measuring 12 cm in length was significantly different com- pared with flaps measuring 6 and 9 cm. Wound dehiscence occurred at areas of flap necrosis.

Application of a platysma myocutaneous flap in two clinical patients with SCC allowed pri- mary wound reconstruction with 100% flap sur- vivability. An ipsilateral flap was used in a fa- cial defect related to periocular resection and ocular exenteration. A contralateral flap was used following pinna resection and total ear ca- nal ablation (Figures 5 and 6).

DlSCUSSlON

Head and neck SCC is the fourth most neoplasm in feline^.^ The oral cavity, aural pin- nae, and are commonly affected locations. Feline SCC is biologically similar to human head

FIGURE 4. Photograph of bilateral platysma myocutaneous flaps based on a cutaneous branch of the caudal auricular artery 6 days following surgery. The experimental flap (A) has greater survivability compared with the control flap (B). Ar- rows = demarcation of devitalized skin.

Table 1. Comparison of survival length of platysrna rnyocutaneous flaps (PMF) and control flaps in cats.

Flap survival

PME Control Flap dimensions (crns)

Cat No. Base width x length ern % ern %

1 2 3 4 5 6 7 8 9

10 11 12

Mean values*

3 x 6 3 x 6 3 x 6 3 x 6 3 x 9 3 x 9 3 x 9 3 x 9 3 x 12 3 x 1 2 3 x 12 3 x 1 2

3.0(0.0) x 9.0(2.6)

6.0 6.0 6.0 4.7 6.5 7.0 9.0 7.0 9.5

10.5 10.5 10.0

7.7( 2.0)

100 0 100 0 100 0 75 0 72 0 77 7

100 0 77.7 79 2 87 5 87 5 83 3

86 7(11 0)

6.0 4.5 6.0 3.5 3.0 4.5 5.5 4.0 6.0 8.0 7.0 7.0

5.4( 1.5)

100.0 75.0

100.0 58.3 33.3 50.0 61 .O 44.4 50.0 66.7 58.3 58.3

62.9(20.3)

'No. in parentheses = SD.

436 Platysma Myocutaneous Flap HEAD & NECK SepternberlOctober 1993

FIGURE 5. Periocular squamous cell carcinoma in a 17-year-old cat (A). The ocular and periocular tissues were resected fol- lowed by wound reconstruction using an ipsilateral platysma myocutaneous flap (a).

FIGURE 6. Aural squamous cell carcinoma in a 10-year-old cat (A). The periaural skin and remaining left pinna were resected followed by total ear canal ablation. The wound was recon- structed using a contralateral platysma myocutaneous flap (B).

and neck SCC: both are locally invasive, and me- tastases to regional lymph nodes and lungs occur late in the course of d i ~ e a s e . ’ ~ ” ~ As in human medicine, treatment of disease limited to small primary SCC (stage I or 11) is surgery or radio- therapy.’””g Unfortunately, felines with SCC are often presented by their owner for advanced, large primary tumors (stage I11 or IV), which are not amendable to local resective surgery or ra- diotherapy as single modalities for treatment.234 In veterinary medicine, the type of surgical treatment is based on neoplasm location, sur- geon skill, and owner preference. Owners of af- fected felines may not desire or comply with ad- junctive therapy recommendations often making surgical cure the operative goal for stage I11 and IV SCC. Fulfillment of this goal requires aggres- sive en bloc resection to optimize tumor-free margins and reconstructive surgical techniques to provide acceptable cosmesis and function.

The platysma myocutaneous flap has been shown to be a useful reconstructive surgical

technique following resection of head and neck neoplasms in humans.20v21 The skin-muscle com- posite has versatility for multiple head and neck regions allowing generous margins, less tissue bulk compared with other regional flaps, adapt- able length, and vascular r e l i a b i l i t ~ . ~ ~ - ~ ~ The feline platysma is intimately associated with subcutaneous tissues,25 Cutaneous vascular sup- ply from multiple vessels, including cutaneous branches of the caudal auricular artery and vein were observed coursing in the lateral cervical re- gion of the platysma muscle. As in humans, the observed vascular supply to the feline platysma myocutaneous flap was consistent in location in our study which emphasized a cranial basis and horizontal orientation. The flap was versatile based on intraoperative manipulation prior to or- thotopic replacement and clinical application in two feline patients. There were no deleterious re- sults related to flap thinness or gravitational ef- fects.

Assessment of survivability was based on the

Platysma Myocutaneows Flap HEAD & NECK SeptemberiOctober 1993 437

disposition of contralateral control flaps, which included division and ligation of the caudal au- ricular artery and vein. Vital dyes (fluorescein and xylenol orange), which stain tissue in rela- tion to vascularity, were not used in this study because they have not been shown to be consis- tently accurate in predicting survivability of ex- perimental axial pattern flaps in canine^.^^'^^,^^ Further studies are necessary to determine if these observations are applicable to similar re- search in felines.

Vascular and cadaver studies provided evi- dence of consistent location of vascular supply which allowed construction of narrow (3 cm) platysma myocutaneous flaps in this study. Nar- row flap width enabled elevat.ion of cranial-based peninsula flaps of extended length incorporating direct myocutaneous vascular supply. Increasing flap width may have improved flap survivability in surgical studies by incorporating potential cu- taneous blood supply from other sources.28 How- ever, vascular input near the flap base was sacri- ficed to isolate cutaneous branches of the caudal auricular artery and vein as the single direct cu- taneous source of vascular supply to the flap. Greater flap width in the two clinical feline pa- tients may have included additional vascular supply to augment the caudal auricular artery and vein extending survivability to 100%.

The mean survival length (7.7 2 2.2 cm) of flaps incorporating vascular supply from the cau- dal auricular artery and vein indicates that the platysma myocutaneous flap may be most useful for caudal head and neck defects compared with more rostra1 defects which occur following resec- tion of neoplasms affecting the nares, premax- illa, or mandibular symphysis. The cervical cuta- neous blood supply in cats is predominantly horizontal. In humans, the blood supply to the platysma is multiaxial emanating from several sources providing potential for multidirectional use of the platysma myocutaneous flaps2' A wider flap base in a ventral direction may have included blood supply from the facial artery and further investigation may show multiaxial vas- cular supply to the platysma muscle as in hu- mans.

The reconstructive surgical technique de- scribed in this study may allow elective neck dis- section with preservation of the caudal auricular artery depending on the size of the operative field, This approach provides access for exci- sional biopsy of mandibular and/or cervical lymph nodes to aid staging and augment surgi-

cal extirpation of metastatic disease. Metastatic routes which may be considered during dissec- tion include perineural, vascular and microvas- cular, lymphatic, and t r a n s ~ a p s u l a r . ~ ' - ~ ~ Ex- tended dissection from the primary site may improve the incidence of free margins related to surgical resection of direct metastatic pathways. This may be of particular importance for neo- plasms of the floor of the mouth and caudal head and neck region. The cranial cervical area was easily observed in conjunction with platysma myocutaneous flap elevation in surgical studies and clinical patients. Direct observation of re- gional lymph nodes allows assessment of gross transcapsular spread of the tumor which may warrant wider margins for adhered lymph nodes.

Clinical application of the platysma myocuta- neous flap demonstrated its viability and versa- tility. Both clinical patients had SCC of chronic duration with gross evidence of local invasion into important structures (ear and eye). Exten- sive neoplasms involving the pinna, as in the pa- tient presented in this study, require resection of the entire ear.'8*36,37 The aforementioned clinical lesions required wide margins necessitating or- bit exenteration and total ear canal ablation. The subsequent surgical wounds were not amendable to primary wound closure. The platysma myocutaneous flap provided single- stage wound reconstruction with durable, tumor- free tissue of extended length.

On the basis of the results of this study, platysma myocutaneous flaps based on the cuta- neous branch of the caudal auricular artery and vein have greater surviving lengths, compared with flaps dependent on the subdermal plexus. This flap has application for facial reconstruction following radical resective procedures of the head and neck. Finally, a clinical study evaluat- ing the effect of radiotherapy and intratumoral chemotherapy (etandiazole) for treatment of spontaneous oral feline SCC has been recently reported.16 The oral feline model was used based on similarities of feline and human head and neck SCC.'6v17*38 The surgical technique reported in this study may provide a surgical treatment option for investigators of comparative multimo- dality therapy for feline and human SCC of the head and neck.

REFERENCES 1. Theilen GH, Madewell BR. Tumors of the skin and sub-

cutaneous tissues. In: Theilen GH, Madewell BR, eds.

438 Platysma Myocutaneous Flap HEAD & NECK SeptemberiOctober 1993

Veterinary cancer. medicine. Philadelphia: Lea & Febiger,

2. Bradley RL. Selected oral, pharyngeal, and upper respi- ratory conditions in the cat. Vet Clin N Am

3. Harvey HJ. Surgery. In: Theilen GH, Madewell BR, eds. Veterinary cancer medicine. Philadelphia: Lea & Febiger,

4. Harvey HJ. Oral tumors. Vet Clin N Am 1985;15:493- 500.

5. Stebbins KE, Morse CC, Goldschmidt MH. Feline oral neoplasia: a ten- year survey. Vet Pathol 1989;26:121- 128.

6. O’Brien CJ, Smith JW, Soong SJ, et al. Neck dissection with and without radiotherapy: prognostic factors, pat- terns of recurrence, and survival. A m J Surg 1986;152:456-463.

7. Forastiere AA. Review: management of advanced stage squamous cell carcinoma of the head and neck. A m J Med Sci 1986;291.:405-415.

8. Caldarelli DD, Rejowski JE. Surgical management of re- current or advanced squamous cell carcinoma of the head and neck. Clin Plast Surg 1985;12:505-514.

9. Slootweg PJ, Muller H. Mandibular invasion by oral squamous cell carcinoma. J Cranio Maxillofac Fac Surg 1989;17:69-74.

10. Kramer S, Marcia1 VA, Pajak TF, et al. Prognostic fac- tors for locoregional control and metastasis and the im- pact on survival. Int J Radiat Oncol Biol Phys

11. Snow JB. Surgical management of head and neck cancer. Sem Oncol 1988; L5:ZO-28.

12. Smith MM, Payne JT, Moon ML, et al. Axial pattern flap based on the caudal auricular artery in dogs. A m J Vet Res 1991;52:922--925.

13. Trevor PB, Smith MM, Waldron DR, et al. Clinical appli- cation of axial pattern flaps in dogs and cats. J A m Vet Med Assoc 1992;201:621-624.

14. Remedios AM, Biiuer MS, Bowen CV. Thoracodorsal and caudal superficial epigastric axial pattern skin flaps in cats. Vet Surg 1989;18:380-385.

15. Shields Henney LH, Pavletic MM. An axial pattern flap based on the superficial brachial artery in the dog. Vet Surg 1988;17:311-317.

16. Evans SM, LaCreta F, Helfand S, et al. Technique, phar- macokinetics, toxicity, and efficacy of intratumoral et- anidazole and radiotherapy for treatment of spontaneous feline oral squamous cell carcinoma. Znt J Radiat Oncol Biol Phys X991;20:703-708.

17. Carpenter JL, Andrews LK, Holtzworth J. Tumors and tumor like lesions. In: Holtzworth J., ed. Diseases of the cat: medicine and surgery, vol 1. Philadelphia: WB Saun- ders, 1987:486-487.

18. Shockley WW, Stucker FJ. Squamous cell carcinoma of the external ear: a review of 75 cases. Otolaryngol Head Neck Surg 1987;97:308-312.

19. Lo TCM, Salzrnari FA, Swartz MR. Radiotherapy for can- cer of the head and neck. Otolaryngol Clin North Am

1987:240- 266.

1984;14:1173-1184.

19871121- 127.

1986;12:573-578.

1985;18:521-531

20. Coleman JJ , Jurkiewicz MJ, Nahai F, et al. The platysma myocutaneous flap: experience with 24 cases. Plast Reconstr Surg 1983;72:315-323.

21. Friedman M, Schild JA, Ventkatesan TK. Platysma my- ocutaneous flap for repair of hyopharyngeal strictures. A n n Otol Rhino1 Laryngol 1990;99:945-950.

22. Coleman JJ , Nahai F, Mathes SJ. Platysma musculocu- taneous flap: clinical and anatomic considerations in head and neck reconstruction. Am J Surg 1982;144:477- 481.

23. Futrell JW, Johns ME, Edgerton MT, et al. Plastysma myocutaneous flap for intraoral reconstruction. Am J Surg 1978;136:504-507.

24. Hunvitz DJ, Rabson JA, Futrell JW. The anatomic basis for the platysma skin flap. Plast Reconstr Surg

25. Ghoshal NG. Carnivore heart and arteries. In: Getty R, ed. The anatomy of the domestic animals, Philadelphia: WB Saunders, 1975:1602- 1611.

26. Pavletic MM. Canine axial pattern flaps, using the omo- cervical, thoracodorsal, and deep circumflex iliac direct cutaneous arteries. A m J Vet Res 1981;42:391-406.

27. Bellah JR, Krahwinkel DJ. Xylenol orange as a vital stain to determine the viability of skin flaps in dogs. Vet Surg 1985;14:124- 126.

28. McClure RC, Dallman MJ, Garrett PD. Cephalic region and central nervous system. Cat anatomy. Philadelphia: Lea & Febiger, 1973:163-171.

29. Kotwall C, Sako K, Razack MS, et al. Metastatic pat- terns insquamous cell cancer of the head and neck. A m J Surg 1987;154:439-442.

30. Cunningham MJ, Johnson JT, Myers EN, et al. Cervical lymph node metastasis after local excision of early squamous cell carcinoma of the oral cavity. Am J Surg

31. Ortega IS, Nieto CS, Forcelledo MFF, et al. Lymph node response and its relationship to prognosis in carcinomas of the head and neck. Clin Otolaryngol 1987;12:241-247.

32. Moore C, Flynn MB, Knox R, et al. Comparison of pri- mary and secondary treatment in squamous oral cancer. J Surg Oncol 1987;34:76-80.

33. So0 KC, Carter RL, O’Brien CJ, et al. Prognostic irnplica- tions of perineural spread in squamous carcinomas of the head and neck. Laryngoscope 1986;96:1145- 1148.

34. Ellis ER, Mendenhall WM, Rao PV, et al. Does node loca- tion affect the incidence of distant metastases in head and neck squamous cell carcinoma? lnt J Radiat Oncol Biol Phys 1989;17:293-297.

35. Close LG, Brown PM, Vuitch MF, et al. Microvascular invasion and survival in cancer of the oral cavity and oropharynx. Arch Otolaryngol Head Neck Surg 1989;

36. Conley J . Management of the ear canal in head and neck surgery. Arch Otolaryngol 1985;111:90-92.

37. Kinney SE. Squamous cell carcinoma of the external au- ditory canal. Am J Otol 1989;lO:lll-116.

38. MacEwen EG. Spontaneous tumors in dogs and cats: models for the study of cancer biology and treatment. Cancer Met Reu 1990;9:125- 136.

1983;72:302-314.

1986;152:361- 366.

11511304-1309.

Platysrna Myocutaneois Flap HEAD & NECK September/October 1993 439