Donor site morbidity of greater auricular nerve graft harvesting

J Oral Maxnllofac 50:803-805.

Surg

1992

Donor Site Morbidity of Greater Auricular Nerve Graft Harvesting JEFFREY

D. SCHULTZ, DDS, MMS,* THOMAS B. DODSON, AND ROGER A. MEYER, MD, DDS$

DMD, MPH,t

To better understand the risks of obtaining greater auricular nerve (GAN) grafts, a retrospective analysis of 29 patients who underwent GAN graft procurement between 1985 and 1990 was conducted. No short-term morbidity was noted. Thirteen patients developed symptomatic nerve injuries, of which 6 reported spontaneous resolution in an average of 4.6 months. Three patients developed neuromas and 1 formed a hypertrophic scar. Persistent nerve injury symptoms were well tolerated in all but one patient, who developed sympathetic-mediated pain. donor site morbidity. Short-term donor site morbidity included seroma, hematoma, wound infecdion, and wound dehiscence. Long-term donor site complications included hypertrophic scar formation, neuroma formation, and symptomatic nerve injury, ie, anesthesia, hypoesthesia, paresthesia, dysesthesia, and sympathetic-mediated pain. Operational definitions of these neurologic variants were as follows: 1) anesthesia, no reflex response to stimuli; 2) paresthesia, spontaneous or evoked abnormal sensation; 3) hypoesthesia, decreased sensation to stimuli; 4) dysesthesia, an unpleasant abnormal sensation that is spontaneous or evoked; and 5) sympathetic-mediated pain, pain caused by increased sympathetic activity, cold, or emotional states.6,7The duration of symptomatic nerve injury was documented. Data were managed and analyzed using an IBM-PC clone and Primer statistical software (McGraw Hill, San Francisco, CA). Means and variance or proportions were computed for each variable. To assess the association between potential risk factors and complications of GAN procurement, either a t test or x2 statistic was computed.

Repair of the lingual and inferior alveolar nerves using either the sural or greater auricular nerve (GAN) as a donor graft has been advocated.1,2 Documented donor site morbidity of sural nerve procurement includes 1) separate surgical donor site and 2) anesthesia of the outer side of the sole and back of the foot.3-5 However, to date there have been no studies published that systematically evaluate donor site morbidity following GAN procurement. The purpose of this study was to evaluate short- and long-term donor site morbidity following GAN procurement. Materials and Methods STUDY DESIGN The study involved an observational, retrospective design. The sample consisted of 29 consecutive patients who underwent GAN graft procurement between 1985 and 1990. Study variables abstracted from patient records included sex, age, length of GAN graft, whether the GAN was reanastomosed after obtainment, and

Surgical Technique

* Chief Resident, Division of Oral and Maxillofacial Surgery, Emory University School of Medicine, Atlanta. t Assistant Professor, Division of Oral and Maxillofacial Surgery, Emory University School of Medicine, Atlanta. $ In private practice, Department of Surgery, Northside Hospital, Atlanta. Presented in abstract form at the 73rd Annual Meeting of the Association of Oral and Maxillofacial Surgeons in Chicago, IL, September 24-29, 199 1. Address correspondence and reprint requests to Dr Dodsen: Division of Oral and Maxillofacial Surgery, Emory University School of Medicine, 1327 Clifton Rd, NE Atlanta, GA 30322.

All donor nerves were removed by the same surgeon (R.A.M.). A natural skin crease at or near the junction of the upper and middle third of the neck overlying the sternocleidomastoid was selected as the location for exposure of the GAN in most patients. A 2- to 3cm horizontal incision was made centered over the external jugular vein. Superficial fascia and the platysma muscle were sharply incised and retracted. The external jugular vein was identified and retracted forward; cutting and ligation of the vein were not necessary. The

0 1992 American Association of Oral and Maxillofacial Surgeons 0278-2391/92/5008-0005$3.00/O

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DONOR SITE MORBIDITY OF CAN HARVESTING

GAN was isolated just posterior to the vein in the fascia on the lateral surface of the stemocleidomastoideus (Fig 1). The operating microscope or surgical loupes (3X to 5X magnification power) were used to identify the nerve and in further dissection. The GAN was mobilized and cleaned of surrounding fascia for several centimeters. Using serrated microdissection scissors, a free nerve graft equal to 1.3 to 1.5 times the distance of the recipient nerve gap (to compensate for contracture of the graft) was taken.8 When the GAN was reanastomosed, the proximal and distal ends were mobilized, brought together without tension, and repaired with 8-O nylon epineural sutures. If tension-free suturing was not possible, the GAN was not reanastomosed. To minimize stump neuroma formation, axoplasm was resected from the proximal stump and the epineurium was closed with 8-O nylon sutures.’ The stump was allowed to retract or was repositioned behind the posterior border of the stemocleidomastoideus to protect it from external irritation. The platysma muscle was closed with a running absorbable suture and the skin incision was closed with continuous subcuticular 5-O nylon. Results There were 8 males and 21 female patients with a mean age of 33.2 f 9.7 (range, 15 to 52) years. The average length of donor nerve removed was 2.0 + 0.4 (range, 1.3 3.0 cm) cm. Twenty patients (69%) underwent direct repair of the GAN following removal. The mean defect of a repaired GAN was 1.8 f 0.4 (range,

Table 4.

Donor Site Morbidity

Symptomatic nerve injury Yes No Spontaneous resolution Yes No Time to resolution (mo)* Length of follow-up for nonresolved cases (mo)* Neuroma formation Hypertrophic scar

13 (46%) 15 (54%) 6 (46%) 7 (54%)7 4.6 + 3.3 (0.8-9) 11.4 f 8.4 (4.3-24.8) 3

I

* Value given as mean f standard deviation. t Sympathetic-mediated pain, 1; dysesthesia, I; hypoesthesia, 3; hyperesthesia, 2.

1.3 to 2.5 cm) cm and the mean defect of an unrepaired GAN was 2.3 + 0.5 (range, 1.8 to 3.0 cm) cm (P = .005). Patients were foIlowed for an average of 11.3 +_ 8.7 (range, 0 to 24.8 months) months. One patient failed to return for postoperative evaluation. The number of postoperative visits averaged 4.9 ? 3.2 (range, 0 to 12). Table 1 summarizes observed donor site morbidity. No short-term morbidity was noted. Thirteen patients (46%) developed symptomatic nerve injuries, of which six (46%) reported spontaneous resolution in an average of 4.6 & 3.3 (range, 0.8 to 9) months. In seven patients, symptomatic nerve injuries failed to resolve by the end of follow-up, ie, 11.4 + 8.4 (range, 4.3 to 24.8) months. Three patients developed neuromas. All were found in patients following direct GAN repair. One patient developed a hypertrophic scar. An assessment of risk factors for sympathetic donor nerve injury is presented in Table 2. There was no significant difference between symptomatic and asymptomatic patients in terms of age, sex, donor length, or reanastomoses of the donor nerve. Discussion

FIGURE 1. Line drawing of the left anterior neck showing the relationship of the great auricular nerve to the external jugular vein and stemocleidomastoid muscle.

Advantages of the GAN as a donor nerve graft are size, proximity to the operative field, and ease of procurement.* To date, however, there have been no published studies of donor site morbidity associated with GAN procurement. lo Incidental reports of GAN injury have been described following parotidectomy” and rhytidectomy. ‘* Brown et al compared the sensory changes associated with preservation of the posterior branch of the GAN with sacrifice of the nerve trunk during routine parotid surgery.” AU patients with GAN trunk section experienced sensory loss from the earlobe to the angle of the mandible that diminished in size 3 to 12 months after surgery. Of those patients who had the posterior branch of the GAN preserved, only one (17%) had extensive sensory loss of the earlobe and

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SCHULTZ. DODSON. AND MEYER

Table 2. Assessment of Potential Risk Cectors for Donor Nerve Injury

Study Variable Age Sex Male Female Donor nerve length (cm)* Reanastomoses of donor nerve Yes No

Symptomatic Nerve Injury

Asymptomatic Nerve Injury

36.2 + 8.5

31.8 f 9.5

4 9

I .9 If-0.3

4 12 2.1 f 0.5

10 3

9 6

P Value

0.22

0.94 0.34

0.58

* Value given as mean 2 standard deviation.

mandibular angle 12 months after surgery. They also reported hyperesthesia in 33% of their patients, which was postulated to be secondary to neuroma formation. Manstein reported a case of bilateral neuromas of the GAN 8 years following rhytidectomy, and also concluded that transection of the CAN often is asymptomatic secondary to multiple innervation pathways of the auricle.” If auricular anesthesia does persist, it is caused by the absence of multi-innervation pathways, including auricular branches of cranial nerve X, the lesser occipital, and the auriculotemporal nerve.12 Powell and Clairmont state that patients should be informed preoperatively of potential anesthesia over the pinna and parotid area, and that variable degrees of dysesthesia and neuralgic pain can occur before normal sensation returns. I3 McKinney et al reported that injury to the GAN during rhytidectomy can be associated with neuroma formation and permanent sensory loss of the lower two thirds of the auricle and preauricular and postauricular skin.14 This study is the first systematic review of donor site morbidity associated with procurement GAN grafts. In all cases, a suitable graft was obtained and no immediate postoperative complications occurred. However, symptomatic nerve injury was a frequent late complication. The symptoms resolved spontaneously within 9 months in 6 of 13 (46%) patients. Persistent nerve injury symptoms were well tolerated in all but one patient who developed sympathetic-mediated pain. Therapy in this patient included pharmacological treatment, transcutaneous electrical nerve stimulation therapy, and subsequent referral to a pain clinic. Despite the direct tension-free repair of a freshly incised GAN, 3 of 20 ( 15%) proceeded to develop symp-

tomatic neuromas. Based on this finding, reanastomosis of the GAN is no longer attempted. Persistent hypoesthesia or anesthesia of the inferior aspect of the ear lobe and angle of mandible is usually well tolerated. Painful neuroma formation, however, is not well tolerated. Based on the results of this study, some may argue that the donor site morbidity following GAN obtainment is minor and therefore not clinically important. When the GAN is removed for reconstruction following extensive, ablative tumor surgery, the donor site morbidity may be perceived as minor relative to that of the primary procedure. When the nerve is removed to reconstruct a lingual or inferior alveolar nerve that has been injured following elective dentoalveolar or orthognathic surgery, however, any donor site morbidity, even if minor, assumes a greater significance. We feel it is important to understand and document the type and frequency of morbidity following GAN procurement so that the clinician and patient can better estimate the risks and benefits of nerve reconstruction using the GAN relative to using the sural nerve. References I Hauseman J-E, Samii M, Schmidsede R: Repair of the mandibular nerve by means of autologous nerve grafting end resection of the lower jaw. J Maxillofac Surg 1:74, 1973 2. Noma H, Kakizawa T, Yamane G, et al: Repair of the mandibular nerve by autogenous grafting after partial resection of the mandible. J Oral Maxillofac Surg 44:30, I986 3. Fisher TR, Cox P: The sural nerve as autogenous nerve grafts. J Bone Joint Surg [B] 56:571, 1974 4. Hill HL, Vasconez LO, Jurkiewicz MJ: Method for obtaining a sum1 nerve graft. Plast Reconstr Surg 6 1:177, 1978 5. Woods DD: Morbidity of sural nerve harvest for the repair of inferior alveolar and lingual nerve injuries. J Oral Maxillofac Surg 48: 149. 1990 6. Gregg JM: Studies of traumatic neuralgia in the maxillofacial region. J Oral Maxillofac Surg 48: 135, 1990 7. Merskey H: Classification of chronic pain: Description of chronic pain syndromes and definition of pain terms. Pain 25:S2 15, 1986 (suppl) 8. Meyer RA: Applications of microneurosurgery to the repair of peripheral tt-igeminal nerve injuries. Oral Maxillofac Surg Clin North Am 4:405, 1992 9. Williams HB: The painful stump neuroma and its treatment. Clin Plast Surg 11:79, 1984 10. Dodson T, Kaban L: Donor site morbidity. Oral Mawillofac Surg Clin North Am 2:489, 1990 I I. Brown JS, Ord RA: Preserving the great auricular nerve in parotid surgery. Br J Oral Maxillofac Surg 27:459, 1990 12. Manstein CH, Manstein G: Bilateral neuromata of the great auricular nerves 8 years following face lift. Plast Reconstr Surg 76~937, 1985 13. PowelI ME, Clairmont AA: Complications of parotidectomy. South Med J 76: 1109, 1983 14. McKinney P, Katrana DJ: Prevention of injury to the great auricular nerve during rhytidectomy. Plast Reconstr Surg 66: 675, 1980