facial nerve rehabilitation after radical parotidectomy

The Laryngoscope Lippincott Williams & Wilkins, Inc., Philadelphia 0 1999 The American Laryngological, Rhinoiogical and Otological Society, Inc.

Facial Nerve Rehabilitation After Radical Parotidectomy Pavan G. Reddy, MD; Richard L. Arden, MD; Robert H. Mathog, MD

Objective: E.namine functional outcomes in patients undergoing radical parotidectomy and facial nerve grafting. Identify factors that may affect rehabilitation in these patients. Study Design: Retrospec- tive chart review and photographic analyses of 12 patients undergoing radical parotidectomy with interposition nerve grafts for facial nerve reconstruction. Methods: Data obtained for each patient regarding age, sex, histology of parotid neoplasm, cable graft source, administration of postoperative radiotherapy, and treatment for eye rehabilitation. Functional outcomes were assessed with the House-Brackmann grading system at 6 months, 1 year, and 2 years after surgery. Results: All nerve grafts were harvested from cervical plexus sensory nerves with microscopic epineural repair performed for all neurorrhaphies. Overall, 9 of 12 patients achieved a grade III 2 years after surgery. All patients under age 30 obtained a grade III. Of the seven patients receiving postoperative radiation, five achieved a grade III. Older patients often required surgical procedures to facilitate eye closure. Conclusions: Facial nerve rehabilitation after radical parotidectomy can be successfully achieved with cervical plexus interposition nerve grafts. Postoperative radiotherapy did not appear to affect return of function, and younger patients consistently achieved good functional outcomes after nerve grafting. Older patients frequently require surgical procedures for eye rehabilitation after radical parotidectomy. Kiy Words: Radical parotidectomy, facial nerve, facial nerve rehabilitation, interposition nerve grafts, functional outcome.

Laryngoscope, 109:894-899,1999

INTRODUCTION Radical parotidectomy, which entails total extirpa-

tion of the parotid gland in conjunction with resection of the facial nerve, is advocated for the surgical treatment of high-grade malignancies and recurrent benign tumors of the parotid that intimately involve the facial nerve.1,2 The

Presented a t the Meeting of the Middle Section of the American Laryngological, Rhinological and Otological Society, Inc., Milwaukee, Wis- consin, January 23, 1999.

From the Department of Otolaryngology-Head and Neck Surgery (P.G.R., R.L.A., R.H.M.), Wayne State University, Detroit, Michigan.

Send Correspondence to Pavan G. Reddy, MD, Wayne State Univer- sity, Department of Otolaryngology-Head and Neck Surgery, 5E UHC, 540 E. Canfield, Detroit, MI 48201, U.S.A.

aesthetic and functional deficits created by sacrifice of the facial nerve can be emotionally traumatizing to the patient while presenting formidable challenges to the recon- structive surgeon. Among the many clinical modalities available for facial nerve rehabilitation, cable nerve grafting has been used successfully to rehabilitate the patient after radical parotidectomy.

In the past few decades much work has been dedicated to the study of nerve regenerati~n~.~ as well as to the refine- ment of microneural repair techniques.5 Still, many contro- versies regarding extratemporal facial nerve grafting exist. Some areas of debate include optimal source for cable nerve grafis, technical aspects of neurorrhaphy, and effects of radiation on hctional outcome. To elucidate the role of the above factors in facial nerve rehabilitation, the present study reviews a single surgeon’s experience with radical parotid- &my and cable nerve grafi reconstruction.

MATERIALSAND METHODS Twelve patients underwent radical parotidectomy with ca-

ble nerve grafting from 1979 to 1996. This group of patients consisted of seven females and five males with ages at the time of surgery ranging from 15 to 83. All patients, with the exception of one, were followed for a minimum of 2 years after surgery with photodocumentation performed at 6-month, l-year, and 2-year intervals. Retrospective chart review in conjunction with photographic analysis was performed for each of the patients by three observers independently. However, the results of the photographic analysis were not reported by an unbiased observer. Histology of resected parotid neoplasms and presence of perineural invasion were obtained from pathology reports.

For resection of parotid neoplasms, a preauricular incision was made that curved underneath the ear lobule and extended along the anterior border of the sternocleidomastoid muscle. A skin-subcutaneous flap was raised over the parotid capsule with fine iris scissors until the distal branches of the facial nerve were seen exiting the gland. The temporal, zygomatic, buccal, and mandibular branches were incised and tagged for later grafting. The main trunk of the facial nerve was identified using the posterior belly of the digastric, the cartilaginous tragal pointer, and the tympanomastoid suture line as landmarks. Once the main trunk was identified, en bloc resection was performed to remove the neoplasm and all portions of the facial nerve that were encased with tumor. If the tumor was localized near the main trunk, a mastoidectomy with relaxation of the facial nerve in the facial canal was performed to provide adequate surgical

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Reddy et al.: Facial Nerve Rehabilitation

margins and to increase the length of the proximal facial nerve stump available for grafting.

The donor nerve graft was subsequently harvested from the cervical sensory plexus, which usually included the great auricular nerve, and occasionally the supraclavicular or lessor occipital nerve. After freshening the cable nerve graft ends as well as the proximal and distal facial nerve stumps with a scalpel, microscopic epineural repair was performed with interrupted 9-0 or 10-0 monofilament nylon sutures, with four to six sutures used at each anastomosis. Graft source and number of branches per graft were noted.

Patients receiving postoperative irradiation were identified with total radiation doses to the primary field recorded. The House-Brackmann facial nerve grading system6 was utilized to assess preoperative facial nerve function and postoperative function at 6-month, 1-year, and 2-year intervals. Postoperative eye management included the use of topical moisturizing agents and various types of oculoplastic procedures including tarsorrhaphy, gold weight placement, or canthoplasty for selected patients.

RESULTS Five patients had impaired preoperative facial nerve

function (Table I). Of these five patients, four had histo- logical evidence of perineural invasion. One patient (patient 8) had perineural invasion despite having normal preoperative nerve function. AU cable nerve grafts were harvested from the cervical sensory plexus. These cable grafts consisted of one to four distal branches that were anastornosed to named distal facial nerve branches (Table

I). Mastoidectomy and relaxation of the facial nerve was performed in 9 of 12 patients.

Postoperative evaluation of facial nerve function re- vealed that at 6 months after nerve grafting, no patient had better than a grade V level of function (Table 11). Two years after surgery, nine patients were classified as grade 111, one grade V, and one other a grade VI. Grade I11 was the highest grade achieved by any patient and all three patients under age 30 in this series achieved this grade.

Seven patients received postoperative external beam radiotherapy, with one patient receiving combined photon and neutron beam therapy. The external beam radiation dose to the primary field ranged from 4000 cGy to 5940 cGy, with a mean of 4987 cGy. Of the irradiated patients, two years after nerve grafting, five achieved good functional return (grade 1111, while two patients, of which one received neutron beam therapy, had poor functional return. Postoperative eye care consisted of only topical moisturizing agents in seven patients; five patients had surgical procedures to facilitate eye closure in addition to topical therapy (Table 11).

DISCUSSION As shown in this series and in reports by Conley?

Lathrop,s and Fisch and Lanser,S cable nerve grafting is an effective technique to restore voluntary facial expres- sion and function after sacrifice of the facial nerve for

~~

TABLE I. Patients Undergoing Radical Parotidectomy.

Patient No.

1 2

3

4

5

6

7

8

9

10

11

12

Age (Y)

29 75

76

34

70

~

16

83

49

65

15

63

47

Nerve Preoperative Sex Histology Invasion Facial Function Cable Graft Source Anastomotic Sites'

F M

F

M

M

F

F

F

F

F

M

M

Acinic cell Melanoma

Basaloid

SCC adenocarcinoma

SCC

Chondrosarcoma

High-grade

Adenoid cystic mucoepidermoid

Adenoid cystic

Recurrent pleomorphic adenoma

Moderate grade mucoepidermoid

Poorly differentiated carcinoma

N N

N

N

N

N

Y

Y

Y

N

Y

Y

Grade I Grade I

Grade I

Grade II

Grade I

Grade 1

Grade IV

Grade I

Grade VI

Grade I

Grade II

Grade 111

Great auricular Supraclavicular

Great auricular

Great auricular

Great auricular

Great auricular

Great auricular

Great auricular

Great auricular

Great auricular; lesser occipital

Great auricular

1 br. cable: upper main trunk to zygomatic 2 br. cable: main trunk to zygomatic and

buccal 2 br. cable: main trunk to zygomatic and

buccal 1 br. cable: mastoid segment to main

extratemporal trunk 2 br. cable: upper trunk to temporal and

zygomatic 2 br. cable: lower trunk to buccal and

mandibular 4 br. cable: main trunk to temporal,

zygomatic, buccal, and mandibular 3 br. cable: main trunk to zygomatic,

buccal, and mandibular 3 br. cable: upper trunk to temporal,

zygornatic, and buccal 3 br. cable: main trunk to temporal,

zygornatic, and buccal 4 br. cable: upper trunk to 2 buccal br.

and 2 zygomatic br. 1 br. cable: lower trunk to mandibular 1 br. cable: upper trunk to zygomatic

Great auricular 4 br. cable: main trunk to temporal, zygomatic, buccal, and mandibular

'Named distal branches. SCC = squamous cell carcinoma.

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895

TABLE II. Postoperative Functional Outcome After Cable Graft Reconstruction.

Postoperative Facial Function

Patient No. Postoperative Radiation 6 mo 1 Y 2 Y Eye Management ~

1 N Grade V Grade 111 Grade 111 Moisturizing agents 2 N Grade V Died Died Moisturizing agents 3 N Grade V Grade 111 Grade Ill Gold weight and canthoplasty 4 5940 cGy Grade V Grade IV Grade 111 Moisturizing agents 5 5000 cGy Grade V Grade Ill Grade 111 6 N Grade V Grade IV Grade 111 Moisturizing agents 7 Neutron beam 8.75 Gy Grade VI Grade VI Grade VI Tarsorrhaphy gold weight and

8 5760 cGy Grade V Grade IV Grade 111 Moisturizing agents 9 5220 cGy Grade V Grade V Grade V Gold weight and canthoplasty

10 N Grade V Grade 111 Grade I l l Moisturizing agents 11 4000 cGy Grade V Grade IV Grade 111 Tarsorrhaphy 12 5000 cGy Grade V Grade IV Grade 111 Moisturizing agents

Tarsorrhaphy

+ Photon 4000 cGy canthoplasty

surgical resection of parotid neoplasms. The return of facial function with cable nerve grafts is widely believed to result in superior functional and cosmetic results in comparison to cross cranial nerve grafting or dynamic and static muscle slings.10 There are, however, a number of intraoperative and postoperative factors that must be taken into account to affect successful functional rehabilitation.

Graft Source and Nerve Coaptation The two major graft sources traditionally used for

extratemporal facial nerve reconstruction after radical pa-

rotidectomy include the great auricular and sural nerves. Although the sural nerve has a greater nerve-to- connective tissue ratio and is a longer graft source, in our experience we prefer the use of the great auricular occasionally in combination with other cervical sensory plexus nerve grafts based on several anatomical characteristics. These characteristics include ease of harvest, appropriate diameter match to the facial nerve, and arborization of the distal branches in these cervical plexus grafts. This exten- sive arborization pattern allows the surgeon to use a single cervical sensory plexus nerve graft to anastomose the proximal facial nerve stump to up to four distal branches

Fig. 1. Improved facial motion over time after nerve grafting. Patient 3. A. One year after surgery. B. Two years after surgery. Grade 111.


896


Fig. 2. Clinical results 2 years after cable grafting among the youngest patients in this series. Top row. Patient 6 (1 5 y/o) A. At rest. B. Eye closing. C. Mimetic motion. Good functional return. Grade 111. Bottom Row. Patient 10 (16 y/o). A. At rest. B. Eye closing. C. Lip protrusion. Grade 111.

(Table I). We believe that facial muscle tone and fmc- tional outcomes improve with the greater the number of distal facial nerve branches grafted. "he outcomes obtained in this series, which are comparable to those of previous studies utilizing cervical plexus interposition grafts,l*J2 further substantiate the cervical sensory plexus as an optimal graft source for extratemporal facial nerve reconstruction after radical parotidectomy.

Even though a wide variety of nerve coaptation techniques exist,13-16 the best microneural repair techniques result in tension-free anastamoses while preserving endoneural architecture.5.10 In terms of microneural suture techniques, debate exists between perineural (interfasicular) versus epineural repair. Interfasicular repair is thought by some surgeons to improve regeneration and reduce synkinesis.gJ7 However, many investigators spec- ulate that interfasicular repair increases endoneural fi- brosis, trauma, and vascular damage while conferring no functional advantage over epineural repair.5JOJe We concur with the latter group, as our results indicate that good functional results can be accomplished with epineural repair. As variability in facial nerve diameter exists between the different branches, an individualized approach to each epineural repair was employed for every patient and ac- counts for the range of sutures used (4 to 6) at the proximal and distal anastomoses.

Nerve Regeneration and Aging Neural regeneration is dependent on many factors

including Schwann cells, elements of the extracellular

matrix, and a variety of neurotrophic factor^.^ Cable grafts, via their endoneural tubules, serve as conduits through which regenerating facial nerve axons travel to distal facial muscle end plates. Regeneration of an unin- terrupted facial nerve occurs at a rate of approximately 1 m d d with return of facial function estimated to take 4 months after repair of the extratemporal portion.19 Our functional outcomes are consistent with such regeneration rates, with the earliest return of facial muscle tone noted at 6 months in 11 of 12 patients, with further improve- ment of facial function over time (Fig. 1 ).

Furthermore, age may portend functional outcome. The youngest patients in this series obtained the best functional outcome (Fig. 2). Morphological and physiolog- ical variations between regenerating neurons of different age may account for age-related discrepancies in functional return after facial nerve grafting.20 Experimental studies indicate that axonal transport and axonal sprout- ing are increased in the young21,22 and become less effective with increased patient age.4 These increased neural regeneration rates in the young may in turn translate into improved functional outcomes.23

Eficts of Radiation Multimodality therapy involving surgery followed by

postoperative irradiation has been reported to improve local-regional control for high-grade and advanced-stage parotid malignancies.24.26 Still, controversy exists regarding the effects of radiation on functional outcome after cable grafting. Several authors argue that postoperative

Laryngoscope 109: June 1999 Reddy et al.: Facial Nerve Rehabilitation

897

Fig. 3. Functional outcome in patient receiving radiation alter cable grafting. Patient 5. A. At rest. B. Eye closing. C. Smiling. Grade I l l .

radiation has a detrimental effect on return of facial function after cable grafting,8926 and they advocate muscle transfers and static slings over nerve grafting when postoperative radiotherapy is planned. On the other hand, several investigators report adequate functional return with interposition nerve grafts despite administration of postoperative radiotherapy.27.28 Our results concur with this later group. After 2 years, five of the seven patients who received postoperative radiation achieved moderate functional return (grade 111) after radiotherapy (Fig. 3). In two of the seven irradiated patients (patients 7 and 91, no significant functional return was observed. In these patients, other factors such as advanced age, preoperative nerve dysfunction, and postoperative neutron beam therapy (patient 7) may have contributed to the absence of functional return.

Eye Management Prevention of ocular complications such as exposure

keratopathy remains of utmost importance in the management of facial palsy. As the earliest return of functional eye closure (grade 111) occurred at 1 year after nerve grafting in our patients (Table II), all patients in our series received topical moisturizing agents. In this series, older patients often received a gold weight and canthoplasty to effect adequate eye closure. On the other hand, younger patients seemed to achieve adequate eye closure without surgery. Still, both groups appeared to benefit from topical moisturizing agents. With the above treatment regimen, none of the patients in this series devel- oped exposure keratopathy.

CONCLUSION After examining several variables including graft

source, age, radiation therapy, nerve coaptation techniques, and postoperative eye management and their role in facial nerve rehabilitation, we arrived at several sets of conclusions. Based on our results, the cervical sensory plexus nerves can serve as an effective graft source for facial nerve reconstruction after radical parotidectomy. Moreover, using epineural repair, nerve grafts with mul- tiple distal branches can yield good functional outcomes even if postoperative radiotherapy is given. Also, younger

patients appear to consistently achieve good functional results after nerve grafting. In terms of rehabilitation of the eye, patient age often dictates postoperative eye management, with older patients often requiring surgical procedures to facilitate eye closure. All patients appear to benefit from topical moisturizing agents. On the whole, we advocate cable nerve pafling as the first-line treatment for facial nerve rehabilitation after radical parotidectomy.

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facial nerve rehabilitation after radical parotidectomy

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