Accepted 5 September 2008 Published online 3 March 2009 in Wiley InterScience ( DOI: /21013

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1 ORIGINAL ARTICLE MARGINAL MANDIBULAR NERVE INJURY DURING NECK DISSECTION AND ITS IMPACT ON PATIENT PERCEPTION OF APPEARANCE Martin D. Batstone, MPhil(Surg), FRACDS(OMS), FRCS(OMFS), 1 Barry Scott, BSc, MCSP, 2 Derek Lowe, MSc, CStat, 3 Simon N. Rogers, FDS, RCS, FRCS, MD 3 1 Department of Maxillofacial Surgery, Royal Brisbane Hospital, Brisbane, Queensland, Australia 2 Department of Physiotherapy, Aintree University Hospitals NHS Foundation Trust, Liverpool, United Kingdom 3 Regional Maxillofacial Unit, Aintree University Hospitals NHS Foundation Trust, Liverpool, United Kingdom. snrogers@doctors.net.uk Accepted 5 September 2008 Published online 3 March 2009 in Wiley InterScience ( DOI: /21013 Abstract: Background. Neck dissection to remove cervical lymph nodes is common practice in head and neck cancer management. The marginal mandibular nerve may be injured during neck dissection, particularly of level 1. The rate of injury to this nerve is underreported in the literature and its impact on patients is not well defined. Methods. An observational study was undertaken on patients who had undergone neck dissection over a 5-year period. The patients were examined for weakness and given a questionnaire related their perception of their appearance and their function. Results. Sixty-six patients were identified who had undergone 85 neck dissections. The rate of House Brackmann injury was 18% when analyzed by patient and 23% by neck. There were moderate correlations between observed injury and subjective responses to questions relating to ability to smile and weakness of the lower lip. Discussion. The rate of smile asymmetry following neck dissection is relatively high; however, severe injuries to the marginal mandibular nerve are uncommon. VC 2009 Wiley Periodicals, Inc. Head Neck 31: , 2009 Correspondence to: S. N. Rogers VC 2009 Wiley Periodicals, Inc. Keywords: head and neck cancer; nerve injury; facial nerve; marginal mandibular; appearance; neck dissection Surgical removal of cervical lymph nodes (neck dissection) is established practice in the treatment of head and neck cancers. The introduction of functional and selective versions of the standard radical neck dissection are an attempt to limit the morbidity caused by removal of neural, vascular, and muscular structures from the neck without compromising oncologic principles. Studies of neural morbidity following neck dissection have tended to focus on the shoulder syndrome caused by damage or division of the spinal accessory nerve 1 and modifications of the neck dissection have been aimed at reducing the morbidity caused by injury to this nerve. 2 The marginal mandibular branch of the facial nerve is also at risk during a neck dissection primarily through removal of lymph nodes in Marginal Mandibular Nerve Injury during Neck Dissection HEAD & NECK DOI /hed May

2 the submandibular triangle (level 1) but also to a much lesser extent in the apex of level 2. The anatomy of the marginal mandibula nerve has been well described 3 and is at risk below the lower border of the mandible though the exact position and number of nerves which course below the lower border is a matter of debate. 4 Various techniques have been described to protect the marginal mandibular nerve during neck dissection, 5,6 though a randomized controlled trial between different methods has not been undertaken. Improvements in technology may provide alternative methods to ensure minimization of nerve injury. 7 Marginal mandibular nerve damage is described following submandibular gland removal with an incidence of permanent injury ranging from 0% 8 to 7.3%, 9 though most studies are retrospective and will underestimate the incidence. The overall neuropraxia rate in a heterogeneous group of patients undergoing neck dissection has been described at 16%. 4 This is the only study identified in the literature which addresses the rate of injury in patients undergoing level 1 neck dissection. Injury to the nerve will cause weakness of depressor anguli oris and depressor labii inferioris leading to asymmetry of the lower lip particularly when smiling. There is some contribution to lower lip depression provided by the platysma muscle which is supplied by the cervical branches of the facial nerve 10 and these nerves are invariably divided during neck dissection. The effect of marginal mandibular nerve injury and its associated deformity on patients with head and neck cancer are not known. Head and neck cancer and its treatment can be mutilating and distressing for both patients and their families despite improvements in reconstructive surgery. 11 A significant proportion of patients have concerns regarding their appearance and a correlation exists between neck dissection and subjective appearance issues. 12 The relative contribution of marginal mandibular nerve injury to appearance concerns in patients with neck dissection is unknown. The aim of this study were twofold: first, to determine the incidence of marginal mandibular nerve injury in a homogenous group of patients undergoing a neck dissection involving level 1 (submandibular triangle); and second, to examine the patients perception of their appearance with correlation to any subjective or objective deformity. PATIENTS AND METHODS An observational study was undertaken on patients identified using the Liverpool head and neck cancer database who were treated with neck dissection involving level 1 (submandibular triangle) for oral and oropharyngeal carcinoma over a 5-year period. Unilateral and bilateral neck dissections were included and in an attempt to eliminate confounding factors for assessment the following groups were excluded: 1. Buccal carcinoma 2. Cutaneous malignancy involving the face or lip 3. Lip or mandibular split access procedures 4. Segmental mandibular resections 5. Deliberate sacrifice of the marginal mandibular nerve Surgery was undertaken by 1 of 3 consultant surgeons or by trainees under their supervision. Skin flaps were raised in the subplatysmal plane using sharp dissection to the lower border of the mandible. An attempt to preserve the marginal mandibular nerve was made in all cases either through direct identification and retraction, or incision low through the deep cervical fascia with superior retraction. No patient underwent preoperative radiotherapy, though postoperative radiotherapy was used in selected cases. Patients were examined at their routine oncologic follow-up between 6 months and 5 years following their surgery to allow any traction neuropraxia to resolve. The examination was performed either by the first or second author using the lower lip domain of the facial nerve scoring system described by House and Brackmann 13 (HB) at both rest and with activity. Patients were also asked to fill out a short questionnaire with 8 items related to lip and smile function, swallowing function and their perception of appearance with responses graded on a Likert Scale. Data were collected on patient demographics, tumor site, TNM status, type of neck dissection, grade of surgeon, and use of radiotherapy. The study was registered with the local ethics committee and audit department. Informed consent was obtained from all patients. The amount of association between House- Brackmann level and ordinal responses to the marginal mandibular nerve injury questionnaire was measured by the Spearman coefficient (r). Association of clinical factors with injury or 674 Marginal Mandibular Nerve Injury during Neck Dissection HEAD & NECK DOI /hed May 2009

3 deficit was tested using Fishers exact text (2 2 tables) or the chi-square test (bigger tables) as appropriate. Statistical significance was regarded as a p <.05. RESULTS One hundred twenty-five patients were considered eligible for the study. Of these, 35 were deceased, 15 had been discharged, and 9 were lost to follow-up. The study cohort therefore comprised 66 patients who underwent 85 neck dissections (47 unilateral, 19 bilateral). The objective injury rate was 18% when analyzed by neck (15 of 85) and 23% when analyzed by patient (15 of 66). Unilateral neck dissections had an injury rate of 28% (13 of 47) and bilateral neck dissections had an injury rate of 11% (2 of 19). Three patients having unilateral neck dissections had grade 3 HB injuries; the remainder had grade 2 injuries. Both patients having bilateral neck dissections had grade 2 injuries on one side only. The characteristics of the patient cohort are shown in Table 1. In the questionnaire patients were first asked whether their smile now was any different from before their operation. In response 50% (33) stated there was no change, 41% (27) a minor change, 5% 3 that their smile bothered them but they remained active, 3%, 2 felt significantly disfigured by their smile and limited their activities due to the appearance of their smile. No one said they could not be with people due to the appearance of their smile, while 1 patient did not answer. Responses to questions 2 to 8 are shown in Table 2. One third of patients (32%) with a unilateral neck dissection reported a lower lip weakness on the operated side, compared with only 6% on the nonoperated side. Similarly 28% of patients with bilateral neck dissection reported a lower lip weakness on either side. One in 6 patients (15%) were bothered by the way their lower lip was moving, and similar percentages felt limited in terms of being able to eat (14%), smile (15%), or drink (18%), with 33% (21 of 65) feeling limited in at least 1 of these 3 aspects. For 9% of patients, other people had commented on their lower lip movement. Also, if they had weakness with lower lip movement patients were asked how this had improved. Of the 15 with weakness, 7 reported no improvement, while 8 said there had been improvement (3 a little bit, 2 a moderate amount, 3 quite a bit). Table 1. Characteristics of 66 patients. No. % Sex Male Age 65þ Time from operation <2 y Tumor site Oral tongue Oral FOM Oral other* 3 5 Oropharynx 5 8 Pathological staging pt pnþ Neck dissection Selective Radical/modified radical 4 6 Side of neck dissection Right Left Bilateral Grade of surgeon Unilateral cons Unilateral trainee Bilateral cons 4 6 Bilateral trainee 9 14 Bilateral mixed cons/trainee 6 9 Adjuvant radiotherapy Yes *Oral other tumor sites comprised retromolar (2), alveolus (1). House-Brackmann injury level 1 3 was associated with the extent of weakness of lower lip (r ¼.41, p ¼.001), of being bothered by the way the lower lip was moving (r ¼.41, p ¼.001), of being limited in the ability to smile because of the lower lip movement (r ¼.31, p ¼.01) and of receiving comment from others about lower lip movement (r ¼.46, p <.001). There was less association with whether smiles now were any different from before their operation (r ¼.10, p ¼.44), with ability to eat (r ¼.003, p ¼.98), or drink (r ¼.21, p ¼.09). Lower-lip weakness was reported in 60% (9 of 15) of those with and in 22% (11 of 50) of those without House-Brackmann injury. Deficits in lower lip movement were reported by 40% (6 of 15) and 8% (4 of 50) respectively, in ability to smile by 33% (5 of 15) and 10% (5 of 50) and in receiving comments from others by 33% (5 of 15) and 2% (1 of 50). All 3 with level 3 House-Brackmann injuries reported some deficit on the questionnaires (questions 1 8), when compared with 83% of those with level 2 injuries and 58% (29 of 50) of those at House-Brackmann level 1. Marginal Mandibular Nerve Injury during Neck Dissection HEAD & NECK DOI /hed May

4 Table 2. Responses to questions 2 to 8 of the marginal mandibular nerve injury questionnaire (65 responders). Likert responses to questions Unilateral neck dissection (n ¼ 47): Patient thinks lower lip is weak on the OPERATED side* Patient thinks lower lip is weak on the NON-OPERATED side* Bilateral neck dissection (n ¼ 18): Patient thinks lower lip is weak either on Left or on right side (worst stated)* Q4. Are you bothered by the way your lower lip MOVES following your surgery? Q5. Have you been limited in your ability to EAT because of your lower lip movement? Q6. Have you been limited in your ability to SMILE because of your lower lip movement? Q7. Have you been limited in your ability to DRINK because of your lower lip movement? Q8. Has any one commented about your lower lip movement? 1. Not at all 2. A little bit 3. A moderate amount 4. Quite a bit 5. A lot No. (%) with problem (ie with responses 2 5) (32) (6) (28) (15) (14) (15) (18) (9) *Questions 2 and 3 actually asked whether the patient thought their lower lip was weak on their left (Q2) or right (Q3) side. This information was converted into operated or nonoperated side for patients with unilateral neck dissection and the worst weakness stated for either side in patients having bilateral neck dissection. The association of clinical factors with injury or deficit reported on questionnaire is summarized in Table 3. There were no statistically significant associations with House-Brackmann injury. In regard to deficits reported from the questionnaire patients with more advanced T3/ T4 tumors reported more problems than patients with earlier tumors. Similarly, patients having adjuvant radiotherapy also reported higher levels of deficit than those treated by surgery alone. A difference in smile was more likely to be reported by patients under 65 years, and in patients having bilateral neck dissection. The ability to drink was most affected in patients with floor of mouth tumors, positive node tumors, bilateral neck dissections and following adjuvant radiotherapy. Women were more likely than men to report adverse comment by others of their lip movement. DISCUSSION Marginal mandibular nerve injury following neck dissection is an underreported complication. Previous studies 1,4 have examined a heterogenous group of patients with varying methodologies. The strengths of this study include the homogeneous patient population, the use of a validated assessment score (House and Brackmann), 13 and the inclusion of subjective patient reported data. The questionnaire used in this study was not validated as the commonly used assessment tools following the treatment of head and neck cancer do not include specific domains for lower lip function and smile esthetics. Despite this previous research from our unit indicates that a droopy lip following neck dissection is mentioned in the free text section of questionnaires such as the University of Washington Quality of Life. 14 The weakness of this study are its cross sectional nature and potentially those patients who had died or been discharged had a different rate of marginal mandibular nerve injury, or a different perception of their appearance issues. The sample size, however, is adequate, and the response rate was very high to the questionnaire as patients completed it at their outpatients visit. The operation notes did not record which method was used to preserve the marginal mandibular nerve so no comment can be made on methods of protection. The injury rate of 18% (by neck) and 23% (by patient) is very similar to the rate of 21% described by Nason et al 4 when the dissection includes level 1. The only other study that describes a rate of 1.26% 1 did not include level 1 dissection in which the marginal mandibular 676 Marginal Mandibular Nerve Injury during Neck Dissection HEAD & NECK DOI /hed May 2009

5 Table 3. Clinical characteristics by House-Brackmann injury and marginal mandibular nerve injury deficits stated on the questionnaire. HB injury Smile any different now (Q1) Lower lip weakness (Q2/Q3 ) Lower lip movement (Q4) Ability to Eat (Q5) Ability to Smile (Q6) Ability to Drink (Q7) Comments about lip movement (Q8) N* n % n % n % n % n % n % n % n % Deficit (Yes, No) stated on questionnaire in regard to: Male Female Age <65 y Age 65þ y Time from operation < 2y Time from operation 2y Oral Tongue Oral FOM Oral other* Oropharynx pt pt pn pnþ Selective dissection Radical/modified radical dissection Right neck dissection Left neck dissection Bilateral neck dissection Surgeon Unilateral consultant Unilateral SpR Bilateral consultant Bilateral SpR Bilateral Mixed consultant/spr Adjuvant radiotherapy No Adjuvant radiotherapy *One patient was graded for House-Brackmann injury but did not complete the questionnaire. For unilateral neck dissection this was as stated for the operated side, for bilateral neck dissection for either side. Denotes p <.05, Fishers Exact test or Chi-Squared test as appropriate (see statistical methods). nerve is most at risk. It is interesting to note that all the injuries in our study were grade 2 or 3 on the House Brackmann scale with no 4, 5, or 6 injuries. The possible reasons for this observed partial injury rate are difficult to ascertain; however, they may include the following: 1. The contribution of the cervical branches and the platysma muscle to lower lip symmetry which are invariably damaged while raising skin flaps 2. The possibility of multiple branches of the marginal mandibular nerve only some of which may be injured during neck dissection The rate in this study and that of Nason et al 1 are higher than typical figures for the removal of submandibular glands. There are several reasons why this may be the case. As discussed earlier the platysma and cervical branches are invariably damaged during neck dissection which may cause asymmetry. Surgeons may feel that oncologic principles overrule concerns about aesthetics and have a less conservative approach to the preservation of the marginal mandibular nerve. Finally, submandibular gland removal is performed in the plane deep to the cervical fascia which tends to protect Marginal Mandibular Nerve Injury during Neck Dissection HEAD & NECK DOI /hed May

6 nerve structures and the more extensive dissection with removal of lymphatic structures in neck dissection may lead to more frequent nerve injury. Fifty percent of patients stated that there was a change in there smile following their surgical procedure. The lack of correlation between this questionnaire response and the observed rate of marginal mandibular nerve injury points to the complexity of a patients perception of their appearance. This finding is confirmed by the higher rate of correlation between observed injury rate and lower lip weakness, lower lip movement, and ability to smile. A high number of patients commented on their dissatisfaction with their smile in relation to their dental status in the free text section of the questionnaire and it would be interesting to examine this facet of smile aesthetics in conjunction with lower lip function to determine their relative importance. The lack of objective injury association with the clinical factors listed in Table 3 appears to indicate that patient characteristics, pt stage, site, grade of surgeon, and postoperative radiotherapy have little impact on the rate of marginal mandibular nerve injury. We had suspected prior to the study that positive nodal disease might lead surgeons to be more radical in their dissection of level 1; however, this was not reflected in a higher injury rate. It is of course possible that the study had insufficient patients to identify a small but real difference. The other associations between the questionnaire responses and clinical factors provide a degree of internal validity. It is perhaps not surprising that younger patients and women patients report higher levels of problems with different smiles and comments about smile, respectively. Likewise, increased problems with swallowing may be expected with floor of mouth tumors and higher-stage disease. The rate of observed asymmetry of lower lip function following neck dissection is important for informed consent and appearance is a factor that impacts on the quality of life of head and neck cancer patients. 11,12,14 This study provides a basis for the informed consent process; however, the questionnaire responses indicate that a patient s perception of his or her aesthetic outcome is complex and dependant on many different factors including patient s sex, age, and dental state. Because of its cross sectional nature, this study cannot provide information on the nature of nerve injury: single versus multiple branch; marginal mandibular versus cervical branch. Nor can it differentiate between different methods of minimizing damage to the facial nerve. Multiple techniques have been used to preserve the facial nerve 5 7 and a prospective trial would be required to determine which of these methods may be superior. Oncologic principles must be obeyed, and the likelihood of involved facial nodes may necessitate a more radical approach. Such principles may compromise prospective studies. Any future trials on marginal mandibular nerve injury or its prevention should include a measure of the patients perception of their appearance, and a recording of their dental state. REFERENCES 1. Prim MP, De Diego JI, Verdaguer JM, Sastre N, Rabanal I. Neurological complications following functional neck dissection. Eur Arch Otorhinolaryngol 2006;263: Remmler D, Byers R, Scheetz J, et al. A prospective study of shoulder disability resulting from radical and modified neck dissections. Head Neck Surg 1986;8: Dingman RO, Grabb WC. Surgical anatomy of the mandibular ramus of the facial nerve based on the dissection of 100 facial halves. Plast Reconstr Surg 1962;29: Nason RW, Binahmed A, Torchia MG, Thliversis J. Clinical observations of the anatomy and function of the marginal mandibular nerve. 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The impact of head and neck cancer and facial disfigurement on the quality of life of patients and their partners. Head Neck 2003;25: Millsopp L, Brandom L, Humphris G, Lowe D, Stat C, Rogers S. Facial appearance after operations for oral and oropharyngeal cancer: a comparison of casenotes and patient-completed questionnaire. Br J Oral Maxillofac Surg 2006;44: House JW, Brackmann DE. Facial nerve grading system. Otolaryngol Head Neck Surg 1985;93: Katre C, Johnson IA, Humphris GM, Lowe D, Rogers SN. Assessment of problems with appearance following surgery for oral and oro-pharyngeal cancer using the University of Washington appearance domain and the Derriford appearance scale. Oral Oncol 2008;44: Marginal Mandibular Nerve Injury during Neck Dissection HEAD & NECK DOI /hed May 2009