Complications after surgery for benign parotid gland neoplasms: A prospective cohort study

Transcription

1 CLINICAL REVIEW David W. Eisele, MD, Section Editor Complications after surgery for benign parotid gland neoplasms: A prospective cohort study Johanna Ruohoalho, MD, 1 * Antti A. M akitie, MD, PhD, 1,2 Katri Aro, MD, PhD, 1 Timo Atula, MD, PhD, 1 Aaro Haapaniemi, MD, 1 Harri Keski S antti, MD, PhD, 1 Annika Takala, MD, PhD, 3 Leif J. B ack, MD, PhD 1 1 Department of Otorhinolaryngology Head and Neck Surgery, University of Helsinki and Helsinki University Hospital, Helsinki, Finland, 2 Division of Ear, Nose, and Throat Diseases, Department of Clinical Sciences, Intervention and Technology, Karolinska Institutet, Karolinska sjukhuset, Stockholm, Sweden, 3 Division of Anaesthesiology, Department of Anaesthesiology, Intensive Care, and Pain Medicine, University of Helsinki and Helsinki University Hospital, Helsinki, Finland. Accepted 22 March 2016 Published online 30 April 2016 in Wiley Online Library (wileyonlinelibrary.com). DOI /hed ABSTRACT: Background. Prospective studies on procedure-specific incidences of complications after benign parotid surgery are lacking. Predictive factors for postoperative facial dysfunction remain controversial. Methods. We conducted a prospective study on 132 patients undergoing parotid surgery for benign parotid neoplasms. We analyzed complication rates and assessed risk factors of postoperative transient facial palsy. Results. Facial palsy rate was 40.2% on the first postoperative day, 28.3% at 2 weeks, 3.9% at 6 months, and 1.6% at 12 months. Immediate postoperative palsy rates in subgroups of partial superficial parotidectomy, superficial parotidectomy, extended parotidectomy, and ECD were 41.5%, 43.8%, 53.8%, and 6.3%, respectively. Age, duration of surgery, and use of ultrasound knife were identified as risk factors for transient facial palsy. Conclusion. Depending on the operation type, up to half of the patients experience facial palsy after benign parotid surgery. Higher age and longer duration of operation increase the risk. The role of operative instrumentation requires further studies. VC 2016 Wiley Periodicals, Inc. Head Neck 39: , 2017 KEY WORDS: parotidectomy, postoperative complication, benign tumor, facial palsy, risk factors INTRODUCTION Parotid gland neoplasms account for approximately 2% of head and neck tumors and three fourths of them are benign. 1 Despite the recent developments in operative techniques, surgery for benign parotid tumors is associated with a relatively high rate of sequelae, most frequently temporary facial nerve palsy. 2 4 The morbidity after parotid surgery for benign tumors is addressed in a number of publications, 2 13 but only a few of these studies are prospective and they are limited with a small number of patients In retrospective studies on benign parotid surgery, reported rates for postoperative temporary facial palsy varies between 18% and 65% 2 10,14 and for permanent weakness between 0 and 19.6%. 2,4,6 10,14,15 This variation can be partly explained by different operation techniques and the timing of evaluation in relation to surgery. However, the most significant limitation of retrospective materials is the lack of standardized methods for the assessment of facial palsy. In addition, the contributory factors associated with post-parotidectomy facial palsy vary considerably from study to study and remain unclear. *Corresponding author: J. Ruohoalho, Department of Otorhinolaryngology Head and Neck Surgery, Helsinki University Hospital, P.O. Box 220, FI HUCH, Helsinki, Finland. johanna.ruohoalho@hus.fi Other commonly reported complications of benign parotid surgery are Frey s syndrome, salivary fistula, postoperative infection, hematoma/hemorrhagia, and sialocele. 2 4,7,14 The definitions for these complications are rarely described, and incidences have wide variance. Especially reporting Frey s syndrome is highly susceptible to biases, because it occurs with a delay and has variable severity. The purpose of this study was to analyze the incidence of and factors associated with postoperative facial nerve dysfunction in parotid surgery for benign neoplasms in a prospective study setting with strictly standardized evaluation methods. In addition, we report the incidences of other defined complications related to parotid surgery. MATERIALS AND METHODS Patients who underwent parotid surgery at the Department of Otorhinolaryngology Head and Neck Surgery, Helsinki University Hospital, Helsinki, Finland, between September 2011 and November 2012 were prospectively enrolled. Exclusion criteria were age <18 years, suspicion of malignancy or facial schwannoma, a tumor extending into the parapharyngeal space, and previous parotid surgery exposing the facial nerve. The study was approved by the Ethics Committee at the Helsinki University Hospital (DNRO 89/13/03/02C/2011) and is registered at ClinicalTrials.gov with the identifier NCT Each 170 HEAD & NECK DOI /HED JANUARY 2017

2 COMPLICATIONS OF BENIGN PAROTID SURGERY TABLE 1. Definitions of complications. Complications Definitions Facial palsy Temporary Any postoperative facial nerve dysfunction with full recovery within 12 mo of the operation. Permanent Any facial nerve dysfunction persisting at 12 mo after the operation. Sialocele/seroma Persistent fluid collection at surgical site lasting over 2 wk from surgery and needing treatment. Salivary fistula Salivary flow from surgical site lasting >7 d. Infection Purulent drainage from the wound and/or microbe isolated in an aseptically obtained culture of fluid or tissue from the surgical site and/or surgeon s diagnosis of infection based on signs or symptoms of infection (fever, pain or tenderness, localized swelling, redness, or heat) within 30 d of surgery. Hemorrhage/hematoma Primary Bleeding/collection of blood at surgical site within 24 h of operation. Secondary Bleeding/collection of blood at surgical site after 24 h of operation. Frey s syndrome Gustatory sweating occurring within 12 mo of operation and leading to outpatient contact. patient gave written informed consent to participate in the study. A wide range of demographic and clinical data were collected at the time of surgery, including age, sex, comorbidities (Charlson comorbidity index [CCI]), body mass index (BMI), American Society of Anesthesiologists (ASA) Physical Status Classification, patients functional status (Karnofsky score), cytological and histological reports, extent of operation, surgical technique, surgeon s experience, and duration of surgery. Extracapsular dissection (ECD) was defined as a resection of the tumor through parotid tissue without identifying the facial nerve trunk. Partial superficial parotidectomy (PSP) included any procedure in which the facial nerve trunk was exposed but only a part of the superficial lobe was removed. Superficial parotidectomy (SP) was defined as a total removal of the lateral lobe of the parotid gland. As previously proposed by Upton et al, 16 operation was considered as extended parotidectomy (EP), if the patient underwent total or subtotal parotidectomy, or if any portion of the deep lobe was removed. Accordingly, the tumors involving the deep lobe are the ones in the EP group, and the tumor locations are not separately reported. Altogether, 11 surgeons performed 1 to 25 operations each. Five of them were experienced head and neck surgeons with at least 10 years of experience on parotid surgery (each performing of the procedures included in the study), 4 were specialized ear, nose, and throat (ENT) doctors with a few years of experience on parotid surgery (1 16 operations each), and 2 were residents (1 2 operations each) operating under supervision of experienced surgeons. Electromyographic monitoring (NIM- Response; Medtronic, Minneapolis, MN) was used in all operations. Surgical techniques used were cold steel with bipolar dissection, cold steel combined with monopolar and bipolar dissection, and cold steel with ultrasound knife. We prospectively recorded the incidents of postoperative complications (facial palsy, Frey s syndrome, infections, hemorrhage [primary <24 hours postoperatively and secondary >24 hours], salivary fistula, and sialocele) occurring within 12 months of the operation. On the first postoperative day, 2 physicians, at least one of them being an experienced head and neck surgeon, separately performed clinical examination of all facial nerve branches. Even a minimal impairment in facial function was considered as palsy. If the facial nerve was postoperatively affected, we evaluated the patient again after 2 weeks, and, if necessary, after 6 months and 12 months. Any facial weakness from which the patient fully recovered during the follow-up period was defined as temporary. Permanent facial palsy was defined as facial weakness remaining after 12 months. Definitions of the complications are presented in Table 1. Before analyzing the data, all patient records were reviewed and any missing data in the prospectively collected background information were completed and the accuracy of complication data was verified. Statistical analyses were performed with SPSS software version 19.0 (IBM, Armonk, NY). Normality distribution of continuous variables was determined visually by using histograms and by using Skewness and Kurtosis measures. Comparisons between the operation groups were performed with the Kruskal Wallis test and 1-way analysis of variance. Risk factors of transient facial palsy were evaluated with logistic regression analysis. As several factors were significant based on univariate analysis, these were included in the multivariable logistic regression model to evaluate the independent risk factors of transient facial palsy. Odds ratios (ORs) with 95% confidence intervals (CIs) of relevant risk factors were reported. Two-sided p values <.05 were considered significant. RESULTS From September 2011 to November 2012, a total of 178 patients underwent parotid surgery at our department. The following patients who had parotid surgery during the study period were not included: age <18 years (n 5 4); malignancy (n 5 25); facial schwannoma (n 5 1); biopsy only (n 5 4); facial nerve exposed in previous surgery (n 5 3); preoperative facial palsy (n 5 1); and patients with tumor extending into the parapharyngeal space (n 5 4). Thus, altogether 136 patients were enrolled. In 4 initially recruited cases, preoperative fineneedle aspiration was suggestive of benign disease, but histological diagnosis was malignant, so they were subsequently excluded. The final study group comprised 132 patients. In 5 patients, the assessment of possible facial palsy on the first postoperative day was not performed in HEAD & NECK DOI /HED JANUARY

3 RUOHOALHO ET AL. TABLE 2. Patient characteristics and surgery-related factors (no. of patients 5 132). Characteristics No. of patients (%) 18 (3 55) Age, y, mean, (SD, range) 54.3 (6 15.4; 20 86) (61.4) >60 51 (38.6) Sex Male 59 (44.7) Female 73 (55.3) BMI, median (range) 26.8 ( ) (29.5) >25 74 (56.1) Side Right 75 (56.8) Left 57 (43.2) CCI 0 96 (72.7) 1 19 (14.4) 2 10 (7.6) 3 7 (5.3) ASA 1 48 (36.4) 2 49 (37.1) (26.5) Karnofsky score* Normal (100%) 98 (77.2) Decreased (90%) 29 (22.8) Extent of operation ECD 17 (12.9) PSP 57 (43.2) SP 32 (24.2) EP 26 (19.7) Surgical technique Cold steel 1 bipolar 69 (52.3) Cold steel 1 monopolar 1 bipolar 38 (28.8) Cold steel 1 ultrasound knife 25 (18.9) Experience of the surgeon Highly experienced 91 (68.9) ENT specialist 38 (28.8) Resident supervised by an 3 (2.3) experienced surgeon Duration of surgery (median, range) 2:02 (0:32 7:17) Histology Pleomorphic adenoma 63 (47.7) Warthin tumor 48 (36.4) Nonneoplastic cyst 10 (7.6) Oxyphilic adenoma 5 (3.8) Other 6 (4.5) Histological size of the tumor (mm; median, range) <20 mm 63 (53.8) 20 mm 54 (46.2) Abbreviations: BMI, body mass index; CCI, Charlson Comorbidity Index; ASA, American Society of Anesthesiologists Physical Status Classification; PSP, partial superficial parotidectomy; SP, superficial parotidectomy; EP, extended parotidectomy; ENT, ear, nose, and throat; ECD, extracapsular dissection. * Value missing in 5 patients. Value missing in 15 patients. the designed manner, and they were excluded from the analysis of facial palsy. Table 2 summarizes patient characteristics and surgeryrelated factors according to operation type. PSP was performed in 57 cases (43.2%), SP in 32 cases (24.2%), and EP in 26 cases (19.7%). Seventeen patients (12.9%) underwent ECD. The groups were different regarding the patients age and duration of surgery. The mean age was 54.3 years (SD ; range, years), patients being younger in the ECD group (PSP ; SD ; range, 20 85; SP ; SD ; range, 25 77; EP ; SD ; range, 20 86; and ECD ; SD ; range, 25 71; p <.05). The median duration of surgery was 2 hours and 2 minutes (range, 0:32 7:17). In the subgroups of PSP, SP, EP, and ECD, median durations of surgery were 1:55 (range, 1:05 3:00), 2:17 (range, 1:25 7:17), 2:29 (range, 1:19 4:32), and 1:05 (range, 0:32 2:25), respectively (p <.001). The most common final pathological diagnosis was pleomorphic adenoma (47.7%; n 5 63), followed by Warthin tumor (36.4%; n 5 48), nonneoplastic cyst (7.6%; n 5 10), and oxyphilic adenoma (3.8%; n 5 5). The other diagnoses included 2 fibromatous lesions, 1 lipoma, 1 oncocytic metaplasia, 1 intraparotid lymph node, and 1 basal cell adenoma. Table 3 shows the incidence of facial palsy by surgical groups in terms of timing in relation to surgery. The overall rate of postoperative facial palsy on the day after surgery was 40.2% (n 5 51 of 127 patients). Only the marginal branch was affected in 23 patients (45.1%) and palsy of several branches was seen in 25 patients (49.0%). Only 3 patients (5.9%) had functional deficiency restricted to a single branch other than the mandibular branch. After 2 weeks, facial nerve function was fully recovered in 29.4% of the affected patients. At 6 months, the recovery rate was 90.2%. Permanent facial palsy occurred in 2 patients (1.6%). In 1 of the patients, 2 minor buccal branches were attached to the tumor and sacrificed. No nerve adherence or visible damage of the facial nerve was noted with the other patient. Both the patients were in the PSP group and the remaining symptoms at 12 months were mild. The second most common complication was postoperative infection (12.8%) followed by salivary fistula (9.8%). Other complications are outlined in Table 4. For analyses of the risk factors of transient facial palsy, the duration of operation was transformed into categorical variable dividing the patients into 3 equal groups and the CCI and the surgeon s experience level were evaluated as dichotomous variables. Results of univariate logistic regression analysis are presented in Table 5. Patient s age >60 years, impaired functional status (decreased Karnofsky score), and higher comorbidity (elevated CCI) had statistically significant association on the development of transient facial palsy. Immediate postoperative palsy risk was significantly lower after ECD than after more extensive operations (PSP %; SP %; EP %; and ECD 5 6.3%; p <.05). At 2 weeks, patients in the EP group had significantly more palsies than patients in the other groups (PSP %; SP %; EP %, and ECD 5 0%; p <.05). The risk of palsy increased significantly both on postoperative day 1 and postoperative day 14 as the operating time was prolonged. Operations performed with an ultrasound knife had an increased risk of transient facial palsy compared with the other techniques (75.0% vs 32.0% [p <.001] on postoperative day 1, and 54.2% vs 22.3% [p <.01] on postoperative day 14). The palsy rate was lower with highly experienced surgeons than with less experienced 172 HEAD & NECK DOI /HED JANUARY 2017

4 COMPLICATIONS OF BENIGN PAROTID SURGERY TABLE 3. Incidence of facial palsy according to operation type and timing in relation to surgery. No. of patients with palsy (%) Time of evaluation All (n 5 127) ECD (n 5 16) PSP (n 5 53) SP (n 5 32) EP (n 5 26) Postoperative day 1 51 (40.2) 1 (6.3) 22 (41.5) 14 (43.8) 14 (53.8) Postoperative day (28.3) 0 14 (26.4) 9 (28.1) 13 (50.0) 6 mo 5 (3.9) 0 3 (5.7) 2 (6.3) 0 12 mo 2 (1.6) 0 2 (3.8) 0 0 Abbreviations: PSP, partial superficial parotidectomy; SP, superficial parotidectomy; EP, extended parotidectomy; ECD, extracapsular dissection. ones (34.9% vs 51.2% [p 5.08] on postoperative day 1, and 23.3% vs 39.0% [p 5.07] on postoperative day 14), but the difference did not reach significance. In multivariable logistic regression analysis, assessing the risk factors of transient facial palsy, advanced age, longer duration of surgery, and use of an ultrasound knife remained as independent risk factors both in the immediate postoperative period and on postoperative day 14 (Table 6). Extent of operation did not reach significance on postoperative day 1 multivariable analysis, and it was excluded from postoperative day 14 analysis because none of the patients in the ECD group had facial palsy at that point. CCI and Karnofsky score were left out from multivariable logistic regression models because of strong multicollinearity with age. As only 5 patients suffered from facial palsy at 6 months after operation, we were unable to perform logistic regression analyses of risk factors at that point. DISCUSSION We conducted a prospective study of 132 patients undergoing benign parotid surgery at our department. Our primary objective was to analyze the incidence of and contributing factors for temporary and permanent postoperative facial palsy with strictly standardized methods in facial nerve function evaluation. In addition, other complications occurring within 12 months of operation were recorded. In the present series, any type of facial nerve dysfunction was observed in 40.2% of patients on the first postoperative day and permanent facial palsy persisting after 12 months in 1.6% of patients. In prospective studies, the incidence of reported temporary facial nerve dysfunction after benign parotid surgery varies between 15% and 66%. 11,13,17,18 A meta-analysis performed by Witt 19 showed that the incidence of temporary facial palsy in benign parotid surgery was, on average, 60% for total parotidectomy, 26% for SP, 18% for PSP, and 11% for ECD. Considering the large proportion of patients with PSP and ECD in our material, our overall rate of temporal facial palsy (40.2%) was slightly higher than expected. This can be partly explained by the prospective setting, a standardized assessment method, and the strict criteria concerning the evaluation of facial dysfunction. In many studies, the time of first postoperative evaluation of facial nerve function has not been standardized, or the first follow-up has been at 1 week, so the present observed high rate is likely to derive also from the early evaluation of facial dynamics (postoperative day 1). Our palsy rate at 2 weeks was 28%, which is rather congruent with previous literature. Our permanent facial palsy rate of 1.6% was low and comparable to the range of 0% to 17% reported in a recent review on benign parotid surgery. 20 The methodology of facial nerve function assessment varies considerably in different studies. Especially in retrospective materials, the evaluation methods are rarely described, and the timing of the evaluation is not standardized. Furthermore, the site of nerve injury is seldom specified. In some studies, the time span of conducted procedures is decades. As the parotidectomy techniques have advanced from total and superficial parotidectomies to more conservative approaches, and the electromyographic monitoring during surgery has become a standard, the populations and complication rates may not be comparable. TABLE 4. Complications other than facial palsy according to the type of surgery. No. of patients with complications (%) Complication All (n 5 132) ECD (n 5 17) PSP (n 5 57) SP (n 5 32) EP (n 5 26) Infection 17 (12.9) 3 (17.6) 9 (15.8) 2 (6.3) 3 (11.5) Hemorrhage Primary 7 (5.3) 1 (5.9) 4 (7.0) 1 (3.1) 1 (3.8) Secondary 2 (1.5) 1 (5.9) 0 1 (3.1) 0 Frey s syndrome 4 (3.0) 0 1 (1.8) 1 (3.1) 2 (7.7) Salivary fistula 13 (9.8) 0 7 (12.3) 4 (12.5) 2 (7.7) Sialocele/seroma 8 (6.1) 1 (5.9) 5 (8.8) 0 2 (7.7) Abbreviations: PSP, partial superficial parotidectomy; SP, superficial parotidectomy; EP, extended parotidectomy; ECD, extracapsular dissection. HEAD & NECK DOI /HED JANUARY

5 RUOHOALHO ET AL. TABLE 5. Univariate logistic regression analysis of factors associated with the development of postoperative facial palsy on postoperative day 1 and postoperative day 14 (no. of patients 5 127). Postoperative day 1 Postoperative day 14 Parameter Palsy % p value OR (95% CI) Palsy % p value OR (95% CI) Age, y Ref Ref. 1 > ( ) ( ) Sex Male 32.1 Ref Ref. 1 Female ( ) ( ) BMI Ref Ref. 1 > ( ) ( ) CCI Ref Ref ( ) ( ) ASA Ref Ref ( ) ( ) ( ) ( ) Karnofsky score 100% 34.7 Ref Ref. 1 90% ( ) ( ) Surgical technique Cold steel 1 monopolar 1 bipolar 21.6 Ref Ref. 1 Cold steel 1 bipolar ( ) ( ) Cold steel 1 ultrasound knife 75.0 < ( ) ( ) Experience of the surgeon Highly experienced 34.9 Ref Ref. ENT specialist/supervised resident ( ) ( ) Extent of operation PSP 41.5 Ref Ref. 1 SP ( ) ( ) EP ( ) ( ) ECD ( ) 0 Duration of surgery 1: Ref Ref. 1 1:50 2: ( ) ( ) 2: < ( ) ( ) Operated side Left 37.7 Ref Ref. 1 Right ( ) ( ) Histology Warthin tumor 35.6 Ref Ref. 1 Pleomorphic adenoma ( ) ( ) Other ( ) ( ) Histological size of the tumor <20 mm 37.3 Ref Ref 1 20 mm ( ) ( ) Abbreviations: OR, odds ratio; CI, confidence interval; Ref., reference; BMI, body mass index; CCI, Charlson Comorbidity Index; ASA, American Society of Anesthesiologists Physical Status Classification; ENT, ear, nose, and throat; PSP, partial superficial parotidectomy; SP, superficial parotidectomy; EP, extended parotidectomy; ECD, extracapsular dissection. Figures in boldface indicate statistical significance. Our method of 2 physicians assessing the postoperative facial dynamics has not been described in previous prospective studies on facial palsy after benign parotid surgery. Furthermore, prospective studies on complications of benign parotid surgery, including all types of operations, could not be found. As the operations included in this study were carried out over a time frame of 14 months, they are comparable with each other in terms of technical details. Malignancy 16,21 23 and the extent of surgery 4,5,7,16,24,25 have been recognized as evident risk factors for postoperative facial palsy in parotid surgery, but controversy remains regarding the other risk factors. Association with advanced age, 8,24,26 tumor size, 8,21 inflammatory histology, 2 revision surgery, 4,27 operating time, 8 tumor location in the deep lobe, 27 and diabetes 5 have been described. Our findings reinforce the role of advanced age, the extent of surgery, and longer operating time in the development of postoperative facial dysfunction. However, as the longer duration of surgery may reflect the difficulty and extent of the operation, and surgeons experience 174 HEAD & NECK DOI /HED JANUARY 2017

6 COMPLICATIONS OF BENIGN PAROTID SURGERY TABLE 6. Multivariable logistic regression analysis of the risk factors for facial palsy on postoperative day 1 and postoperative day 14. Postoperative day 1 Postoperative day 14 Parameter Palsy % p value OR (95% CI) Palsy % p value OR (95% CI) Age, y Ref Ref. 1 > ( ) ( ) Surgical technique Cold steel 1 monopolar 1 bipolar 21.6 Ref Ref. 1 Cold steel 1 bipolar ( ) ( ) Cold steel 1 ultrasound knife 75.0 < ( ) 54.2 < ( ) Duration of surgery 1: Ref Ref. 1 1:50 2: ( ) ( ) 2: ( ) ( ) Extent of operation * PSP 41.5 Ref. 1 SP ( ) EP ( ) ECD ( ) Abbreviations: OR, odds ratio; CI, confidence interval; Ref., reference; PSP, partial superficial parotidectomy; SP, superficial parotidectomy; EP, extended parotidectomy; ECD, extracapsular dissection. * Extent of operation could not be analyzed in postoperative day 14 multivariable analysis because no palsies occurred in the extracapsular dissection group. Figures in boldface indicate statistical significance. level and personal operative speed may also impact on operating time, its role as an independent risk factor seems controversial. In addition, the operation technique reached significance in the risk factor analysis. The operations carried out with an ultrasound knife seemed to lead to an increased risk of transient facial palsy. As only 1 experienced head and neck surgeon in our institution has adopted the technique and the instrumentation is only one of the elements in a complex operation, we cannot rule out the presence of confounding factors in this finding. Despite the possibility of bias, we consider the reporting of this finding important, as the role of operative instrumentation is largely unknown and will require further research. The occurrence of Frey s syndrome varies between 0% and 66% and depends strongly on the methodological factors and diagnostic examinations. In this study, the diagnosis of Frey s syndrome was made based on spontaneous clinical complains of the patients, as our scope was to register the complications with clinical relevance. Our rate of 3.0% is similar to that reported in other studies with the same methodology. 8,16 Frey s syndrome is thought to be a result of aberrant reinnervation between the damaged auriculotemporal nerve branches stimulating parotid secretion and the sympathetic nerve branches of cutaneous eccrine sweat glands. 1 In the light of this reinnervation theory, our follow-up time of 12 months was rather short and may partly explain the low incidence. The other postoperative complication rates (sialocele, salivary fistula, infection, and hemorrhage) at our institution are comparable to those previously reported in the literature. 2,13,14 Our study had some limitations. Although we had standardized the methods of evaluation of facial palsy, other complications were not assessed in such a strict manner. We did not arrange regular follow-up visits for patients with normal facial function on the first postoperative day. Thereby, complications other than facial dysfunction were registered based on the patient contacting our department if they were experiencing problems in recovery. In the assessment of facial nerve function, the degree of nerve injury was not recorded, because, in the present study, our primary purpose was to report the rate of any postoperative facial nerve palsy, the pattern of its temporary or permanent character, and the affected branches. We consider that the use of available grading scales to determine the degree of facial dysfunction would not have provided added value for this study. Even though more than 20 physicians participated in the evaluation process, they were all given detailed instructions regarding the methodology to assure that the assessment followed high standards. Moreover, to stress the importance of the objectivity of facial function evaluation, we wanted it to be a consensus of 2 doctors. Five patients had to be excluded from the analysis of facial palsy because the standardized assessment of nerve function was not implemented as planned. All except one of them were operated on Friday, which led to the challenge of getting 2 physicians evaluation outside standard working hours on the first postoperative day, although, in most of the cases, it was achieved. Long time interval between the second and third evaluation (2 weeks to 6 months) may also be considered a limitation. However, any persisting dysfunction would not have led to any actions at that point. In conclusion, preoperative patient information should emphasize the observation that, depending on the extent of the operation, up to half of the patients experience some degree of facial palsy after benign parotid surgery. However, this dysfunction is rarely permanent. Patients age, duration of surgery, and surgical technique used may influence the risk of postoperative facial dysfunction. The HEAD & NECK DOI /HED JANUARY

7 RUOHOALHO ET AL. role of operative instrumentation requires further clarification with larger scale randomized prospective studies. Acknowledgment The authors thank Tero Vahlberg (University of Turku, Turku, Finland) for support and assistance in statistical analysis and reporting of the results. REFERENCES 1. Cummings CF, Flint PW, eds. Cummings otolaryngology head & neck surgery. 5th ed. Philadelphia, PA: Mosby Elsevier; Nouraei SA, Ismail Y, Ferguson MS, et al. Analysis of complications following surgical treatment of benign parotid disease. ANZ J Surg 2008;78: Chulam TC, Noronha Francisco AL, Goncalves Filho J, Pinto Alves CA, Kowalski LP. Warthin s tumour of the parotid gland: our experience. Acta Otorhinolaryngol Ital 2013;33: Guntinas Lichius O, Klussmann JP, Wittekindt C, Stennert E. Parotidectomy for benign parotid disease at a university teaching hospital: outcome of 963 operations. Laryngoscope 2006;116: Yuan X, Gao Z, Jiang H, et al. Predictors of facial palsy after surgery for benign parotid disease: multivariate analysis of 626 operations. Head Neck 2009;31: Sethi N, Tay PH, Scally A, Sood S. Stratifying the risk of facial nerve palsy after benign parotid surgery. J Laryngol Otol 2014;128: Koch M, Zenk J, Iro H. Long-term results of morbidity after parotid gland surgery in benign disease. Laryngoscope 2010;120: Guntinas Lichius O, Gabriel B, Klussmann JP. Risk of facial palsy and severe Frey s syndrome after conservative parotidectomy for benign disease: analysis of 610 operations. Acta Otolaryngol 2006;126: Dell Aversana Orabona G, Bonavolonta P, Iaconetta G, Forte R, Califano L. Surgical management of benign tumors of the parotid gland: extracapsular dissection versus superficial parotidectomy our experience in 232 cases. J Oral Maxillofac Surg 2013;71: Marshall AH, Quraishi SM, Bradley PJ. Patients perspectives on the shortand long-term outcomes following surgery for benign parotid neoplasms. J Laryngol Otol 2003;117: Roh JL, Park CI. Function-preserving parotid surgery for benign tumors involving the deep parotid lobe. J Surg Oncol 2008;98: O Regan B, Bharadwaj G. Comparison of facial nerve injury and recovery rates after antegrade and retrograde nerve dissection in parotid surgery for benign disease: prospective study over 4 years. Br J Oral Maxillofac Surg 2011;49: Thahim K, Udaipurwala IH, Kaleem M. Clinical manifestations, treatment outcome and post-operative complications of parotid gland tumours an experience of 20 cases. J Pak Med Assoc 2013;63: Laccourreye H, Laccourreye O, Cauchois R, Jouffre V, Menard M, Brasnu D. Total conservative parotidectomy for primary benign pleomorphic adenoma of the parotid gland: a 25-year experience with 229 patients. Laryngoscope 1994;104: Papadogeorgakis N, Kalfarentzos EF, Vourlakou C, Malta F, Exarhos D. Simultaneous pleomorphic adenoma of the left parotid gland and adenoid cystic carcinoma of the contralateral sublingual salivary gland: a case report. Oral Maxillofac Surg 2009;13: Upton DC, McNamar JP, Connor NP, Harari PM, Hartig GK. Parotidectomy: ten-year review of 237 cases at a single institution. Otolaryngol Head Neck Surg 2007;136: O Regan B, Bharadwaj G, Bhopal S, Cook V. Facial nerve morbidity after retrograde nerve dissection in parotid surgery for benign disease: a 10-year prospective observational study of 136 cases. Br J Oral Maxillofac Surg 2007;45: Grosheva M, Klussmann JP, Grimminger C, et al. Electromyographic facial nerve monitoring during parotidectomy for benign lesions does not improve the outcome of postoperative facial nerve function: a prospective two-center trial. Laryngoscope 2009;119: Witt RL. The significance of the margin in parotid surgery for pleomorphic adenoma. Laryngoscope 2002;112: Borumandi F, George KS, Cascarini L. Parotid surgery for benign tumours. Oral Maxillofac Surg 2012;16: Dulguerov P, Marchal F, Lehmann W. Postparotidectomy facial nerve paralysis: possible etiologic factors and results with routine facial nerve monitoring. Laryngoscope 1999;109: Ellingson TW, Cohen JI, Andersen P. The impact of malignant disease on facial nerve function after parotidectomy. Laryngoscope 2003;113: Bron LP, O Brien CJ. Facial nerve function after parotidectomy. Arch Otolaryngol Head Neck Surg 1997;123: Szwedowicz P, Osuch Wojcikiewicz E, Bruzgielewicz A, CheR cinski P, Nyckowska J. Complications of parotid surgery for pleomorphic adenomas [in Polish]. Otolaryngol Pol 2011;65(5 Suppl): Witt RL, Rejto L. Pleomorphic adenoma: extracapsular dissection versus partial superficial parotidectomy with facial nerve dissection. Del Med J 2009;81: Mra Z, Komisar A, Blaugrund SM. Functional facial nerve weakness after surgery for benign parotid tumors: a multivariate statistical analysis. Head Neck 1993;15: Musani MA, Zafar A, Suhail Z, Malik S, Mirza D. Facial nerve morbidity following surgery for benign parotid tumours. J Coll Physicians Surg Pak 2014;24: HEAD & NECK DOI /HED JANUARY 2017