Preoperative determination of the location of parotid gland tumors by analysis of the position of the facial nerve

MR-Neurography of the facial nerve in parotid tumors: intra-parotid nerve visualization and surgical correlation

PURPOSE

One of the most severe complications in surgery of parotid tumors is facial palsy. Imaging of the intra-parotid facial nerve is challenging due to small dimensions. Our aim was to assess, in patients with parotid tumors, the ability of high-resolution 3D double-echo steady-state sequence with water excitation (DE3D-WE) (1) to visualize the extracranial facial nerve and its tracts, (2) to evaluate their relationship to the parotid lesion and (3) to compare MRI and surgical findings.

METHODS

A retrospective study was conducted including all patients with parotid tumors, who underwent MRI from April 2022 to December 2023. Two radiologists independently reviewed DE3D-WE images, assessing quality of visualization of the facial nerve bilaterally and localizing the nerve's divisions in relation to the tumor. MRI data were compared with surgical findings.

RESULTS

Forty consecutive patients were included (M:F = 22:18; mean age 56.3 ± 17.4 years). DE3D-WE could excellently visualize the nerve main trunk and the temporofacial division in all cases. The cervicofacial branch was visible in 99% of cases and visibility was good. Distal divisions were displayed in 34% of cases with a higher visibility on the tumor side (p < 0.05). Interrater agreement was high (weighted kappa 0.94 ± 0.01 [95% CI 0.92-0.97]). Compared to surgery accuracy of MRI in localizing the nerve was 100% for the main trunk, 96% for the temporofacial and 89% for the cervicofacial branches.

CONCLUSIONS

Facial nerve MR-neurography represents a reliable tool. DE3D-WE can play an important role in surgical planning of patients with parotid tumors, reducing the risk of nerve injury.

The Relationship Between the Retromandibular Vein and the Extratemporal Segment of the Facial Nerve: A Prospective Cadaveric Study of 24 Hemifaces

INTRODUCTION

Anatomical preservation and functional integrity of the facial nerve (FN) are the main concerns of parotid surgery. Even though a variety of anatomical landmarks have been proposed and widely utilized, temporal or permanent postoperative FN palsy is still a significant comorbidity of parotid surgery. Therefore, the literature must fully elucidate the consistency of the anatomical relationship between the FN and the retromandibular vein (RMV).

METHODS

We conducted a cadaveric study of 24 hemifaces to map the relationship between the FN and the RMV. Three distinct patterns were identified. Fourteen of the hemifaces were males, and 10 were females. Thirteen cadaveric dissections were performed on the right side and 11 on the left side.

RESULTS

Our study found three distinct patterns and proposed a classification system. Type I (66.7%) is when the nerve lies exclusively lateral to the RMV. Type II (29.2%) is when the FN lies superficial to the RMV, but its mandibular branch lies deep to the anterior branch of the RMV, and type III (4.1%) is when the FN lies exclusively medial to the RMV.

CONCLUSION

The FN and RMV relationship is not constant, and surgeons should be aware of every anatomical variation. Especially in cases where the FN is estimated to lie more in-depth to the level of the RMV, a retrograde approach may be required to avoid a FN injury.

The efficacy of clinicopathological and imaging features in differentiating benign from malignant parotid micro- and minitumors: a retrospective analysis

OBJECTIVE

To compare clinicopathological and imaging features of micro- and minitumors of the parotid gland and provide a reference for preoperative prediction of benign vs malignant status.

STUDY DESIGN

Patients with parotid gland tumors treated surgically were selected. Relevant clinicopathological and imaging data were collected for patients with maximum tumor diameters ≤20 mm on preoperative computed tomography (CT). The lesions were divided into 2 groups, microtumors and minitumors, based on maximum tumor diameter. CT imaging features of benign and malignant tumors were compared through binary logistic regression analysis.

RESULTS

Microtumors and minitumors were categorized by maximum diameters <10 mm (n = 74) and 10-20 mm (n = 611), respectively. Benign and malignant minitumors exhibited significant differences in boundary, tumor density, margin morphology, spiculation margin, and CT values in the plain and arterial phase (P ≤ .027), resembling those found in typical malignant parotid gland tumors. However, no significant differences were observed between benign and malignant microtumors. Logistic regression analysis identified boundary, margin morphology, and spiculation margin as independent predictors of malignancy. The prediction model excelled in identifying benign lesions but was less successful in identifying malignancies.

CONCLUSION

Parotid gland minitumors had imaging features similar to typical larger malignant tumors. Active exclusion of the malignant risk and early surgical treatment is recommended for these tumors.

Surgical treatment for a giant venous malformation of the parotid area

This report discusses the surgical treatment of a giant parotid venous malformation (VM) that had grown beyond the dimensions of the parotid gland, causing significant displacement. Special attention was paid to identifying the facial nerve, which was found to traverse the surface of the VM. Although, in our case, the facial nerve ran superficially on the VM, it is possible that a portion of it penetrated the mass. A two-stage excision and revision surgery strategy was employed due to the complexity of assessing deformities after removing the giant lesion. During the initial surgery, the displaced superficial lobe of the parotid gland was repositioned to its original location and carefully laid over the facial nerve, ensuring its safety during the subsequent procedure.

Ultrasonographic Localization of Parotid Gland Tumor Relative to the Facial Nerve Using Stensen's Duct Criterion

PURPOSE

During the preoperative evaluation of parotid gland tumors, 1 of the main concerns is to determine the location of the tumors in relation to the facial nerve. This study aims to assess the value of ultrasound for determination of the location of parotid gland tumors in relation to the facial nerve using Stensen's duct.

METHODS

This is a retrospective cross-sectional study at a single institute. The subjects who underwent preoperative ultrasound and parotidectomy for parotid gland tumors were included. The subjects with incomplete operative records or no reference standard for the location of parotid gland tumor were excluded. The primary predictor was ultrasound tumor location, which was defined as the location of parotid gland tumors determined by preoperative ultrasound as to whether the tumors were superficial or deep to the facial nerve. The operative records were used as the reference standard for the location of parotid gland tumors. The primary outcome was diagnostic performances of preoperative ultrasound in predicting the location of parotid gland tumors, which were calculated by comparing ultrasound tumor location to the reference standard. Covariates were sex, age, type of surgery, tumor size, and tumor histology. Data analysis involved descriptive and analytic statistics; P < .05 was considered significant.

RESULTS

One hundred and two of 140 eligible subjects met inclusion and exclusion criteria. There were 50 male and 52 female, with a mean age of 53.3 years. Ultrasound tumor location was classified as deep in 29 subjects, superficial in 50, and indeterminate in 23. The reference standard was deep in 32 subjects and superficial in 70. Indeterminate ultrasound tumor location results were grouped as either deep or superficial to make every possible cross table in which ultrasound tumor location results were presented as a dichotomy. The mean sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of the ultrasound to predict the deep location of parotid tumors were 87.5, 82.1, 70.2, 93.6, and 83.8%, respectively.

CONCLUSIONS

Stensen's duct on ultrasound can be a useful criterion to determine the location of parotid gland tumor relative to the facial nerve.

Does three-dimensional intraglandular location predict malignancy in parotid tumors?

Tumors arising within the parotid encompass a heterogeneous mix of benign and malignant neoplasms and other tissue growths. The purpose of this study was to determine the association between the location of intraparotid masses and the risk of malignancy. A retrospective cohort study was performed of patients diagnosed with parotid tumors following open tumor excision. The primary predictor variable was the location of the epicenter of the tumor in three-dimensional space, as determined from preoperative imaging. Other variables were patient demographics and clinical parameters. The primary outcome variable was the final histopathologic diagnosis of a benign or malignant process. A χ² analysis was performed to test for any significant associations between demographic, clinical, and radiographic factors in relation to the outcome, and backwards stepwise logistic regression analysis was used to control for variables. Both increasing age (P = 0.002) and the presence of local pain (P = 0.020) were associated with malignancy. Tumors located anterior to the posterior border of the retromandibular vein had 2.18 times higher odds of malignancy (95% confidence interval 1.13-4.21; P = 0.020). Multivariate regression analysis suggested that patient age, the presence of pain, and tumor location anterosuperiorly and superoinferiorly could all assist in determining the odds of malignancy.

Comparison of different methods for evaluating the relationship between facial nerve and benign parotid tumors

Objectives

The goals of benign parotid gland tumor resection are complete resection of the lesion and preservation of the facial nerve function. As the facial nerve cannot be directly visualized via imaging modalities, several methods, including the facial nerve line, Utrecht line, retromandibular vein, Stenon duct, and minimum fascia-tumor distance techniques, have been developed to estimate its location. However, there are no reports on their accuracy in determining tumor location. In the present study, we aimed to assess the diagnostic accuracy of these methods based on tumor location.

Methods

This retrospective study analyzed medical records and histological reports of 359 patients with various types of benign parotid gland tumors who underwent a parotidectomy between April 2014 and March 2020. The tumor location was subdivided into the following sections: anterior, superior, inferior, and middle. The tumor location was estimated using five methods: facial nerve line, Utrecht line, retromandibular vein, Stenon duct, and minimum fascia-tumor distance. The final diagnosis of superficial or deep lobe tumor was made based on surgical findings.

Results

Each method showed a higher accuracy for superficial tumors (was more than 90%) than for deep lobe tumors. In contrast, for deep lobe tumors, the accuracy of diagnosis with the facial nerve line, Utrecht line, and retromandibular vein methods was low, in the 30% range. Among all methods, the Stenon duct method had the highest accuracy in the diagnosis of deep lobe tumors. The SD method was most useful in cases where both the duct and tumors were detected. The minimum fascia-tumor distance method had the second highest diagnostic accuracy (63%); however, for anterior tumors, it tended to provide false negatives.

Conclusions

All tested methods were useful in diagnosing superficial lobe tumors; however, they were not helpful in diagnosing deep lobe tumors, especially anterior tumors.

The external jugular vein axis: a new anatomical landmark for pre-operative prediction of the location of parotid gland tumours

The relationships between parotid tumours and the facial nerve determine duration of surgical procedure and risks involved. As the division of the facial nerve is not visible using standard imaging techniques, other anatomical landmarks are used to determine the pre-operative location of tumours. This retrospective study aimed to evaluate reliability of the 'external jugular vein axis' compared with other landmarks generally used in imaging, such as the retromandibular vein, Conn's arc, the facial nerve line and the Utrecht line. Forty-eight pre-operative imaging exams of patients who underwent parotid benign tumour surgery between 2010 and 2016 were examined. We determined the location of tumour using the five markers. A pre-operative simulation was compared with the description given by the surgeon intraoperatively, in terms of sensitivity and specificity for each marker. External jugular vein axis and retromandibular vein are the most sensitive markers for locating suprafacial tumours (Se = 1). External jugular vein axis and Conn's arc are the most specific markers for locating suprafacial tumours (Spe = 0.92). External jugular vein axis is reproducible and present on all radiological sections, thereby overcoming any anatomical and nomenclature variations. This landmark appears to be the most representative marker of the dividing branches of the facial nerve.

Surgery combined with iodine-125 interstitial brachytherapy for treatment of parotid adenoid cystic carcinoma: A single-institution experience

PURPOSE

The purpose of this study was to analyze the effectiveness and safety of the combination of surgery plus postoperative iodine-125 interstitial brachytherapy for treatment of adenoid cystic carcinoma (ACC) of the parotid.

METHODS AND MATERIALS

This study included a retrospective analysis of the data of patients who underwent postoperative iodine-125 interstitial brachytherapy for histology-confirmed ACC of the parotid between January 2002 and November 2018 in Peking University Hospital of Stomatology. Acute and long-term radiation-related toxicities were assessed by the criteria of the Radiation Therapy Oncology Group and European Organization for Research and Treatment of Cancer. Multivariate analysis was used to identify the factors affecting overall survival, disease-free survival (DFS), and distant metastasis-free survival (DMFS).

RESULTS

A total of 86 patients (53 women; median age 50 years, SD = 13.1) were included. Median followup was for 45.5 months. About half the patients (44/86, 51.3%) had clinical stage IV disease. Local recurrence occurred in 11 of 86 (12.8%) patients. No patient had nodal metastases in the followup period. The five- and 10-year DFS rates were 74.8% and 66.6%, respectively. The mean DMFS was 60.6 months. On multivariate analysis, preoperative facial palsy, type of surgery, perineural spread (PNS), and distant metastases were independent prognostic factors for DFS; preoperative facial palsy, nodal metastases, and PNS were independent prognostic factors for overall survival; and preoperative facial palsy, type of surgery, PNS, and pathological type were independent prognostic factor for DMFS.

CONCLUSIONS

The combination of surgery and iodine-125 interstitial brachytherapy appears to be an effective and safe treatment for primary ACC of the parotid.

A new landmark for the identification of the facial nerve during parotid surgery: A cadaver study

OBJECTIVE

Precise knowledge of facial nerve anatomy is crucial for parotid surgery. Although several surgical landmarks to identify the facial nerve have been described in literature, their position is variable, inconsistent, and difficult to follow in some cases. The purpose of this study was to prove that the facial nerve trunk (FNT) is located midway between the mastoid tip (MT) and osteocartilaginous junction of the external auditory canal (EAC).

METHODS

A prospective study of 7 frozen cadaver specimens, of which 13 facial sides were dissected. The distances between the osteocartilaginous junction and the MT, between the FNT and the MT, and between the FNT and the osteocartilaginous junction were recorded, respectively.

RESULTS

The distance between the osteocartilaginous junction and the MT ranged from 17 to 21 mm, with a mean of 19.5 mm (SD = ±1.19). The mean distances between the osteocartilaginous junction and the FNT and between the MT and the FNT were 9.2 mm (±1.58) and 10.3 mm (±1.79), respectively.

CONCLUSION

The FNT was consistently located close to the midpoint between mastoid tip inferiorly and bony-cartilaginous junction of the EAC superiorly.

LEVEL OF EVIDENCE

NA.

Magnetic resonance diffusion weighted imaging using constrained spherical deconvolution-based tractography of the extracranial course of the facial nerve

OBJECTIVE

To evaluate the accuracy of magnetic resonance diffusion weighted imaging (DWI) featuring constrained spherical deconvolution-based tractography in tracking the extracranial course of the facial nerve to provide a reliable facial nerve map to facilitate well-tolerated and effective tumor resection.

STUDY DESIGN

Magnetic resonance DWI was conducted on 2 parotid-healthy cadaveric patients with various protocols to identify the best representation of the extracranial facial nerve tract. This was subsequently correlated to dissection of the facial nerves to ascertain anatomic validation. These protocols were applied to 2 live, parotid-healthy patients to assess feasibility of in vivo facial nerve tract identification.

RESULTS

Correlations between imaged tracts and the anatomic course of the extracranial facial nerve were identified to an accuracy of 1 mm. The main trunk and bifurcation tracts were identified on imaging. Fractional anisometry values in cadaveric and live patients were within the range expected for the facial nerve within the parotid gland.

CONCLUSIONS

Our results indicated the potential for accurate 3-dimensional visualization of the extracranial course of the facial nerve, which could have diagnostic implications in differentiating benign from malignant tumors and, crucially, neural involvement. Preoperative planning applications of DWI could help in planning surgical approaches and providing focused counseling.

Displacement of the Facial Nerve by Deep Parotid Lobe Lesions in the Pediatric Population

Objectives

To describe and investigate facial nerve displacement in deep lobe parotid lesions in children and to determine clinical and radiographic predictors of abnormal facial nerve position.

Methods

Retrospective case review of children who underwent total parotidectomy for deep lobe parotid lesions at a tertiary care center between January 2014 and December 2017. Aberrant facial nerve trajectory was defined as ascension of the nerve at an angle of 45° or greater. Elongation was defined as the main trunk >2 cm in length. Patient demographics, radiographic, pathologic results, postoperative nerve weakness, and intraoperative nerve findings were collected. Wilcoxon rank‐sum test and Fisher's exact test were used to assess the associations between variables of interest and facial nerve position.

Results

A total of 20 patients were included. The mean age was 7.7 ± 5 years. The most common pathologies were lymphatic malformation, pleomorphic adenoma, and first branchial cleft cyst. Twelve out of twenty (60.0%) patients had abnormal intraoperative facial nerve position. There was no significant difference in distribution of pathologies between those with or without an abnormal intraoperative nerve position (P = .41). Neither radiographic lesion size nor distance between the lesion and proximal portion of the facial nerve (mastoid tip) were associated with abnormal facial nerve position intraoperatively.

Conclusion

Pediatric deep lobe parotid lesions can displace the facial nerve and distort its anatomy in a posterior lateral direction, in approximately 60% of patients. Statistical analysis of increased numbers of patients to further define predictors of aberrant nerve course is warranted.

Level of Evidence

4.

Anatomy of the facial nerve branching patterns, the marginal mandibular branch and its extraparotid ramification in relation to the lateral palpebral line

Background: Surgery of face and parotid gland may cause injury to branches of the facial nerve, which results in paralysis of muscles of facial expression. Knowledge of branching patterns of the facial nerve and reliable landmarks of the surrounding structures are essential to avoid this complication. Objective: Determine the facial nerve branching patterns, the course of the marginal mandibular branch (MMB), and the extraparotid ramification in relation to the lateral palpebral line (LPL). Materials and methods: One hundred cadaveric half-heads were dissected for determining the facial nerve branching patterns according to the presence of anastomosis between branches. The course of the MMB was followed until it entered the depressor anguli oris in 49 specimens. The vertical distance from the mandibular angle to this branch was measured. The horizontal distance from the LPL to the otobasion superious (LPL-OBS) and the apex of the parotid gland (LPL-AP) were measured in 52 specimens. Results: The branching patterns of the facial nerve were categorized into six types. The least common (1%) was type I (absent of anastomosis), while type V, the complex pattern was the most common (29%). Symmetrical branching pattern occurred in 30% of cases. The MMB was coursing below the lower border of the mandible in 57% of cases. The mean vertical distance was 0.91±0.22 cm. The mean horizontal distances of LPL-OBS and LPLAP were 7.24±0.6 cm and 3.95±0.96 cm, respectively. The LPL-AP length was 54.5±11.4% of LPL-OBS. Conclusion: More complex branching pattern of the facial nerve was found in this population and symmetrical branching pattern occurred less of ten. The MMB coursed below the lower border of the angle of mandible with a mean vertical distance of one centimeter. The extraparotid ramification of the facial nerve was located in the area between the apex of the parotid gland and the LPL.

Easy and Safe Method for Facial Nerve Identification in Parotid Surgery

Background A safe and easy anatomical landmark is proposed to identify the facial nerve in parotid surgery. The facial nerve forms the center point between the base of the styloid process and the origin of the posterior belly of the digastric muscle. Objective To evaluate the consistency, accuracy, and safety of the landmark in identifying the facial nerve. Methods The study was designed in three steps: a cadaver study, a radiologic study, and a prospective clinical study. Anatomy was initially studied in two cadavers. Then the images of 200 temporal styloid regions were studied for consistency of the presence of the styloid base. In the second part of the radiologic study, the distance between the styloid base and the origin of the posterior belly of the digastric muscle was studied in 50 parotid regions. The clinical study involved 25 patients who underwent parotidectomy. Results The styloid base was present in all the images studied. The mean distance between the styloid base and the origin of the posterior belly of the digastric was found to be 0.72 cm (range: 0.45-0.99 cm). The facial nerve could be identified consistently and safely in all patients. Conclusion This trident landmark provided safe, accurate, and easy identification of the facial nerve using two fixed bony landmarks.

Utilization of the tympanomastoid fissure for intraoperative identification of the facial nerve: a cadaver study

PURPOSE

Intraoperative identification of the facial nerve is an essential component of parotid gland surgery. Failure to visualize the facial nerve during the procedure can result in significant complications such as facial palsy. Several anatomic landmarks are used clinically to identify the facial nerve trunk; however, most of these structures have variable locations with respect to the nerve. The tympanomastoid fissure is the closest and least variable of the anatomic landmarks used in parotid gland surgery. The aim of this study was to evaluate the distance between the tympanomastoid fissure and the facial nerve trunk.

MATERIALS AND METHODS

Thirty cadaver sides were dissected. A modified Blair incision exposed the facial nerve trunk, and the dissection was extended to the stylomastoid foramen and adjacent mastoid process. The distance between the most lateral aspect of the tympanomastoid fissure and facial nerve trunk was obtained using a digital caliper.

RESULTS

The distance from the tympanomastoid fissure to the facial nerve trunk ranged from 3.3 to 9.2 mm with a mean of 4.9 mm.

CONCLUSIONS

The results showed that the tympanomastoid fissure is a close and predictable anatomic landmark that can be used to identify the facial nerve trunk intraoperatively.

Do magnetic resonance imaging and ultrasound add anything to the preoperative workup of parotid gland tumors?

PURPOSE

To assess the additional value of magnetic resonance imaging (MRI) and ultrasound (US) to physical examination (PE) and fine needle aspiration cytology (FNAC) in the preoperative determination of the location and histology of parotid gland tumors.

PATIENTS AND METHODS

Prospectively, 99 patients with 77 benign and 22 malignant lesions were included; 82 underwent parotidectomy. FNAC was performed in 88 patients. On PE, the location of the tumor was predicted. Eighty-nine patients had MRI and 47 US. Various characteristics and the presumed diagnosis were assessed. Furthermore, the location of the tumor in relation to the facial nerve was predicted. The results were compared with the definite histology and the location during surgery.

RESULTS

Of the MRI characteristics, incomplete demarcation from normal parotid gland tissue showed the highest positive predictive value (PPV) for malignancy of 0.48. Of the US characteristics, enlarged lymph nodes yielded the highest PPV for malignancy of 0.5. Cytology correctly predicted the benign or malignant nature of the tumor in all cases. Superficial location was well predicted on PE with a PPV of 0.8, slightly better on MRI (PPV of 0.87), and worse on US (PPV of 0.7).

CONCLUSION

FNAC is the only accurate investigation for classifying a parotid gland tumor as benign or malignant. Palpation and MRI are superior to US in predicting tumor location. Because the results for palpation and MRI are almost equal, MRI should only be reserved for specific cases, and not routinely requested.

Landmarks of the facial nerve: implications for parotidectomy

Facial nerve paralysis is a daunting potential complication of parotid surgery and is widely reported. Knowledge of the key landmarks of the facial nerve trunk is essential for safe and effective surgical intervention in the region of the parotid gland. In current practice, wide ranges of landmarks are used to identify the facial nerve trunk, however, there is much debate in the literature about the safety and reliability of each of these landmarks. The aim of this study, therefore, was to evaluate the relation of the surrounding anatomical structures and surgical landmarks to the facial nerve trunk. The anatomical relationship of the facial nerve trunk to the surrounding structures was determined after micro-dissection on 40 adult cadavers. The shortest distances between the facial nerve and the "tragal pointer", attachment of the posterior belly of digastric muscle, tympanomastoid suture, external auditory canal, transverse process of the axis, angle of the mandible and the styloid process were measured. In addition, these distances were compared in the right and left sides, males and females and edentulous and non-edentulous mandibles. The distance of the facial nerve trunk from each of the surrounding landmarks ranged from (mm): tragal pointer, 24.3 to 49.2 (mean 34); posterior belly of digastric, 9.7 to 24.3 (mean 14.6); external auditory canal, 7.3 to 21.9 (mean 13.4); tympanomastoid suture, 4.9 to 18.6 (mean 10.0); styloid process, 4.3 to 18.6 (mean 9.8); transverse process of the axis, 9.7 to 36.8 (mean 16.9); angle of the mandible, 25.3 to 48.69 (mean 38.1). The length of the facial nerve trunk from its point of exit from the stylomastoid foramen to its bifurcation into upper and lower divisions ranged from (mm) 8.6 to 22.8 (mean 14.0). The results demonstrated that the posterior belly of digastric, tragal pointer and transverse process of the axis are consistent landmarks to the facial nerve trunk. However, it should be noted that the tragal pointer is cartilaginous, mobile, asymmetrical and has a blunt, irregular tip. This study advocates the use of the transverse process of the axis as it is easily palpated, does not require a complex dissection and ensures minimum risk of injury to the facial nerve trunk.

The location of parotid gland tumors in relation to the facial nerve on magnetic resonance images and computed tomography scans

PURPOSE

The facial nerve, which cannot be visualized radiographically in its intraparotid part, divides the parotid gland into 2 lobes. When planning surgery, it is important to know where to locate a parotid gland tumor in relation to the facial nerve, because the location can influence the duration and difficulty of the operation. In this study, an anatomic line that predicts the course of the facial nerve in the parotid gland, is applied clinically and compared with another line recently described to evaluate the usefulness of both tools in the use of computed tomography scans and magnetic resonance images.

MATERIALS AND METHODS

We reviewed 28 scans (15 computed tomography and 13 magnetic resonance) and used both lines to predict tumor location in the parotid gland. The accuracy of each prediction was checked later by referring to the surgical report.

RESULTS

This new anatomic line helped us to correctly predict tumor location in relation to the facial nerve in 24 cases (85.7%), whereas the other line was helpful in 20 cases (71.4%).

CONCLUSION

Our new line may be a very useful tool to predict the location of parotid gland tumors.