Evaluating Perineural Spread to the Intratemporal Facial Nerve on Magnetic Resonance Imaging

Abstract

Objectives To determine the sensitivity and specificity of magnetic resonance imaging (MRI) for the detection of perineural spread (PNS) along the intratemporal facial nerve (ITFN) in patients with head and neck cancers. Study Design Case series with chart review. Setting Tertiary care center. Subjects and Methods We included 58 patients with head and neck malignancies who underwent sacrifice of the ITFN between August 1, 2002, and November 30, 2015. Demographics, preoperative facial nerve function, prior oncologic treatment, and timing between MRI and surgery were recorded. Histopathology slides and preoperative MRI were reviewed retrospectively by a neuropathologist and a neuroradiologist, respectively, both blinded to clinical data. The mastoid segment of the facial nerve (referred to as the descending facial nerve [DFN]) and stylomastoid foramen (SMF) were evaluated separately. A grading system was devised when radiographically assessing PNS along the DFN. Results Histopathologic evidence of PNS was found in 21 patients (36.2%). The sensitivity and specificity of MRI in detecting PNS to the DFN were 72.7% and 87.8%, respectively. MRI showed higher sensitivity but slightly lower specificity when evaluating the SMF (80% and 82.8%, respectively). Prior oncologic treatment did not affect the false-positive rate (P = .7084). Sensitivity was 100% when MRI was performed within 2 weeks of surgery and was 62.5% to 73.3% when the interval was greater than 2 weeks. This finding was not statistically significant (SMF, P = .7076; DFN, P = .4143). Conclusion MRI shows fair to good sensitivity and good specificity when evaluating PNS to the ITFN.

Lateral temporal bone resection for cutaneous carcinomas of the external auditory canal and peri-auricular region

“…Evidence suggests that the accuracy of MRI in detecting facial nerve perineural invasion, based on post-operative histopathology findings, is between 83 and 87 per cent. 24,25 We believe MRI should be a routine part of the pre-operative investigation for patients with temporal bone malignancy. Further research is required, however, to investigate findings of clinical versus radiological facial nerve involvement, and their relative importance for predicting survival outcomes in this patient group.…”

Diagnostic Accuracy of Contrast-Enhanced MRI for Detection of Perineural Spread in Head and Neck Cancer: A Systematic Review and Meta-Analysis

“…32 Ultimately, nine studies met the eligibility criteria. [33][34][35][36][37][38][39][40][41] The reference lists of all the included articles were also manually checked for additional articles. No additional suitable publications meeting the inclusion criteria were identified.…”

“…Two studies failed to provide data on specificity and thus could not be included in the joint effect size meta-analysis. 37,39 The diagnostic performance of CE-MRI was analyzed on a per patient basis in six studies 34,[37][38][39][40][41] and on a per lesion basis in three studies. 33,35,36 All studies were performed using a 1.5-T MRI, except for two that used a 3-T MRI.…”

Perineural Invasion of the Intratemporal Facial Nerve: How Far Proximally Do We Chase the Positive Margin?

“…MRI may show enhancement of the intratemporal facial nerve, prompting our involvement, though this is a less reliable finding (18,19). We previously reviewed our experience with 58 patients who underwent facial nerve sacrifice for various head and neck malignancies.…”

“…We previously reviewed our experience with 58 patients who underwent facial nerve sacrifice for various head and neck malignancies. The sensitivity and specificity of predicting perineural spread to the facial nerve on the basis of preoperative MRI were shown to be 73% and 88%, respectively (18). Therefore, while imaging to evaluate the facial nerve specifically can be useful, the location of the bulk of the tumor is typically more meaningful in determining our involvement in the case.…”