Determining Etiology of Facial Nerve Paralysis With MRI: Challenges in Malignancy Detection

Abstract

Objective: Compare experts’ ability to differentiate malignant and benign causes of facial nerve paralysis (FNP) using the initial presenting magnetic resonance image (MRI) for each patient. Methods: This retrospective case-controlled study compared MRIs for 9 patients with a malignant cause for FNP, 8 patients with Bell’s palsy, and 9 cochlear implant patients serving as controls. The initial presenting MRI for each condition was used such that raters were evaluating real-world rather than optimal studies. Three blinded expert raters independently evaluated each segment of the facial nerve for abnormalities, provided a diagnosis, and graded MRI quality. Cohen’s and Light’s kappa were used to calculate interrater reliability and overall index of agreement, respectively. Results: MRI protocols for the malignancy group were universally suboptimal. There was poor agreement among raters for abnormalities of the facial nerve along the brainstem (0.13), geniculate (0.10), tympanic segment (0.12), and mastoid segment (0.13); moderate agreement along the cisternal segment (0.58) and internal auditory canal (0.55); and fair agreement along the labyrinthine segment (0.26) and extratemporal segment (0.36). Agreement regarding final diagnosis was fair (0.37) when compared to the true diagnosis. There were 2 false negative interpretations (failure to correctly identify malignancy) and 1 false positive interpretation. Conclusion: MRI for FNP is often initially performed with an incorrect protocol and thus may fail to reliably differentiate neoplastic from inflammatory FNP even when interpreted by experienced clinicians. Nevertheless, expert readers correctly diagnosed 87.5% of malignant causes of FNP despite these limitations.

Incidence of Underlying Abnormal Findings on Routine Magnetic Resonance Imaging for Bell Palsy

“…Finally, isolated PFP can also be caused by ischemic or hemorrhagic lesions in the pons involving the nucleus of the facial nerve, but these lesions rarely manifest as PFP alone . One of the benefits of MRI in cases of presumed BP is the elimination of causative diseases with clinical presentations that mimic those of BP …”

Peripheral facial nerve palsy in children: clinical manifestations, treatment and prognosis

“…More recent techniques such as constructive interference in steady-state and 3D-magnetization-prepared rapid gradient echo can also be used to evaluate anatomical details of the inner ear and facial nerve. It should be indicated especially in patients presenting with atypical clinical findings and not improving as expected [ 6 , 21 ].…”

“…Children with atypical signs and symptoms of systemic or additional neurological involvement were further investigated. Diagnostic visualization of the brain and internal acoustic canal was performed by magnetic resonance imaging (MRI-1.5T MR Philip Intra 2008 model)) and computed tomography (CT-Siemens Somatom 16 Ct) when clinically indicated as in cases of trauma were done [ 6 , 21 ]. Children with Bell’s palsy were treated for 7–10 days with oral prednisolone (1–2 mg/kg/day, max dose 60 mg/day); prednisolone treatment was subsequently tapered off within the next 3–5 days.…”

Petrous Apex Cholesterol Granuloma Revealed by Facial Palsy

“…Moreover, the latest American and Canadian guidelines do not recommend routine diagnostic imaging for patients with new onset Bell palsy when clinical and audiometric assessment is normal 1–3 . However, recent data show that 8 to 12% of cases of suspected Bell palsy are of tumoral origin, and approximately 30% of those are malignancies 4 . In confirmed Bell palsy, there is characteristic but nonspecific enhancement of the facial nerve ipsilateral to the neurological lesion.…”

“…[1][2][3] However, recent data show that 8 to 12% of cases of suspected Bell palsy are of tumoral origin, and approximately 30% of those are malignancies. 4 In confirmed Bell palsy, there is characteristic but nonspecific enhancement of the facial nerve ipsilateral to the neurological lesion. Ultimately, MRI is the examination of choice, being the best technique to explore the entire neural course.…”