False-negative magnetic resonance imaging in the evaluation of facial nerve paralysis

Misdiagnosis of Bell's palsy: Case series and literature review

Although Bell's palsy is a common etiology for isolated facial paralysis, it is important clinicians perform a complete neurologic examination to avoid misdiagnosis. Multiple cranial neuropathy is often caused by tumor or infection.

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

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.

Parotid carcinoma: Current diagnostic workup and treatment

In this review we present recent progress in diagnostic workup, prognostic evaluation, treatment options and resulting outcomes. Whenever possible, complete resection remains the mainstay of treatment. Sacrifice of facial nerve branches is reserved for the clinically or electromyographically dysfunctioning facial nerve. Clinical or radiological neck disease demands combined surgery and radiotherapy. Treatment of the N0 neck is indicated for advanced stage-high grade tumors but the question remains unanswered whether this should be surgical or radiotherapeutic elective treatment. Surgery alone will cure low stage, low grade tumors, that show no additional negative prognostic factors following adequate resection. In all other tumors postoperative radiotherapy will improve locoregional control. This approach results in good locoregional control, in a way that distant metastasis remains the typical presentation of treatment failure. In this setting, the results of systemic treatment today remain limited, but a huge effort in the molecular biology field has been done to introduce targeted therapy into this domain of head and neck cancer. Disease control remains variable within the patient population. This variation can increasingly be predicted by systems that incorporate the combined information of multivariately identified and quantified prognostic factors into an individualized prognosis for the parotid carcinoma patient.

Facial nerve paralysis secondary to occult malignant neoplasms

OBJECTIVE

This study reviewed patients with unilateral facial paralysis and normal clinical and imaging findings who underwent diagnostic facial nerve exploration. Study design and setting Fifteen patients with facial paralysis and normal findings were seen in the Mayo Clinic Department of Otorhinolaryngology.

RESULTS

Eleven patients were misdiagnosed as having Bell palsy or idiopathic paralysis. Progressive facial paralysis with sequential involvement of adjacent facial nerve branches occurred in all 15 patients. Seven patients had a history of regional skin squamous cell carcinoma, 13 patients had surgical exploration to rule out a neoplastic process, and 2 patients had negative exploration. At last follow-up, 5 patients were alive.

CONCLUSIONS

Patients with facial paralysis and normal clinical and imaging findings should be considered for facial nerve exploration when the patient has a history of pain or regional skin cancer, involvement of other cranial nerves, and prolonged facial paralysis.

SIGNIFICANCE

Occult malignancy of the facial nerve may cause unilateral facial paralysis in patients with normal clinical and imaging findings.

The usefulness of MR imaging of the temporal bone in the evaluation of patients with facial and audiovestibular dysfunction

OBJECTIVE

To evaluate the clinical utility of MR imaging of the temporal bone in patients with facial and audiovestibular dysfunction with particular emphasis on the importance of contrast enhancement.

MATERIALS AND METHODS

We retrospectively reviewed the MR images of 179 patients [72 men, 107 women; average age, 44 (range, 1-77) years] who presented with peripheral facial palsy (n=15), audiometrically proven sensorineural hearing loss (n=104), vertigo (n=109), or tinnitus (n=92). Positive MR imaging findings possibly responsible for the patients' clinical manifestations were categorized according to the anatomic sites and presumed etiologies of the lesions. We also assessed the utility of contrast-enhanced MR imaging by analyzing its contribution to the demonstration of lesions which would otherwise not have been apparent. All MR images were interpreted by two neuroradiologists, who reached their conclusions by consensus.

RESULTS

MR images demonstrated positive findings, thought to account for the presenting symptoms, in 78 (44%) of 179 patients, including 15 (100%) of 15 with peripheral facial palsy, 43 (41%) of 104 with sensorineural hearing loss, 40 (37%) of 109 with vertigo, and 39 (42%) of 92 with tinnitus. Thirty (38%) of those 78 patients had lesions that could be confidently recognized only at contrast-enhanced MR imaging.

CONCLUSION

Even though its use led to positive findings in less than half of these patients, MR imaging of the temporal bone is a useful diagnostic procedure in the evaluation of those with facial and audiovestibular dysfunction. Because it was only at contrast-enhanced MR imaging that a significant number of patients showed positive imaging findings which explained their clinical manifestations, the use of contrast material is highly recommended.