A comparison of transcranial magnetic stimulation with electroneuronography as a predictive test in patients with Bell's palsy

Transcranial Magnetic Stimulation in the Differential Diagnosis of Unilateral Peripheral Facial Nerve Palsy

(1) Background: This study aims to assess the diagnostic accuracy of parameters based on a combination of transcranial magnetic stimulation (TMS) and electrical stimulation (ES) in the differentiation between idiopathic and secondary facial palsy in a large cohort of patients. (2) Methods: Patients with unilateral facial palsy ≤7 days after symptom onset were included. Compound muscle action potential (CMAP) amplitudes were measured after stimulation of both facial nerves at (A) the internal acoustic meatus using TMS, CMAP-TMS, and (B) at the stylomastoid foramen using electrical stimulation, CMAP-ES. To express the degree of nerve dysfunction in the facial canal specifically, the amplitude reduction of the CMAP-TMS in relation to CMAP-ES was calculated and expressed as a percentage (amplitude reduction over the facial canal, ARFC). Receiver Operating Characteristic (ROC) curves were constructed to assess the diagnostic accuracy of ARFC as a marker to discriminate between patients with idiopathic and secondary facial palsy. (3) Results: Data from 498 patient records were analyzed. Idiopathic facial palsy was diagnosed in 424 patients, and secondary facial palsy in 74 patients. The area under the ROC curve for ARFC was 0.398. (4) Conclusions: The overall diagnostic accuracy of this method to differentiate secondary from idiopathic facial palsy is low.

Evaluation of a physiotherapeutic treatment intervention in "Bell's" facial palsy

The aim of this study was to evaluate a physiotherapeutic treatment intervention in Bell's palsy. A consecutive series of nine patients with Bell's palsy participated in the study. The subjects were enrolled 4-21 weeks after the onset of facial paralysis. The study had a single subject experimental design with a baseline period of 2-6 weeks and a treatment period of 26-42 weeks. The patients were evaluated using a facial grading score, a paresis index and a written questionnaire created for this study. Every patient was taught to perform an exercise program twice daily, including movements of the muscles surrounding the mouth, nose, eyes and forehead. All the patients improved in terms of symmetry at rest, movement and function. In conclusion, patients with remaining symptoms of Bell's palsy appear to experience positive effects from a specific training program. A larger study, however, is needed to fully evaluate the treatment.

Prognostication of Bell's palsy using transcranial magnetic stimulation

Transcranial magnetic stimulation (TMS) provides a method to noninvasive excitation of the facial nerve in its intracranial segment close to the internal acoustic meatus. Thus, the site of facial nerve activation with TMS is proximal to or within the site of the lesion in Bell's palsy. To evaluate the prognostic capability of TMS in unilateral Bell's palsy we examined 137 patients with this method, and compared the results with electroneuronography (ENoG). Within 0-4 days from the onset of palsy, the patients with elicitable TMS responses recovered better than those in whom TMS responses were not elicitable. If TMS was performed 5-9 days or 10-28 days after the onset of palsy, it did not provide any prognostic information. Based on amplitude side-to-side differences, ENoG did not contribute prognostic information during the first 9 days from the onset of palsy. Later on, 10-28 days after the onset of palsy, ENoG showed an increased capability to discriminate the patients with poor prognosis. Thus, elicitable facial motor response with TMS predicts good prognosis of Bell's palsy at an early stage whereas poor response with ENoG predicts less favorable prognosis at a later stage.