Evaluation of Trigeminal Nerve Involvement Using Blink Reflex Test in Bell's Palsy

ABSTRACT

BACKGROUND AND OBJECTIVES: Facial nerve dysfunction in Bell's palsy is evaluated using various parameters including physical examination and electrophysiological studies. Associated symptoms of facial numbness or paresthesia are reported by some patients with Bell's palsy. The aim of this study was to investigate trigeminal nerve involvement in Bell's palsy using blink reflex test. SUBJECTS AND METHODS: Facial nerve and trigeminal nerve functions were assessed using House-Brackmann (HB) grading system, electroneuronography (ENoG) and blink reflex tests in 28 patients diagnosed as Bell's palsy. RESULTS: HB grades correlated with degeneration ratio from ENoG (p=0.002, chi-square test). The ipsilateral R1 reponse of the blink reflex was absent or abnormal in 27/28 patients (96.4%), and ipsilateral R2 response was absent or abnormal in 26/28 patients (92.8%). Contralateral R2 was abnormal in 5/28 patients (17.8%), suggesting involvement of trigeminal nerve in a portion of patients. The results of blink reflex test showed no significant correlation to the outcome of facial nerve function (HB grade) in Bell's palsy patients. CONCLUSIONS: Blink reflex test provides information about trigeminal and facial nerve functions in addition to ENoG results. Our study suggests that subclinical involvement of trigeminal nerve may accompany facial nerve dysfunction in Bell's palsy.