Somatosensory-evoked blink reflex in peripheral facial palsy

Abstract

Somatosensory-evoked blink reflex (SBR) is an eye blink response obtained from electrical stimulation of peripheral nerves or the skin area of the body away from the face. The aim of this study was to investigate the presence of SBR in peripheral facial palsy (PFP) and its relation with clinical and electrophysiological changes occurring in PFP as compared with postfacial syndrome (PFS). This was a single-center, public hospital-based electromyography laboratory study. It was designed as a cross-sectional examination of consecutive patients with PFP and PFS and apparently healthy volunteers. The study included 25 patients with PFP, 25 patients with PFS, and 31 healthy volunteers. Facial nerve motor conduction, trigeminal blink reflex, and SBR were studied. Quantitative data were compared using the Mann–Whitney test and the Kruskal–Wallis test. Qualitative data were analyzed using Pearson’s Chi-square test. SBR was elicited in 67.7% of controls, in 68% of PFS patients, and in 32% of PFP patients. In the PFP group, SBR was found on the nonparalytic side in 28% of patients with paralyzed side stimulation and in 24% of patients with healthy side stimulation. For the PFS group, SBR was found on the nonparalytic side in 48%. Bilateral SBR elicitability was higher than its unilateral elicitability. SBR occurs in patients with PFP and PFS and in healthy individuals. It has no relation with the clinical and electrophysiological changes occurring in PFP and PFS. Increased brainstem interneurons excitability is not essential to generate SBR. The hypothetical sensory-motor gating mechanism could be responsible for SBR generation.