Blink reflex in patients with postparalytic facial syndrome and blepharospasm: trigeminal and auditory stimulation

The enhancement of blink reflex (BR) excitability was shown in patients with postparalytic facial syndrome (PFS) and essential blepharospasm (EB). We prospectively investigated patients with PFS and EB whether BR alterations demonstrated by trigeminal stimulation will similarly be observed upon auditory stimulation.

Fifteen patients with PFS, 15 patients with EB, and 30 healthy volunteers were involved. Electrically stimulated trigeminal BR and auditory BR were studied bilaterally.

The mean R2 amplitude and duration values were highest in EB patients, being significantly higher than PFS patients (p < 0.05) and control group (p < 0.01). The mean R2 duration in PFS patients were also significantly longer in compared to control group (p = 0.025). EB patients showed a higher mean R (auditory) amplitude and duration than PFS patients (p < 0.05) and controls (p < 0.04). The mean R (auditory) duration was longer on symptomatic side of PFS patients in compared to controls (p = 0.05).

We observed that there is an enhanced excitability of BR circuit in postparalytic facial syndrome and essential blepharospasm, which could be evoked by auditory stimulation in addition to trigeminal stimulation.

The enhanced excitability in patients with EB and PFS probably originates from the final common pathway of BR circuit, namely facial motor or premotor neurons.