Blink reflex studies in peripheral versus central enhancement: postparalytic facial syndrome and blepharospasm: trigeminal and extra-trigeminal somatosensory stimulation
8 slide(s) – English – 2011-09-10
Background: We aimed to study blink reflex circuits in peripheral (postparalytic facial syndrome, PFS) versus central (essential blepharospasm, EB) enhancement that causes changes in excitability of brainstem interneurons.
Patients & Methods: A total of 26 patients with PFS, 17 patients with EB, and 36 healthy volunteers as control group were consecutively involved. Electrically stimulated trigeminal blink reflex (BR) and extra-trigeminal somatosensory blink reflexes (SBR) were studied bilaterally.
Results: There was no statistically significant difference in gender or age distribution among three groups. The trigeminal BR responses were elicited in all participants. The SBR responses were elicited in 44.4% of healthy subjects. The frequency of excitability of SBR was highest in PFS patients, and lowest in patients with EB (p=0.050). In trigeminal stimulation, the mean R2 amplitude and duration values were highest in EB patients, being significantly higher than PFS patients (p=0.035 and p=0.05, respectively) and control group (p=0.003 and p=0.018, respectively). In patients with PFS, the mean SBR response latency on symptomatic side was significantly shorter in compared to those on asymptomatic side (p=0.006). The mean Rs amplitudes were highest in EB patients, being significantly higher than patients with PFS (p=0.050). The mean Rs duration was also highest in EB patients, being significantly higher than both PFS patients (p=0.015) and controls (p=0.044).
Conclusion: Our study suggests that motoneuronal excitability in brainstem interneurons is enhanced in patients with PFS and EB, and the hypersensitivity of the reflex circuit could be evoked by somatosensory stimulation in addition to trigeminal stimulation.