BLINK REFLEX RECOVERY CYCLE IN PATIENTS WITH BLEPHAROSPASM UNILATERALLY TREATED WITH BOTULINUM TOXIN

To determine whether Botulinum Toxin Type A (BTXA) has an effect on th e Central Nervous System, the authors studied the excitability of the blink reflex recovery cycle in 12 patients with blepharospasm before a nd 3 weeks after unilateral BTXA injections. To avoid recording from s everely denervated muscles, the R2 response of the blink reflex was ob tained from the untreated orbicularis oculi with both ipsilateral and contralateral supraorbital nerve stimulation. Baseline recovery curves were compared with a control group (n = 11) and showed an enhanced re covery of the R2 component. There were no significant differences betw een the recovery curves of the R2 component of the blink reflex taken before BTXA treatment and those taken after treatment. This finding co nfirms that BTXA does not modify the excitability of brainstem interne urons that mediate the bilateral R2 response of the blink reflex in pa tients with blepharospasm.