Orbicularis oculi and orbicularis oris reflexes in blepharospasm and torticollis spasmodica during spasm-free intervals

To investigate possible abnormalities of the blink reflex pathways, we anal yzed the latencies and amplitudes of the blink reflex responses in the orbi cularis oculi (Ooculi) muscle, following supraorbital nerve stimulation, in 19 patients with blepharospasm, 16 patients with torticollis spasmodica an d 22 control subjects. Furthermore, in order to examine the suprasegmental control of the responses, the reflex responses were also evoked in the orbi cularis oris (Ooris) muscle after stimulation of the ipsilateral supraorbit al nerve. The responses were recorded only when subjects had no contraction s of the eyelid muscles, either involuntarily, voluntarily or spontaneously ; this could be controlled by a sound signal. The metrics of the reflex res ponses in the Ooculi and Ooris muscles in patient groups were comparable to those in controls. Our data indicate that the afferent and efferent pathwa ys of the reflex arc and the suprasegmental control of the reflex are intac t in patients with blepharospasm and torticollis spasmodica, at least durin g spasm-free intervals. Alterations of responses may occur during spasms du e to either segmental or suprasegmental changes. Copyright (C) 2001 S. Karg er AG, Basel.