Alteration of the Orbicularis Oculi Reflex by Pontine Lesions

THE RESPONSE of the orbicularis oculi muscle to a tap over the brow has two separate components: an early ipsilateral reflex and a late bilateral reflex.1Electrical stimulation of the supraorbital nerve also evokes two separate contractile responses in the orbicularis oculi muscle (Fig 1) which are almost identical to the response to glabellar tap.2,3The use of electrical stimulation has made it possible to apply this method in the ordinary electromyographic laboratory, and normal values and variations of this reflex have been well established.4,5In recent years, alteration of the reflex in various diseases of the nervous system has been recognized.2-6 The reflex arc may be affected by lesions of the trigeminal nerve (afferent path), the facial nerve (efferent path), or of the pons (central connections). Practical application of this technique to the study of peripheral facial nerve paralysis5and of trigeminal nerve