Crossed linguo-buccal reflex in post-stroke patients

A pathological crossed orofacial reflex, called crossed linguo-buccal refle x in the present study, was observed in approximately 1/3 of post-stroke pa tients with central facial palsy. Stroking with pressure two or three times with a split wooden tongue-blade to the tongue or palate contralateral to the central facial palsy elicited a reflex movement consisting of retractio n of the angle of mouth and medio-posterior withdrawal of the buccal mucosa on the paretic side. Seventy-seven patients with central hemifacial palsy caused by a unilateral cerebral lesion were examined clinically, electromyo graphically and by computed tomography (CT) and magnetic resonance imaging (MRI). In addition, three men with bilateral cerebral lesions and bilateral crossed linguo-buccal reflexes were electromyographically examined. Twenty -two patients with unilateral cerebral lesions had this reflex. It was foun d that this reflex was most frequently observed in patients with a capsulo- caudate lesion involving the head of the caudate nucleus, the anterior limb and genu of the internal capsule. The electromyogram of the reflex showed increased activity in the orbicularis oris, depressor anguli oris, risorius , zygomaticus major and buccinator muscles on the paretic side with a long latency (254-856 ms), and a prolonged after-discharge after the stimulation . Reciprocal inhibition was observed in patients with bilateral positive re flexes. These findings suggest that liberation of the polysynaptic brainste m reflex in the medulla oblongata and pens from the indirect corticobulbar inhibition may underlie the occurrence of the crossed linguo-buccal reflex in post-stroke patients. (C) 2000 Elsevier Science B.V. All rights reserved .