THE JAW-OPENING REFLEX - A NEW TECHNIQUE FOR EVALUATION OF FACIAL SENSORY DISTURBANCES .2. OBSERVATIONS IN PATIENTS WITH TRIGEMINAL NERVE BRANCH LESIONS

In a previous study (13), the jaw opening reflex proved as a stable an d technically simple electrodiagnostic procedure. The value of this re flex in the analysis of trigeminal sensory disturbances was investigat ed in 38 patients with mechanical lesions of the lower trigeminal nerv e branches (Tab. 1). Fair correspondence was found between the clinica l status and electrophysiological results: No reflex was to be elicite d in patients with surgical transection of the respective trigeminal b ranches (Fig. 1); in patients with hypaesthesia the jaw opening reflex was to be elicited in its typical pattern, but with an increased refl ex threshold (Fig. 2, 4). On repeated follow-ups, there was normalizat ion of the pathologically increased reflex threshold (Fig. 5) as well as stability of reflex thresholds in normal regions. Similar findings were observed in lesions of the lingual nerve (Fig. 3); with stimulati on of the tongue surface, thresholds for detection of the stimulus and for reflex elicitation were somewhat lower as compared to the lips. D etermination of reflex thresholds on both sides appeared as the most s ensitive parameter. Delayed latencies of the reflex onset were seen in only a few cases (Fig. 1). The results show that the jaw opening refl ex is an objective and reliable, but simple and convenient means in th e evaluation of trigeminal nerve branch lesions.