THE R3 COMPONENT OF THE BLINK REFLEX - NORMATIVE DATA AND APPLICATIONIN SPINAL LESIONS

The clinical value of the R3 component (R3) of the blink reflex (BR) f or differentiating between lesions at the medulla oblongata and cervic al spinal cord level is still unclear. In 50 healthy volunteers (25 wo men, 25 men, aged 20-75 years) reproducible ipsi- and contralateral R3 responses could be evoked showing a mean onset latency of 84 ms, a du ration of 32 ms and a side-to-side difference of almost 3 ms. The late ncy increased with age. Eleven patients with lesions of the cervical s pinal cord (segments C1-C6) showed normal R3 latencies. In 4 patients with pathology of the brain-stem, however, R3 was abnormal, showing id entical changes as observed with the R2 component. Our results suggest that the reflex are of R3 does not descend to the cervical spinal cor d but within the brain-stem possibly takes the same connections as the R2 component.