Objective
To compare the R3 response of the blink reflex in medullar and spinal cord lesion and to investigate whether the reflex arc of the R3 response descend to the cervical spinal cord or not.

Method
We have studied 3 patients with medullar lesion and 5 patients with cervical spinal cord or vertebral lesion. Normal ranges of the R3 response refer to the results suggested by Moon et al.

Results
In 3 patients with medullar lesion, two patients with lateral medullar lesion showed delayed R3 latency or no evoked potential. Four patients with cervial spinal cord lesion showed no R3 response. In one patient with disc protrusion R3 was normal.

Conclusion
Our results support the hypothesis that the reflex arc of the R3 response descend to the cervical spinal cord.