The plantar response in narcosis

THE SPINAL REFLEX responses evoked by painful stimuli applied to the skin of the foot represent a highly purposeful defense mechanism capable of discriminating between stimuli of different strength, modality, and site.1-3 This is largely the result of a cerebral control directing transmission in spinal interneuron chains and capable of establishing the complex and elaborate connections between skin and muscle displayed by the reflexes. The effects of disorders of this supraspinal control have been studied in patients with various types of organic le~ions.l-~-G An attempt was made to trace the pathways responsible for the discriminative power of the reflex mechanism and thus to increase the diagnostic value of reflex examinations. When assessing the results, however, one must remember that even the normal reflex response may show wide individual variations.2 Thus, the development of a pathological reflex preferably should be followed up in the same patient in experiments performed under fairly uniform conditions. For a long time it has been known7 that patients who have normal reflexes when awake may exhibit a Babinski reflex under narcosis; a functional blocking of the pathways thus may disturb the supraspinal control of the reflex mechanism. This paper gives an account of investigations designed to study how a reflex elicited by a punctiform, painful electric stimulus applied to the hollow of the foot and the hallux ball may change with increasing depth of the anesthesia. Special attention has been given to the “reflex pattern” obtained on simultaneous electromyographic recording in the short hallux flexor and extensor. The strength