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Nociceptive reflexes and pain sensation in man
408
Pain, 10 (1981) 408--410 © Elsevier/North-Holland Biomedical Press
re.: Nociceptive reflexes and pain sensation in man
Hamburg, 19 February 1981 Dear Editor, In the following w e correct the statements of Wilier et al.,w h o criticized in their letter to the Editor (this issue of Pain) a part of our paper "Withdrawal reflex, skin resistance reaction and pain ratings due to electrical stimuli in m a n " [1 ]. Firstly: the withdrawal reflex is not necessarily a flexor reflex. Sherrington [9] described the nociceptive flexor reflex in studies on spinal animals. W e know, in the meantime, that the so-called flexor reflex afferents can also activate extensor motoneurons [cf. 8]; which of the two reflex arcs are primarily excited depends for example on supraspinal control, on the position of the stimulated limb or on the stimulation site [5,6]. For this reason we prefer the formulation that the withdrawal reflex, in the intact organism, describes an appropriate movement away from the offending object [6,7]. In our experiments we stimulated the palmar surface of the finger tip and only observed vn extension of the referred finger and hand, even upon stimulus intensities of more than 2-fold pain threshold. Therefore, we chose to record from the extensor digitorum muscle. Secondly: all the observations cited in the letter (including Cambier et al. [2,3]) of the two reflex activities(RII, RIll) were from flexor muscles under direct electrical nerve stimulation. Electrical skin stimuli -- which we applied --were only used by Willer [10] and Willer et al. [12], in the lower limb, with the result that "stimulation of the skin elicits only a late nociceptive (RIll) response in the BF. The threshold of this response was ... found to be that of pain" ([10], B F = biceps femoris muscle). Or: "In these conditions no tactile RII response was ever observed" [12]. W e stimulated the skin in the upper limb, and we also found only one reflex component, with stimulus intensities up to 2.5-fold pain threshold strength. But we found that this motor reaction could consistently be elicited by intensitiessignificantly lower than the pain threshold. Therefore, we cited Wilier [10] and Wilier et al. [ 12 ] and not Cambier et al. [ 2,3 ]. Willer et al. [letter] assert that we measured the tactile reflex RII with electrical skin stimuli, though Willer et al. [12] previously had emphasized that in these conditions no tactile RII response was ever observed, in the lower limb. The figure in the letter is not pertinent to that assertion: The two reflex responses were elicited by nerve stimulation and measured in the antagonist of the muscle investigated by us. We are surprised about the corresponding latencies discussed in this context: Cambier et al. [2] reported for the flexor digitorum superficialis muscle of the upper limb latencies of
409
3 5 - - 5 5 msec for RII, Willer et al. [letter], for the same muscle, 5 0 - - 8 0 msec for RII. It seems apparent that Willer et al. in the course of the letter changed over to the data for the lower limb with which these values are in perfect agreement [ 11 ]. We know from own measurements that A~ afferents (14--21 m/sec at 31 ° C) are excitable by electrical skin stimulation of the finger tip. Exact correlation, however, o f Aa/A~ or A5 activity in the afferent nerve with the recorded withdrawal reflex generally is problematic, as can be seen, for example, by comparing Wilier et al. [ 12] and Willer et al. [ ]L3]. This was not a topic of our study. We roughly estimated the conduction velocity of the afferents possibly involved from the measured reflex time (even an efferent conduction velocity of 55 m/sec yields an afferent conduction velocity estimation of about 18 m/sec). In conclusion, Wilier et al. failed to prove the withdrawa:[ reflex measured by us to be an RII reflex according to their nomenclature We avoided this nomenclature, since it was derived under completely different experimental conditions. As such, we reject their objections. REFERENCES 1 Bromm, B. and Treede, R.-D., Withdrawal reflex, skill resistance reaction and pain
2 3 4 5 6
7 8 9 10 11 12
ratings due to electrical stimuli in man, Pain, 9 (1980) 339--354. Cambier, J., Dehen, H. et Bathien, N., La pr6hension pathologique: son 6rude par l'enregistrement des r6flexes polysynaptiques au membre supdrieur, Rev. neurol. (Paris), 126 (1972) 17--29. Cambier, J., Dehen, H. and Bathien, N., Upper limb cutaneous polysynaptic reflexes, J. neurol. Sci., 22 (1974) 39--49. Francini, F., Zoppi, M., Maresca, M. and Procacci, P., Skin potential and EMG changes induced by cutaneous electrical stimulation, Appi. Neurophysiol., 42 (1979) 113-124. Hagbarth, K.-E., Excitatory and inhibitory skin areas for flexor and extensor motoneurones, Acts physiol, scand., 26, Suppl. 94 (1952) 1--58. Hagbarth, K.-E. and Finer, B.L., The plasticity of human withdrawal reflexes to noxious skin stimuli in lower limbs, Prog. Brain Res., 1 (1963) 65---78. Kugelberg, E., Eklund, K. and Grimby, L., An eJectromyographic study of the nociceptive reflexes o f the lower limb. Mechanism of the plantar responses, Brain, 83 (1960) 394--414. Lundberg, A., Multisensory control of spinal reflex pathways, Progr. Brain Res., 50 (1979) 11--28. Sherrington, C.S., Flexion-reflex of the limb, crossed extension-reflex and reflex stepping and standing, J. Physiol. (Lond.), 40 (1910) 28--121. Wilier, J.C., Comparative study of perceived pain and nociceptive flexion reflex in man, Pain, 3 (1977) 69--80. Wilier, J.C. and Bathien, N., Determination of an indication of pain by the saphenobicipital reflex method: physiological and pharmacological :ariations, EMG clin. Neurophysiol., 15 (1975) 127--135. Wilier, J.C., Bathien, N. and Hugelin, A., Evaluation of central and peripheral pain mechanisms by nociceptive flexion reflex in man. In: J.J. Bonica and D. Albe-Fessard (Eds.), Advances in Pain Research and Therapy, Vol. I, Raven I~re';s, New York, 1976, pp. 131--135.
410
13 Wilier, J.C., Boureau, F. and Albe-Fessard, D., Human nociceptive reactions: effects of spatial summation of afferent input from relatively large c~iameter fibers, Brain Res., 201 (1980) 465--470.
Ph ysiologisches Institu t, Universit(fts-Kr~nkenhaus Eppendorf, D-2000 Hamburg 20 (G.F.R.)
B. B R O M M R.-D. T R E E D E
Pain, 10 (1981) 408--410 © Elsevier/North-Holland Biomedical Press
re.: Nociceptive reflexes and pain sensation in man
Hamburg, 19 February 1981 Dear Editor, In the following w e correct the statements of Wilier et al.,w h o criticized in their letter to the Editor (this issue of Pain) a part of our paper "Withdrawal reflex, skin resistance reaction and pain ratings due to electrical stimuli in m a n " [1 ]. Firstly: the withdrawal reflex is not necessarily a flexor reflex. Sherrington [9] described the nociceptive flexor reflex in studies on spinal animals. W e know, in the meantime, that the so-called flexor reflex afferents can also activate extensor motoneurons [cf. 8]; which of the two reflex arcs are primarily excited depends for example on supraspinal control, on the position of the stimulated limb or on the stimulation site [5,6]. For this reason we prefer the formulation that the withdrawal reflex, in the intact organism, describes an appropriate movement away from the offending object [6,7]. In our experiments we stimulated the palmar surface of the finger tip and only observed vn extension of the referred finger and hand, even upon stimulus intensities of more than 2-fold pain threshold. Therefore, we chose to record from the extensor digitorum muscle. Secondly: all the observations cited in the letter (including Cambier et al. [2,3]) of the two reflex activities(RII, RIll) were from flexor muscles under direct electrical nerve stimulation. Electrical skin stimuli -- which we applied --were only used by Willer [10] and Willer et al. [12], in the lower limb, with the result that "stimulation of the skin elicits only a late nociceptive (RIll) response in the BF. The threshold of this response was ... found to be that of pain" ([10], B F = biceps femoris muscle). Or: "In these conditions no tactile RII response was ever observed" [12]. W e stimulated the skin in the upper limb, and we also found only one reflex component, with stimulus intensities up to 2.5-fold pain threshold strength. But we found that this motor reaction could consistently be elicited by intensitiessignificantly lower than the pain threshold. Therefore, we cited Wilier [10] and Wilier et al. [ 12 ] and not Cambier et al. [ 2,3 ]. Willer et al. [letter] assert that we measured the tactile reflex RII with electrical skin stimuli, though Willer et al. [12] previously had emphasized that in these conditions no tactile RII response was ever observed, in the lower limb. The figure in the letter is not pertinent to that assertion: The two reflex responses were elicited by nerve stimulation and measured in the antagonist of the muscle investigated by us. We are surprised about the corresponding latencies discussed in this context: Cambier et al. [2] reported for the flexor digitorum superficialis muscle of the upper limb latencies of
409
3 5 - - 5 5 msec for RII, Willer et al. [letter], for the same muscle, 5 0 - - 8 0 msec for RII. It seems apparent that Willer et al. in the course of the letter changed over to the data for the lower limb with which these values are in perfect agreement [ 11 ]. We know from own measurements that A~ afferents (14--21 m/sec at 31 ° C) are excitable by electrical skin stimulation of the finger tip. Exact correlation, however, o f Aa/A~ or A5 activity in the afferent nerve with the recorded withdrawal reflex generally is problematic, as can be seen, for example, by comparing Wilier et al. [ 12] and Willer et al. [ ]L3]. This was not a topic of our study. We roughly estimated the conduction velocity of the afferents possibly involved from the measured reflex time (even an efferent conduction velocity of 55 m/sec yields an afferent conduction velocity estimation of about 18 m/sec). In conclusion, Wilier et al. failed to prove the withdrawa:[ reflex measured by us to be an RII reflex according to their nomenclature We avoided this nomenclature, since it was derived under completely different experimental conditions. As such, we reject their objections. REFERENCES 1 Bromm, B. and Treede, R.-D., Withdrawal reflex, skill resistance reaction and pain
2 3 4 5 6
7 8 9 10 11 12
ratings due to electrical stimuli in man, Pain, 9 (1980) 339--354. Cambier, J., Dehen, H. et Bathien, N., La pr6hension pathologique: son 6rude par l'enregistrement des r6flexes polysynaptiques au membre supdrieur, Rev. neurol. (Paris), 126 (1972) 17--29. Cambier, J., Dehen, H. and Bathien, N., Upper limb cutaneous polysynaptic reflexes, J. neurol. Sci., 22 (1974) 39--49. Francini, F., Zoppi, M., Maresca, M. and Procacci, P., Skin potential and EMG changes induced by cutaneous electrical stimulation, Appi. Neurophysiol., 42 (1979) 113-124. Hagbarth, K.-E., Excitatory and inhibitory skin areas for flexor and extensor motoneurones, Acts physiol, scand., 26, Suppl. 94 (1952) 1--58. Hagbarth, K.-E. and Finer, B.L., The plasticity of human withdrawal reflexes to noxious skin stimuli in lower limbs, Prog. Brain Res., 1 (1963) 65---78. Kugelberg, E., Eklund, K. and Grimby, L., An eJectromyographic study of the nociceptive reflexes o f the lower limb. Mechanism of the plantar responses, Brain, 83 (1960) 394--414. Lundberg, A., Multisensory control of spinal reflex pathways, Progr. Brain Res., 50 (1979) 11--28. Sherrington, C.S., Flexion-reflex of the limb, crossed extension-reflex and reflex stepping and standing, J. Physiol. (Lond.), 40 (1910) 28--121. Wilier, J.C., Comparative study of perceived pain and nociceptive flexion reflex in man, Pain, 3 (1977) 69--80. Wilier, J.C. and Bathien, N., Determination of an indication of pain by the saphenobicipital reflex method: physiological and pharmacological :ariations, EMG clin. Neurophysiol., 15 (1975) 127--135. Wilier, J.C., Bathien, N. and Hugelin, A., Evaluation of central and peripheral pain mechanisms by nociceptive flexion reflex in man. In: J.J. Bonica and D. Albe-Fessard (Eds.), Advances in Pain Research and Therapy, Vol. I, Raven I~re';s, New York, 1976, pp. 131--135.
410
13 Wilier, J.C., Boureau, F. and Albe-Fessard, D., Human nociceptive reactions: effects of spatial summation of afferent input from relatively large c~iameter fibers, Brain Res., 201 (1980) 465--470.
Ph ysiologisches Institu t, Universit(fts-Kr~nkenhaus Eppendorf, D-2000 Hamburg 20 (G.F.R.)
B. B R O M M R.-D. T R E E D E