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Which side?
Parkinson et al: Spinal Cord Concussion
Intervals between impacts varied from one hour in the first frog to thirty minutes in the subsequent 4 frogs. Thus, i frog received 5 blows and the other 4 received 10. T h e reappearance of the normal preconcussion sciatic response required a mean of 31.29 seconds, with a standard deviation of 1.32 seconds (Fig. 3).
Discussion Our stent placement transmitted the impact over a 2 mm segment about midway between the cervical enlargement and the lumbar enlargement of the frog spinal cord, which terminates at about the iliac crest and originates just behind the eyeballs. T h e force was thus administered halfway between the region of the afferent synapses from the forearm and the region of the efferent leaving the cord to the opposite sciatic nerve. Thus, whereas other functions of the spinal cord may also be interrupted by such a blow, we observed the loss and recovery of the propagation of an impulse down the spinal cord, presumably along axons. This belief is substantiated by the fact that an identical force in the paraspinal or shoulder region would not interrupt this stimulus-response sequence.
349
T h e average recovery time of 31.29 seconds is considerably less than that for higher functions, and considerably longer than that for motor function following cerebral concussions in both rats and humans.
References 1. Croft TJ, Brodkey JS, Nulsen FE: Reversible spinal cord trauma: a model for electrical monitoring of spinal cord function. J Neurosurg 36:402-406, 1972 2. Denny-Brown D, Brenner C: The effect of percussion of nerve. J Neurol Neurosurg Psychiatry 7:76-95, 1944 3. Dohrmann GJ, Panjabi MM, Banks D: Biomechanicsof experimental spinal cord trauma. J Neurosurg 48:993-1001, 1978 4. Gray JAB, Ritchie JM: Effects of stretch on single myelinated nerve fibers. J Physiol I24:84-99, 1954 5. Kandel ER: Small systems of neurons. Sci Am 241:67-76, 1979 6. Krems AD, Schoepfle GM, Erlanger J: Nerve concussion. Proc Soc Exp Biol Med 49:73-79, 1942 7. Lloyd D: Variability of multisynaptic long spinal reflex. J Neurophysiol 6:435-458, 1942 8. Parkinson D: Concussion. Mayo Clin Proc 52:492-496, 1977 9. Parkinson D, West M, Pathiraja T: Concussion: comparison of humans and rats. Neurosurgery 3:176-180, 1978 10. Richardson PM, Thomas PK: Percussive injury to peripheral nerve roots in rats. J Neurosurg 51:178-187, 1979 11. Shetter AG, Demakas JJ: The pathophysiology of concussion. A review. Adv Neurol 22:5-14, 1979
Letter to the Editor W h i c h Side? I have battled, m Chicago, for about live years with the various (.'T-scanning installations to have them put right and left on their lilms, since the sides vary with the machines used. At one time we almost operated on the wrong side for a frontal tumor without lateralizing signs because of this. Now 1 hnd that Peter Weinberg and Kwang Kim have published in Surgical Neurolo,w (15:212214, 1981) figures without any lateral izing data for the CT scans, but with indications of the side for the angiograms. For the obviously subtle changes which they are emphasizing, and fi.)r the self-testing of most readers who try to see what the lesion is before being told, it really would have been nice to have seen which side is which!
()scar Sugar, M. D. Chicago,, Illinois
Intervals between impacts varied from one hour in the first frog to thirty minutes in the subsequent 4 frogs. Thus, i frog received 5 blows and the other 4 received 10. T h e reappearance of the normal preconcussion sciatic response required a mean of 31.29 seconds, with a standard deviation of 1.32 seconds (Fig. 3).
Discussion Our stent placement transmitted the impact over a 2 mm segment about midway between the cervical enlargement and the lumbar enlargement of the frog spinal cord, which terminates at about the iliac crest and originates just behind the eyeballs. T h e force was thus administered halfway between the region of the afferent synapses from the forearm and the region of the efferent leaving the cord to the opposite sciatic nerve. Thus, whereas other functions of the spinal cord may also be interrupted by such a blow, we observed the loss and recovery of the propagation of an impulse down the spinal cord, presumably along axons. This belief is substantiated by the fact that an identical force in the paraspinal or shoulder region would not interrupt this stimulus-response sequence.
349
T h e average recovery time of 31.29 seconds is considerably less than that for higher functions, and considerably longer than that for motor function following cerebral concussions in both rats and humans.
References 1. Croft TJ, Brodkey JS, Nulsen FE: Reversible spinal cord trauma: a model for electrical monitoring of spinal cord function. J Neurosurg 36:402-406, 1972 2. Denny-Brown D, Brenner C: The effect of percussion of nerve. J Neurol Neurosurg Psychiatry 7:76-95, 1944 3. Dohrmann GJ, Panjabi MM, Banks D: Biomechanicsof experimental spinal cord trauma. J Neurosurg 48:993-1001, 1978 4. Gray JAB, Ritchie JM: Effects of stretch on single myelinated nerve fibers. J Physiol I24:84-99, 1954 5. Kandel ER: Small systems of neurons. Sci Am 241:67-76, 1979 6. Krems AD, Schoepfle GM, Erlanger J: Nerve concussion. Proc Soc Exp Biol Med 49:73-79, 1942 7. Lloyd D: Variability of multisynaptic long spinal reflex. J Neurophysiol 6:435-458, 1942 8. Parkinson D: Concussion. Mayo Clin Proc 52:492-496, 1977 9. Parkinson D, West M, Pathiraja T: Concussion: comparison of humans and rats. Neurosurgery 3:176-180, 1978 10. Richardson PM, Thomas PK: Percussive injury to peripheral nerve roots in rats. J Neurosurg 51:178-187, 1979 11. Shetter AG, Demakas JJ: The pathophysiology of concussion. A review. Adv Neurol 22:5-14, 1979
Letter to the Editor W h i c h Side? I have battled, m Chicago, for about live years with the various (.'T-scanning installations to have them put right and left on their lilms, since the sides vary with the machines used. At one time we almost operated on the wrong side for a frontal tumor without lateralizing signs because of this. Now 1 hnd that Peter Weinberg and Kwang Kim have published in Surgical Neurolo,w (15:212214, 1981) figures without any lateral izing data for the CT scans, but with indications of the side for the angiograms. For the obviously subtle changes which they are emphasizing, and fi.)r the self-testing of most readers who try to see what the lesion is before being told, it really would have been nice to have seen which side is which!
()scar Sugar, M. D. Chicago,, Illinois