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Contributions by brown-séquard on spinal cord trauma and pathology
Brain Research Bulletin, Vol. 22, pp. 3-5. o Pergamon Press plc, 1989. Printed in the U.S.A.
0361.9230/89 $3.00 + .oO
Contributions by Brown-Skquard on Spinal Cord Trauma and Pathology FILIPE ANDR&
Institut d’Anatomie, TRANSLATOR’S
Universite’ de Lausanne,
Rue du Bugnon 9, 1005 Lausanne, Switzerland appointed to the National Hospital, Queen Square, and became a Fellow of the Royal College of Surgeons and of the Royal Society, the next year. In 1863 he resigned from this post and became Professor of Physiology and Pathology of the nervous system at Harvard. In 1878, he took the post left by Claude Bernard at the College de France, becoming a member of the Academy of Sciences in 1886, and a French citizen almost at the same time. A few years later, in 1894, he died of a cerebral thrombosis. On the Relationships that Exist Between Sensory and Motor Roots by Brown-Sequard, Comptes Rendus SociCtC Biologie, vol. 1, pages 15-17, 1849. In the meeting of February 3rd Mr. Brown-Sequard communicated some results of his research on the independence of sensibility and motricity. The following is a summary of that interesting communication and of the experiments upon which he based himself.
NOTE
The history of the study of spinal cord trauma and pathology is an old one. It goes back to 3000-2500 B.C. in Egypt, as demonstrated by the description of two cases of traumatic spinal cord compression, in the Edwin Smith surgical papyrus. After that time, we hear from it by Hippocrates (460-370 B.C.) who made precise descriptions of the clinical consequences of spinal cord lesions, and later by Galen (129-199 A.D.) who inaugurated experimental research on spinal cord functions. Then comes a long period of torpor during which the Galenic influence is maintained. Until the end of the 18th century several experiments were made without great contribution to the knowledge of spinal cord function. Then, and at the beginning of the 19th century things changed somewhat, for the better, when moderate animists such as Robert Whytt (1714-1766) and Johann August Unzer (1727-1799) gradually brought down the concept of soul, and raised the concept that voluntary and involuntary activities are the effect of a central nervous system mechanism; when Marshall Hall (1790-1857) provided the basis to the concept of the spinal cord neural arc, and Charles Bell (1774-1842) made the differentiation between the functions of the anterior and posterior spinal roots. It is in this context that the pioneer works of Brown-Sequard (1817-1894) on spinal cord trauma and regeneration, make their appearance. The three following notes express well his ideas on this subject. These works have not only historical but also scientific value for investigators working on the spinal cord trauma. With these considerations it was deemed necessary to provide translations of the four classical pieces of work by Brown-Sequard to the English speaking scientists. During translation of these four works great care was taken to translate with fidelity the author’s views. For this reason, in some places, the translation came close to transliteration, to better reproduce the turns of mind of the author. I thank the Societe de Biologie, in particular its General Secretary, Professor J. Roche, for having kindly accepted my request to translate and publish the following historical papers by Brown-Sequard. BIOGRAPHICAL SKETCH OF CHARLES EDWARD BROWN-StiQUARD
Brown-Sequard was born in 1817, from an American father and a Mauritian-French mother. This “small, dark man with a smile full of kindness,” as he was once described, studied medicine in Paris and obtained his doctorate at the age of 29. In spite of the frequent and sometimes profound changes in his life, Brown-SCquard was a prolific author, publishing more than 500 works. Out of his several appointments the following three were probably the most well-known. In 1859, he was
3
ANDRGS 1. When the posterior roots of all nerves of an anterior limb of a frog are cut, it obeys much less well, for some time afterwards, than the other limb; however, this difference does not last long, for after a fifteen minute resting period, it is difficult to recognize which is the anesthetised limb. 2. When all posterior roots of the hindlimbs are cut, the movements produced by these limbs are visibly disturbed, and although the animal can jump and swim after a certain resting time, it is quite evident that the movements then produced still lack precision. 3. After section of all posterior roots, the frogs can still move and even jump and swim, but then the anterior limb movements seem to be much weaker than those produced by the posterior limbs. 4. Sometimes, when the skin of the face or the eye of a frog, all of whose posterior roots have been cut, is pinched or pricked, the animal is capable of projecting forward one posterior limb, to remove the exciting cause. A similar movement is seen when the skin of the head, or that of the forelimbs is pinched, in frogs whose posterior roots of one hindlimb were cut. 5. One or two days after cutting the sensory roots of one or several limbs, one sees a tetanic stiffness develop in the affected limbs as soon as the animal is sharply stimulated. This partial tetanus is sometimes very strong and may last from a few seconds to five or six minutes. 6. Several observations, and among them those gathered in a thesis by Mr. O’Brien, indisputably show that, in some situations, the “will” has almost the same power in anesthetised as in healthy limbs. These observations show that we know to have accomplished “willed” movements, only by means of the sensations that either accompany or follow these movements. In the absence of tactile sensations, or of sensations coming from the contracted muscles, the anesthetised animals use sight as a means to know if they have produced the desired movement. 7. Sensibility is used to give precision to the movement, to direct it; thus, it is used in all cases in which movements have to be measured, as for instance in singing, in playing the piano, etc. 8. The trouble caused by anesthesia in the production of voluntary movements, varies as it is placed in the brain, in the spinal cord or in the posterior roots. Mr. Marshall Hall proved that there are marked differences between paralysis due to a cerebral or a peripheral nerve lesion. Not less important differences exist between an anesthesia due to a brain lesion and to a lesion of the posterior roots. In the last case, besides anesthesia, there is a paralysis of reflex activity; nowadays, it is generally accepted that reflex activity intervenes in all locomotor movements and particularly in walking and standing, due to stimulation of the nerves in the plantar surface of feet. In respect to voluntary movements, it is therefore necessary to distinguish an anesthesia due to a lesion in the brain from an anesthesia due to a small lesion in the spinal cord, which allows reflex activity. Two pathological observations, one of a brain lesion and another of a lesion placed in the posterior roots, show how voluntary movements are stronger and more sustained in the first case, than in the second. Mr. BrownSequard has decided to present several facts that support his present purposes in another paper. Experiments Involving Lesions of the Spinal Cord by Brown-Sequard, Comptes Rendus Societe Biologie, vol. 1, pages 17-18, 1849. Pathological observations prove that spinal cord lesions are not always fatal, and that paraplegia, which is the consequence,
may disappear more or less completely; however, there is no observation showing cure, neither recurrence of sensibility nor voluntary movements, after complete transection of the spinal cord. The experiments made by Arnemann and Mr. Flourens lead to similar results; moreover, the small number of these experiments and the localization of their lesions do not allow the deduction of rigorous consequences. Following are the results of several experiments made by Mr. Brown-Sequard with guinea-pigs, rabbits and pigeons: I. The lesions affecting a more or less large extent of the spinal cord of pigeons, between the two enlargements corresponding to the limbs, lead to a loss of sensibility varying between one hour and one day. Voluntary activity is usually affected for a longer time. 2. Similar lesions in mammals are less quickly followed by a return of voluntary activity. Sensibility returns almost as quickly. It happens frequently that mammals and pigeons enter a hyperesthetic state on the day after the operation, which persists for several days. 3. After complete transection of the spinal cord, life expectancy is generally much longer in pigeons than in mammals. The maximum survival has been six months. 4. In three pigeons, the results of the complete sectioning of the spinal cord, caudal to the enlargement corresponding to the wings, are quite appropriate to show that this lesion is not necessarily fatal and that it can be followed by a return of sensibility, as well as of voluntary activity. Unfortunately, two animals were killed by accident, at a time when their paraplegia was beginning to disappear; defecation which had not taken place for two months, but by regurgitation, was then taking place at will. The third pigeon, which has been shown to the society, begins to make some voluntary movements; up to now it has only eliminated faeces and urine by regurgitation. 5. Although many mammals and pigeons have survived a complete transection of the spinal cord for several months, none but the three preceding ones have recovered sensibility and voluntary activity, with almost as much energy on their last day of life as on the day next to the operation. These movements are much more active, fast and repeated in pigeons, than in mammals. It is known that in man in similar conditions, reflex movements greatly vary in intensity and are not produced unless by stimulation of the sole of the foot, the anus, the glans penis or the urethra. 6. At autopsy, a more or less bleached blood clot was found adherent to the region where the spinal cord had been sectioned. In the two cases showing functional recovery, instead, a gray reddish substance of higher consistency than the spinal cord itself was found, crossed by white filaments. 7. The ulcers existing in the compressed regions of the hindlimbs of animals whose spinal cord was transected, are a consequence of the compressions themselves and not of a so-called nutritional problem that would produce paralysis. Whatever the survival time of paraplegic animals no ulcers are found if compressions are avoided. 8. The “burns” and wounds of paralysed animals, whose spinal cord was transected, heal as fast as those of intact animals. Mr. Brown-Sequard says to have made this important observation a large number of times. Regeneration of Spinal Cord Tissues by Brown-Sequard, Comptes Rendus SociCtC Biologie, vol. 2, page 3, 1850. The author reports to have transected the spinal cord of an adult pigeon. Three months later the animal was killed and the interrupted spinal cord was found reconnected. Mr. Follin willingly helped Mr. Brown-Sequard to study the scar tissue with a microscope. Gray matter cells and nerve fibres were found
BROWN-SEQUARD
CONTRIBUTIONS
less numerous than in normal state. Regeneration had not been adequate to allow a significant return of sensibility and voluntary movements. The legs, the tail and the anus produced very active reflex movements, but there was no trace of voluntary movements. Yet, this is a very interesting case, as it is the first one in which regeneration of cells and nerve fibres was found after complete cross section of the spinal cord. This case acquires even more importance if related to the cases described by Brown-Sequard in the Compt. Rend. of this society (February 1849; Gaz. Med. no. ll), in which a return of sensibility and of voluntary movements was observed. On Several Cases of Wound Healing in the Spinal Cord, with Return of Lost Functions by Brown-Sequard, Comptes Rendus SociCtC Biologie, vol. 3, pages 77-79, 1851. In the course of the last three years, Mr. Brown-Sequard made a large number of experiments with the intention of finding out the capacity of spinal cord wounds to heal; his first results were published in the Gazette Medicale (Comptes Rendus Sot. Biol., Feb. 1849 and Jan. 1850). Until then he had not seen but a partial return of sensibility and voluntary movements. Since then he has seen pigeons which had undergone a complete transection of the spinal cord doing voluntary movements almost as well as normal ones, and showing a complete return of sensibility. Two out of three pigeons died without being examined, during a trip of Mr. Brown-Sequard. The third one, operated fifteen months ago, is still alive; its spinal cord was completely transected at the level of the fifth or the sixth costal vertebra. Obviously, after the operation there were no traces of sensibility or voluntary movements in the hindlimbs. After three months some voluntary movements could be recognized among the reflex movements, and sensibility seemed to reappear. This return to normality increased progressively, and after six months this pigeon could stand for some time; but as soon as it began to walk it would fall. During the seventh month it was able to walk, but frequently stumbled and was forced to use its wings to brace itself. At the end of the eighth month it walked quite well, if slowly and not disturbed. Whenever it wanted to go faster it would fall on either side, unless it could unfold one wing to be used as a support. Every time it walked a little faster the wings were a little spread out as if ready to be used as a parachute, or as a balancing pole. Finally, twelve months after the operation it could run, and today (end of the fifteenth month) it would be otherwise normal if its gait was not a little steep. Mr. Brown-Sequard noticed the partial return of voluntary movements in several guinea-pigs in which one lateral half of the spinal cord was sectioned seven or eight months earlier. In one guinea-pig, operated about a year earlier, which had an almost complete return of sensibility but a not so important return of voluntary movements, Mr. Brown-Sequard examined
5 the spinal cord scar with the help of a skillful micrographer, Mr. Laboulbene. The following is what they have observed. The skin removed, they saw what Mr. Brown-Sequard has always seen in similar cases, the posterior vertebral arcs affected by the lesion, had completely regenerated and taken almost normal dimensions. Underneath the arcs, and adhering to them, was a thick fibrous membrane to which the spinal cord was fixed. Once separated from this membrane, it was noticed that the diameter of the spinal cord was reduced in this region. The operation made more than one year earlier, had consisted of the transections of the right half and left posterior cordon of the spinal cord, so that the two posterior cordons plus the lateral and the right anterior cordons, as well as the gray substance of this half of the spinal cord were cut at the same level. In a carefully made study of the spinal cord it was noticed that the shrinking existed only in the region that had been sectioned. At the level of this kind of coarctation, even if rather slight, there was a whitish line. This white line and depression indicated most certainly the place of the lesion. A very small fragment of the posterior surface of the spinal cord, collected at the depressed and whitish region, showed: 1. A large number of “tissue fibres” forming the whitish scar. These fibres, with 0.001 to 0.002 mm in diameter, are, for the most part, transversally or very slightly obliquely oriented, crossing the nerve fibres more or less perpendicularly. 2. Nerve fibres with double outline, and 0.004 to 0.006 mm in diameter. These nervous tubes exist in large number within the microscopic field, and are situated among the “cell fibres”. None show traces of deformation or rupture; they course the whole scar without interruption, that is, the region where “cell fibres” exist as well as in front and behind it. 3. Rarely, “nervous corpuscles” could be found scattered among the nerve fibres. The microscopical study of the whitish region showed a considerable number of “cell fibres” in its middle part, may be larger than that of nervous fibres. With slight displacements of the preparation it could be seen that the number of “cell fibres” decreased until finally none could be seen, while the nerve fibres were always visible with the same aspect inside and outside the scar. From these experiments it can be concluded: 1. That spinal cord lesions can heal, as Mr. Flourens, Ollivier and Jobert had already observed. 2. That spinal cord functions can return to normal, even after a complete transection. We will add that, according to what Mr. Brown-Sequard saw in three cases: once with Mr. Lebert, another time with Mr. Follin and above all what he last saw with Mr. Laboulb&e, the scars of old spinal cord lesions contain many nerve fibres of normal appearance, which are in continuity with the fibres of the intact regions.
0361.9230/89 $3.00 + .oO
Contributions by Brown-Skquard on Spinal Cord Trauma and Pathology FILIPE ANDR&
Institut d’Anatomie, TRANSLATOR’S
Universite’ de Lausanne,
Rue du Bugnon 9, 1005 Lausanne, Switzerland appointed to the National Hospital, Queen Square, and became a Fellow of the Royal College of Surgeons and of the Royal Society, the next year. In 1863 he resigned from this post and became Professor of Physiology and Pathology of the nervous system at Harvard. In 1878, he took the post left by Claude Bernard at the College de France, becoming a member of the Academy of Sciences in 1886, and a French citizen almost at the same time. A few years later, in 1894, he died of a cerebral thrombosis. On the Relationships that Exist Between Sensory and Motor Roots by Brown-Sequard, Comptes Rendus SociCtC Biologie, vol. 1, pages 15-17, 1849. In the meeting of February 3rd Mr. Brown-Sequard communicated some results of his research on the independence of sensibility and motricity. The following is a summary of that interesting communication and of the experiments upon which he based himself.
NOTE
The history of the study of spinal cord trauma and pathology is an old one. It goes back to 3000-2500 B.C. in Egypt, as demonstrated by the description of two cases of traumatic spinal cord compression, in the Edwin Smith surgical papyrus. After that time, we hear from it by Hippocrates (460-370 B.C.) who made precise descriptions of the clinical consequences of spinal cord lesions, and later by Galen (129-199 A.D.) who inaugurated experimental research on spinal cord functions. Then comes a long period of torpor during which the Galenic influence is maintained. Until the end of the 18th century several experiments were made without great contribution to the knowledge of spinal cord function. Then, and at the beginning of the 19th century things changed somewhat, for the better, when moderate animists such as Robert Whytt (1714-1766) and Johann August Unzer (1727-1799) gradually brought down the concept of soul, and raised the concept that voluntary and involuntary activities are the effect of a central nervous system mechanism; when Marshall Hall (1790-1857) provided the basis to the concept of the spinal cord neural arc, and Charles Bell (1774-1842) made the differentiation between the functions of the anterior and posterior spinal roots. It is in this context that the pioneer works of Brown-Sequard (1817-1894) on spinal cord trauma and regeneration, make their appearance. The three following notes express well his ideas on this subject. These works have not only historical but also scientific value for investigators working on the spinal cord trauma. With these considerations it was deemed necessary to provide translations of the four classical pieces of work by Brown-Sequard to the English speaking scientists. During translation of these four works great care was taken to translate with fidelity the author’s views. For this reason, in some places, the translation came close to transliteration, to better reproduce the turns of mind of the author. I thank the Societe de Biologie, in particular its General Secretary, Professor J. Roche, for having kindly accepted my request to translate and publish the following historical papers by Brown-Sequard. BIOGRAPHICAL SKETCH OF CHARLES EDWARD BROWN-StiQUARD
Brown-Sequard was born in 1817, from an American father and a Mauritian-French mother. This “small, dark man with a smile full of kindness,” as he was once described, studied medicine in Paris and obtained his doctorate at the age of 29. In spite of the frequent and sometimes profound changes in his life, Brown-SCquard was a prolific author, publishing more than 500 works. Out of his several appointments the following three were probably the most well-known. In 1859, he was
3
ANDRGS 1. When the posterior roots of all nerves of an anterior limb of a frog are cut, it obeys much less well, for some time afterwards, than the other limb; however, this difference does not last long, for after a fifteen minute resting period, it is difficult to recognize which is the anesthetised limb. 2. When all posterior roots of the hindlimbs are cut, the movements produced by these limbs are visibly disturbed, and although the animal can jump and swim after a certain resting time, it is quite evident that the movements then produced still lack precision. 3. After section of all posterior roots, the frogs can still move and even jump and swim, but then the anterior limb movements seem to be much weaker than those produced by the posterior limbs. 4. Sometimes, when the skin of the face or the eye of a frog, all of whose posterior roots have been cut, is pinched or pricked, the animal is capable of projecting forward one posterior limb, to remove the exciting cause. A similar movement is seen when the skin of the head, or that of the forelimbs is pinched, in frogs whose posterior roots of one hindlimb were cut. 5. One or two days after cutting the sensory roots of one or several limbs, one sees a tetanic stiffness develop in the affected limbs as soon as the animal is sharply stimulated. This partial tetanus is sometimes very strong and may last from a few seconds to five or six minutes. 6. Several observations, and among them those gathered in a thesis by Mr. O’Brien, indisputably show that, in some situations, the “will” has almost the same power in anesthetised as in healthy limbs. These observations show that we know to have accomplished “willed” movements, only by means of the sensations that either accompany or follow these movements. In the absence of tactile sensations, or of sensations coming from the contracted muscles, the anesthetised animals use sight as a means to know if they have produced the desired movement. 7. Sensibility is used to give precision to the movement, to direct it; thus, it is used in all cases in which movements have to be measured, as for instance in singing, in playing the piano, etc. 8. The trouble caused by anesthesia in the production of voluntary movements, varies as it is placed in the brain, in the spinal cord or in the posterior roots. Mr. Marshall Hall proved that there are marked differences between paralysis due to a cerebral or a peripheral nerve lesion. Not less important differences exist between an anesthesia due to a brain lesion and to a lesion of the posterior roots. In the last case, besides anesthesia, there is a paralysis of reflex activity; nowadays, it is generally accepted that reflex activity intervenes in all locomotor movements and particularly in walking and standing, due to stimulation of the nerves in the plantar surface of feet. In respect to voluntary movements, it is therefore necessary to distinguish an anesthesia due to a lesion in the brain from an anesthesia due to a small lesion in the spinal cord, which allows reflex activity. Two pathological observations, one of a brain lesion and another of a lesion placed in the posterior roots, show how voluntary movements are stronger and more sustained in the first case, than in the second. Mr. BrownSequard has decided to present several facts that support his present purposes in another paper. Experiments Involving Lesions of the Spinal Cord by Brown-Sequard, Comptes Rendus Societe Biologie, vol. 1, pages 17-18, 1849. Pathological observations prove that spinal cord lesions are not always fatal, and that paraplegia, which is the consequence,
may disappear more or less completely; however, there is no observation showing cure, neither recurrence of sensibility nor voluntary movements, after complete transection of the spinal cord. The experiments made by Arnemann and Mr. Flourens lead to similar results; moreover, the small number of these experiments and the localization of their lesions do not allow the deduction of rigorous consequences. Following are the results of several experiments made by Mr. Brown-Sequard with guinea-pigs, rabbits and pigeons: I. The lesions affecting a more or less large extent of the spinal cord of pigeons, between the two enlargements corresponding to the limbs, lead to a loss of sensibility varying between one hour and one day. Voluntary activity is usually affected for a longer time. 2. Similar lesions in mammals are less quickly followed by a return of voluntary activity. Sensibility returns almost as quickly. It happens frequently that mammals and pigeons enter a hyperesthetic state on the day after the operation, which persists for several days. 3. After complete transection of the spinal cord, life expectancy is generally much longer in pigeons than in mammals. The maximum survival has been six months. 4. In three pigeons, the results of the complete sectioning of the spinal cord, caudal to the enlargement corresponding to the wings, are quite appropriate to show that this lesion is not necessarily fatal and that it can be followed by a return of sensibility, as well as of voluntary activity. Unfortunately, two animals were killed by accident, at a time when their paraplegia was beginning to disappear; defecation which had not taken place for two months, but by regurgitation, was then taking place at will. The third pigeon, which has been shown to the society, begins to make some voluntary movements; up to now it has only eliminated faeces and urine by regurgitation. 5. Although many mammals and pigeons have survived a complete transection of the spinal cord for several months, none but the three preceding ones have recovered sensibility and voluntary activity, with almost as much energy on their last day of life as on the day next to the operation. These movements are much more active, fast and repeated in pigeons, than in mammals. It is known that in man in similar conditions, reflex movements greatly vary in intensity and are not produced unless by stimulation of the sole of the foot, the anus, the glans penis or the urethra. 6. At autopsy, a more or less bleached blood clot was found adherent to the region where the spinal cord had been sectioned. In the two cases showing functional recovery, instead, a gray reddish substance of higher consistency than the spinal cord itself was found, crossed by white filaments. 7. The ulcers existing in the compressed regions of the hindlimbs of animals whose spinal cord was transected, are a consequence of the compressions themselves and not of a so-called nutritional problem that would produce paralysis. Whatever the survival time of paraplegic animals no ulcers are found if compressions are avoided. 8. The “burns” and wounds of paralysed animals, whose spinal cord was transected, heal as fast as those of intact animals. Mr. Brown-Sequard says to have made this important observation a large number of times. Regeneration of Spinal Cord Tissues by Brown-Sequard, Comptes Rendus SociCtC Biologie, vol. 2, page 3, 1850. The author reports to have transected the spinal cord of an adult pigeon. Three months later the animal was killed and the interrupted spinal cord was found reconnected. Mr. Follin willingly helped Mr. Brown-Sequard to study the scar tissue with a microscope. Gray matter cells and nerve fibres were found
BROWN-SEQUARD
CONTRIBUTIONS
less numerous than in normal state. Regeneration had not been adequate to allow a significant return of sensibility and voluntary movements. The legs, the tail and the anus produced very active reflex movements, but there was no trace of voluntary movements. Yet, this is a very interesting case, as it is the first one in which regeneration of cells and nerve fibres was found after complete cross section of the spinal cord. This case acquires even more importance if related to the cases described by Brown-Sequard in the Compt. Rend. of this society (February 1849; Gaz. Med. no. ll), in which a return of sensibility and of voluntary movements was observed. On Several Cases of Wound Healing in the Spinal Cord, with Return of Lost Functions by Brown-Sequard, Comptes Rendus SociCtC Biologie, vol. 3, pages 77-79, 1851. In the course of the last three years, Mr. Brown-Sequard made a large number of experiments with the intention of finding out the capacity of spinal cord wounds to heal; his first results were published in the Gazette Medicale (Comptes Rendus Sot. Biol., Feb. 1849 and Jan. 1850). Until then he had not seen but a partial return of sensibility and voluntary movements. Since then he has seen pigeons which had undergone a complete transection of the spinal cord doing voluntary movements almost as well as normal ones, and showing a complete return of sensibility. Two out of three pigeons died without being examined, during a trip of Mr. Brown-Sequard. The third one, operated fifteen months ago, is still alive; its spinal cord was completely transected at the level of the fifth or the sixth costal vertebra. Obviously, after the operation there were no traces of sensibility or voluntary movements in the hindlimbs. After three months some voluntary movements could be recognized among the reflex movements, and sensibility seemed to reappear. This return to normality increased progressively, and after six months this pigeon could stand for some time; but as soon as it began to walk it would fall. During the seventh month it was able to walk, but frequently stumbled and was forced to use its wings to brace itself. At the end of the eighth month it walked quite well, if slowly and not disturbed. Whenever it wanted to go faster it would fall on either side, unless it could unfold one wing to be used as a support. Every time it walked a little faster the wings were a little spread out as if ready to be used as a parachute, or as a balancing pole. Finally, twelve months after the operation it could run, and today (end of the fifteenth month) it would be otherwise normal if its gait was not a little steep. Mr. Brown-Sequard noticed the partial return of voluntary movements in several guinea-pigs in which one lateral half of the spinal cord was sectioned seven or eight months earlier. In one guinea-pig, operated about a year earlier, which had an almost complete return of sensibility but a not so important return of voluntary movements, Mr. Brown-Sequard examined
5 the spinal cord scar with the help of a skillful micrographer, Mr. Laboulbene. The following is what they have observed. The skin removed, they saw what Mr. Brown-Sequard has always seen in similar cases, the posterior vertebral arcs affected by the lesion, had completely regenerated and taken almost normal dimensions. Underneath the arcs, and adhering to them, was a thick fibrous membrane to which the spinal cord was fixed. Once separated from this membrane, it was noticed that the diameter of the spinal cord was reduced in this region. The operation made more than one year earlier, had consisted of the transections of the right half and left posterior cordon of the spinal cord, so that the two posterior cordons plus the lateral and the right anterior cordons, as well as the gray substance of this half of the spinal cord were cut at the same level. In a carefully made study of the spinal cord it was noticed that the shrinking existed only in the region that had been sectioned. At the level of this kind of coarctation, even if rather slight, there was a whitish line. This white line and depression indicated most certainly the place of the lesion. A very small fragment of the posterior surface of the spinal cord, collected at the depressed and whitish region, showed: 1. A large number of “tissue fibres” forming the whitish scar. These fibres, with 0.001 to 0.002 mm in diameter, are, for the most part, transversally or very slightly obliquely oriented, crossing the nerve fibres more or less perpendicularly. 2. Nerve fibres with double outline, and 0.004 to 0.006 mm in diameter. These nervous tubes exist in large number within the microscopic field, and are situated among the “cell fibres”. None show traces of deformation or rupture; they course the whole scar without interruption, that is, the region where “cell fibres” exist as well as in front and behind it. 3. Rarely, “nervous corpuscles” could be found scattered among the nerve fibres. The microscopical study of the whitish region showed a considerable number of “cell fibres” in its middle part, may be larger than that of nervous fibres. With slight displacements of the preparation it could be seen that the number of “cell fibres” decreased until finally none could be seen, while the nerve fibres were always visible with the same aspect inside and outside the scar. From these experiments it can be concluded: 1. That spinal cord lesions can heal, as Mr. Flourens, Ollivier and Jobert had already observed. 2. That spinal cord functions can return to normal, even after a complete transection. We will add that, according to what Mr. Brown-Sequard saw in three cases: once with Mr. Lebert, another time with Mr. Follin and above all what he last saw with Mr. Laboulb&e, the scars of old spinal cord lesions contain many nerve fibres of normal appearance, which are in continuity with the fibres of the intact regions.