- Email: [email protected]
RABIES VACCINES
40 We have avoided these drawbacks by constructing low platforms behind the beds, similar to those used by Dr. B. W. Watson in a cardiac laboratory at St. Bartholomew’s Hospital.l The service outlets are left on the wall in the usual place. A platform, 12 cm. high and 75 cm. wide is placed between bed and wall, extending beyond the width
of the bed by 35 cm. at each side. At both sides the top of the platform is replaced by a hinged lid, 30 cm. x 70 cm., leaving a 5 cm. gap at the wall end through which the cables and tubes enter. Under the lid the front of the platform is cut out to form an outlet. For use, the platform lid is raised, cables and tubes plugged into the wall outlets, are dropped into the channel, and the lid is closed, leaving a flat surface free from obstruction (see accompanying figure). The platform prevents the bed from being pushed against the wall and gives free access to the back of the bed. I thank Mr. F. E.
Eversfield, Manchester Regional Hospital
Board, for his help. Department of Pathology, Burnley General Hospital,
G. BEHR.
Lancs.
ORANGE SOLES 2 SIR,-Dr. Bray describes orange palms and soles and high serum-carotene levels in two Nigerian children. This is a common finding in children from the Eastern region of Nigeria and other areas where palm oil is used. This orange-coloured oil has a high carotene content and is not only used extensively for cooking but is also rubbed into the skin after the daily bath. NORMA M. BASSETT A. B. AJDUKIEWICZ.
make experience (especially if it is not available) fit a predetermined plan. This can only bring the whole programme
The
into disrepute.
R. W. COPE W. J. GLOVER E. F. BATTERSBY D. J. HATCH.
Hospital for Sick Children, Great Ormond Street, London WC1N 3JH.
WORK OF THE ANÆSTHETIST SiR,-Dr. Bourne (June 13, p. 1288) writes that "... we anaathetists know that. even the most decrepit patient will come to harm only if we make a monumental blunder." As an anaesthetist, I, for one, wish to dissociate myself from this view, with which I disagree most strongly. Further, I do not believe that one should ever approach an anaesthetic, even if the patient is not decrepit, expecting that it will necessarily be a routine procedure. Trainees, whether they be doctors or paramedical technicians, should be taught that it is in routine, as well as unusual, operations that things may go wrong, even in experienced hands and without monumental blunders. Personally, I think Dr. Rubin’s arguments (May 30, p. 1170) for the orthodox role of the anaesthetist stand up very well to the scrutiny suggested by Dr. Bourne. It is when Dr. Rubin’s " old-fashioned approach is no longer acceptable or possible that I believe the standard of anaesthesia in the operating-theatres will begin to slip. St. Bartholomew’s Hospital, ROBERT BALLANTINE. London E.C.1. "
RABIES VACCINES
TRAINING OF ANÆSTHETISTS SIR,-We welcome the effort which the Faculty of Anaesthetists of the Royal College of Surgeons of England is making to improve the training of anaesthetists.3 However, the scheme outlined recommending three months’ training in pxdiatric anaesthesia appears to have overlooked the lack of clinical material in pa:diatric anaesthesia in the country as a whole. A population of 2 million is usually regarded as a reasonable number on which to base a paediatric surgical centre. In a three-month period there will be a total of 7500 births. The expected total of neonatal emergencies which may arise is as follows: Spina bifida 20; Hirschsprung’s disease 3; msophageal atresia 1; rectal atresia 1; small-intestinal atresias 1; exomphalos 3;
diaphragmatic
hernia 1.
Not all neonatal centre. Some will operated upon by
emergencies reach
a
paediatric surgical
survive, and some infants may be specialist surgeons in their own adult not
hospitals. Perhaps at its most favourable two-thirds of patients may present for treatment at the paediatric
the
centre.
Since these are emergencies, if the trainee undergoing " higher professional training " is on duty one night in three, and provided he takes no leave (annual or study), then in a three-month period he would see approximately 5 neonates of whom approximately 4 would have spina bifida. The number of infants requiring anaesthesia in the first year of life is also very small. We are fully aware of the difficulties
attempting
to
confronting
anyone purpose of attemntins’ to
improve postgraduate training. Our
in writing this letter is
to
show the
error
1. Watson, B. W. Bio-med. Eng. 1968, 2. Bray, B. V. Lancet, 1970, i, 1348. 3. See ibid. p. 1214.
3, 460.
SIR,-Dr. Macraequestions the rationale of human post-exposure therapy in rabies, a subject that has always been contentious. It is doubtful whether post-exposure vaccination after any virus infection could be effective unless the virus remained accessible to vaccine-induced antibody for a considerable time. Antibody responses to rabies vaccines are not detectable before 6-8 days. The many differences between biting incidents make it difficult to predict in any particular case the route by which rabies virus reaches the central nervous system and the time required for this to occur. If, as seems generally accepted, virus is present in the peripheral nerves within a few hours of exposure, vaccine therapy would be valueless and specific antiserum itself useful only if given immediately. On the other hand, if virus remains for relatively long periods in extraneural sites as suggested by Krause,2 then antibody could be of value either passively administered or actively and rapidly induced by vaccine. Experiments of the type suggested by Dr. Macrae have in fact already been done by Krause, who showed that post-exposure vaccination of mice was of undoubted value in reducing the mortality-rate of animals infected by inoculation of the plantar pedis. Of greater relevance, the findings of Veeraraghavan3 on the comparative mortality of bitten persons who were left untreated or given rabies vaccine point to the value of human post-exposure therapy, even though interpretation of data derived from human cases is difficult because there can be no certainty that the persons involved had been infected by the bite. Many groups likely to be exposed to rabies are already prophylactically immunised, but we agree with Dr. Macrae that it would be desirable to have more pre-exposure vaccination if the risk of rabies becomes more widespread. 1. Macrae, A. J. Lancet, 1970, i, 1229. 2. Krause, W. W. Proceedings of International Symposium Rabies; vol. I, p. 153. Talloires, 1965. 3. Veeraraghavan, N. Bull. Wld Hlth Org. 1954, 10, 789.
on
41
Until some of the more basic questions concerning infection of man with rabies have been answered, however, it would be safer to continue with post-exposure therapy. It would also seem preferable to use vaccines which can elicit better antibody responses than the currently used duck-embryo vaccine. Animal Virus Research Institute
Pirbright, Woking, Surrey, and Lister Institute for Preventive Medicine, Elstree, Herts.
JOAN CRICK F. BROWN G. S. TURNER.
THE DISTENDING FORCE IN THE PRODUCTION OF COMMUNICATING SYRINGOMYELIA SIR,-Dr. Ellertsson and Professor Greitz are to be congratulated on their demonstration of pressure elevations within a syrinx relative to the pressure in the subarachnoid space at the same level in patients with communicating syringomyelia (June 6, p. 1234). Their records might be improved if the time-scale was included and if the method of zeroing were mentioned. There seems to be a peculiarly constant pressure-differential between the inside and the outside of the cyst. I have managed to obtain simultaneous pressure recordings from the lateral ventricle and within a syrinx together with recordings from the subarachnoid space. I can confirm that arterial pulsation is not significantly different between the inside and the outside of the cyst, although both pressure traces are a little lower in amplitude than in the ventricles, as would be expected from the findings in normal patients. I hope that these mutual observations may help dispose of the theory that arterial pulsation engendered chiefly within the ventricles can excavate the grey matter and distend the spinal cord. I certainly agree that defective drainage of the cyst may be present and may be more important than the foramenmagnum abnormality in subsequent tracking of fluid within the cyst. Such a valve-like mechanism has to be present for syringobulbia to occur. However, it must always be secondary to the foramen-magnum abnormality, and to say that it is the cause of the cyst is certainly wrong. The opening between the central canal and the syrinx is most commonly in the cervical enlargement.2 When fluid or air tracks cranially (upwards) it may become trapped in a cul-de-sac which may flatten the communication (fig. 1). Ellertsson himself has commented on this phenomenonand at operation one can see that a syrinx inflated with a syringe may not quickly subside; it is not always easy to do as Conway4 suggests and demonstrate a communication from the syrinx to the ventricles by injecting dye into the syrinx and squeezing it out from the floor of the fourth ventricle. Pressure studies done in patients in the upright position during Valsalva’s manoeuvre indicate that the pressure in the lumbar theca almost always rises sharply before that in the cistern or ventricle. Restatement of the hypothesis5 is now necessary. The initial movement of cerebrospinal fluid (c.s.F.) during Valsalva’s manoeuvre is usually cephalad; it is caused by distension of spinal veins. The rebound movement from cranium to spinal space is accompanied by relative constriction of the subarachnoid pathway compared with the Both the foramen-magnum (primary) communication. valve and the communication/syrinx (secondary) valve may contribute to this flow preference. Restating the hypothesis in this form has further advantages. The distensibilitv of the dura mav have been open to 1. Bering, E. A. Archs Neurol. Psychiat. 1955, 73, 165. 2. Greenfield, J. G., Blackwood, W., McMenemy, W. H., Meyer, Norman, R. M. Neuropathology. London. 1958. 3. Ellertsson, A. B., Greitz, T. Acta neurol. scand. 1969, 45, 418. 4. Conway, L. W. J. Neurosurg. 1967, 27, 501. 5. Williams, B. Lancet, 1969, ii, 189.
Fig. 1-Mechanism of syringobulbia. When fluid tracks through the soft grey matter alongside the central canal it may compress the canal in such a way as to form a valve. When the c.s.F. is thrust upwards at the onset of straining, the fluid cannot quickly escape along the communication, and is forced along the grey matter into the medulla.
Fig. 2-Mechanism of communicating syringomyelia after paraplegia. The initial injury may destroy the inside of the cord and produce varying patterns of external adhesions. If, during resolution, the c.s.F. pathways communicate with an intra-cord cavity, and if a funnel-shaped cavity is present, then the upthrust of c.s.F. during
subsequent straining may
excavate
the grey matter
upwards.
debate, but there can be no doubt of its compressibility. The force of the upthrust producing syringobulbia is also easier to understand as a primary phenomenon than as a rebound. The upward thrust of c.s.F. is the most probable explanation for those cases of late-onset syringomyelia following paraplegia in which the syrinx contains c.s.F. There are now a very large number of case-reports 6-18 in which, between four months and fourteen years after the onset of paraplegia (due to accident or operation for Pott’s disease, intramedullary tumour, or kyphoscoliosis) a syringomyelia develops at the level immediately above the paraplegia or in the cervical enlargement. In these case-reports the onset of symptoms in relation to a sudden strain is noted even more commonly than in the usual communicating syrinx.Some are reported as having a syrinx containing proteinous fluid. One of Rossier and Werner’s cases was said to have a communication between the fourth ventricle 6. Barnett, M. J. M., 7. 8. 9. 10. 11. 12. 13. 14. 15.
A., 16. 17. 18.
Botterell, E. H., Jousse, A. T., Wynne-Jones, M. Brain, 1966, 89, 159. Cossa, P. Revue neurol. 1943, 75, 39. Finkle, J. R. Proceedings of the Ninth Annual Clinical Spinal Cord Injury Conference; p. 45. 1960. Foster, J. B. Personal communication. Freeman, L. W. J. Neurosurg. 1959, 16, 120. Jung, E. Med. Klin. 1960, 55, 1678. Martin, C., Maury, M. Presse méd. 1964, 48, 2839. Nurick, S., Russell, J. A., Deck, M. J. F. Brain, 1970, 93, 211. Riffat, G., Domenach, J. Lyon med. 1964, 212, 1043. Rossier, A. B., Werner, A., Wildi, E., Berney, J. J. Neurol. Neurosurg. Psychiat. 1968, 31, 99. Schott, B., Trillet, M., Vauterin, C., Koshbin, Revue neurol. 1962, 106, 751. Werner, A. Schweiz Arch. Neurol. Neurochir. Psychiat. 1969, 104, 77. Zdrojewski, B. Neurochirurgie, 1969, 15, 153.
of the bed by 35 cm. at each side. At both sides the top of the platform is replaced by a hinged lid, 30 cm. x 70 cm., leaving a 5 cm. gap at the wall end through which the cables and tubes enter. Under the lid the front of the platform is cut out to form an outlet. For use, the platform lid is raised, cables and tubes plugged into the wall outlets, are dropped into the channel, and the lid is closed, leaving a flat surface free from obstruction (see accompanying figure). The platform prevents the bed from being pushed against the wall and gives free access to the back of the bed. I thank Mr. F. E.
Eversfield, Manchester Regional Hospital
Board, for his help. Department of Pathology, Burnley General Hospital,
G. BEHR.
Lancs.
ORANGE SOLES 2 SIR,-Dr. Bray describes orange palms and soles and high serum-carotene levels in two Nigerian children. This is a common finding in children from the Eastern region of Nigeria and other areas where palm oil is used. This orange-coloured oil has a high carotene content and is not only used extensively for cooking but is also rubbed into the skin after the daily bath. NORMA M. BASSETT A. B. AJDUKIEWICZ.
make experience (especially if it is not available) fit a predetermined plan. This can only bring the whole programme
The
into disrepute.
R. W. COPE W. J. GLOVER E. F. BATTERSBY D. J. HATCH.
Hospital for Sick Children, Great Ormond Street, London WC1N 3JH.
WORK OF THE ANÆSTHETIST SiR,-Dr. Bourne (June 13, p. 1288) writes that "... we anaathetists know that. even the most decrepit patient will come to harm only if we make a monumental blunder." As an anaesthetist, I, for one, wish to dissociate myself from this view, with which I disagree most strongly. Further, I do not believe that one should ever approach an anaesthetic, even if the patient is not decrepit, expecting that it will necessarily be a routine procedure. Trainees, whether they be doctors or paramedical technicians, should be taught that it is in routine, as well as unusual, operations that things may go wrong, even in experienced hands and without monumental blunders. Personally, I think Dr. Rubin’s arguments (May 30, p. 1170) for the orthodox role of the anaesthetist stand up very well to the scrutiny suggested by Dr. Bourne. It is when Dr. Rubin’s " old-fashioned approach is no longer acceptable or possible that I believe the standard of anaesthesia in the operating-theatres will begin to slip. St. Bartholomew’s Hospital, ROBERT BALLANTINE. London E.C.1. "
RABIES VACCINES
TRAINING OF ANÆSTHETISTS SIR,-We welcome the effort which the Faculty of Anaesthetists of the Royal College of Surgeons of England is making to improve the training of anaesthetists.3 However, the scheme outlined recommending three months’ training in pxdiatric anaesthesia appears to have overlooked the lack of clinical material in pa:diatric anaesthesia in the country as a whole. A population of 2 million is usually regarded as a reasonable number on which to base a paediatric surgical centre. In a three-month period there will be a total of 7500 births. The expected total of neonatal emergencies which may arise is as follows: Spina bifida 20; Hirschsprung’s disease 3; msophageal atresia 1; rectal atresia 1; small-intestinal atresias 1; exomphalos 3;
diaphragmatic
hernia 1.
Not all neonatal centre. Some will operated upon by
emergencies reach
a
paediatric surgical
survive, and some infants may be specialist surgeons in their own adult not
hospitals. Perhaps at its most favourable two-thirds of patients may present for treatment at the paediatric
the
centre.
Since these are emergencies, if the trainee undergoing " higher professional training " is on duty one night in three, and provided he takes no leave (annual or study), then in a three-month period he would see approximately 5 neonates of whom approximately 4 would have spina bifida. The number of infants requiring anaesthesia in the first year of life is also very small. We are fully aware of the difficulties
attempting
to
confronting
anyone purpose of attemntins’ to
improve postgraduate training. Our
in writing this letter is
to
show the
error
1. Watson, B. W. Bio-med. Eng. 1968, 2. Bray, B. V. Lancet, 1970, i, 1348. 3. See ibid. p. 1214.
3, 460.
SIR,-Dr. Macraequestions the rationale of human post-exposure therapy in rabies, a subject that has always been contentious. It is doubtful whether post-exposure vaccination after any virus infection could be effective unless the virus remained accessible to vaccine-induced antibody for a considerable time. Antibody responses to rabies vaccines are not detectable before 6-8 days. The many differences between biting incidents make it difficult to predict in any particular case the route by which rabies virus reaches the central nervous system and the time required for this to occur. If, as seems generally accepted, virus is present in the peripheral nerves within a few hours of exposure, vaccine therapy would be valueless and specific antiserum itself useful only if given immediately. On the other hand, if virus remains for relatively long periods in extraneural sites as suggested by Krause,2 then antibody could be of value either passively administered or actively and rapidly induced by vaccine. Experiments of the type suggested by Dr. Macrae have in fact already been done by Krause, who showed that post-exposure vaccination of mice was of undoubted value in reducing the mortality-rate of animals infected by inoculation of the plantar pedis. Of greater relevance, the findings of Veeraraghavan3 on the comparative mortality of bitten persons who were left untreated or given rabies vaccine point to the value of human post-exposure therapy, even though interpretation of data derived from human cases is difficult because there can be no certainty that the persons involved had been infected by the bite. Many groups likely to be exposed to rabies are already prophylactically immunised, but we agree with Dr. Macrae that it would be desirable to have more pre-exposure vaccination if the risk of rabies becomes more widespread. 1. Macrae, A. J. Lancet, 1970, i, 1229. 2. Krause, W. W. Proceedings of International Symposium Rabies; vol. I, p. 153. Talloires, 1965. 3. Veeraraghavan, N. Bull. Wld Hlth Org. 1954, 10, 789.
on
41
Until some of the more basic questions concerning infection of man with rabies have been answered, however, it would be safer to continue with post-exposure therapy. It would also seem preferable to use vaccines which can elicit better antibody responses than the currently used duck-embryo vaccine. Animal Virus Research Institute
Pirbright, Woking, Surrey, and Lister Institute for Preventive Medicine, Elstree, Herts.
JOAN CRICK F. BROWN G. S. TURNER.
THE DISTENDING FORCE IN THE PRODUCTION OF COMMUNICATING SYRINGOMYELIA SIR,-Dr. Ellertsson and Professor Greitz are to be congratulated on their demonstration of pressure elevations within a syrinx relative to the pressure in the subarachnoid space at the same level in patients with communicating syringomyelia (June 6, p. 1234). Their records might be improved if the time-scale was included and if the method of zeroing were mentioned. There seems to be a peculiarly constant pressure-differential between the inside and the outside of the cyst. I have managed to obtain simultaneous pressure recordings from the lateral ventricle and within a syrinx together with recordings from the subarachnoid space. I can confirm that arterial pulsation is not significantly different between the inside and the outside of the cyst, although both pressure traces are a little lower in amplitude than in the ventricles, as would be expected from the findings in normal patients. I hope that these mutual observations may help dispose of the theory that arterial pulsation engendered chiefly within the ventricles can excavate the grey matter and distend the spinal cord. I certainly agree that defective drainage of the cyst may be present and may be more important than the foramenmagnum abnormality in subsequent tracking of fluid within the cyst. Such a valve-like mechanism has to be present for syringobulbia to occur. However, it must always be secondary to the foramen-magnum abnormality, and to say that it is the cause of the cyst is certainly wrong. The opening between the central canal and the syrinx is most commonly in the cervical enlargement.2 When fluid or air tracks cranially (upwards) it may become trapped in a cul-de-sac which may flatten the communication (fig. 1). Ellertsson himself has commented on this phenomenonand at operation one can see that a syrinx inflated with a syringe may not quickly subside; it is not always easy to do as Conway4 suggests and demonstrate a communication from the syrinx to the ventricles by injecting dye into the syrinx and squeezing it out from the floor of the fourth ventricle. Pressure studies done in patients in the upright position during Valsalva’s manoeuvre indicate that the pressure in the lumbar theca almost always rises sharply before that in the cistern or ventricle. Restatement of the hypothesis5 is now necessary. The initial movement of cerebrospinal fluid (c.s.F.) during Valsalva’s manoeuvre is usually cephalad; it is caused by distension of spinal veins. The rebound movement from cranium to spinal space is accompanied by relative constriction of the subarachnoid pathway compared with the Both the foramen-magnum (primary) communication. valve and the communication/syrinx (secondary) valve may contribute to this flow preference. Restating the hypothesis in this form has further advantages. The distensibilitv of the dura mav have been open to 1. Bering, E. A. Archs Neurol. Psychiat. 1955, 73, 165. 2. Greenfield, J. G., Blackwood, W., McMenemy, W. H., Meyer, Norman, R. M. Neuropathology. London. 1958. 3. Ellertsson, A. B., Greitz, T. Acta neurol. scand. 1969, 45, 418. 4. Conway, L. W. J. Neurosurg. 1967, 27, 501. 5. Williams, B. Lancet, 1969, ii, 189.
Fig. 1-Mechanism of syringobulbia. When fluid tracks through the soft grey matter alongside the central canal it may compress the canal in such a way as to form a valve. When the c.s.F. is thrust upwards at the onset of straining, the fluid cannot quickly escape along the communication, and is forced along the grey matter into the medulla.
Fig. 2-Mechanism of communicating syringomyelia after paraplegia. The initial injury may destroy the inside of the cord and produce varying patterns of external adhesions. If, during resolution, the c.s.F. pathways communicate with an intra-cord cavity, and if a funnel-shaped cavity is present, then the upthrust of c.s.F. during
subsequent straining may
excavate
the grey matter
upwards.
debate, but there can be no doubt of its compressibility. The force of the upthrust producing syringobulbia is also easier to understand as a primary phenomenon than as a rebound. The upward thrust of c.s.F. is the most probable explanation for those cases of late-onset syringomyelia following paraplegia in which the syrinx contains c.s.F. There are now a very large number of case-reports 6-18 in which, between four months and fourteen years after the onset of paraplegia (due to accident or operation for Pott’s disease, intramedullary tumour, or kyphoscoliosis) a syringomyelia develops at the level immediately above the paraplegia or in the cervical enlargement. In these case-reports the onset of symptoms in relation to a sudden strain is noted even more commonly than in the usual communicating syrinx.Some are reported as having a syrinx containing proteinous fluid. One of Rossier and Werner’s cases was said to have a communication between the fourth ventricle 6. Barnett, M. J. M., 7. 8. 9. 10. 11. 12. 13. 14. 15.
A., 16. 17. 18.
Botterell, E. H., Jousse, A. T., Wynne-Jones, M. Brain, 1966, 89, 159. Cossa, P. Revue neurol. 1943, 75, 39. Finkle, J. R. Proceedings of the Ninth Annual Clinical Spinal Cord Injury Conference; p. 45. 1960. Foster, J. B. Personal communication. Freeman, L. W. J. Neurosurg. 1959, 16, 120. Jung, E. Med. Klin. 1960, 55, 1678. Martin, C., Maury, M. Presse méd. 1964, 48, 2839. Nurick, S., Russell, J. A., Deck, M. J. F. Brain, 1970, 93, 211. Riffat, G., Domenach, J. Lyon med. 1964, 212, 1043. Rossier, A. B., Werner, A., Wildi, E., Berney, J. J. Neurol. Neurosurg. Psychiat. 1968, 31, 99. Schott, B., Trillet, M., Vauterin, C., Koshbin, Revue neurol. 1962, 106, 751. Werner, A. Schweiz Arch. Neurol. Neurochir. Psychiat. 1969, 104, 77. Zdrojewski, B. Neurochirurgie, 1969, 15, 153.