- Email: [email protected]
THE VETERANS ADMINISTRATION
1226
preliminary to hypothermic storage than bloodless solutions containing low-molecular-weight dextran. 4,6,7 The practical and possible antigenic difficulties associated with the use of blood in human cadaveric transplantation makes the success of the C4 solution described by Collins et al.1 the more
welcome.
St. Paul’s Hospital, London W.C.2.
W. F. HENDRY.
ORGAN EXCHANGE AND TISSUE TYPING SiR,-The exchange of cadaver kidneys between transplant centres within the United Kingdom and abroad is necessary only because of the current concern with leucocyte-antigen (HL-A) matching of donors and recipients. The evidence for the pre-eminent role of HL-A matching is derived not from cadaver-kidney transplants but from transplants between ABO-compatible relatives. Study of cadaver-organ transplants 8-11 makes it clear that, for individual patients, HL-A matching is not yet a guarantee of success. There is, however, little doubt that tissue typing, properly performed, can be a major factor in improving the overall results of a series of cadaver-organ transplants. It is imperative, therefore, to examine the probable reasons for the present limitations in the predictive value of HL-A matching. The results of cadaver-organ transplantation have imimproved in the past few years, and between 42% 1Z and 59% 13 function for one year or more. These improvements have coincided with the development of tissue typing, but have largely been due to better clinical selection of organs and recipients, the greater caution with which systemic corticosteroids are employed, the introduction of azathioprine, the virtual abandonment of immunosuppression by whole-body irradiation, and the use of antilymphocyte globulin. In addition, few now dispute the need for renal dialysis in conjunction with transplantation. It is also possible that some of the apparent correlation between poor matching and poor results may have resulted from bias introduced by unsuitable patients and poorly matched kidneys. Patients for clinical or logistical reasons, may be offered the first available ABO-compatible kidney as a life-saving measure. This will tend to produce poor because these recipients are often clinicresults, transplant ally unsuitable for transplantation. In contrast, patients who
doing well on a low-protein diet or dialysis are now rarely offered transplants unless the donor kidneys are excellent both physiologically and in terms of leucocyte-antigen match. The association between good matching and good survival and function, at least in the short term, in some of these patients may be fortuitous. Since in most published series early failures have been ascribed to technical complications, the role of poor matching is even less clear in the three months following transplantation, when many kidneys are are
apparently rejected. The problems associated with typing moribund or dead donors-often in difficult circumstances-have, in the past, been underestimated, and the results of such typing may sometimes have been of doubtful validity. Techniques 6.
7. 8.
9. 10. 11. 12. 13.
D. E., Calne, R. Y., Pryse-Davies, J., Leigh-Brown, F. Ann. N.Y. Acad. Sci. 1964, 120, 506. Karlson, K. E., Dormont, J., Hamburger, J. in Organ Perfusion and Preservation (edited by J. C. Norman); p. 687. New York, 1968. van Rood, J. J., van Leeuwen, A., Pearce, R., van der Does, J. Transplant. Proc. 1969, 1, 372. Patel, R., Mickey, M. R., Terasaki, P. I. New Engl. J. Med. 1968, 279, 501. Batchelor, J. R., Joysey, V. C. Lancet, 1969, i, 790. Morris, P. J., Ting, A., Kincaid-Smith, P. in Histocompatibility Testing (edited by P. I. Terasaki). Copenhagen (in the press). Kidney Transplant Registry. Transplantation, 1968, 8, 721. Calne, R. Y., Shackman, R., Nolan, B., Petrie, J., Woodruff, M. Lancet, March 28, 1970, p. 671.
Pegg,
in healthy volunteers may not always be suitable in these circumstances, and poorly reproducible techniques have escaped comment since in many cases the donor cannot be retested later. For example, it has been shown that venous-blood-lymphocyte suspensions from cadaver donors -especially those with brain damage-may be heavily contaminated with granulocytes, and are unsuitable for the currently used lymphocytotoxic typing test.14
applicable
Leucocyte antigens are considerably less well defined than the red-cell groups important in blood-transfusion. This is partly because of genetic complexity (HL-A and non-HL-A), and partly because of the rarity of monospecific antisera. No-one familiar with HL-A antisera doubts that most are weak and more or less contaminated with unwanted antibodies, and that variations in the sensitivity of typing tests may easily result in different reaction patterns between laboratories. The terms " weak " and " strong " transplantation antigen have meaning only when related to the genotype of donor and recipient and to the state of immunity of the recipient,"5 and there is little evidence that, considered individually, some HL-A antigens are more likely to provoke rejection than others.
Renal-allograft recipients preimmunised by pregnancy, transfusion, transplantation, and (possibly) heteroantigens, may within hours of operation hyperacutely reject apparently well-matched ABO-compatible kidney grafts because they have pre-existing humoral antibodies reactive against donor cells.16 Early rejection may possibly result from undetected preimmunisation, since routine screening and cross-matching procedures are capable of picking up only strong or moderately strong humoral antibodies; weak antibodies and associated cellular immunity may be overlooked. The ability of a recipient to mount an immune reaction is influenced by uraemia, immunosuppressive drugs, and his inherent immunological reactivity. It also appears likely that immunological enhancement or tolerance have been fortuitously achieved in long-lasting cadaver donor kidney transplants. In view of the problems outlined here, it is not surprising that the full value of tissue typing is yet to be determined. A single national organ-exchange scheme comparable with those already functioning in Europe, and having as its primary heuristic aim the rigorous comparison of HL-A matching with transplantation outcome, is essential. This scheme must incorporate a standardised system of tissue typing, since little general agreement on methods has yet
been achieved and a state of technical Balkanisation has arisen. One cannot argue by analogy that technical standardisation was not necessary or desirable in bloodtransfusion work. Blood-exchange schemes on the scale envisaged for organ exchange are not required, and the present complexity of routine HL-A typing greatly exceeds that of most red-cell grouping for transfusion purposes. Emphasis must be given to the reproducibility of techniques. Department of Medical Genetics, R. HARMS. Manchester Royal Infirmary.
THE VETERANS ADMINISTRATION statement of your Round the World correspondent (April 25, p. 887) that private-practice physicians have been willing to testify against Government or Veterans Administration medical personnel or hospitals, but unwilling to testify against private hospitals or colleagues in private practice, is misleading. Many private-practice physicians
SiR,ŅThe
14.
Harris, R., Wentzel, J., Cocking, H., Dodsworth, H., Ukaejiofo, E. O. in Histocompatibility Testing (edited by P. I. Terasaki). Copenhagen (in the press). 15. Transplant. Rev. 1970, vol. III. 16. Kissmeyer Nielsen, F., Olsen, S., Petersen, V. P., Fjeldborg, O. Lancet, 1966, ii, 662.
1227 or colleagues in private in the United States. A few may behave as your correspondent suggests but to imply that this attitude is universal or even common here is unfair. Other allegations by your correspondent are arguable; some feel that the V.A. hospital system, far from being denigrated, has in the past been treated as a sacred cow by some of the most influential segments of the profession including the great specialty organisations and their leaders and the medical schools and their deans and administrations. Corvallis Clinic, Corvallis, CRAIG B. LEMAN. Oregon 97330, U.S.A.
testify against private hospitals
practice
CONTAMINATION OF BLOOD STORED IN PLASTIC PACKS
SIR,-Dr. Marcel and Dr. Noel (Jan. 3, p. 35) report that dihexyl phthalate is present in plasma of blood stored for 21 days in plastic packs, at levels up to 11-5 mg. per 100 ml As a major manmacturer of plastic blood packs, we wish to that the plasticiser used in our polyvinyl chloride is di(2-ethyl hexyl)phthalate—di-octylphthalate or D.o.P.and not dihexyl phthalate. This information has been published previously,1 and we have identified dioctyl phthalate in extracts of plasma stored in plastic packs by thinlayer and gas chromatography. Dioctyl phthalate and dihexyl phthalate cannot be distinguished by ultraviolet absorption spectra, and differentiation by infrared spectrophotometry is difficult. Dr. Marcel and Dr. Noel conclude their report by inferring that, because of the presence of these levels of plasticiser in stored blood, large-volume transfusion of such blood or plasma may not be safe. This concern apparently is based upon the reported toxicity of a different plasticiser, dibutyl phthalate,2 which they state has " moderate " toxicity. While the toxicology of dibutyl phthalate may be of interest, it is hardly relevant to a consideration of the use-safety of transfused blood or plasma stored in a plastic that contains D.o.p. as the plasticiser, and it would be irrelevant even if the plastic did contain dihexyl phthalate. Toxicity data on D.o.P. have been published.3-6 These data, and the results of our own studies, indicate that the acute toxicity of D.O.P. is substantially less than that of dibutyl phthalate. L.D’50 values reported for D.o.p. administered intraperitoneally to mice and rats range from 14-19 to more than 128 g. per kg. The D.O.P. used in our plastic has an intraperitoneal L.D’50 in CF-1 mice of more than 75 g. per kg. Even the lowest L.D’50 value of 14-19 g. per kg. state
represents an amount of D.o.p. some 2500 times greater than the amount a 70 kg. adult would receive in a complete exchange transfusion if the plasma contained 11-5 mg. of D.O.P. per 100 ml. It is doubtful whether any other blood component, including water, has a comparable margin of safety. Certainly the raised plasma-potassium of aged blood and the total citrate load of multiple units should be of more concern to the physician. On the other hand, we cannot argue that this low level of D.O.P. in plasma serves any useful purpose. Therefore an objective of continuing research should be to develop even safer plastics. Departments of Pharmacology and Pharmaceutical Research and Development, R. M. GESLER Travenol Laboratories, Inc., N. J. KARTINOS. Morton Grove, Illinois. 1. Guess, W. L., Jacob, J., Autian, J. Drug Intell. 1967, 1, 120. 2. Smith, C. C. Archs ind. Hyg. 1953, 1, 310. 3. Hodge, H. C. Proc. Soc. exp. Biol. Med. 1943, 53, 20. 4. Shaffer, C. B., Carpenter, C. P., Smyth, H. F. J. ind. Hyg. Toxicol. 1945, vol. XXVII, no. 5. 5. Calley, D., Autian, J., Guess, W. L. J. pharm. Sci. 1966, 55, 158. 6. Guess, W. L., Haberman, S. J. biomed. Mater. Res. 1968, 2, 313.
THE RECURRENT LARYNGEAL NERVES AT THYROIDECTOMY SIR,-I have awaited critical comment on your editorial of Feb. 21 (p. 398) on the visual identification and tests for functional integrity of the recurrent laryngeal nerves at thyroidectomy. None has been forthcoming, and I feel I should present the alternative view held by many thyroid surgeons.
Riddell’s1 thesis is twofold: firstly, that when the laryngeal nerve is identified, cord paresis is less frequent than when it is not identified; and secondly that, following resection of the first lobe of the thyroid, the integrity of the related recurrent laryngeal nerve should be demonstrated by electrical stimulation before the second lobe is interfered with. Techniques of thyroidectomy vary, and Riddell justifies his procedure of routine nerve exposure by showing a reduction of the injury-rate from 2-0% when the nerve was not seen to 0-6% when it was definitely identified. In the course of a routine thyroidectomy I do not positively identify the recurrent laryngeal nerve, but I do record (as with the parathyroids) whether the nerve has been seen during the operation. A recent survey of my records of thyrotoxic patients shows that one recurrent laryngeal nerve was seen in 14% and both nerves in 2% of patients. Impairment of cord movement in the immediate postoperative period was noted in 4% of patients, but, at one year, impairment amounting to paresis was present in fractionally less than 1%. Translated into terms of nerves at risk, 7% were seen during the course of operation, with subsequent impairment of movement in 2%, and permanent paresis in 0.5%. These were the findings as revealed by indirect laryngoscopy. A parallel study by stroboscopy is under review, and it may be that this more sophisticated technique will reveal a much higher percentage of minor disabilitiese.g., obliquity of the cords and failure of anterior approximation. It is possible, however, that stroboscopy may highlight the defects of superior laryngeal nerve involvement as well. These results are similar to those of other series with or without elective exposure of the recurrent laryngeal nerve. This is perhaps understandable, since the commonest site of nerve injury is not at or below inferior thyroid artery level, but at the most anterior point of an arch made by the recurrent laryngeal nerve before it plunges behind the articulation of the inferior cornu of the thyroid cartilage. This is the point of greatest fixation of the thyroid lobe, and it is exceptional for the recurrent laryngeal nerve to be seen here during a routine subtotal thyroidectomy, though it can be observed more proximally, in relation to the cricothyroid articulation. I regard positive identification of the recurrent laryngeal nerve as mandatory (a) where total lobectomy is contemplated, whether for a benign or neoplastic lesion; (b) where distortion of the nerve is to be expected, as in a retrosternal goitre, or in the presence of an adenomatous nodule or the lingula occasionally present in some thyrotoxic glands; (c) where abnormal anatomical features are present, such as the direct-approach laryngeal nerve, which may be heralded by the absence of the inferior thyroid artery; and (d) where a second subtotal thyroidectomy is contemplated, though the current concept that recurrent thyrotoxicosis is a L.A.T.S. response unlikely to respond to a second subtotal thyroidectomy tends to make repeat thyroidectomy less recurrent
acceptable. In performing thyroidectomy without elective nerve exposure, several basic principles must be observed. The risks in thyroidectomy are not inconsiderable, and apprenticeship in thyroid surgery should be long and exacting, so that every thyroid surgeon should know within 1 mm. where 1.
Riddell, V. H. Br. J. Surg. 1970, 57,
1.
preliminary to hypothermic storage than bloodless solutions containing low-molecular-weight dextran. 4,6,7 The practical and possible antigenic difficulties associated with the use of blood in human cadaveric transplantation makes the success of the C4 solution described by Collins et al.1 the more
welcome.
St. Paul’s Hospital, London W.C.2.
W. F. HENDRY.
ORGAN EXCHANGE AND TISSUE TYPING SiR,-The exchange of cadaver kidneys between transplant centres within the United Kingdom and abroad is necessary only because of the current concern with leucocyte-antigen (HL-A) matching of donors and recipients. The evidence for the pre-eminent role of HL-A matching is derived not from cadaver-kidney transplants but from transplants between ABO-compatible relatives. Study of cadaver-organ transplants 8-11 makes it clear that, for individual patients, HL-A matching is not yet a guarantee of success. There is, however, little doubt that tissue typing, properly performed, can be a major factor in improving the overall results of a series of cadaver-organ transplants. It is imperative, therefore, to examine the probable reasons for the present limitations in the predictive value of HL-A matching. The results of cadaver-organ transplantation have imimproved in the past few years, and between 42% 1Z and 59% 13 function for one year or more. These improvements have coincided with the development of tissue typing, but have largely been due to better clinical selection of organs and recipients, the greater caution with which systemic corticosteroids are employed, the introduction of azathioprine, the virtual abandonment of immunosuppression by whole-body irradiation, and the use of antilymphocyte globulin. In addition, few now dispute the need for renal dialysis in conjunction with transplantation. It is also possible that some of the apparent correlation between poor matching and poor results may have resulted from bias introduced by unsuitable patients and poorly matched kidneys. Patients for clinical or logistical reasons, may be offered the first available ABO-compatible kidney as a life-saving measure. This will tend to produce poor because these recipients are often clinicresults, transplant ally unsuitable for transplantation. In contrast, patients who
doing well on a low-protein diet or dialysis are now rarely offered transplants unless the donor kidneys are excellent both physiologically and in terms of leucocyte-antigen match. The association between good matching and good survival and function, at least in the short term, in some of these patients may be fortuitous. Since in most published series early failures have been ascribed to technical complications, the role of poor matching is even less clear in the three months following transplantation, when many kidneys are are
apparently rejected. The problems associated with typing moribund or dead donors-often in difficult circumstances-have, in the past, been underestimated, and the results of such typing may sometimes have been of doubtful validity. Techniques 6.
7. 8.
9. 10. 11. 12. 13.
D. E., Calne, R. Y., Pryse-Davies, J., Leigh-Brown, F. Ann. N.Y. Acad. Sci. 1964, 120, 506. Karlson, K. E., Dormont, J., Hamburger, J. in Organ Perfusion and Preservation (edited by J. C. Norman); p. 687. New York, 1968. van Rood, J. J., van Leeuwen, A., Pearce, R., van der Does, J. Transplant. Proc. 1969, 1, 372. Patel, R., Mickey, M. R., Terasaki, P. I. New Engl. J. Med. 1968, 279, 501. Batchelor, J. R., Joysey, V. C. Lancet, 1969, i, 790. Morris, P. J., Ting, A., Kincaid-Smith, P. in Histocompatibility Testing (edited by P. I. Terasaki). Copenhagen (in the press). Kidney Transplant Registry. Transplantation, 1968, 8, 721. Calne, R. Y., Shackman, R., Nolan, B., Petrie, J., Woodruff, M. Lancet, March 28, 1970, p. 671.
Pegg,
in healthy volunteers may not always be suitable in these circumstances, and poorly reproducible techniques have escaped comment since in many cases the donor cannot be retested later. For example, it has been shown that venous-blood-lymphocyte suspensions from cadaver donors -especially those with brain damage-may be heavily contaminated with granulocytes, and are unsuitable for the currently used lymphocytotoxic typing test.14
applicable
Leucocyte antigens are considerably less well defined than the red-cell groups important in blood-transfusion. This is partly because of genetic complexity (HL-A and non-HL-A), and partly because of the rarity of monospecific antisera. No-one familiar with HL-A antisera doubts that most are weak and more or less contaminated with unwanted antibodies, and that variations in the sensitivity of typing tests may easily result in different reaction patterns between laboratories. The terms " weak " and " strong " transplantation antigen have meaning only when related to the genotype of donor and recipient and to the state of immunity of the recipient,"5 and there is little evidence that, considered individually, some HL-A antigens are more likely to provoke rejection than others.
Renal-allograft recipients preimmunised by pregnancy, transfusion, transplantation, and (possibly) heteroantigens, may within hours of operation hyperacutely reject apparently well-matched ABO-compatible kidney grafts because they have pre-existing humoral antibodies reactive against donor cells.16 Early rejection may possibly result from undetected preimmunisation, since routine screening and cross-matching procedures are capable of picking up only strong or moderately strong humoral antibodies; weak antibodies and associated cellular immunity may be overlooked. The ability of a recipient to mount an immune reaction is influenced by uraemia, immunosuppressive drugs, and his inherent immunological reactivity. It also appears likely that immunological enhancement or tolerance have been fortuitously achieved in long-lasting cadaver donor kidney transplants. In view of the problems outlined here, it is not surprising that the full value of tissue typing is yet to be determined. A single national organ-exchange scheme comparable with those already functioning in Europe, and having as its primary heuristic aim the rigorous comparison of HL-A matching with transplantation outcome, is essential. This scheme must incorporate a standardised system of tissue typing, since little general agreement on methods has yet
been achieved and a state of technical Balkanisation has arisen. One cannot argue by analogy that technical standardisation was not necessary or desirable in bloodtransfusion work. Blood-exchange schemes on the scale envisaged for organ exchange are not required, and the present complexity of routine HL-A typing greatly exceeds that of most red-cell grouping for transfusion purposes. Emphasis must be given to the reproducibility of techniques. Department of Medical Genetics, R. HARMS. Manchester Royal Infirmary.
THE VETERANS ADMINISTRATION statement of your Round the World correspondent (April 25, p. 887) that private-practice physicians have been willing to testify against Government or Veterans Administration medical personnel or hospitals, but unwilling to testify against private hospitals or colleagues in private practice, is misleading. Many private-practice physicians
SiR,ŅThe
14.
Harris, R., Wentzel, J., Cocking, H., Dodsworth, H., Ukaejiofo, E. O. in Histocompatibility Testing (edited by P. I. Terasaki). Copenhagen (in the press). 15. Transplant. Rev. 1970, vol. III. 16. Kissmeyer Nielsen, F., Olsen, S., Petersen, V. P., Fjeldborg, O. Lancet, 1966, ii, 662.
1227 or colleagues in private in the United States. A few may behave as your correspondent suggests but to imply that this attitude is universal or even common here is unfair. Other allegations by your correspondent are arguable; some feel that the V.A. hospital system, far from being denigrated, has in the past been treated as a sacred cow by some of the most influential segments of the profession including the great specialty organisations and their leaders and the medical schools and their deans and administrations. Corvallis Clinic, Corvallis, CRAIG B. LEMAN. Oregon 97330, U.S.A.
testify against private hospitals
practice
CONTAMINATION OF BLOOD STORED IN PLASTIC PACKS
SIR,-Dr. Marcel and Dr. Noel (Jan. 3, p. 35) report that dihexyl phthalate is present in plasma of blood stored for 21 days in plastic packs, at levels up to 11-5 mg. per 100 ml As a major manmacturer of plastic blood packs, we wish to that the plasticiser used in our polyvinyl chloride is di(2-ethyl hexyl)phthalate—di-octylphthalate or D.o.P.and not dihexyl phthalate. This information has been published previously,1 and we have identified dioctyl phthalate in extracts of plasma stored in plastic packs by thinlayer and gas chromatography. Dioctyl phthalate and dihexyl phthalate cannot be distinguished by ultraviolet absorption spectra, and differentiation by infrared spectrophotometry is difficult. Dr. Marcel and Dr. Noel conclude their report by inferring that, because of the presence of these levels of plasticiser in stored blood, large-volume transfusion of such blood or plasma may not be safe. This concern apparently is based upon the reported toxicity of a different plasticiser, dibutyl phthalate,2 which they state has " moderate " toxicity. While the toxicology of dibutyl phthalate may be of interest, it is hardly relevant to a consideration of the use-safety of transfused blood or plasma stored in a plastic that contains D.o.p. as the plasticiser, and it would be irrelevant even if the plastic did contain dihexyl phthalate. Toxicity data on D.o.P. have been published.3-6 These data, and the results of our own studies, indicate that the acute toxicity of D.O.P. is substantially less than that of dibutyl phthalate. L.D’50 values reported for D.o.p. administered intraperitoneally to mice and rats range from 14-19 to more than 128 g. per kg. The D.O.P. used in our plastic has an intraperitoneal L.D’50 in CF-1 mice of more than 75 g. per kg. Even the lowest L.D’50 value of 14-19 g. per kg. state
represents an amount of D.o.p. some 2500 times greater than the amount a 70 kg. adult would receive in a complete exchange transfusion if the plasma contained 11-5 mg. of D.O.P. per 100 ml. It is doubtful whether any other blood component, including water, has a comparable margin of safety. Certainly the raised plasma-potassium of aged blood and the total citrate load of multiple units should be of more concern to the physician. On the other hand, we cannot argue that this low level of D.O.P. in plasma serves any useful purpose. Therefore an objective of continuing research should be to develop even safer plastics. Departments of Pharmacology and Pharmaceutical Research and Development, R. M. GESLER Travenol Laboratories, Inc., N. J. KARTINOS. Morton Grove, Illinois. 1. Guess, W. L., Jacob, J., Autian, J. Drug Intell. 1967, 1, 120. 2. Smith, C. C. Archs ind. Hyg. 1953, 1, 310. 3. Hodge, H. C. Proc. Soc. exp. Biol. Med. 1943, 53, 20. 4. Shaffer, C. B., Carpenter, C. P., Smyth, H. F. J. ind. Hyg. Toxicol. 1945, vol. XXVII, no. 5. 5. Calley, D., Autian, J., Guess, W. L. J. pharm. Sci. 1966, 55, 158. 6. Guess, W. L., Haberman, S. J. biomed. Mater. Res. 1968, 2, 313.
THE RECURRENT LARYNGEAL NERVES AT THYROIDECTOMY SIR,-I have awaited critical comment on your editorial of Feb. 21 (p. 398) on the visual identification and tests for functional integrity of the recurrent laryngeal nerves at thyroidectomy. None has been forthcoming, and I feel I should present the alternative view held by many thyroid surgeons.
Riddell’s1 thesis is twofold: firstly, that when the laryngeal nerve is identified, cord paresis is less frequent than when it is not identified; and secondly that, following resection of the first lobe of the thyroid, the integrity of the related recurrent laryngeal nerve should be demonstrated by electrical stimulation before the second lobe is interfered with. Techniques of thyroidectomy vary, and Riddell justifies his procedure of routine nerve exposure by showing a reduction of the injury-rate from 2-0% when the nerve was not seen to 0-6% when it was definitely identified. In the course of a routine thyroidectomy I do not positively identify the recurrent laryngeal nerve, but I do record (as with the parathyroids) whether the nerve has been seen during the operation. A recent survey of my records of thyrotoxic patients shows that one recurrent laryngeal nerve was seen in 14% and both nerves in 2% of patients. Impairment of cord movement in the immediate postoperative period was noted in 4% of patients, but, at one year, impairment amounting to paresis was present in fractionally less than 1%. Translated into terms of nerves at risk, 7% were seen during the course of operation, with subsequent impairment of movement in 2%, and permanent paresis in 0.5%. These were the findings as revealed by indirect laryngoscopy. A parallel study by stroboscopy is under review, and it may be that this more sophisticated technique will reveal a much higher percentage of minor disabilitiese.g., obliquity of the cords and failure of anterior approximation. It is possible, however, that stroboscopy may highlight the defects of superior laryngeal nerve involvement as well. These results are similar to those of other series with or without elective exposure of the recurrent laryngeal nerve. This is perhaps understandable, since the commonest site of nerve injury is not at or below inferior thyroid artery level, but at the most anterior point of an arch made by the recurrent laryngeal nerve before it plunges behind the articulation of the inferior cornu of the thyroid cartilage. This is the point of greatest fixation of the thyroid lobe, and it is exceptional for the recurrent laryngeal nerve to be seen here during a routine subtotal thyroidectomy, though it can be observed more proximally, in relation to the cricothyroid articulation. I regard positive identification of the recurrent laryngeal nerve as mandatory (a) where total lobectomy is contemplated, whether for a benign or neoplastic lesion; (b) where distortion of the nerve is to be expected, as in a retrosternal goitre, or in the presence of an adenomatous nodule or the lingula occasionally present in some thyrotoxic glands; (c) where abnormal anatomical features are present, such as the direct-approach laryngeal nerve, which may be heralded by the absence of the inferior thyroid artery; and (d) where a second subtotal thyroidectomy is contemplated, though the current concept that recurrent thyrotoxicosis is a L.A.T.S. response unlikely to respond to a second subtotal thyroidectomy tends to make repeat thyroidectomy less recurrent
acceptable. In performing thyroidectomy without elective nerve exposure, several basic principles must be observed. The risks in thyroidectomy are not inconsiderable, and apprenticeship in thyroid surgery should be long and exacting, so that every thyroid surgeon should know within 1 mm. where 1.
Riddell, V. H. Br. J. Surg. 1970, 57,
1.