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D lill "
Angiographic
Ablation of Mediastinal
Parathyroid Adenoma ersistent hyperparathyroidism is an infrequent occurrence after initial neck exploration for primary hyperparathyroidism. When it does occur, however, it is an extremely disappointing outcome for the patient and the surgeon. Because initial operations are successful in resolving the hyperparathyroid state in more than 95% of cases, patients undergo these procedures with the expectation that the problem will be resolved. Even though surgeons may discuss in detail the risks of persistent or recurrent hyperparathyroidism, patients frequently do not seriously consider the possibility that they will find themselves in the very small minority whose hyperparathyroidism has not been resolved by the initial neck exploration. Instead of leaving the hospital within a few days and returning to normal activities, patients with persistent hyperparathyroidism face an intimidating array of diagnostic tests of both the noninvasive and invasive types as well as the possibility of another operation that predictably will be more difficult, have a higher risk of complications, and has a lower chance of being successful than the initial procedure. Not unexpectedly, many of these patients are devastated by these prospects. Perhaps the outlook for some of these patients is brighter as a result of the advances in management of persistent hyperparathyroidism developed by Dr. John Doppman and his colleagues at the National Institutes of Health and reported in this issue. Instead of facing the inevitable prospect of median sternotomy, selected patients with persistent hyperparathyroidism can now be managed by angiographic ablation of the mediastinal parathyroid adenoma. For those who can be managed successfully, this method certainly constitutes a significant advance. This also is another example of how the multidisciplinary NIH group has parlayed its rich experience with persistent and recurrent hyperparathyroidism into scientific advances that benefit all patients with these problems. The use of preoperative localization studies in patients undergoing initial neck exploration for primary hyperparathyroidism continues to be investigated. Because more than 95% of patients undergoing these procedures performed by experienced parathyroid surgeons are treated successfully, it is difficult to rationalize the routine P
use of these expensive tests in this situation unless they can be shown to increase success rate or decrease operative time. In a recent report,' it appears that they do not accomplish either of these objectives. Further studies should continue, particularly as new imaging techniques become available. At this point, however, the consensus is perhaps best expressed by Dr. Doppman in his address to the NIH Consensus Development Conference on Asymptomatic Primary Hyperparathyroidism when he stated that "the only localization procedure required prior to initial neck exploration for primary hyperparathyroidism is the localization of an experienced parathyroid surgeon." In contradistinction to the situation with initial neck exploration, accurate localization procedures are absolutely critical to success in treating patients with persistent or recurrent hyperparathyroidism. The morbidity rate is higher and the cure rate is lower for these reoperations, which must be conducted in an operative field where the normal anatomy is obscured by scarring from the previous procedure. The availability of accurate preoperative localization translates directly into improved surgical cure rates. In other words, the reoperative parathyroid surgeon's best friend is the radiologist who localizes the offending gland before the surgical procedure. That this requires great expertise is demonstrated by the fact that for mediastinal adenomas, noninvasive procedures are not very effective in demonstrating the lesion. Ultrasound and technetium-thallium scintigraphy actually have higher false-positive rates than true-positive rates, and for computed tomography (CT) and magnetic resonance, less than 30% of patients had accurate localization. The invasive studies are much more likely to provide accurate localization, and it is these procedures that are quite operator dependent, with good results achieved most consistently by those with the most experience. It is therefore unlikely that the excellent results reported here will be widely reproducible because this standard is set by the group with the most experience with these techniques. The use of angiographic methods to ablate mediastinal parathyroid adenomas was quite interestingly discovered serendipitously. When the technique was refined and performed purposefully, it was found to have great promise for improving management of selected patients. In the
99
100
LEIGHT
current report, 61% of patients who had angiographic ablation of a mediastinal parathyroid adenoma appear to be cured on long-term follow-up. This success rate would certainly warrant using ablation as the first option in those patients undergoing angiography for mediastinal adenoma who are likely to have functional normal parathyroid tissue in the neck. The authors correctly emphasize that hypoparathyroidism occurs at a significant rate in patients undergoing reoperation and that the availability of parathyroid tissue for autotransplantation is advantageous in some of these patients. This emphasizes again the importance of not removing normal parathyroid glands at the initial neck exploration. Other pertinent points are that even under the best of conditions transplantation of cryopreserved tissue is not uniformly successful and, as is demonstrated from this study and our own experience, parathyroid tissue that has been exposed to contrast material may not be optimal for cryopreservation. It is interesting to speculate whether the tissue may over time recover from this insult and once again be suitable for cryopreservation. If patients are carefully selected for angiographic ablation, however, the risk of hypoparathyroidism would not appear to be great enough to deny patients this less invasive procedure. This conclusion is reinforced by the finding that, should ablation fail, the
Ann. Surg. * February 1992
patient then can have mediastinal exploration with the same expectation for successful resolution of the hyperparathyroidism as those who have not undergone attempted ablation. The observation that staining on CT may have some predictive value regarding the success of the angiographic ablation procedure is an interesting observation, but not one of great practical importance. The success or failure of the procedure is ultimately determined by measuring serum calcium levels, which can be done with much less expense than obtaining another CT scan. Once again, the multidisciplinary NIH group is to be congratulated for the discovery and development of the technique of angiographic ablation. This represents another step forward in the management of the very difficult clinical problem of persistent hyperparathyroidism. GEORGE S. LEIGHT, JR., M.D. Durham, North Carolina
Reference 1. Wilson SD, Hoffmann RG, Cerletty JM, et al. Parathyroidectomy for primary hyperparathyroidism: the influence of preoperative localizing studies on cure rate and operative time. (Submitted for publication).
D lill "
Angiographic
Ablation of Mediastinal
Parathyroid Adenoma ersistent hyperparathyroidism is an infrequent occurrence after initial neck exploration for primary hyperparathyroidism. When it does occur, however, it is an extremely disappointing outcome for the patient and the surgeon. Because initial operations are successful in resolving the hyperparathyroid state in more than 95% of cases, patients undergo these procedures with the expectation that the problem will be resolved. Even though surgeons may discuss in detail the risks of persistent or recurrent hyperparathyroidism, patients frequently do not seriously consider the possibility that they will find themselves in the very small minority whose hyperparathyroidism has not been resolved by the initial neck exploration. Instead of leaving the hospital within a few days and returning to normal activities, patients with persistent hyperparathyroidism face an intimidating array of diagnostic tests of both the noninvasive and invasive types as well as the possibility of another operation that predictably will be more difficult, have a higher risk of complications, and has a lower chance of being successful than the initial procedure. Not unexpectedly, many of these patients are devastated by these prospects. Perhaps the outlook for some of these patients is brighter as a result of the advances in management of persistent hyperparathyroidism developed by Dr. John Doppman and his colleagues at the National Institutes of Health and reported in this issue. Instead of facing the inevitable prospect of median sternotomy, selected patients with persistent hyperparathyroidism can now be managed by angiographic ablation of the mediastinal parathyroid adenoma. For those who can be managed successfully, this method certainly constitutes a significant advance. This also is another example of how the multidisciplinary NIH group has parlayed its rich experience with persistent and recurrent hyperparathyroidism into scientific advances that benefit all patients with these problems. The use of preoperative localization studies in patients undergoing initial neck exploration for primary hyperparathyroidism continues to be investigated. Because more than 95% of patients undergoing these procedures performed by experienced parathyroid surgeons are treated successfully, it is difficult to rationalize the routine P
use of these expensive tests in this situation unless they can be shown to increase success rate or decrease operative time. In a recent report,' it appears that they do not accomplish either of these objectives. Further studies should continue, particularly as new imaging techniques become available. At this point, however, the consensus is perhaps best expressed by Dr. Doppman in his address to the NIH Consensus Development Conference on Asymptomatic Primary Hyperparathyroidism when he stated that "the only localization procedure required prior to initial neck exploration for primary hyperparathyroidism is the localization of an experienced parathyroid surgeon." In contradistinction to the situation with initial neck exploration, accurate localization procedures are absolutely critical to success in treating patients with persistent or recurrent hyperparathyroidism. The morbidity rate is higher and the cure rate is lower for these reoperations, which must be conducted in an operative field where the normal anatomy is obscured by scarring from the previous procedure. The availability of accurate preoperative localization translates directly into improved surgical cure rates. In other words, the reoperative parathyroid surgeon's best friend is the radiologist who localizes the offending gland before the surgical procedure. That this requires great expertise is demonstrated by the fact that for mediastinal adenomas, noninvasive procedures are not very effective in demonstrating the lesion. Ultrasound and technetium-thallium scintigraphy actually have higher false-positive rates than true-positive rates, and for computed tomography (CT) and magnetic resonance, less than 30% of patients had accurate localization. The invasive studies are much more likely to provide accurate localization, and it is these procedures that are quite operator dependent, with good results achieved most consistently by those with the most experience. It is therefore unlikely that the excellent results reported here will be widely reproducible because this standard is set by the group with the most experience with these techniques. The use of angiographic methods to ablate mediastinal parathyroid adenomas was quite interestingly discovered serendipitously. When the technique was refined and performed purposefully, it was found to have great promise for improving management of selected patients. In the
99
100
LEIGHT
current report, 61% of patients who had angiographic ablation of a mediastinal parathyroid adenoma appear to be cured on long-term follow-up. This success rate would certainly warrant using ablation as the first option in those patients undergoing angiography for mediastinal adenoma who are likely to have functional normal parathyroid tissue in the neck. The authors correctly emphasize that hypoparathyroidism occurs at a significant rate in patients undergoing reoperation and that the availability of parathyroid tissue for autotransplantation is advantageous in some of these patients. This emphasizes again the importance of not removing normal parathyroid glands at the initial neck exploration. Other pertinent points are that even under the best of conditions transplantation of cryopreserved tissue is not uniformly successful and, as is demonstrated from this study and our own experience, parathyroid tissue that has been exposed to contrast material may not be optimal for cryopreservation. It is interesting to speculate whether the tissue may over time recover from this insult and once again be suitable for cryopreservation. If patients are carefully selected for angiographic ablation, however, the risk of hypoparathyroidism would not appear to be great enough to deny patients this less invasive procedure. This conclusion is reinforced by the finding that, should ablation fail, the
Ann. Surg. * February 1992
patient then can have mediastinal exploration with the same expectation for successful resolution of the hyperparathyroidism as those who have not undergone attempted ablation. The observation that staining on CT may have some predictive value regarding the success of the angiographic ablation procedure is an interesting observation, but not one of great practical importance. The success or failure of the procedure is ultimately determined by measuring serum calcium levels, which can be done with much less expense than obtaining another CT scan. Once again, the multidisciplinary NIH group is to be congratulated for the discovery and development of the technique of angiographic ablation. This represents another step forward in the management of the very difficult clinical problem of persistent hyperparathyroidism. GEORGE S. LEIGHT, JR., M.D. Durham, North Carolina
Reference 1. Wilson SD, Hoffmann RG, Cerletty JM, et al. Parathyroidectomy for primary hyperparathyroidism: the influence of preoperative localizing studies on cure rate and operative time. (Submitted for publication).
