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Percutaneous stereotactic differential radiofrequency thermal rhizotomy for the treatment of trigeminal neuralgia
WILLIAM
111
C. BROADDUS
18. Harris W: Rare forms of paroxysmal trigeminal neuralgia, and their relationship to disseminated sclerosis. Br Med J 2:1015, 1950 19. Hilton DA, Love S, Gradidge T, et al: Pathologic findings associated with trigeminal neuralgia caused by vascular compression. Neurosurgery 35:299, 1994 20. Storrs TJ, Roberts CI: Adult chiari malformation with headache and trigeminal dysesthesia. Oral Surg Oral Med Oral Path01 82:284, 1996 21. Komiyama M, Fu Y, Yagura H, et al: Pontine hemorrhage presenting as trigeminal neuropathy: Report of three cases. Neurol Med Chir 33:224,1993 22. Kim JS: Trigeminal sensory symptoms due to midbrain lesion. Eur Neural 33:218, 1993 M, Maciewicz E, Bouckoms A, et al: Facial pain 23. Nguyen symptoms in patients with cerebellopontine angle tumors: A report of 44 cases of cerebellopontine angle meningioma and a review of the literature. Clin J Pain 2:3, 1986 24. Cheng TMW, Cascino TL, Onofrlo BM: Comprehensive study of diagnosis and treatment of trigeminal neuralgia secondary to tumors. Neurology 43:2298, 1993 25. Jannetta PJ: Arterial compression of the trigeminal nerve at the pons in patients with trigeminal neuralgia. J Neurosurg 26: 159, 1967 (suppl) 26. Tash RR, Sze G, Leslie DR: Trigeminal neuralgia: MR imaging features. Radiology 172:767, 1989 27. Meaney JF, Eldridge PR, Dunn LT, et al: Demonstration of neurovascular compression in trigeminal neuralgia with magnetic resonance imaging: Comparison with surgical findings in 52 consecutive operative cases. J Neurosurg 83:799, 1995
J Oral
Maxillofac
57:l
11-l 12, 1999
28. Burchiel KJ, Clarke H, Haglund M, et al: Long-term efficacy of microvascular decompression in trigeminal neuralgia. J Neurosurg 69:35, 1988 decompression of the trigeminal 29. Jannetta PJ: Microvascular nerve for the treatment of tic douloureux, in Youmans J (ed): Neurological Surgery (ed 4). Philadelphia, PA, Saunders, 1996, pp 3404-3415 of trigeminal neuralgia, 30. Fromm GH, Sessle BJ: Pathophysiology in Fromm GH, Sessle BJ (eds): Trigeminal Neuralgia: Current Concepts Regarding Pathogenesis and Treatment. Boston, MA, Butterworth-Heinemann, 1991, pp 105-130 31. Taha JM, TewJM, Buncher CR: A prospective 15;year follow up of 154 consecutive patients with trigeminal neuralgia treated by percutaneous stereotactic radiofrequency thermal rhizotomy. J Neurosurg 89:989, 1995 of surgical treatments for 32. Taha JM, Tew JM: Comparison trigeminal neuralgia: Reevaluation of radiofrequency rhizotomy. Neurosurgery 38:865, 1996 33. Barker FG, Jannetta PJ, Bissonette DJ, et al: The long-term outcome of microvascular decompression for trigeminal neuralgia. N Engl J Med 334:1077, 1996 D, Lundsford LD, Flickinger JC, et al: Stereotactic 34. Kondziolka radiosurgery for trigeminal neuralgia: A multiinstitutional study using the gamma unit. J Neurosurg 84:940, 1996 SS, Grimm P, et al: Gamma knife 35. Young RF, Vermeulen rediosurgery for the treatment of trigeminal neuralgia: Idiopathic and tumor related. Neurology 48:608, 1997 R, Scrivani SJ: Trigeminal neuralgia: gamma radiosur36. Maciewicz gery may provide new options for treatment. Neurology 48:565, 1997
Surg
Discussion Percutaneous Stereotactic Differential Radiofrequency Thermal Rhizotomy for the Treatment of Trigeminal Neuralgia William C. Broaddus, MD, PhD Assistant Professor, Division Commonwealth University, Richmond,Virginia
of Neurosurgery, Medical College
Virginia of Virginia,
The authors of this study have excellent results and lay out a very reasonable algorithm for managing patients with trigeminal neuralgia. They point out that their high rate of success in managing the patients’ symptoms may relate to the tailored approach they use, taking advantage of the ability to produce temporary lesions with the radiofrequency probe to help guide the extent of permanent lesion generation. This is certainly an advantage over other ablative procedures designed to reduce the symptoms of trigeminal neuralgia, such as glycerol rhizolysis. However, I have three major concerns with the article as presented. First, it is not clear what the follow-up rate is for the study. One interpretation of the data as presented would be that 100% of 215 patients who underwent radiofrequency thermal rhizotomy (RTR) were followed for 9 to 68 months without any lost to
follow-up. If this is true, then these statistics should be explicitly stated. If not, then it should be noted either in the Methods or the Results section how many patients were lost to follow-up and at what times. Parenthetically, the duration of pain relief should be amenable to survival analysis techniques. The benefit of this approach would be a graphic depiction of the length of pain-free survival in the population studied. The second concern regarding this study comes from a review of the introduction. This section provides a definition of trigeminal neuralgia that involves a somewhat archaic distinction between idiopathic and secondary types. Secondary types are defined as being related to “lesions,” demyelinating plaques, or vascular abnormalities visible on magnetic resonance imaging (MRI) scan. The authors go on to say that the idiopathic types in which the MN is normal (ie, lacking these features) have a cause that “remains unknown.” This statement is simply misleading. There are at least a substantial number of neurosurgeons, if not a majority, who agree that most cases of classic trigeminal neuralgia are related to microvascular compression syndromes that are commonly not visible on MRI scan. Indeed, it is the experience of many neurosurgeons that vascular anomalies that appear to be impinging on the trigeminal nerve (such as an ectatic basilar artery) are often not the offending lesion. Even in these cases a smaller arterial or,
112 less commonly, a venous loop can be found impinging on the trigeminal root entry zone. Thus, there is a growing consensus that most “idiopathic” cases of typical trigeminal neuralgia are indeed caused by microvascular compression that is not evident on conventional MRI scanning (and often not with specialized MRI techniques). Although it would be quite reasonable for the authors to take a contrary stance on this point, the controversy certainly deserves greater discussion so as not to mislead those less familiar with this pathologic entity into believing that the cause of idiopathic trigeminal neuralgia is truly unknown. The very fact that microvascular decompression is, as the authors admit, so successful in long-term follow-up argues that the origin for most of these cases is, indeed, well understood (and due to microvascular compression). My third concern regarding this article has to do with the fact that a part of the discussion section is more Iike a strongly worded editorial than a reasoned discussion of the findings. Simply put, the discussion lacks balance. Although the authors emphasize heavily the potential risks of craniotomy, there is no discussion of the potential adverse consequences on quality of life that “aggressive medical management” may have for patients with trigeminal neuralgia. The discussion of the risks and safety of posterior fossa exploration are generally overstated or inaccurate: Microvascular decompression (MVD) “requires a craniotomy with retraction of the cerebellum and brainstem.” This is incorrect. MVD requires minimal retraction of the cerebellum and no retraction of the brainstem. “There are certain potential complications inherent in performing a craniotomy for any reason, especially in a non-life-threatening process.” The potential complications are indeed inherent, and not especially in a non-lifethreatening process. Elective procedures have lower risks than emergent or urgent procedures, but otherwise the
DISCUSSION “non-life-threatening” nature of MYD has no bearing on the inherent risks. “In addition to the risk of long general anesthesia and craniotomy, .” The typical MVD case cannot be considered a “long” procedure under general anesthesia. I would speculate that the RTR procedure as described in the Methods section of this report, in which the patient is awakened to test sensory function and then “deepened” to perform each radiofrequency lesion, must take considerably longer than the time required for a routine MVD. “Those who perform MVD routinely argue that the procedure is safe and effective. The procedure is effective, yet it should not be considered ‘safe’.” Ifthe authors wish to assert that MVD is “not safe,” then perhaps they should provide a definition of “safe,” particularly because they go on to state that “surgical treatment with RTR is a safe and effective way to manage patients with TN.” The risks they acknowledge for MVD certainly qualify this procedure as “safe” in my view, although they could make a valid argument that RTR is safer than MVD. “We believe that RTR should be considered the procedure of choice.” Given the highly controversial nature of this issue, this statement is purely editorial, and represents only one viewpoint based on the data and discussion that the authors have provided. The crux of the issue is whether RTR is safer than MVD and as effective. Although RTR represents an ablative procedure that masks symptoms of the pathologic condition, MVD in most cases directly addresses and “cures” the condition itself. Weighing the benefits and risks of these issues should guide the management of patients requiring surgical therapy, rather than attempting to establish a single dogmatic approach through editorial comments in the discussion section of an otherwise excellent paper.
111
C. BROADDUS
18. Harris W: Rare forms of paroxysmal trigeminal neuralgia, and their relationship to disseminated sclerosis. Br Med J 2:1015, 1950 19. Hilton DA, Love S, Gradidge T, et al: Pathologic findings associated with trigeminal neuralgia caused by vascular compression. Neurosurgery 35:299, 1994 20. Storrs TJ, Roberts CI: Adult chiari malformation with headache and trigeminal dysesthesia. Oral Surg Oral Med Oral Path01 82:284, 1996 21. Komiyama M, Fu Y, Yagura H, et al: Pontine hemorrhage presenting as trigeminal neuropathy: Report of three cases. Neurol Med Chir 33:224,1993 22. Kim JS: Trigeminal sensory symptoms due to midbrain lesion. Eur Neural 33:218, 1993 M, Maciewicz E, Bouckoms A, et al: Facial pain 23. Nguyen symptoms in patients with cerebellopontine angle tumors: A report of 44 cases of cerebellopontine angle meningioma and a review of the literature. Clin J Pain 2:3, 1986 24. Cheng TMW, Cascino TL, Onofrlo BM: Comprehensive study of diagnosis and treatment of trigeminal neuralgia secondary to tumors. Neurology 43:2298, 1993 25. Jannetta PJ: Arterial compression of the trigeminal nerve at the pons in patients with trigeminal neuralgia. J Neurosurg 26: 159, 1967 (suppl) 26. Tash RR, Sze G, Leslie DR: Trigeminal neuralgia: MR imaging features. Radiology 172:767, 1989 27. Meaney JF, Eldridge PR, Dunn LT, et al: Demonstration of neurovascular compression in trigeminal neuralgia with magnetic resonance imaging: Comparison with surgical findings in 52 consecutive operative cases. J Neurosurg 83:799, 1995
J Oral
Maxillofac
57:l
11-l 12, 1999
28. Burchiel KJ, Clarke H, Haglund M, et al: Long-term efficacy of microvascular decompression in trigeminal neuralgia. J Neurosurg 69:35, 1988 decompression of the trigeminal 29. Jannetta PJ: Microvascular nerve for the treatment of tic douloureux, in Youmans J (ed): Neurological Surgery (ed 4). Philadelphia, PA, Saunders, 1996, pp 3404-3415 of trigeminal neuralgia, 30. Fromm GH, Sessle BJ: Pathophysiology in Fromm GH, Sessle BJ (eds): Trigeminal Neuralgia: Current Concepts Regarding Pathogenesis and Treatment. Boston, MA, Butterworth-Heinemann, 1991, pp 105-130 31. Taha JM, TewJM, Buncher CR: A prospective 15;year follow up of 154 consecutive patients with trigeminal neuralgia treated by percutaneous stereotactic radiofrequency thermal rhizotomy. J Neurosurg 89:989, 1995 of surgical treatments for 32. Taha JM, Tew JM: Comparison trigeminal neuralgia: Reevaluation of radiofrequency rhizotomy. Neurosurgery 38:865, 1996 33. Barker FG, Jannetta PJ, Bissonette DJ, et al: The long-term outcome of microvascular decompression for trigeminal neuralgia. N Engl J Med 334:1077, 1996 D, Lundsford LD, Flickinger JC, et al: Stereotactic 34. Kondziolka radiosurgery for trigeminal neuralgia: A multiinstitutional study using the gamma unit. J Neurosurg 84:940, 1996 SS, Grimm P, et al: Gamma knife 35. Young RF, Vermeulen rediosurgery for the treatment of trigeminal neuralgia: Idiopathic and tumor related. Neurology 48:608, 1997 R, Scrivani SJ: Trigeminal neuralgia: gamma radiosur36. Maciewicz gery may provide new options for treatment. Neurology 48:565, 1997
Surg
Discussion Percutaneous Stereotactic Differential Radiofrequency Thermal Rhizotomy for the Treatment of Trigeminal Neuralgia William C. Broaddus, MD, PhD Assistant Professor, Division Commonwealth University, Richmond,Virginia
of Neurosurgery, Medical College
Virginia of Virginia,
The authors of this study have excellent results and lay out a very reasonable algorithm for managing patients with trigeminal neuralgia. They point out that their high rate of success in managing the patients’ symptoms may relate to the tailored approach they use, taking advantage of the ability to produce temporary lesions with the radiofrequency probe to help guide the extent of permanent lesion generation. This is certainly an advantage over other ablative procedures designed to reduce the symptoms of trigeminal neuralgia, such as glycerol rhizolysis. However, I have three major concerns with the article as presented. First, it is not clear what the follow-up rate is for the study. One interpretation of the data as presented would be that 100% of 215 patients who underwent radiofrequency thermal rhizotomy (RTR) were followed for 9 to 68 months without any lost to
follow-up. If this is true, then these statistics should be explicitly stated. If not, then it should be noted either in the Methods or the Results section how many patients were lost to follow-up and at what times. Parenthetically, the duration of pain relief should be amenable to survival analysis techniques. The benefit of this approach would be a graphic depiction of the length of pain-free survival in the population studied. The second concern regarding this study comes from a review of the introduction. This section provides a definition of trigeminal neuralgia that involves a somewhat archaic distinction between idiopathic and secondary types. Secondary types are defined as being related to “lesions,” demyelinating plaques, or vascular abnormalities visible on magnetic resonance imaging (MRI) scan. The authors go on to say that the idiopathic types in which the MN is normal (ie, lacking these features) have a cause that “remains unknown.” This statement is simply misleading. There are at least a substantial number of neurosurgeons, if not a majority, who agree that most cases of classic trigeminal neuralgia are related to microvascular compression syndromes that are commonly not visible on MRI scan. Indeed, it is the experience of many neurosurgeons that vascular anomalies that appear to be impinging on the trigeminal nerve (such as an ectatic basilar artery) are often not the offending lesion. Even in these cases a smaller arterial or,
112 less commonly, a venous loop can be found impinging on the trigeminal root entry zone. Thus, there is a growing consensus that most “idiopathic” cases of typical trigeminal neuralgia are indeed caused by microvascular compression that is not evident on conventional MRI scanning (and often not with specialized MRI techniques). Although it would be quite reasonable for the authors to take a contrary stance on this point, the controversy certainly deserves greater discussion so as not to mislead those less familiar with this pathologic entity into believing that the cause of idiopathic trigeminal neuralgia is truly unknown. The very fact that microvascular decompression is, as the authors admit, so successful in long-term follow-up argues that the origin for most of these cases is, indeed, well understood (and due to microvascular compression). My third concern regarding this article has to do with the fact that a part of the discussion section is more Iike a strongly worded editorial than a reasoned discussion of the findings. Simply put, the discussion lacks balance. Although the authors emphasize heavily the potential risks of craniotomy, there is no discussion of the potential adverse consequences on quality of life that “aggressive medical management” may have for patients with trigeminal neuralgia. The discussion of the risks and safety of posterior fossa exploration are generally overstated or inaccurate: Microvascular decompression (MVD) “requires a craniotomy with retraction of the cerebellum and brainstem.” This is incorrect. MVD requires minimal retraction of the cerebellum and no retraction of the brainstem. “There are certain potential complications inherent in performing a craniotomy for any reason, especially in a non-life-threatening process.” The potential complications are indeed inherent, and not especially in a non-lifethreatening process. Elective procedures have lower risks than emergent or urgent procedures, but otherwise the
DISCUSSION “non-life-threatening” nature of MYD has no bearing on the inherent risks. “In addition to the risk of long general anesthesia and craniotomy, .” The typical MVD case cannot be considered a “long” procedure under general anesthesia. I would speculate that the RTR procedure as described in the Methods section of this report, in which the patient is awakened to test sensory function and then “deepened” to perform each radiofrequency lesion, must take considerably longer than the time required for a routine MVD. “Those who perform MVD routinely argue that the procedure is safe and effective. The procedure is effective, yet it should not be considered ‘safe’.” Ifthe authors wish to assert that MVD is “not safe,” then perhaps they should provide a definition of “safe,” particularly because they go on to state that “surgical treatment with RTR is a safe and effective way to manage patients with TN.” The risks they acknowledge for MVD certainly qualify this procedure as “safe” in my view, although they could make a valid argument that RTR is safer than MVD. “We believe that RTR should be considered the procedure of choice.” Given the highly controversial nature of this issue, this statement is purely editorial, and represents only one viewpoint based on the data and discussion that the authors have provided. The crux of the issue is whether RTR is safer than MVD and as effective. Although RTR represents an ablative procedure that masks symptoms of the pathologic condition, MVD in most cases directly addresses and “cures” the condition itself. Weighing the benefits and risks of these issues should guide the management of patients requiring surgical therapy, rather than attempting to establish a single dogmatic approach through editorial comments in the discussion section of an otherwise excellent paper.