Neurosurgical forum Letters
to
the
editor
Precise Terminology in Scientific Communications EDITORIALCOMMENT:The importance of the use of precise terms is exemplified in several papers that have recently crossed the Editor's desk. The case in point relates to the use of the term "embolization" for the management of intracranial aneurysms with balloons and coils. We have systematically corrected every paper coming to us implying that coils or balloons were placed by embolization techniques. Before I became Editor, the neurovascular and neurosurgical literature routinely referred to these techniques as "embolization procedures." That is entirely wrong. The catheter that places the coils and the cellulose acetate polymer are placed within the aneurysm itself. Similarly, when balloons are guided into the aneurysm, they are placed in the aneurysm. Using the term "embolization" implies that the agents, coils, or balloons were dislodged at some point in the vascular tree proximal to the site of the aneurysm and thereafter floated or were carried by the bloodstream to the aneurysm. This is incorrect. Aneurysms are thrombosed using the coil technique, obliterated using cellulose acetate polymer, and packed using balloons by having the catheter directly within the aneurysm itself. This is not a minor point as the implications of the procedure are quite significant. Placing a catheter within the aneurysm has the risk of rupturing the aneurysm. Embolizing the aneurysm has the risk of occluding some vessel other than the aneurysm itself. As you will note from the bibliography of some of the articles we publish on this subject, the term "embolization" is often used incorrectly in the literature. Thus, it is not a minor issue. THORALFM. SUNDT,JR., M.D. Editor, Journal of Neurosurgery Rochester, Minnesota
Traumatic Coma Data Bank Data-Collection Protocol To THE EDITOR: It was most interesting to see the November supplement to the Journal of Neurosurgery and I would like to take the opportunity to congratulate the Principal Investigators on their accomplishments. I have recently heard that many of the forms and datacollection procedures developed during the formative phases of the Traumatic Coma Data Bank (TCDB) project are currently used to support clinical trials in this country and around the world. As Project Officer directly responsible for the project from 1978 to early
d. Neurosurg. / Volume 77~July, 1992
1986, I would like to point out that this multicenter observational study initiated several innovative concepts and currently serves as a model for other studies. Microcomputers were not in common use in the late 1970's and yet we introduced them to the data-collection sites and electronically transmitted the data to a central site. Computer-based editing, also innovative, was actively used. The concepts of a common datacollection protocol, extensive data definitions, quality control studies, and patient follow-up monitoring were innovative for observational studies and were all incorporated into the TCDB. The formative and data-collection stages of the TCDB involved many people who were not mentioned in the supplement, in addition to myself. William Weiss, then Chief of the Office of Biometry and Field Studies, should be recognized for his initiation of the project and his diligent efforts to guide the multicenter complex effort. Cynthia Gross, Ph.D., headed the research aspects of the project and it was through her efforts that intercenter studies in observational variations were conducted. We also conducted several expert task force meetings that led to the development of multidisciplinary measures of outcome. Rene Kozloff, Ph.D., acted as a consultant to this important part of the data definition process. Thomas Langfitt, M.D., served as head of the Advisory Group and provided an active voice in guiding the project. Robert Grossman, M.D., and Donald Becker, M.D., served as Principal Investigators during the pilot effort. These persons should be acknowledged for their contributions to the TCDB. SELMAC. KUNITZ,PH.D.
Rockville, Maryland
Treatment of Trigeminal Neuralgia by Ophthalmic Anesthetic To THE EDITOR: The June 5, 1991, issue of the Journal of the American Medical Association included a letter by Zavon and Fichte2 describing the serendipitous discovery that two drops of an eye anesthetic agent (0.5% proparacaine hydrochloride), instilled for ophthalmological examination prior to cataract removal, yielded lasting relief of symptoms of trigeminal neuralgia. Proparacaine hydrochloride, 0.5%, is a benzoic ester with topical anesthetic effect, used in ophthalmic procedures mainly to produce transient corneal anesthesia with little or no initial irritation. Its main site of action is the cell membrane, probably lim159
Neurosurgical forum iting sodium ion permeability, thus preventing the basic changes necessary for generation of the action potential. Being closely concerned with the treatment oftrigemihal neuralgia and goaded by such a curious observation, we resolved to test this drug in patients affected by tic douloureux not completely controlled by pharmacological treatment who were awaiting a percutaneous retrogasserian rhizolysis. Our aim was to verify if we could achieve similar results. Our initial trial was with the instillation in eight patients of two drops of 0.5% proxymetacaine hydrochloride (an almost equivalent drug); however, it proved quite ineffective, producing only a temporary effect for 12 to 24 hours. We then started to use 0.5 % proparacaine hydrochloride and obtained encouraging results. Our series included 31 patients affected by de novo or recurrent trigeminal neuralgia. Six cannot be fully evaluated because they were lost to follow-up review or underwent other treatments too soon for assessment; thus, we report our results in 25 patients. The first, second, and third divisions were involved in two patients, the second and third divisions in eight, the first and second in two, the third in five, the second in six, and the first in two. A clear effect was obtained in 15 patients; this was evidenced by an improvement of symptoms, with withdrawal of any medication in eight patients and reduction (ranging from 50% to 75%) of the daily dose of carbamazepine in another seven patients. These results were stable (the period of observation was at least 1 month) and were obtained after a second instillation in 13 patients or a third in two patients an interval of I week apart. In these 15 patients, the first, second, and third divisions were involved in two, the second and third in three, the first and second in one, the third in two, the second in five, and the first in two. In the remaining 10 cases no significant results were obtained. From our experience, we cannot propose the mechanism by which a topical anesthetic can produce lasting relief of a neuralgia affecting divisions different from that on which the drug acts directly. Based on our present knowledge, the effect of a treatment carried out on a site distal to the gasserian ganglion is mainly related to reduction of sensitive stimulations and suppression of the trigger zones. The manner in which a topical short-lasting agent acting on the first division may produce long-lasting relief of neuralgic symptoms on the second and third divisions is quite mysterious. Neither does any evidence exist to suggest a "central" action of the drug. The initial report was based on only two cases. 2 Our preliminary results in 25 patients justify, in our opinion, an interest in such treatment, also in view of its absolute harmlessness (no side effects in all 31 cases). As we believe that no stone must be left unturned in an effort to find a more efficacious and less invasive treatment of this terrible disease, we resolved to report our results in your Journal, with the goal of stimulating the interest 160
of neurosurgeons. We hope that a greater number of patients will be treated in this manner and, with a longer follow-up period, reliable evaluation of its effects can be obtained. RENATOSPAZIANTE,M.D. PAOLOCAPPABIANCA,M.D.
MARCOSAINt,M.D. CARMELAPECA,M.D. GIUSEPPEMARINIELLO,M.D. ENRICODE DIVlTIIS,M.D.
University of Naples School of Medicine Naples, Italy References 1. Ritchie JM, Cohen PJ: Cocaine, procaine and other synthetic local anesthetics, in Goodman LS, Gilman A, Gilman AG, et al (eds): The Pharmacological Basis of Therapeutics, ed 5. New York: Macmillan, 1975, pp 379-403 2. Zavon MR, Fichte CM: Trigeminal neuralgia relieved by opthalmic anesthetic. JAMA 265:2807, 199 l (Letter)
Breakage of Mayfield Head Rest To THE EDITOR:The Mayfield head clamp is one of the most widely used head-fixation devices in neurosurgical practice. We recently experienced life-threatening damage of the base unit of the clamp during aneurysm surgery. We would like to warn your readers of the possibility of such a dangerous accident in the use of the Mayfield head clamp. A 68-year-old woman underwent clipping of an anterior communicating artery aneurysm with her head fixed to the operating table as usual by a Mayfield head clamp.* During the microsurgical procedure, the patient's head suddenly fell onto the surgeon's lap. On inspection of the fixation device, we found that the supporting arm of the clamp had broken at the joint (Fig. 1). The operator held the patient's head while the broken part was replaced with a part obtained from a spare clamp. The operation was continued and the postoperative course was uneventful. We have used this Mayfield clamp for about 8 years. Although there is no record of the actual number of operations performed with this clamp, a rough estimate would be at least 1200 operations. No part of the clamp had been sterilized in an autoclave. Careful inspection disclosed that the broken surface was thinly covered with a povidone-iodine solution, which indicated that a crack had been present before the clipping operation. The broken part of the clamp appeared to receive the strongest shearing force when the joint tightened. This mechanical force is considered to have resulted in metal fatigue of this part after repeated use of the clamp. The screw hole in this joint seems to render the part more fragile. Furthermore, the base unit is made of an aluminum alloy cast, which is not very resistant to shearing force. * Mayfield head clamp manufactured by Ohio Medical Instrument Co., Cincinnati, Ohio. J. Neurosurg. / Volume 77/July, 1992
to
the
editor
Precise Terminology in Scientific Communications EDITORIALCOMMENT:The importance of the use of precise terms is exemplified in several papers that have recently crossed the Editor's desk. The case in point relates to the use of the term "embolization" for the management of intracranial aneurysms with balloons and coils. We have systematically corrected every paper coming to us implying that coils or balloons were placed by embolization techniques. Before I became Editor, the neurovascular and neurosurgical literature routinely referred to these techniques as "embolization procedures." That is entirely wrong. The catheter that places the coils and the cellulose acetate polymer are placed within the aneurysm itself. Similarly, when balloons are guided into the aneurysm, they are placed in the aneurysm. Using the term "embolization" implies that the agents, coils, or balloons were dislodged at some point in the vascular tree proximal to the site of the aneurysm and thereafter floated or were carried by the bloodstream to the aneurysm. This is incorrect. Aneurysms are thrombosed using the coil technique, obliterated using cellulose acetate polymer, and packed using balloons by having the catheter directly within the aneurysm itself. This is not a minor point as the implications of the procedure are quite significant. Placing a catheter within the aneurysm has the risk of rupturing the aneurysm. Embolizing the aneurysm has the risk of occluding some vessel other than the aneurysm itself. As you will note from the bibliography of some of the articles we publish on this subject, the term "embolization" is often used incorrectly in the literature. Thus, it is not a minor issue. THORALFM. SUNDT,JR., M.D. Editor, Journal of Neurosurgery Rochester, Minnesota
Traumatic Coma Data Bank Data-Collection Protocol To THE EDITOR: It was most interesting to see the November supplement to the Journal of Neurosurgery and I would like to take the opportunity to congratulate the Principal Investigators on their accomplishments. I have recently heard that many of the forms and datacollection procedures developed during the formative phases of the Traumatic Coma Data Bank (TCDB) project are currently used to support clinical trials in this country and around the world. As Project Officer directly responsible for the project from 1978 to early
d. Neurosurg. / Volume 77~July, 1992
1986, I would like to point out that this multicenter observational study initiated several innovative concepts and currently serves as a model for other studies. Microcomputers were not in common use in the late 1970's and yet we introduced them to the data-collection sites and electronically transmitted the data to a central site. Computer-based editing, also innovative, was actively used. The concepts of a common datacollection protocol, extensive data definitions, quality control studies, and patient follow-up monitoring were innovative for observational studies and were all incorporated into the TCDB. The formative and data-collection stages of the TCDB involved many people who were not mentioned in the supplement, in addition to myself. William Weiss, then Chief of the Office of Biometry and Field Studies, should be recognized for his initiation of the project and his diligent efforts to guide the multicenter complex effort. Cynthia Gross, Ph.D., headed the research aspects of the project and it was through her efforts that intercenter studies in observational variations were conducted. We also conducted several expert task force meetings that led to the development of multidisciplinary measures of outcome. Rene Kozloff, Ph.D., acted as a consultant to this important part of the data definition process. Thomas Langfitt, M.D., served as head of the Advisory Group and provided an active voice in guiding the project. Robert Grossman, M.D., and Donald Becker, M.D., served as Principal Investigators during the pilot effort. These persons should be acknowledged for their contributions to the TCDB. SELMAC. KUNITZ,PH.D.
Rockville, Maryland
Treatment of Trigeminal Neuralgia by Ophthalmic Anesthetic To THE EDITOR: The June 5, 1991, issue of the Journal of the American Medical Association included a letter by Zavon and Fichte2 describing the serendipitous discovery that two drops of an eye anesthetic agent (0.5% proparacaine hydrochloride), instilled for ophthalmological examination prior to cataract removal, yielded lasting relief of symptoms of trigeminal neuralgia. Proparacaine hydrochloride, 0.5%, is a benzoic ester with topical anesthetic effect, used in ophthalmic procedures mainly to produce transient corneal anesthesia with little or no initial irritation. Its main site of action is the cell membrane, probably lim159
Neurosurgical forum iting sodium ion permeability, thus preventing the basic changes necessary for generation of the action potential. Being closely concerned with the treatment oftrigemihal neuralgia and goaded by such a curious observation, we resolved to test this drug in patients affected by tic douloureux not completely controlled by pharmacological treatment who were awaiting a percutaneous retrogasserian rhizolysis. Our aim was to verify if we could achieve similar results. Our initial trial was with the instillation in eight patients of two drops of 0.5% proxymetacaine hydrochloride (an almost equivalent drug); however, it proved quite ineffective, producing only a temporary effect for 12 to 24 hours. We then started to use 0.5 % proparacaine hydrochloride and obtained encouraging results. Our series included 31 patients affected by de novo or recurrent trigeminal neuralgia. Six cannot be fully evaluated because they were lost to follow-up review or underwent other treatments too soon for assessment; thus, we report our results in 25 patients. The first, second, and third divisions were involved in two patients, the second and third divisions in eight, the first and second in two, the third in five, the second in six, and the first in two. A clear effect was obtained in 15 patients; this was evidenced by an improvement of symptoms, with withdrawal of any medication in eight patients and reduction (ranging from 50% to 75%) of the daily dose of carbamazepine in another seven patients. These results were stable (the period of observation was at least 1 month) and were obtained after a second instillation in 13 patients or a third in two patients an interval of I week apart. In these 15 patients, the first, second, and third divisions were involved in two, the second and third in three, the first and second in one, the third in two, the second in five, and the first in two. In the remaining 10 cases no significant results were obtained. From our experience, we cannot propose the mechanism by which a topical anesthetic can produce lasting relief of a neuralgia affecting divisions different from that on which the drug acts directly. Based on our present knowledge, the effect of a treatment carried out on a site distal to the gasserian ganglion is mainly related to reduction of sensitive stimulations and suppression of the trigger zones. The manner in which a topical short-lasting agent acting on the first division may produce long-lasting relief of neuralgic symptoms on the second and third divisions is quite mysterious. Neither does any evidence exist to suggest a "central" action of the drug. The initial report was based on only two cases. 2 Our preliminary results in 25 patients justify, in our opinion, an interest in such treatment, also in view of its absolute harmlessness (no side effects in all 31 cases). As we believe that no stone must be left unturned in an effort to find a more efficacious and less invasive treatment of this terrible disease, we resolved to report our results in your Journal, with the goal of stimulating the interest 160
of neurosurgeons. We hope that a greater number of patients will be treated in this manner and, with a longer follow-up period, reliable evaluation of its effects can be obtained. RENATOSPAZIANTE,M.D. PAOLOCAPPABIANCA,M.D.
MARCOSAINt,M.D. CARMELAPECA,M.D. GIUSEPPEMARINIELLO,M.D. ENRICODE DIVlTIIS,M.D.
University of Naples School of Medicine Naples, Italy References 1. Ritchie JM, Cohen PJ: Cocaine, procaine and other synthetic local anesthetics, in Goodman LS, Gilman A, Gilman AG, et al (eds): The Pharmacological Basis of Therapeutics, ed 5. New York: Macmillan, 1975, pp 379-403 2. Zavon MR, Fichte CM: Trigeminal neuralgia relieved by opthalmic anesthetic. JAMA 265:2807, 199 l (Letter)
Breakage of Mayfield Head Rest To THE EDITOR:The Mayfield head clamp is one of the most widely used head-fixation devices in neurosurgical practice. We recently experienced life-threatening damage of the base unit of the clamp during aneurysm surgery. We would like to warn your readers of the possibility of such a dangerous accident in the use of the Mayfield head clamp. A 68-year-old woman underwent clipping of an anterior communicating artery aneurysm with her head fixed to the operating table as usual by a Mayfield head clamp.* During the microsurgical procedure, the patient's head suddenly fell onto the surgeon's lap. On inspection of the fixation device, we found that the supporting arm of the clamp had broken at the joint (Fig. 1). The operator held the patient's head while the broken part was replaced with a part obtained from a spare clamp. The operation was continued and the postoperative course was uneventful. We have used this Mayfield clamp for about 8 years. Although there is no record of the actual number of operations performed with this clamp, a rough estimate would be at least 1200 operations. No part of the clamp had been sterilized in an autoclave. Careful inspection disclosed that the broken surface was thinly covered with a povidone-iodine solution, which indicated that a crack had been present before the clipping operation. The broken part of the clamp appeared to receive the strongest shearing force when the joint tightened. This mechanical force is considered to have resulted in metal fatigue of this part after repeated use of the clamp. The screw hole in this joint seems to render the part more fragile. Furthermore, the base unit is made of an aluminum alloy cast, which is not very resistant to shearing force. * Mayfield head clamp manufactured by Ohio Medical Instrument Co., Cincinnati, Ohio. J. Neurosurg. / Volume 77/July, 1992
