Neurosurgery 31; 979-980, 1992 Microvascular Anatomy of the Uncus and the Parahippocampal Gyrus To The Editor: Regarding the article, "Microvascular Anatomy of the Uncus and the Parahippocampal Gyrus," by Marinkovic et al. (1), I would like to commend them on their detailed anatomical study and in addition, add two references. The original study was carried out in detail by Uchimura at the Kaiser Wilhelm Institute in Munich in 1927 (3). This extensive anatomical work formed the basis of Spielmeyer's thesis on the pathology in the CA1 field of the hippocampus. The second reference of interest by Olivier and de Lotbiniere (2) describes the use of the anterior choroidal artery on stereotactic digital substration angiography as a means for anatomical mapping and location of depth electrode placement in the amygdala and hippocampus based on the choroidal point 2 and the M1 portion of the middle cerebral artery. Richard M. Lehman New Brunswick, New Jersey REFERENCES: (1-3) 1.
2. 3.
Marinkovi< SV, Milisavljevi< MM, Vuckovi< VD: Microvascular anatomy of the uncus and the parahippocampal gyrus. Neurosurgery 29:805-814. Olivier A, de Lotbiniere A: State of the art reviews. Stereotactic Techniques in Epilepsy 2:263, 1987. Uchimura J: Uber die Gefassversorgung des Ammonshotnes. Zfdg Neuro u Psych 112:119, 1928.
Intramedullary Epidermoid Associated with an Intramedullary Spinal Abscess Secondary to a Dermal Sinus To the Editor: I wish to amplify the caveats provided by the excellent account of intramedullary epidermoid/abscess recently reported by Benzil et al. (1) . A 7-month-old boy with vertebral defects, anal atresia, tracheoesophageal fistula with esophageal atresia, and radial and renal anomalies and recently repaired imperforate anus was referred because of lumbar dermal sinus marked by midline external os filled with stiff, short hairs. His lower extremity function appeared normal. The parents accepted the rationale for the prophylactic removal of the sinus and any intradural mass. At surgery, the sinus was followed to a large extramedullary dermoid cyst that was histologically typical, and the entire lesion was removed, including a capsule adherent to the dorsal conus. The conus was elongated, but otherwise
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unremarkable. Four months later, the child stopped moving his legs, complained of sore back and legs, and had bouts of fever. Magnetic resonance imaging demonstrated a huge mass within the conus (Fig. 1). Reexposure of the conus revealed a large intramedullary dermoid cyst containing frank pus and an abscess extension into the cauda equina. Total removal was accomplished, with significant but incomplete recovery of leg and sphincter function 2 years later. If the intramedullary dermoid cyst was in continuity with the extramedullary lesion at the initial operation, the connection must have been tenuous, indeed, for no evidence of same was seen under magnified vision. The first procedure was done without benefit of magnetic resonance imaging because of constraints placed by the third-party payor, and whether the intramedullary lesion would have been seen at that time is moot. The discussion of intramedullary dermoid/epidermoid cysts presented by Benzil et al. is thorough and apropos. Such lesions are rare, but catastrophic. A. Loren Amacher Danville, Pennsylvania REFERENCES: (1) 1.
Benzil DL, Epstein MH, Knuckey NW: Intramedullary Epidermoid Associated with an Intramedullary Spinal Abscess Secondary to a Dermal Sinus. Neurosurgery 30:118-120, 1992.
Partial Callosal Resection for Pericallosal Aneurysms To the Editor: Although it was interesting to note that resection of the anterior 2.5 cm of the corpus callosum can be performed without causing any neurological deficit (1), the necessity for so doing must remain in doubt. Brain resection should be performed only where absolutely necessary. Deliberate brain resection is against modern methods of neurosurgery. Anterior disconnection syndrome is well described, and good results in two patients (ages, 56 and 44 years) where resection of the genu of the corpus callosum has been performed must be viewed with caution. Figure 1 in the article is oversimplified, presenting no details of site and size of the craniotomy or dural opening, and suggests that the surgeon will be facing the fundus first before reaching the neck. This can pose serious difficulties during surgery and may lead to manipulative difficulties in the narrow space. For 5 years at the Department of Neurological Surgery, Preston, United Kingdom, anterior midline aneurysms have been approached by an anterior frontal trephine with interhemispheric dissection (3). Of 75 patients with midline aneurysms, 7 have had peripheral anterior cerebral aneurysms successfully operated on using this method (4). In no patient was it necessary to resect any of the corpus callosum, yet
Redistribution of this article permitted only in accordance with the publisher’s copyright provisions.
Neurosurgery 1992-98 November 1992, Volume 31, Number 5 979 Correspondence Departments: Correspondence
proximal vessel exposure was always possible. Brain resection in our series has been kept to a minimum, and this is a major factor in making this approach well tolerated even in the elderly (20 of our patients were over the age of 60) and fragile patients (ASA Class 2 or 3) (2). A.J. Keogh R.R. Sharma G.K. Vanner Preston, United Kingdom
1.
2. 3. 4.
Dickey PS, Bloomgarden GM, Arkins TJ, Spencer DD: Partial callosal resection for pericallosal aneurysms. Neurosurgery 30:136137, 1992. Dripps RD, Lamont A, Eckenhoff JE: The role of anesthesia in surgical mortality. JAMA 178:261, 1961. Keogh AJ: Trephine approach to anterior midline aneurysms--an initial communication. Br J Neurosurg 4:337-338, 1990. Keogh AJ, Sharma RR, Vanner GK: Anterior midline aneurysms via anterior inter-hemispheric trephine approach (in press).
Reply: We thank Dr. Keogh and colleagues for their interesting comments. Certainly there are several acceptable techniques from which to choose for treating pericallosal aneurysms, and we eagerly await publication of their complete series of trephination and low midline frontal approach for these lesions. We believe that our anterior interhemispheric approach provides good exposure and requires less dissection and retraction than other methods (3). Many authors have performed limited callosal sections for surgical treatment of epilepsy, tumors, and vascular lesions and have emphasized the low morbidity of this maneuver (1,2,4). Although it is true the fundus of the aneurysm is seen before the neck in our approach, there is no dissection of the aneurysm until both proximal and distal control of the pericallosal artery have been gained. Once control is established, dissection of the neck can proceed safely. In our experience, it is difficult to visualize and control the distal vessel with a low anterior or subfrontal exposure. This is problematic because these lesions are associated with a high rate of intraoperative rupture (5). The authors describe excellent results in treating these difficult lesions. However, anterior frontal lobe dysfunction that occurs as a result of retraction can be difficult to demonstrate at routine bedside examination. We hope that Dr. Keogh and others who report on their approaches for this aneurysm will employ detailed neuropsychological evaluation, as we have, when they assess the safety and advisability of their techniques. Phillip S. Dickey
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REFERENCES: (1-4)
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Figure 1. Sagittal thoracolumbar magnetic resonance imaging scan showing infected dermoid cyst of conus medullaris and abscess extension to surround the cauda equina.
2. 3.
Marinkovi< SV, Milisavljevi< MM, Vuckovi< VD: Microvascular anatomy of the uncus and the parahippocampal gyrus. Neurosurgery 29:805-814. Olivier A, de Lotbiniere A: State of the art reviews. Stereotactic Techniques in Epilepsy 2:263, 1987. Uchimura J: Uber die Gefassversorgung des Ammonshotnes. Zfdg Neuro u Psych 112:119, 1928.
Intramedullary Epidermoid Associated with an Intramedullary Spinal Abscess Secondary to a Dermal Sinus To the Editor: I wish to amplify the caveats provided by the excellent account of intramedullary epidermoid/abscess recently reported by Benzil et al. (1) . A 7-month-old boy with vertebral defects, anal atresia, tracheoesophageal fistula with esophageal atresia, and radial and renal anomalies and recently repaired imperforate anus was referred because of lumbar dermal sinus marked by midline external os filled with stiff, short hairs. His lower extremity function appeared normal. The parents accepted the rationale for the prophylactic removal of the sinus and any intradural mass. At surgery, the sinus was followed to a large extramedullary dermoid cyst that was histologically typical, and the entire lesion was removed, including a capsule adherent to the dorsal conus. The conus was elongated, but otherwise
Downloaded from https://academic.oup.com/neurosurgery/article-abstract/31/5/979/2281218 by Frankfurt Univesity Library user on 05 March 2018
unremarkable. Four months later, the child stopped moving his legs, complained of sore back and legs, and had bouts of fever. Magnetic resonance imaging demonstrated a huge mass within the conus (Fig. 1). Reexposure of the conus revealed a large intramedullary dermoid cyst containing frank pus and an abscess extension into the cauda equina. Total removal was accomplished, with significant but incomplete recovery of leg and sphincter function 2 years later. If the intramedullary dermoid cyst was in continuity with the extramedullary lesion at the initial operation, the connection must have been tenuous, indeed, for no evidence of same was seen under magnified vision. The first procedure was done without benefit of magnetic resonance imaging because of constraints placed by the third-party payor, and whether the intramedullary lesion would have been seen at that time is moot. The discussion of intramedullary dermoid/epidermoid cysts presented by Benzil et al. is thorough and apropos. Such lesions are rare, but catastrophic. A. Loren Amacher Danville, Pennsylvania REFERENCES: (1) 1.
Benzil DL, Epstein MH, Knuckey NW: Intramedullary Epidermoid Associated with an Intramedullary Spinal Abscess Secondary to a Dermal Sinus. Neurosurgery 30:118-120, 1992.
Partial Callosal Resection for Pericallosal Aneurysms To the Editor: Although it was interesting to note that resection of the anterior 2.5 cm of the corpus callosum can be performed without causing any neurological deficit (1), the necessity for so doing must remain in doubt. Brain resection should be performed only where absolutely necessary. Deliberate brain resection is against modern methods of neurosurgery. Anterior disconnection syndrome is well described, and good results in two patients (ages, 56 and 44 years) where resection of the genu of the corpus callosum has been performed must be viewed with caution. Figure 1 in the article is oversimplified, presenting no details of site and size of the craniotomy or dural opening, and suggests that the surgeon will be facing the fundus first before reaching the neck. This can pose serious difficulties during surgery and may lead to manipulative difficulties in the narrow space. For 5 years at the Department of Neurological Surgery, Preston, United Kingdom, anterior midline aneurysms have been approached by an anterior frontal trephine with interhemispheric dissection (3). Of 75 patients with midline aneurysms, 7 have had peripheral anterior cerebral aneurysms successfully operated on using this method (4). In no patient was it necessary to resect any of the corpus callosum, yet
Redistribution of this article permitted only in accordance with the publisher’s copyright provisions.
Neurosurgery 1992-98 November 1992, Volume 31, Number 5 979 Correspondence Departments: Correspondence
proximal vessel exposure was always possible. Brain resection in our series has been kept to a minimum, and this is a major factor in making this approach well tolerated even in the elderly (20 of our patients were over the age of 60) and fragile patients (ASA Class 2 or 3) (2). A.J. Keogh R.R. Sharma G.K. Vanner Preston, United Kingdom
1.
2. 3. 4.
Dickey PS, Bloomgarden GM, Arkins TJ, Spencer DD: Partial callosal resection for pericallosal aneurysms. Neurosurgery 30:136137, 1992. Dripps RD, Lamont A, Eckenhoff JE: The role of anesthesia in surgical mortality. JAMA 178:261, 1961. Keogh AJ: Trephine approach to anterior midline aneurysms--an initial communication. Br J Neurosurg 4:337-338, 1990. Keogh AJ, Sharma RR, Vanner GK: Anterior midline aneurysms via anterior inter-hemispheric trephine approach (in press).
Reply: We thank Dr. Keogh and colleagues for their interesting comments. Certainly there are several acceptable techniques from which to choose for treating pericallosal aneurysms, and we eagerly await publication of their complete series of trephination and low midline frontal approach for these lesions. We believe that our anterior interhemispheric approach provides good exposure and requires less dissection and retraction than other methods (3). Many authors have performed limited callosal sections for surgical treatment of epilepsy, tumors, and vascular lesions and have emphasized the low morbidity of this maneuver (1,2,4). Although it is true the fundus of the aneurysm is seen before the neck in our approach, there is no dissection of the aneurysm until both proximal and distal control of the pericallosal artery have been gained. Once control is established, dissection of the neck can proceed safely. In our experience, it is difficult to visualize and control the distal vessel with a low anterior or subfrontal exposure. This is problematic because these lesions are associated with a high rate of intraoperative rupture (5). The authors describe excellent results in treating these difficult lesions. However, anterior frontal lobe dysfunction that occurs as a result of retraction can be difficult to demonstrate at routine bedside examination. We hope that Dr. Keogh and others who report on their approaches for this aneurysm will employ detailed neuropsychological evaluation, as we have, when they assess the safety and advisability of their techniques. Phillip S. Dickey
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Redistribution of this article permitted only in accordance with the publisher’s copyright provisions.
REFERENCES: (1-4)
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Figure 1. Sagittal thoracolumbar magnetic resonance imaging scan showing infected dermoid cyst of conus medullaris and abscess extension to surround the cauda equina.
