J Neurosurg 75:976-979, 1991
Intradural extraosseous chordoma in the foramen magnum region Case report YolCtil KATAYAMA, M.D., PtI.D., TAKAStII TSUBOKAWA, M.D., D.Sc., TAKEttlKO HIRASAWA, M.D., TETSUYA TAKAIIATA, M.D., AND NORIMICttI NEMOTO, M.D., D.Sc.
Departments t~/ Neurological Surgery and Pathoh~gy. Nihon University School qj"Medicine, Tokyo, Japan ~" Chordomas that are entirely extraosseous and intradural are extremely rare. The tumors described in the literature were observed mostly in the prepontine region. This is the first case reported of an intradural extraosseous chordoma occurring in the foramen magnum region. The tumor was totally excised. The distinction between an intradural extraosseous chordoma and a classic chordoma is important from a clinical viewpoint because of the potential for complete surgical excision and a more benign growth pattern.
chordoma notochord
foramenmagnum
HORDOMAS that are entirely extraosseous and intradural are extremely rare; such tumors described previously in the literature have been observed primarily in the prepontine region. ~6 We report the case of an intradural extraosseous chordoma occurring in the foramen magnum region, which was totally excised via a suboccipital craniectomy, and discuss the clinical features that differentiate intradural extraosseous chordomas from classic chordomas.
C
Case Report This 32-year-old pregnant woman had been in excellent health until she suffered an episode of transient gait disturbance and tinnitus in July, 1989. These symptoms disappeared spontaneously, and she had a normal delivery in August.
Examination. In September, the patient developed pyrexia and was diagnosed as having aseptic meningitis. An examination of the cerebrospinal fluid revealed moderate pleocytosis (cell count, 27 to 238: monocytes 27 to 229; polymorphonuclear cells 0 to 9; total protein content 194 to 2680 mg/ml). Tinnitus and a hearing disturbance in the right ear were noted in October and deteriorated progressively thereafter. In April, 1990, the 976
ecchordosis physaliphora
brain neoplasm
patient suddenly developed paraparesis with hypesthesia of the left lower extremity and the patient became comatose within 1 week. Computerized tomography revealed hydrocephalus. Following placement of a ventriculoperitoneal shunt, she became conscious, but her paraparesis and hypesthesia remained. Computerized tomography scans (Fig. 1) and a magnetic resonance (MR) image (Fig. 2a) demonstrated a well-circumscribed extra-axial mass in the foramen magnum region. The mass was isointense on Tx- and T2-weighted MR images but was homogeneously enhanced by the intravenous infusion of gadoliniumdiethylenetriamine penta-acetic acid. The dura of the clivus was not enhanced, and the tumor was not contiguous with the clivus. No tumor was detected in any other organ.
Operation. The patient was referred to us in July, 1990, and underwent surgical removal of the tumor through a suboccipital craniectomy. When the dura was opened, it was found that the caudal medulla and cervical cord were displaced posterolaterally to the left side by a soft gray tumor covered by the thickened arachnoid. The tumor was located below the stretched rootlets of the left C-2 nerve and the left vertebral and posterior inferior cerebellar arteries. The gelatinous tuJ. Neurosurg. / Volume 75/December, 1991
Intradural extraosseous chordoma
FIG. 1. Computerized tomography scans after intravenous infusion of contrast medium showing a well-circumscribed extra-axial mass within the foramen magnum region.
mor tissue was dissected away from these nerves and arteries and was totally removed by piecemeal excision. No pedicle connecting the tumor to the dura of the clivus was noted. Thus, the tumor was located totally within the intradural space. It was found that the tumor was attached to the junction of the left and right vertebral arteries (Fig. 2a).
Postoperative Course. The postoperative course was uneventful. An MR image revealed no evidence of residual tumor mass (Fig. 2b). One week after surge~,, the patient began to demonstrate diminished paraparesis and hypesthesia. No radiation therapy or chemotherapy was administered. Eleven months after surgery, there was no evidence of regrowth of the tumor or of metastasis. Pathological Examination. The tumor tissue was characterized histologically by lobules composed of typical physaliphorous cells with abundantly vacuolated cytoplasm (Fig. 3). These cells demonstrated "cording"
FIG. 2. Magnetic resonance images, sagittal view, showing a mass within the region of the foramen magnum, a: Presurgical T~-weighted image after intravenous infusion of gadolinium-DTPA demonstrating the tumor attached to the junction of the left and right vertebral arteries (arrow). b: Postsurgical T~-weighted image after intravenous infusion of gadolinium-DTPA demonstrating no evidence of residual tumor mass. and were embedded in an acellular matrix. Neither mitotic figures nor cytological atypia were observed. There were many blood vessels between the lobules, surrounded by prominent lymphocytic infiltration. Scattered areas of petechial hemorrhages were also noted.
Discussion To the best of our knowledge, only six cases of totally intradural extraosseous chordomas have been reported with documentation of clinical symptoms and signs (Table 1). Five of these were located in the prepontine region ~.~3.L4.J6.1s and one was in the suprasellar region. ' Our case is the first reported occurrence of an intradural extraosseous chordoma located in the foramen magnum region. These lesions are undoubtedly of notochordal origin, and the histological features are indistinguishable from those of a typical c h o r d o m a . 9"13'14'1618
FIG. 3. Photomicrographs of an intradural extraosseous tumor showing a lobulated structure composed of nests or cords of physaliphorous cells embedded in a loose myxomatous matrix, a: H & E, x 85. b: H & E, x 350.
J. Neurosurg. / Volume 75 /December, J991
977
Y. Katayama, el a/. ~ABLE 1
Authors & Year
Sex. Age (yrsl
Bartolini, 1974 Stare & Kamphorst, 1982 Mapstone, e! al.. 1983
M, 57 M, "5 M, 26
prcpontine prepontinc prcpontine-CPA
Yuhi. ez' a/,. 19S6 Wolfe & Scheithauer. 1987 Case 1 Case 2 Kalayama, et aL. 1991
M, 28
prepontine
M, 44 F, 70 F, 3~)
prepontine suprasellar foramen magnum
Tumor Loeatit,tz*
( omplications hemorrhage hemorrhaf.e intratumt~ral hemorriaagc, hsdroccphalus h?droccphalus hydrocephalus metaingitis :ntratumoral hemorrhage, hydrocephalus
Extent of SurgeD'
Follow-Up Results
none none subtotal excision
died died well
total excision
well
exploration gross total excision total excision
died well well
* C P A = c e r e b e l l o p o n t i n e angle.
Literature Review
A review of the literature reveals that intradural extraosseous chordomas exhibit features clearb different from those of typical chordomas. The classic chordoma is a malignant extradural neoplasm which most often originates in bone. Bone involvement by chordomas is so characteristic that osseous destruction has often been described as a hallmark of these tumors. 5`J: Chordomas frequentb have ill-defined margins in bone and are not easily resectable because of their osseous involvement. In contrast, complete resection is feasible for intradural extraosseous chordomas because of their sharply circumscribed margins and the absence of bone involvement. Good results were obtained in four reported cases in which subtotal or total excision of the tumor was achieved. 9.16.~ In addition to differences in location and growth pattern, intradural extraosseous chordomas appear to differ from classic chordomas in their biological behavior. Classic chordomas have been reported to exhibit both hematogenous and lymphatic metastasis. Metastasis has been observed clinicall? in 10% to 15% of cases with classic chordoma and in 45% of those examined at autopsy] In contrast, metastasis has never been reported associated with intradural extraosseous chordomas. Our patient has not demonstrated metastasis over the 23-month interval since the onset of her symptoms. These features of intradural chordomas appear to justify distinguishing these tumors from classic chordomas.
significance.:,~ E~5.~7It has been suggested by some that ecchordosis physaliphoras do not give rise to true chordomasfl f'~ however, others have postulated that the tumors under consideration are chordomas arising from ecchordesis physaliphoras. 9,H.~ The regions in which the intradural extraosseous chordomas, including the tumor in our case, were found are the areas in which ecchordosis physaliphoras are usually seen. It is noteworthy that, in two reported cases, the clinical manifestations of these lesions were the result of intratumoral and extratumoral hemorrhages. ~,t4 In two other cases, including our own, there was evidence that the intratumoral hemorrhages might be responsible for the sudden onset of symptoms. ~This suggests that hemorrhages rather than active proliferation of tumor cells may be more important in the onset of clinical symptoms and signs in this group of tumors. Some authors have even suggested that intradural extraosseous chordomas could be regarded as giant ecchordosis physaliphoras. J4,16Further accumulation of cases is, however, necessary to establish this claim, which implies that these iesions are simply a developmental vestige rather than a neoplasm. The recent development in neuroradiologicat imaging technique appears to greatly facilitate the detection of intradural extraosseous chordomas 9 and ecchordosis physaliphoras. Differentiation of intradural extraosseous chordomas from classic chordomas is important from a clinical viewpoint because of the potential for complete surgical excision and a more benign growth pattern.
Ecchordosis Plo,sa/iphoras
In approximately 0.6% to 5% of routine autopsies, a small gelatinous nodule of notochordal tissue a few millimeters to 2 cm in size is found intradurally in the prepontine region.: ,o.~J~ J~These intradural ectopias of notochord often have a delicate filiform bone attachment, and the remnants have been given the name "ecchordosis physaliphoras. "'',~.s Although ecchordosis physaliphoras have been classified b5 some authors as benign chordomas, -~ they are clearly defined benign developmental lesions and are of no apparent clinical 978
References
1. Bartomli G: II cordema de1 clivus quale causa di emorragia cerebrale: discussicne anatomo-clinica su di una osservazione autopica. Bull Soc Ital Biol Sper 50:912-918, t 974
2. Congdon CC: Benign and malignant chordomas. A olinice-anatomical stud} of twent?-two cases. Am J Pathol 28:7~3-821. 1952 3. Crawtbrd T: The staining reactions of chordoma. J Clin Pathol 11:110-113, 1958 4. Dahlin DC, MacCarty CS: Chordoma. A study of fiftynine cases. Cancer 5:1170-1178, 1952 .]. Neto+o~urg. / I ~+dzone 75 / December, 1991
Intradural extraosseous chordoma 5. Danziger J, Allen KL, Bloch S: Intracranial chordomas. Clin Radiol 25:309-316, 1974 6. Hardy J, Vezina JL: Transsphenoidal neurosurgery of intracranial neoplasm, in Thompson RA, Green JR (eds): Advances in Neurology. Vol 15: Neoplasia in the Central Nervous System. New York: Raven Press, 1976, pp 261-274 7. Higinbotham NL, Phillips RF, Farr HW, et al: Chordoma. Thirty-five-year study at Memorial Hospital. Cancer 20:1841-1850, 1967 8. Ho KL: Ecchordosis physaliphora and chordoma: a comparative ultrastructural study. Clin Neuropathol 4:77-86, 1985 9. Mapstone TB, Kaufman B, Ratcheson RA: lntradural chordoma without bone involvement: nuclear magnetic resonance (NMR) appearance. Case report. J Neurosurg 59:535-537, 1983 10. Russell DS, Rubinstein LJ: Pathology of Tumours of the Nervous System, ed 5. Baltimore: Williams & Wilkins, 1989, pp 353-365 11. Sassin JF: Intracranial chordoma, in Vinken PJ, Bruyn GW (eds): Handbook of Clinical Neurology. Vol 18: Tumours of the Brain and Skull, Part II1. Amsterdam: North-Holland, 1975, pp 151-164 12. Scheehter MM, Liebeskind AL, Azar-Kia B: Intracranial chordomas. Neuroradiology 8:67-82, t 974
J. Neurosurg. / Volume 75 /December, 1991
13. Simonscn J: Fatal subarachnoid hemorrhage originating in an intracranial chordoma. Acta Pathol Microbiol Scand 59:13-20, 1963 14. Stare FC, Kamphorst W: Ecchordosis physaliphora as a cause of fatal pontine hemorrhage. Eur Neurol 21: 90-93, 1982 15. Willis RA: Pathology of Tumours, ed 4. New York: Appleton-Century-Croft, 1967, pp 300-301 16. Wolfe JT IlL Scheithauer BW: "Intradural chordoma" or "giant ecchordosis physaliphora?" Report of two cases. Clio Neuropathol 6:98-103, 1987 17. Wyatt RB, Schochet SS Jr, McCormick WF: Ecchordosis physaliphora. An electron microscopic study. J Neurosurg 34:672-677, 1971 18. Yuhi F, Asakura T, Tomosugi T, et al: [A case of clival chordoma without bone destruction.] No Shinkei Geka 14:547-552, 1986 (Jpn)
Manuscript received January 28, 1991. Accepted in final form May 28, 1991. Address reprint requests to. Yoichi Katayama, M.D., Ph.D., Department of Neurological Surgery, Nihon University School of' Medicine, 30 Oyaguchi Kamimachi, Itabashiku, Tokyo 173, Japan.
979
Intradural extraosseous chordoma in the foramen magnum region Case report YolCtil KATAYAMA, M.D., PtI.D., TAKAStII TSUBOKAWA, M.D., D.Sc., TAKEttlKO HIRASAWA, M.D., TETSUYA TAKAIIATA, M.D., AND NORIMICttI NEMOTO, M.D., D.Sc.
Departments t~/ Neurological Surgery and Pathoh~gy. Nihon University School qj"Medicine, Tokyo, Japan ~" Chordomas that are entirely extraosseous and intradural are extremely rare. The tumors described in the literature were observed mostly in the prepontine region. This is the first case reported of an intradural extraosseous chordoma occurring in the foramen magnum region. The tumor was totally excised. The distinction between an intradural extraosseous chordoma and a classic chordoma is important from a clinical viewpoint because of the potential for complete surgical excision and a more benign growth pattern.
chordoma notochord
foramenmagnum
HORDOMAS that are entirely extraosseous and intradural are extremely rare; such tumors described previously in the literature have been observed primarily in the prepontine region. ~6 We report the case of an intradural extraosseous chordoma occurring in the foramen magnum region, which was totally excised via a suboccipital craniectomy, and discuss the clinical features that differentiate intradural extraosseous chordomas from classic chordomas.
C
Case Report This 32-year-old pregnant woman had been in excellent health until she suffered an episode of transient gait disturbance and tinnitus in July, 1989. These symptoms disappeared spontaneously, and she had a normal delivery in August.
Examination. In September, the patient developed pyrexia and was diagnosed as having aseptic meningitis. An examination of the cerebrospinal fluid revealed moderate pleocytosis (cell count, 27 to 238: monocytes 27 to 229; polymorphonuclear cells 0 to 9; total protein content 194 to 2680 mg/ml). Tinnitus and a hearing disturbance in the right ear were noted in October and deteriorated progressively thereafter. In April, 1990, the 976
ecchordosis physaliphora
brain neoplasm
patient suddenly developed paraparesis with hypesthesia of the left lower extremity and the patient became comatose within 1 week. Computerized tomography revealed hydrocephalus. Following placement of a ventriculoperitoneal shunt, she became conscious, but her paraparesis and hypesthesia remained. Computerized tomography scans (Fig. 1) and a magnetic resonance (MR) image (Fig. 2a) demonstrated a well-circumscribed extra-axial mass in the foramen magnum region. The mass was isointense on Tx- and T2-weighted MR images but was homogeneously enhanced by the intravenous infusion of gadoliniumdiethylenetriamine penta-acetic acid. The dura of the clivus was not enhanced, and the tumor was not contiguous with the clivus. No tumor was detected in any other organ.
Operation. The patient was referred to us in July, 1990, and underwent surgical removal of the tumor through a suboccipital craniectomy. When the dura was opened, it was found that the caudal medulla and cervical cord were displaced posterolaterally to the left side by a soft gray tumor covered by the thickened arachnoid. The tumor was located below the stretched rootlets of the left C-2 nerve and the left vertebral and posterior inferior cerebellar arteries. The gelatinous tuJ. Neurosurg. / Volume 75/December, 1991
Intradural extraosseous chordoma
FIG. 1. Computerized tomography scans after intravenous infusion of contrast medium showing a well-circumscribed extra-axial mass within the foramen magnum region.
mor tissue was dissected away from these nerves and arteries and was totally removed by piecemeal excision. No pedicle connecting the tumor to the dura of the clivus was noted. Thus, the tumor was located totally within the intradural space. It was found that the tumor was attached to the junction of the left and right vertebral arteries (Fig. 2a).
Postoperative Course. The postoperative course was uneventful. An MR image revealed no evidence of residual tumor mass (Fig. 2b). One week after surge~,, the patient began to demonstrate diminished paraparesis and hypesthesia. No radiation therapy or chemotherapy was administered. Eleven months after surgery, there was no evidence of regrowth of the tumor or of metastasis. Pathological Examination. The tumor tissue was characterized histologically by lobules composed of typical physaliphorous cells with abundantly vacuolated cytoplasm (Fig. 3). These cells demonstrated "cording"
FIG. 2. Magnetic resonance images, sagittal view, showing a mass within the region of the foramen magnum, a: Presurgical T~-weighted image after intravenous infusion of gadolinium-DTPA demonstrating the tumor attached to the junction of the left and right vertebral arteries (arrow). b: Postsurgical T~-weighted image after intravenous infusion of gadolinium-DTPA demonstrating no evidence of residual tumor mass. and were embedded in an acellular matrix. Neither mitotic figures nor cytological atypia were observed. There were many blood vessels between the lobules, surrounded by prominent lymphocytic infiltration. Scattered areas of petechial hemorrhages were also noted.
Discussion To the best of our knowledge, only six cases of totally intradural extraosseous chordomas have been reported with documentation of clinical symptoms and signs (Table 1). Five of these were located in the prepontine region ~.~3.L4.J6.1s and one was in the suprasellar region. ' Our case is the first reported occurrence of an intradural extraosseous chordoma located in the foramen magnum region. These lesions are undoubtedly of notochordal origin, and the histological features are indistinguishable from those of a typical c h o r d o m a . 9"13'14'1618
FIG. 3. Photomicrographs of an intradural extraosseous tumor showing a lobulated structure composed of nests or cords of physaliphorous cells embedded in a loose myxomatous matrix, a: H & E, x 85. b: H & E, x 350.
J. Neurosurg. / Volume 75 /December, J991
977
Y. Katayama, el a/. ~ABLE 1
Authors & Year
Sex. Age (yrsl
Bartolini, 1974 Stare & Kamphorst, 1982 Mapstone, e! al.. 1983
M, 57 M, "5 M, 26
prcpontine prepontinc prcpontine-CPA
Yuhi. ez' a/,. 19S6 Wolfe & Scheithauer. 1987 Case 1 Case 2 Kalayama, et aL. 1991
M, 28
prepontine
M, 44 F, 70 F, 3~)
prepontine suprasellar foramen magnum
Tumor Loeatit,tz*
( omplications hemorrhage hemorrhaf.e intratumt~ral hemorriaagc, hsdroccphalus h?droccphalus hydrocephalus metaingitis :ntratumoral hemorrhage, hydrocephalus
Extent of SurgeD'
Follow-Up Results
none none subtotal excision
died died well
total excision
well
exploration gross total excision total excision
died well well
* C P A = c e r e b e l l o p o n t i n e angle.
Literature Review
A review of the literature reveals that intradural extraosseous chordomas exhibit features clearb different from those of typical chordomas. The classic chordoma is a malignant extradural neoplasm which most often originates in bone. Bone involvement by chordomas is so characteristic that osseous destruction has often been described as a hallmark of these tumors. 5`J: Chordomas frequentb have ill-defined margins in bone and are not easily resectable because of their osseous involvement. In contrast, complete resection is feasible for intradural extraosseous chordomas because of their sharply circumscribed margins and the absence of bone involvement. Good results were obtained in four reported cases in which subtotal or total excision of the tumor was achieved. 9.16.~ In addition to differences in location and growth pattern, intradural extraosseous chordomas appear to differ from classic chordomas in their biological behavior. Classic chordomas have been reported to exhibit both hematogenous and lymphatic metastasis. Metastasis has been observed clinicall? in 10% to 15% of cases with classic chordoma and in 45% of those examined at autopsy] In contrast, metastasis has never been reported associated with intradural extraosseous chordomas. Our patient has not demonstrated metastasis over the 23-month interval since the onset of her symptoms. These features of intradural chordomas appear to justify distinguishing these tumors from classic chordomas.
significance.:,~ E~5.~7It has been suggested by some that ecchordosis physaliphoras do not give rise to true chordomasfl f'~ however, others have postulated that the tumors under consideration are chordomas arising from ecchordesis physaliphoras. 9,H.~ The regions in which the intradural extraosseous chordomas, including the tumor in our case, were found are the areas in which ecchordosis physaliphoras are usually seen. It is noteworthy that, in two reported cases, the clinical manifestations of these lesions were the result of intratumoral and extratumoral hemorrhages. ~,t4 In two other cases, including our own, there was evidence that the intratumoral hemorrhages might be responsible for the sudden onset of symptoms. ~This suggests that hemorrhages rather than active proliferation of tumor cells may be more important in the onset of clinical symptoms and signs in this group of tumors. Some authors have even suggested that intradural extraosseous chordomas could be regarded as giant ecchordosis physaliphoras. J4,16Further accumulation of cases is, however, necessary to establish this claim, which implies that these iesions are simply a developmental vestige rather than a neoplasm. The recent development in neuroradiologicat imaging technique appears to greatly facilitate the detection of intradural extraosseous chordomas 9 and ecchordosis physaliphoras. Differentiation of intradural extraosseous chordomas from classic chordomas is important from a clinical viewpoint because of the potential for complete surgical excision and a more benign growth pattern.
Ecchordosis Plo,sa/iphoras
In approximately 0.6% to 5% of routine autopsies, a small gelatinous nodule of notochordal tissue a few millimeters to 2 cm in size is found intradurally in the prepontine region.: ,o.~J~ J~These intradural ectopias of notochord often have a delicate filiform bone attachment, and the remnants have been given the name "ecchordosis physaliphoras. "'',~.s Although ecchordosis physaliphoras have been classified b5 some authors as benign chordomas, -~ they are clearly defined benign developmental lesions and are of no apparent clinical 978
References
1. Bartomli G: II cordema de1 clivus quale causa di emorragia cerebrale: discussicne anatomo-clinica su di una osservazione autopica. Bull Soc Ital Biol Sper 50:912-918, t 974
2. Congdon CC: Benign and malignant chordomas. A olinice-anatomical stud} of twent?-two cases. Am J Pathol 28:7~3-821. 1952 3. Crawtbrd T: The staining reactions of chordoma. J Clin Pathol 11:110-113, 1958 4. Dahlin DC, MacCarty CS: Chordoma. A study of fiftynine cases. Cancer 5:1170-1178, 1952 .]. Neto+o~urg. / I ~+dzone 75 / December, 1991
Intradural extraosseous chordoma 5. Danziger J, Allen KL, Bloch S: Intracranial chordomas. Clin Radiol 25:309-316, 1974 6. Hardy J, Vezina JL: Transsphenoidal neurosurgery of intracranial neoplasm, in Thompson RA, Green JR (eds): Advances in Neurology. Vol 15: Neoplasia in the Central Nervous System. New York: Raven Press, 1976, pp 261-274 7. Higinbotham NL, Phillips RF, Farr HW, et al: Chordoma. Thirty-five-year study at Memorial Hospital. Cancer 20:1841-1850, 1967 8. Ho KL: Ecchordosis physaliphora and chordoma: a comparative ultrastructural study. Clin Neuropathol 4:77-86, 1985 9. Mapstone TB, Kaufman B, Ratcheson RA: lntradural chordoma without bone involvement: nuclear magnetic resonance (NMR) appearance. Case report. J Neurosurg 59:535-537, 1983 10. Russell DS, Rubinstein LJ: Pathology of Tumours of the Nervous System, ed 5. Baltimore: Williams & Wilkins, 1989, pp 353-365 11. Sassin JF: Intracranial chordoma, in Vinken PJ, Bruyn GW (eds): Handbook of Clinical Neurology. Vol 18: Tumours of the Brain and Skull, Part II1. Amsterdam: North-Holland, 1975, pp 151-164 12. Scheehter MM, Liebeskind AL, Azar-Kia B: Intracranial chordomas. Neuroradiology 8:67-82, t 974
J. Neurosurg. / Volume 75 /December, 1991
13. Simonscn J: Fatal subarachnoid hemorrhage originating in an intracranial chordoma. Acta Pathol Microbiol Scand 59:13-20, 1963 14. Stare FC, Kamphorst W: Ecchordosis physaliphora as a cause of fatal pontine hemorrhage. Eur Neurol 21: 90-93, 1982 15. Willis RA: Pathology of Tumours, ed 4. New York: Appleton-Century-Croft, 1967, pp 300-301 16. Wolfe JT IlL Scheithauer BW: "Intradural chordoma" or "giant ecchordosis physaliphora?" Report of two cases. Clio Neuropathol 6:98-103, 1987 17. Wyatt RB, Schochet SS Jr, McCormick WF: Ecchordosis physaliphora. An electron microscopic study. J Neurosurg 34:672-677, 1971 18. Yuhi F, Asakura T, Tomosugi T, et al: [A case of clival chordoma without bone destruction.] No Shinkei Geka 14:547-552, 1986 (Jpn)
Manuscript received January 28, 1991. Accepted in final form May 28, 1991. Address reprint requests to. Yoichi Katayama, M.D., Ph.D., Department of Neurological Surgery, Nihon University School of' Medicine, 30 Oyaguchi Kamimachi, Itabashiku, Tokyo 173, Japan.
979
