BRIEF COMMUNICATIONS A N D CASE REPORTS
Subarachnoid Spread of Ependymoma: Diagnosis and Evaluation of Therapy by Computerized Tomography Robert B. Geehr, MD, George J. Dohrmann, MD, PhD, Stephen L. G. Rothman, MD, E. Leon Kier, MD, Franklin C. Wagner, MD, and Daniel S. Kapp, M D
The potential of ependymomas to spread throughout the intracranial subarachnoid space is well documented, though the incidence is disputed. This relates i n part to the time required for such metastases to produce symptoms. The diagnosis of such spread, however, is important for therapeutic management. This report demonstrates the effectiveness of computerized tomography in diagnosing spread of ependymoma throughout the basal cisterns and cerebral fissures. Geehr RB, Dohrmann GJ, Rothman SLG, et al: Subarachnoid spread of ependymoma: diagnosis and evaluation of therapy by computerized tomography. Ann Neurol 6:538-539, 1979
The ability of intracranial ependymomas, particularly those of the fourth ventricle, to disseminate throughout the basal cisterns and spinal subarachnoid space has been well documented, though the incidence of such tumor spread is in dispute [ 1, 71. This undoubtedly relates to the difficulty in making the diagnosis of intracranial tumor implantation antemortem, as few patients with subarachnoid spread of ependymomas have related symptoms [6]. Since radiation therapy of ependymomas [3, 51 is planned in part around the potential spread of tumor, this uncertainty takes on added importance. A 35-year-old left-handed man underwent suboccipital craniectomy for removal of an ependymoma of the fourth ventricle that extended through the vallecula to the posterior arch of C1. At the conclusion of the operation it was thought that all gross tumor had been excised with the exception of a small plaque firmly attached to the floor of the fourth ventricle. computerized tomography performed From the Section of Neuroradiology, Department of Diagnostic Radiology, the Secrion of Neurosurgery, Department of Surgery, and the Department of Therapeutic Radiology, Yale University School of Medicine. New Haven, CT, and the Division of Neurosurgery, University of Chicago Medical Center, Chicago, IL. Accepted for public-ation June 26, 1978. Address reprint requests to Dr Geehr, Department of Diagnostic Radiology, Yale University School of Medicine, 333 Cedar St, New Haven. CT 06510.
at this time demonstrated the midline tumor extending into the cisterna magna, though the remaining basal cisterns remained normal. The patient received radiation therapy to the posterior fossa and upper cervical spinal cord postoperatively. He returned one year later with a two-week history of increasing numbness and weakness of both lower extremities. A CT scan revealed postoperative changes in the posterior fossa, normal ventricle size, a ventricular shunt in place, and normal basal cisterns. A myelogram demonstrated multiple intradural, extramedullary masses throughout the thoracic and lumbar region, consistent with subarachnoid seeding of ependymoma. These implants were caudal to the level of radiation therapy. H e was treated with steroids and further radiation therapy. His symptoms improved, and a repeat myelogram showed regression of the lesions. The steroids were gradually tapered. Six months later he was readmitted to the hospital with increasing unsteadiness, head and neck pain, and nausea. Physical examination revealed marked meningismus; nystagmus on left lateral gaze was noted. Computerized tomography performed at the time of admission (Fig 1) revealed diffuse contrast enhancement throughout the basal cisterns, surrounding the brainstem and extending into the sylvian and interhemispheric fissures; no midline structures were displaced. The appearance was thought to reflect subarachnoid spread of tumor. Cytological examination of the spinal fluid obtained by a Iateral cervical puncture at C1-2 showed class IV malignant small cells, confirming the diagnosis. He received additional radiation therapy to the brain and was started on steroid therapy. As the treatment progressed, his headaches, neck pain, and nystagmus resolved. A repeat scan performed two weeks into this admission (Fig 2) showed no evidence of contrast enhancement in the basal cisterns or in the sylvian or interhemispheric fissures.
Discussion T h e diagnosis of subarachnoid spread of ependymoma, particularly to the basal cisterns, can be difficult since such spread may be clinically silent. This information, however, may affect the planning of radiation therapy. The presence of tumor cells in the cerebrospinal fluid may be an equivocal finding and does not yield definite information o n the location or even the presence of such metastatic deposits. Myelography is helpful in defining the limits of spread to the spinal subarachnoid space. Angiography is useful in assessing extraaxial growth of ependymomas, though this modality depends on mass effect causing vascular displacement. The present case illustrates the ability of computerized tomography not only to detect and localize subarachnoid spread of ependymoma but also to evaluate the effect of therapy. Though steroids alone have been shown to cause a mild decrease in tumor enhancement with contrast material [2], in none of the reported cases was the lesion rendered undetectable, or even apparently de-
538 0364-5134/79/120538-02$01.25 @ 1978 by Robert B. Geehr
larly important in patients who have not yet become symptomatic from these implants. We suggest that both noncontrast and contrast-enhanced computerized tomographic scans be performed at routine intervals in patients with ependymomas, particularly those of the posterior fossa, with special attention paid to the basal cisterns. References
. ....
F i g I . C T scan perfarmed after intravenous injection of a contrast agent, demonstrating marked enhancement throughout the basal cisterns, surrounding the brainstem, and i n the interhemispheric and sylvian fissures.
1. Barone BM, Elvidge AR: Ependymomas. A clinical survey. J Neurosurg 33:428-438, 1970 2. Crocker EF, Zimmerman RA, Phelps ME, et al: The effect of steroids on the extravascular distribution of radiographic contrast material and technetium pertechnetate in brain tumors as determined by computed tomography. Radiology 119:47 1474, 1976 3. Dohrmann GJ, Farwell JR, Flannery JT: Ependymomas and ependymoblastomas in children. J Neurosurg 45:273-283, 1976 4. Enzmann DR, Norman D, Levin V, et al: Computed tomography in the follow-up of medulloblastomas and ependymomas. Radiology 128:5 7-63, 1978 5. Phillips TL, Sheline GE, Boldrey E: Therapeutic considerations in tumors affecting the central nervous system: ependymomas. Radiology 8398-105, 1964 6. Svien HJ, Gates EM, Kernohan JW: Spinal subarachnoid implantation associated with ependymoma. Arch Neurol Psychiatry 62:847-856, 1949 7 . Tarlov IM, Davidoff LM: Subarachnoid and ventricular implants in ependymal and other gliomas. J Neuropathol Exp Neurol 5:213-224, 1946
F i g 2. Contrast-enhanced C T scan performed two weeks after therapy reveals no enhancement of the basal cisterns or of the interhemispheric or sylvian fissures.
creased in size, after steroid treatment. Therefore, we think that our inability to demonstrate enhancing tumor on CT scan after therapy was due to the effect of both radiation and the steroids. The patient’s clinical improvement certainly indicated that the therapy was successful. Computerized tomography is a useful method of diagnosing the spread of ependymomas into the intracranial subarachnoid space, and the information helps in the planning of therapy [4].This is particu-
Case Report: Geehr et al: Computed Tomography in Ependymoma
539
Subarachnoid Spread of Ependymoma: Diagnosis and Evaluation of Therapy by Computerized Tomography Robert B. Geehr, MD, George J. Dohrmann, MD, PhD, Stephen L. G. Rothman, MD, E. Leon Kier, MD, Franklin C. Wagner, MD, and Daniel S. Kapp, M D
The potential of ependymomas to spread throughout the intracranial subarachnoid space is well documented, though the incidence is disputed. This relates i n part to the time required for such metastases to produce symptoms. The diagnosis of such spread, however, is important for therapeutic management. This report demonstrates the effectiveness of computerized tomography in diagnosing spread of ependymoma throughout the basal cisterns and cerebral fissures. Geehr RB, Dohrmann GJ, Rothman SLG, et al: Subarachnoid spread of ependymoma: diagnosis and evaluation of therapy by computerized tomography. Ann Neurol 6:538-539, 1979
The ability of intracranial ependymomas, particularly those of the fourth ventricle, to disseminate throughout the basal cisterns and spinal subarachnoid space has been well documented, though the incidence of such tumor spread is in dispute [ 1, 71. This undoubtedly relates to the difficulty in making the diagnosis of intracranial tumor implantation antemortem, as few patients with subarachnoid spread of ependymomas have related symptoms [6]. Since radiation therapy of ependymomas [3, 51 is planned in part around the potential spread of tumor, this uncertainty takes on added importance. A 35-year-old left-handed man underwent suboccipital craniectomy for removal of an ependymoma of the fourth ventricle that extended through the vallecula to the posterior arch of C1. At the conclusion of the operation it was thought that all gross tumor had been excised with the exception of a small plaque firmly attached to the floor of the fourth ventricle. computerized tomography performed From the Section of Neuroradiology, Department of Diagnostic Radiology, the Secrion of Neurosurgery, Department of Surgery, and the Department of Therapeutic Radiology, Yale University School of Medicine. New Haven, CT, and the Division of Neurosurgery, University of Chicago Medical Center, Chicago, IL. Accepted for public-ation June 26, 1978. Address reprint requests to Dr Geehr, Department of Diagnostic Radiology, Yale University School of Medicine, 333 Cedar St, New Haven. CT 06510.
at this time demonstrated the midline tumor extending into the cisterna magna, though the remaining basal cisterns remained normal. The patient received radiation therapy to the posterior fossa and upper cervical spinal cord postoperatively. He returned one year later with a two-week history of increasing numbness and weakness of both lower extremities. A CT scan revealed postoperative changes in the posterior fossa, normal ventricle size, a ventricular shunt in place, and normal basal cisterns. A myelogram demonstrated multiple intradural, extramedullary masses throughout the thoracic and lumbar region, consistent with subarachnoid seeding of ependymoma. These implants were caudal to the level of radiation therapy. H e was treated with steroids and further radiation therapy. His symptoms improved, and a repeat myelogram showed regression of the lesions. The steroids were gradually tapered. Six months later he was readmitted to the hospital with increasing unsteadiness, head and neck pain, and nausea. Physical examination revealed marked meningismus; nystagmus on left lateral gaze was noted. Computerized tomography performed at the time of admission (Fig 1) revealed diffuse contrast enhancement throughout the basal cisterns, surrounding the brainstem and extending into the sylvian and interhemispheric fissures; no midline structures were displaced. The appearance was thought to reflect subarachnoid spread of tumor. Cytological examination of the spinal fluid obtained by a Iateral cervical puncture at C1-2 showed class IV malignant small cells, confirming the diagnosis. He received additional radiation therapy to the brain and was started on steroid therapy. As the treatment progressed, his headaches, neck pain, and nystagmus resolved. A repeat scan performed two weeks into this admission (Fig 2) showed no evidence of contrast enhancement in the basal cisterns or in the sylvian or interhemispheric fissures.
Discussion T h e diagnosis of subarachnoid spread of ependymoma, particularly to the basal cisterns, can be difficult since such spread may be clinically silent. This information, however, may affect the planning of radiation therapy. The presence of tumor cells in the cerebrospinal fluid may be an equivocal finding and does not yield definite information o n the location or even the presence of such metastatic deposits. Myelography is helpful in defining the limits of spread to the spinal subarachnoid space. Angiography is useful in assessing extraaxial growth of ependymomas, though this modality depends on mass effect causing vascular displacement. The present case illustrates the ability of computerized tomography not only to detect and localize subarachnoid spread of ependymoma but also to evaluate the effect of therapy. Though steroids alone have been shown to cause a mild decrease in tumor enhancement with contrast material [2], in none of the reported cases was the lesion rendered undetectable, or even apparently de-
538 0364-5134/79/120538-02$01.25 @ 1978 by Robert B. Geehr
larly important in patients who have not yet become symptomatic from these implants. We suggest that both noncontrast and contrast-enhanced computerized tomographic scans be performed at routine intervals in patients with ependymomas, particularly those of the posterior fossa, with special attention paid to the basal cisterns. References
. ....
F i g I . C T scan perfarmed after intravenous injection of a contrast agent, demonstrating marked enhancement throughout the basal cisterns, surrounding the brainstem, and i n the interhemispheric and sylvian fissures.
1. Barone BM, Elvidge AR: Ependymomas. A clinical survey. J Neurosurg 33:428-438, 1970 2. Crocker EF, Zimmerman RA, Phelps ME, et al: The effect of steroids on the extravascular distribution of radiographic contrast material and technetium pertechnetate in brain tumors as determined by computed tomography. Radiology 119:47 1474, 1976 3. Dohrmann GJ, Farwell JR, Flannery JT: Ependymomas and ependymoblastomas in children. J Neurosurg 45:273-283, 1976 4. Enzmann DR, Norman D, Levin V, et al: Computed tomography in the follow-up of medulloblastomas and ependymomas. Radiology 128:5 7-63, 1978 5. Phillips TL, Sheline GE, Boldrey E: Therapeutic considerations in tumors affecting the central nervous system: ependymomas. Radiology 8398-105, 1964 6. Svien HJ, Gates EM, Kernohan JW: Spinal subarachnoid implantation associated with ependymoma. Arch Neurol Psychiatry 62:847-856, 1949 7 . Tarlov IM, Davidoff LM: Subarachnoid and ventricular implants in ependymal and other gliomas. J Neuropathol Exp Neurol 5:213-224, 1946
F i g 2. Contrast-enhanced C T scan performed two weeks after therapy reveals no enhancement of the basal cisterns or of the interhemispheric or sylvian fissures.
creased in size, after steroid treatment. Therefore, we think that our inability to demonstrate enhancing tumor on CT scan after therapy was due to the effect of both radiation and the steroids. The patient’s clinical improvement certainly indicated that the therapy was successful. Computerized tomography is a useful method of diagnosing the spread of ependymomas into the intracranial subarachnoid space, and the information helps in the planning of therapy [4].This is particu-
Case Report: Geehr et al: Computed Tomography in Ependymoma
539
