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Background Central nervous system neoplasms are the most common solid tumors in children, and more than 40% are low-grade gliomas. Variable locations, extent of resection, postoperative neurodiagnostic evaluation, and histology have confounded therapy and outcome. Objectives To investigate disease control and survival after surgery. Methods A prospective natural history trial from 1991 to 1996 produced a subset of patients with low-grade gliomas managed by primary surgery and subsequent observation. Patients were evaluable if eligibility, tumor location, and extent of resection were confirmed by pathological diagnosis, preoperative and postoperative imaging, and the surgeon's report. Primary end points were overall survival (OS), progression-free survival (PFS), and postprogression survival. Results Of 726 patients enrolled, 518 were fully evaluable for analysis. The 5- and 8-year OS rates were 97% ± 0.8% and 96% ± 0.9%, respectively, and PFS rates were 80% ± 1.8% and 78% ± 2.0%. In univariate analyses, histological type, extent of residual tumor, and disease site were significantly associated with PFS and OS. In multivariate analysis, gross total resection (GTR) without residual disease was the predominant predictor of PFS. In patients with limited residual disease, 56% were free of progression at 5 years. Conclusion GTR should be the goal when it can be achieved with an acceptable functional outcome. The variable rate of progression after incomplete resection highlights the need for new predictors of tumor behavior.

OBJECTIVE AND IMPORTANCE Hypertrophic neuropathy of the cauda equina (HNCE) is a rare form of peripheral neuropathy. The diagnosis is complicated by an insidious clinical presentation and complex radiographic images. We present a case of HNCE caused by chronic inflammatory demyelinating polyneuropathy with symptomatic improvement after decompressive lumbar laminectomy and dural expansion. CLINICAL PRESENTATION A 54-year-old woman with a history of back pain since she was in her 20s presented with low back and radicular pain that had increased during a period of 6 months, bilateral lower-extremity weakness, and sensory loss in the right thigh. Magnetic resonance imaging of the lumbosacral spine revealed multiple, poorly enhancing mass lesions and apparent intrathecal nerve root thickening from L1 to L5. INTERVENTION An L1-L5 decompressive laminectomy, performed with continuous somatosensory evoked potential and electromyographic monitoring, revealed multiple segmentally enlarged nerve roots. One nerve root that did not respond to high levels of stimulation was identified. This root was resected and submitted for pathological analysis. The dura was expanded with an 11-cm-long dural patch. The pathological examination revealed hypertrophic neuropathy, with extensive S-100-positive “onion bulb” formation. The patient's symptoms improved postoperatively. CONCLUSION HNCE is a rare disorder that can cause radicular pain and lower-extremity weakness, sensory loss, and hyporeflexia. One possible cause is demyelinating polyneuropathy. Although medical management is typically effective in the treatment of demyelinating polyneuropathy, it has little effect on compressive symptoms caused by intradural nerve root enlargement. As this case demonstrates, surgical management of symptomatic radiculopathy by lumbar laminectomy is a reasonable and effective approach to the treatment of HNCE.

OBJECTIVE: Pilocytic astrocytoma (PA) is a common type of pediatric brain tumor that can arise within the hypothalamic/chiasmatic region and typically has an excellent outcome. We identified a group of tumors, previously classified as PAs, with unique histological features and aggressive behavior. This article describes the clinicopathological features of these unusual neoplasms, which are currently known as pilomyxoid astrocytomas (PMAs), to better differentiate them from typical PAs. METHODS: Medical information and surgical specimens were obtained for 42 PA cases and 21 PMA cases. Patient demographic features, treatment modalities, progression-free servival (PFS) times, times, overall survival (OS) times, and outcomes were compared between the groups with nonparametric tests. RESULTS: The PMA group included 12 male and 9 femule patients. The PA group included 27 male and 15 female patients. The mean ages at diagnosis for the PMA and PA groups were 18 months (range, 2-84 mo) and 58 months (range, 4-189 mo), respectively (P < 0.01). The mean PFS times for the PMA and PA groups were 26 and 147 months, respectively (P < 0.001). The mean OS times for the PMA and PA groups were 63 and 213 months, respectively (P < 0.001). Sixteen patients with PMAs (76%) experienced local recurrence, and three of those patients demonstrated evidence of cerebrospinal fluid dissemination, Twenty-one patients with PAs (50%) experienced local recurrence, none with evidence of cerebrospinal fluid dissemination. Within the follow up period, seven patient with PMAs (33%) and seven patients with PAs (17%) died as a result of their disease. In an age-matched set, the mean PFS times for the PMA and PA groups were 25 and 163 months. respectively (P < 0.01), and the mean OS times for the PMA and PA groups were 60 and 233 month, respectively (P < 0.001). CONCLUSION: Hypothalamic/chiasmatic PMAs occurred in a significantly younger population and were associated with substantially shorter PFS and OS times than were typical PAs. Increased recognition of these lesions could affect the prognosis and treatment of pediatric astrocytomas.

OBJECTIVE AND IMPORTANCE Melanocytic colonization of nonpigmented extracranial tumors has been reported in adenocarcinomas, squamous cell carcinomas, skin appendage tumors, and dermatofibrosarcoma protuberans. To our knowledge, melanocytic colonization of a meningioma has not previously been described. CLINICAL PRESENTATION We report an unusual case of a 70-year-old African-American woman who presented with a large frontoparietal meningioma that extended through the calvarium. INTERVENTION Craniotomy with gross total resection of the tumor was performed. Histochemistry, immunocytochemistry, ultrastructural analysis, and molecular genetic study via fluorescence in situ hybridization confirmed melanocytic colonization of a meningothelial meningioma. CONCLUSION With the inclusion of meningothelial meningioma, the spectrum of tumors affected by melanocytic colonization continues to expand.

OBJECTIVE The objective of the Brain Tumor Cooperative Group NIH Trial 87-01 trial was to investigate the effect of additional implanted radiation therapy in newly diagnosed patients with pathologically confirmed malignant gliomas.METHODS The study involved a randomized comparison of surgery, extern

OBJECTIVE: The clinicopathological spectra of a dysembryoplastic neuroepithelial tumor (DNT) and a rosette-forming glioneuronal tumor (RGNT) are expanding. We report here the autopsy findings of a case of complex glioneuronal tumor with combined histological features of both a DNT and an RGNT. CLINICAL PRESENTATION: A 79-year-old man presented with a 1-month history of confusion and gait difficulties. A magnetic resonance imaging scan revealed obstructive hydrocephalus attributed to a mass in the posterior third ventricle. INTERVENTION: A third ventriculostomy was performed. Postoperatively, the mass remained unchanged in size for more than 14 months. Thirty-eight months after his initial manifestations, he experienced minor head trauma and was then hospitalized. Despite placement of an external ventricular drain and other supportive treatment, he deteriorated and died. A full autopsy was performed, with emphasis on the brain. The mass lesion and a few independent microfoci situated primarily around the third ventricle showed histological features of pilocytic astrocytoma with recurrent hemorrhage. Far more numerous were microfoci with histological features of a DNT, including floating neurons, as well as typical RGNT-associated, synaptophysin-positive rosettes and perivascular pseudorosettes. CONCLUSION: The advanced age of the patient, the coexisting histological features of the DNT and RGNT, and the distinctive anatomic distribution of the lesions, being centered on the third ventricle, may lend insight into the histogenetic relationship of a DNT, an RGNT, and mixed glioneuronal tumors.

Objective and importance We report a case of a well-differentiated papillary adenocarcinoma arising in an supratentorial enterogenous cyst. The clinicopathological features of this case and a brief review of the literature are presented. Clinical presentation A 45-year-old woman presented with abrupt onset of sensory seizures and abnormal sensation on the left side of her face, left leg, and left arm. Radiological studies showed a cystic extraaxial tumor with mass effect in the right parietal area. The initial clinical impression was a metastatic lesion, and a comprehensive metastatic workup revealed no evidence of tumor elsewhere. Intervention A gross total resection of the solid cystic tumor was achieved by a frontoparietal craniotomy. Sixteen months after the initial surgery, the patient presented with signs of increased intracranial pressure and a large parietal cyst. The cyst was fenestrated at the time of the second craniotomy. Conclusion A pathological study of the initial surgical material revealed it to be a well-differentiated papillary adenocarcinoma in association with an enterogenous cyst. The second surgical specimen consisted only of the benign cyst wall. The patient recovered uneventfully from the second surgery and was free of symptoms 6 months postoperatively. The importance of recognizing the rare possibility of malignant progression of a benign enterogenous cyst in the central nervous system is discussed.

Three cases of adult patients with subacute courses of progressive caudal spinal cord disease are presented. Computed tomography, magnetic resonance imaging, and myelographic studies were interpreted preoperatively as representing a spinal cord neoplasm in each case. No evidence of enlarged or abnormal surface vessels was observed by neuroimaging or intraoperatively. Biopsy specimens from each spinal cord lesion showed the typical histopathological features of a spinal vascular malformation. We conclude that vascular malformations of the caudal spinal cord can appear as isolated intramedullary lesions with apparently normal surface vessels and that these lesions may be difficult to distinguish from spinal cord neoplasms.

Desmoplastic infantile gangliogliomas are massive cystic tumors, typically occurring in the cerebral hemispheres of infants. They are remarkable pathologically for a prominent desmoplasia and, in some cases, for a cellular mitotically active component that can be readily interpreted as a malignant neoplasm. Four children less than 1 year of age were diagnosed with desmoplastic infantile gangliogliomas in the Pediatric Oncology Group infant brain tumor study (Protocol number 8633). All had been diagnosed by their respective institutions as having malignant tumors, i.e., Grade III astrocytoma, malignant meningioma, leptomeningeal fibrosarcoma, and gliosarcoma. All had increased intracranial pressure, and two had seizures. The tumors were extremely large, with one measuring 12 x 9 x 9 cm. None had evidence of metastatic disease. One patient had a gross total resection, and the other three had debulking procedures. All four children were treated with chemotherapy (cyclophosphamide, vincristine, cisplatinum, etoposide) for periods ranging from 12 to 24 months. Of those with postoperative measurable disease, one child had a complete response, one a partial response, and one had stable disease at the conclusion of chemotherapy. No child received radiation therapy. All children are alive with progression-free survivals after diagnosis of more than 36, 42, 48, and 60 months, respectively. Although desmoplastic infantile gangliomas are rare, recognition of this tumor type is essential because, despite their massive size and pathologically malignant appearance, they may have a relatively benign clinical course. If total surgical resection can be achieved, further therapy may not be indicated. In those patients in whom residual disease is present, chemotherapy appears to be an effective form of therapy.(ABSTRACT TRUNCATED AT 250 WORDS)

A 28-year-old woman with prior neurosurgery involving the placement of a cadaveric dural graft developed a rapidly progressive neurodegenerative disorder with prominent cerebellar dysfunction that was proven at autopsy to be Creutzfeldt-Jakob disease. She represents the second American to develop Creutzfeldt-Jakob disease in association with a dural graft. The unusual features of the case include the patient's initial clinical presentation with cerebellar ataxia in the absence of dementia, the widespread presence of kuru-type amyloid plaques on a histological examination of the brain, the development of clinical symptoms during pregnancy, and the subsequent delivery of a child who remains healthy at the age of 3 years.

OBJECTIVE: It remains unknown whether the extent of surgical resection affects survival or disease progression in patients with supratentorial low-grade gliomas. METHODS: We conducted a retrospective cohort study (n = 170) between 1996 and 2007 at a single institution to determine whether increasing extent of surgical resection was associated with improved progression-free survival (PFS) and overall survival (OS). Surgical resection of gliomas defined as gross total resection (GTR) (complete resection of the preoperative fluid-attenuated inversion recovery signal abnormality), near total resection (NTR) (

Objective and importance Neurocytomas are uncommon tumors of the CNS. To date, none have been described in association with a cranial nerve. We described the clinicopathological features of an example arising in the cochlear-vestibular portion of the VIIIth nerve with extension into the cerebellopontine angle. Clinical presentation The patient, a 42-year-old female, presented approximately 6 months ago with several episodes of worsening dizziness. On magnetic resonance imaging studies, a 2-cm enhancing lesion occupying the left internal auditory canal and protruding into the cerebellopontine angle cistern was detected with signal characteristics suggestive of vestibular neuroma. Intervention At surgery, the tumor was seen to originate from the cochlear-vestibular nerve bundle lying within the internal auditory canal, extended laterally to the level of the fundus and 4 mm medially into the cerebellopontine angle. No dural attachment was noted. With use of sharp dissection and bipolar cautery, portions of the tumor within the auditory canal were debulked. Conclusion A unique example of a neurocytoma in association with a cranial nerve is documented. Possible explanations for the occurrence are explored. The topography of neurocytomas continues to expand.

OBJECTIVE AND IMPORTANCE: Silent somatotrophinomas are very rare, typically large pituitary adenomas that present with mild or no acromegalic features despite positive immunostaining for growth hormone and autonomous (nonglucose-suppressible) growth hormone secretion. Because of this, they may be amenable to treatment with somatostatin analogues. CLINICAL PRESENTATION: We report a giant somatotrophinoma (7 cm in maximal diameter) in a young woman with 6 years of amenorrhea who had no clinical features of acromegaly despite frankly elevated serum insulin-like growth factor 1 level at the time of diagnosis. Immunohistochemistry revealed focal strong positive staining for growth hormone in only 10% of the surgical specimen. Mutations in exons 8 or 9 of GNAS1, which are present in 40% of somatotrophinomas, were absent in the surgical specimen. The patient's clinical, biochemical, and radiological presentation is described and is compared with previously reported cases of silent somatotrophinomas. INTERVENTION: ABecause of the size and visual symptomatology, partial resection was performed via a transcranial approach. External adjuvant beam radiotherapy was used. As insulin-like growth factor 1 levels remained elevated, treatment with somatostatin analogue is being pursued. CONCLUSION: This case represents one of the largest somatotrophinomas described to date, and it demonstrates that serum insulin-like growth factor 1 should be measured even in the absence of acromegalic features in patients presenting with apparently nonsecreting macroadenomas. In addition to surgery and radiotherapy, somatostatin analogues may play an important role in controlling tumor growth.

OBJECTIVE: L-buthionine sulfoximine (BSO) inhibits glutathione synthesis and may modulate tumor resistance to some alkylating agents, but it has not been proven effective in the treatment of intracranial neoplasms. To evaluate this drug for the treatment of brain tumors, we studied the use of BSO for potentiating the antineoplastic effect of 4-hydroxyperoxycyclophosphamide (4-HC) in the rat 9L glioma model. METHODS: The survival of male Fischer 344 rats with intracranial 9L gliomas was measured after implantation of controlled-release polymers containing one of the following: no drug, BSO, 4-HC, or both BSO and 4-HC. The efficacy of intracranial 4-HC treatment was assessed with and without serial systemic intraperitoneal BSO injections. Tissue glutathione levels were measured in the brains, tumors, and livers of animals treated with intraperitoneal injections or local delivery of BSO. RESULTS: The median survival of animals treated with intracranial polymers containing 4-HC was 2.3 times greater than that of controls. This survival benefit was doubled by local delivery of BSO. In contrast, systemic BSO therapy did not improve survival time. In animals that were treated systemically, both liver and tumor glutathione levels were significantly lower than they were in control animals. In the locally treated animals, glutathione levels were reduced in the brain tumor but not in the liver. CONCLUSION: These results demonstrate that local but not systemic delivery of BSO enhances the antineoplastic effect of 4-HC in this rat 9L glioma model. In addition, because local delivery of BSO within the brain did not deplete glutathione levels systemically, this method of treatment may be safer than systemic administration of BSO.

OBJECTIVE: Spinal cord hamartomas are a rare occurrence characterized by well-differentiated mature elements located in an irregular position in the spinal cord. CLINICAL PRESENTATION: The authors present the unique case of a 12-year-old boy who originally presented to our center for treatment of a right thalamic astrocytoma. One year after his initial presentation, the child developed progressive bilateral leg weakness with decreased sensation. Spinal magnetic resonance imaging performed at this time revealed an intramedullary spinal cord lesion from T4 to T8, which was later found to be composed of hamartomatous tissue. INTERVENTION: The patient underwent bilateral T4 to T8 laminectomies with subtotal resection of the hamartomatous lesion, and his symptoms improved postoperatively. CONCLUSION: Although typically described in the literature as spinal cord hamartomas because of their histological composition, these rare hamartomatous lesions may be the result of a neurulation defect rather than true hamartomas. In patients presenting with multiple neurological conditions, as in our case, diagnosis may be more complex. For those presenting with neurological signs and symptoms, surgical treatment is essential.

In an effort to improve survival from malignant gliomas, investigators have used intratumoral chemotherapy protocols to deliver high doses of tumoricidal agents directly to the brain. Theoretically, these infusions bypass the blood-brain barrier, minimize systemic drug levels and the side effects of chemotherapy, and achieve prolonged elevations of intracerebral chemotherapeutic agents relative to those obtainable by systemic administration. Almost all major classes of chemotherapeutic agents have been examined as possible intratumoral therapies via delivery approaches ranging from simple intratumoral injections to implantable computer-driven constant infusion pumps and biodegradable polymer matrices. In this review, we summarize the major clinical trials and experimental investigations underlying the development of intratumoral chemotherapy as a treatment for gliomas.

Histological grading of fibrillary astrocytic neoplasms has proved to be a valuable prognostic tool, but potentially could benefit from more objective data, such as estimates of proliferative rate. The authors have investigated the prognostic utility of quantitative Ki-67 immunoreactivity in a prospective survival analysis of 36 adult patients with astrocytoma, anaplastic astrocytoma, or glioblastoma multiforme diagnosed between 1987 and 1992. A digital image analyzer was used to assay proliferation indices (PIs) in surgical biopsy specimens obtained at first diagnosis (32 of 36) or at a second biopsy of histologically unchanged high-grade disease (4 of 36). A Ki-67 PI ofor = 7.5% was associated with higher histological grade and poorer survival, and the Ki-67 PI was more significantly related to survival (P0.001) than histological grade as determined by a modified Ringertz grading system (P = 0.002). Survival analysis within histological grades suggested that astrocytoma patients with PIor = 3% may be at increased risk for shorter survival than those with PI3%.

Twelve children with pathologically confirmed, well-differentiated spinal cord astrocytomas were studied, and correlations among the degree of resection, pathological characteristics, and time of recurrence were examined. Eight tumors were sampled for biopsy or subtotally resected, and 4 were thought to have been totally removed. Clinical recurrence was seen in 4 of 12 patients, 2 of whom died of their disease. The time to recurrence was 1, 2, 2, and 35 years, respectively. The other 8 children remain free of symptoms, with follow-up ranging from 6 months to 35 years (mean, 8.8 years). In 3 of 8 patients who underwent biopsy or subtotal resection, the tumor recurred, and 2 patients died, whereas there was one recurrence in the patients in whom a “total” resection had been obtained. The histologically well-differentiated nature of the lesions correlated well with the relatively prolonged clinical course seen in this series during the period of observation. The relatively long clinical courses seen in our limited series should be considered before high-risk therapy for spinal cord astrocytomas in children is implemented. The presence of four pilocytic astrocytomas in this group was of special interest, and it seems likely that these discrete neoplasms can be distinguished from the more infiltrating fibrillary astrocytic neoplasms by magnetic resonance imaging with enhancement with gadopentetate dimeglumine.

OBJECTIVE: Isolated amyloidomas rarely manifest in nervous system tissues. To the authors knowledge, there have been 52 documented cases of primary amyloid tumors of the central nervous system and closely associated structures. The authors present a case of a woman with a history of presumptive trigeminal neuralgia who was found to have an amyloidoma of the trigeminal ganglion. CLINICAL PRESENTATION: A 32-year-old Caucasian patient presented with a chief complaint of severe numbness and pain throughout the right side of her face. Her symptoms had been progressive over the previous 3 years. Medical management of her presumptive diseases with Zotoft (Pfizer Inc., New York, NY) and Neurontin (Pfizer Inc.) failed to improve or halt her right facial numbness and pain. Brain magnetic resonance imaging was acquired, demonstrating abnormal contrast enhancement and enlargement of the right trigeminal ganglion. The lesion abutted and indented the right internal carotid artery and extended from Meckel's cave into the inferior cavernous sinus and distally to the foramen ovale. INTERVENTION: The patient underwent a right frontotemporal craniotomy for resection of the gasserian ganglion lesion. A delicate incision was made in the wall of the cavernous sinus, allowing confirmatory biopsy of the lesion. With the site of the tumor within the cavernous sinus verified by pathology, the remainder of the tumor was removed. A final pathological review of the resected tumor confirmed a diagnosis of amyloidoma of the trigeminal ganglion. CONCLUSION: We present the case of a patient with a rare trigeminal ganglion amyloidoma that closely mimicked idiopathic trigeminal neuralgia. Even in the absence of systemic signs of amyloidosis, this benign protein deposition disease should be considered in the differential for atypical dysesthesias of the trigeminal dermatomes. Furthermore, central and peripheral nervous system amyloidomas respond well to surgical resection and rarely recur.

Objective Ependymomas of the conus medullaris-cauda equina-filum terminale region are typically solitary lesions. In this report, we describe the clinical presentation, radiographic findings, operative details, and pathological features of a patient with a conus medullaris ependymoma and a filum terminale lipoma. Clinical presentation A 40-year-old woman presented with increasing low back pain and bowel and bladder dysfunction. Magnetic resonance imaging revealed a partially cystic enhancing lesion at the conus medullaris and a T1-weighted hyperintense mass within the filum terminale. Intervention An L2-L3 laminotomy/laminoplasty was performed for gross total resection of the mass. Histopathological examination demonstrated a conus medullaris ependymoma and filum terminale lipoma. The patient experienced complete resolution of her preoperative symptoms. Conclusion Spinal cord ependymomas are almost exclusively single lesions and their coexistence with other pathological entities is rare. In this report, we describe a patient with a concomitant conus medullaris ependymoma and filum terminale lipoma.

A case of glioblastoma multiforme that occurred 14 years after radiotherapy for acromegaly is presented. The striking correspondence between the anatomy of the tumor and the geometry of the radiation ports is suggestive of a causal relationship. Previously reported cases of radiation-associated glioma are reviewed, and a brief appraisal of the evidence for induction of these lesions by radiation is presented. The differentiation of radiation-associated neoplasms from radionecrosis is also discussed.

Ollier's disease or multiple enchondromatosis is a deforming dysplastic disease of cartilage involving primarily the metaphyses and diaphyses of long bones. It is only rarely associated with sarcomatous degeneration of the enchondromas or other generalized neoplasms. A related disease, Maffucci's syndrome, is, however, associated with generalized tumors. We present the case of a 29-year-old, albino, black man with Ollier's disease who, as a child, underwent a number of orthopedic procedures for multiple limb deformities and fractures. At age 25, he developed hydrocephalus, progressive cranial nerve palsies, and a large enchondroma of the skull base. He subsequently underwent multiple shunt procedures and two suboccipital craniectomies. Eighteen months later, a brain computed tomographic (CT) scan revealed an intracerebellar mass, which was found to be an anaplastic astrocytoma. Two years later, he developed a right hemiparesis and sensory dysfunction with a diffuse supratentorial mass on CT scan. A stereotactic biopsy showed this to be a similar anaplastic astrocytoma. The literature concerning Ollier's disease is reviewed, and the intracerebral lesions associated with both Ollier's disease and Maffucci's syndrome are examined.

Adipose tissue in the filum terminale is frequently associated with tethering of the spinal cord in patients with spina bifida occulta. We recently saw a patient with low back pain and no spina bifida occulta, in whom adipose tissue was noted in the area of the filum on an unenhanced computed tomographic (CT) scan. The patient had a tethered cord. This case suggested that, when CT scanning is done as the first imaging study in the evaluation of low back pain, fatty tissue in the area of the filum may be an indicator for tethering of the spinal cord. The present study was undertaken to determine the validity of using CT scan-detectable filal fat in the identification of possible tethered spinal cords among a group of patients experiencing low back pain. The presence of fat in the fila of 12 patients with the radiologically and histologically tethered cord syndrome was evaluated and the fila of 47 autopsied patients whose clinical history showed no back pain were examined histologically. There were accumulations of adipose tissue in the fila of 11 of the 12 (91%) patients with the tethered cord syndrome and in the fila of 9 of the 47 patients (17%) in the autopsy series. Of the 9 autopsy patients with fat in their fila, however only 3 patients (6%) exhibited collections of adipose tissue in the CT detection range (2 mm).(ABSTRACT TRUNCATED AT 250 WORDS)

Initial experience using the Gildenberg technique for computed tomography-guided stereotactic biopsies is reviewed. Of 50 patients, adequate tissue was obtained in 49. In one patient, the stereotactic frame was unable to reach the selected biopsy site. In 32 of 49 patients, the diagnosis was obtained with one biopsy: in the remainder, two to five samples were required. In 4 cases, a subsequent craniotomy was performed: these provided similar histopathological tissue and in no case was the diagnosis altered. The lesions were categorized by CT as ring-enhancing lesions (REL), enhancing lesions with surrounding low density (ELLD), and low density lesions with and without peripheral areas of enhancement. Of the REL, 21 of 23 were primary tumors. Of the ELLD, 5 of 13 were primary tumors: the remainder had a wide spectrum of disease. Of the low density lesions without enhancement, 6 were primary tumors and 1 was an inflammatory process. Three patients had low density lesions with peripheral areas of enhancement and proved to have malignant primary tumors. The remaining patients had multiple lesions with both primary and metastatic disease. Twelve RELs were biopsied in multiple sites. An accurate diagnosis was best obtained by performing the first biopsy in the enhancing rim with additional biopsies as needed in the low density center. Homogeneous lesions could be biospied with target selection based upon a primary regard for safety rather than imaging characteristics. Three patients had transiently increased hemiparesis and one had a transient decrease in level of consciousness after biopsy. There were no patients with long-term morbidity in this series. From our experience, we believe this technique offers a safe, accurate, and relatively inexpensive alternative for performing-CT-guided intracranial biopsies.

Adipose tissue in the filum terminale is frequently associated with tethering of the spinal cord in patients with spina bifida occulta (3, 8). We recently saw a patient with low back pain and no spina bifida occulta, in whom adipose tissue was noted in the area of the filum on an unenhanced computed tomographic (CT) scan. The patient had a tethered cord. This case suggested that, when CT scanning is done as the first imaging study in the evaluation of low back pain, fatty tissue in the area of the filum may be an indicator for tethering of the spinal cord. The present study was undertaken to determine the validity of using CT scan-detectable filal fat in the identification of possible tethered spinal cords among a group of patients experiencing low back pain. The presence of fat in the fila of 12 patients with the radiologically and histologically tethered cord syndrome was evaluated and the fila of 47 autopsied patients whose clinical history showed no back pain were examined histologically. There were accumulations of adipose tissue in the fila of 11 of the 12 (91%) patients with the tethered cord syndrome and in the fila of 9 of the 47 patients (17%) in the autopsy series. Of the 9 autopsy patients with fat in their fila, however only 3 patients (6%) exhibited collections of adipose tissue in the CT detection range (2 mm). These results demonstrate that, although CT scan-detectable adipose tissue can be found in the filum of an occasional patient without tethered cord, CT detectable fat in the filum of a patient with low back pain should prompt an evaluation for a tethered spinal cord. CT scanning has potential as a noninvasive tool in such a work-up.