Quantification and pharmacokinetics of blood-brain barrier disruption in humans

Hyperosmolar blood-brain barrier disruption (HBBBD), produced by infusion of mannitol into the cerebral arteries, has been used in the treatment of brain tumors to increase drug delivery to tumor and adjacent brain. However, the efficacy of HBBBD in brain tumor therapy has been controversial. The goal of this study was to measure changes in vascular permeability after HBBBD in patients with malignant brain tumors. The permeability (K1) of tumor and normal brain blood vessels was measured using rubidium-82 and positron emission tomography before and repeatedly at 8- to 15-minute intervals after HBBBD. Eighteen studies were performed in 13 patients, eight with glioblastoma multiforme and five with anaplastic astrocytoma. The HBBBD increased K1 in all patients. Baseline K1 values were 2.1 +/- 1.4 and 34.1 +/- 22.1 microl/minute/ml (+/- standard deviation) for brain and tumor, respectively. The peak absolute increases in K1 following HBBBD were 20.8 +/- 11.7 and 19.7 +/- 10.7 microl/minute/ml for brain and tumor, corresponding to percentage increases of approximately 1000% in brain and approximately 60% in tumor. The halftimes for return of K1 to near baseline for brain and tumor were 8.1 +/- 3.8 and 4.2 +/- 1.2 minutes, respectively. Simulations of the effects of HBBBD made using a very simple model with intraarterial methotrexate, which is exemplary of drugs with low permeability, indicate that 1) total exposure of the brain and tumor to methotrexate, as measured by the methotrexate concentration-time integral (or area under the curve), would increase with decreasing infusion duration and would be enhanced by 130% to 200% and by 7% to 16%, respectively, compared to intraarterial infusion of methotrexate alone; and 2) exposure time at concentrations above 1 microM, the minimal concentration required for the effects of methotrexate, would not be enhanced in tumor and would be enhanced by only 10% in brain. Hyperosmolar blood-brain barrier disruption transiently increases delivery of water-soluble compounds to normal brain and brain tumors. Most of the enhancement of exposure results from trapping the drug within the blood-brain barrier, an effect of the very transient alteration of the blood-brain barrier by HBBBD. Delivery is most effective when a drug is administered within 5 to 10 minutes after disruption. However, the increased exposure and exposure time that occur with methotrexate, the permeability of which is among the lowest of the agents currently used clinically, are limited and the disproportionate increase in brain exposure, compared to tumor exposure, may alter the therapeutic index of many drugs.

CT-guided stereotactic biopsy of nonenhancing brain lesions

The majority of computer tomography stereotactic biopsy lesions enhance after administration of intravenous contrast, whereas patients with nonenhancing lesions are often followed conservatively or undergo craniotomies. There are few studies showing the effectiveness of stereotactic biopsies of nonenhancing cerebral lesions. Stereotactic biopsies were performed on 19 patients with lesions that did not enhance on CT after intravenous contrast. Pathological diagnoses were made in 90% (17/19) of patients. Four HIV-positive patients had progressive multifocal leukoencephalopathy, 11 patients had gliomas (4 astrocytomas, 6 anaplastic astrocytomas, and 1 ganglioma), 1 had multiple sclerosis, and 1 had herpes encephalitis. In 2 patients multiple biopsies revealed only gliosis. There was no morbidity or mortality. Stereotactic biopsies for nonenhancing brain lesions have a high diagnostic yield and can favorably alter the treatment course.

Boron neutron capture therapy for murine malignant gliomas

Boron neutron capture therapy (BNCT) involves administration of a boron compound followed by neutron irradiation of the target organ. The boron atom captures a neutron, which results in the release of densely ionizing helium and lithium ions that are highly damaging and usually lethal to cells within their combined track length of approximately 12 microns. Prior to Phase I clinical trials for patients with malignant gliomas, mice with glioma 261 intracerebral tumors were fed D,L-3-(p-boronophenyl)alanine and irradiated with total tumor doses of 1000-5000 RBE-cGy of single fraction thermal neutrons to determine the maximum tolerated dose and effect on survival. These mice were compared to mice that received D,L-3-(p-boronophenyl)alanine alone, neutron irradiation alone, photon irradiation alone, or no treatment. Additional normal mice received escalating doses of neutron irradiation to determine its toxicity to normal brain. BNCT caused a dose-dependent, statistically significant prolongation in survival at 1000-5000 RBE-cGy. At 3000 RBE-cGy, median survival rates of the BNCT and untreated control groups were 68 and 22 days, respectively, with a long-term survival rate of 33%. At 4000 RBE-cGy, median survival was 72 and 21 days, respectively, with a long-term survival rate of 43%. At lower radiation doses, the extended survival was comparable between the BNCT and photon-irradiated mice; however, at 3000 and 4000 RBE-cGy the median survival of BNCT-treated mice was significantly greater than photon-irradiated mice. The maximum tolerated single fraction dose to normal brain was approximately 2000 RBE-cGy.

Treatment of murine primary brain tumors with systemic interleukin-2 and tumor-infiltrating lymphocytes

Methods have recently been described for the isolation and expansion of lymphocytes that have trafficked into animal and human tumors. These CD8-positive tumor-infiltrating lymphocytes (TIL's) have exceptional trafficking ability to, and efficacy against, tumor targets in extracranial sites. Prior to Phase I clinical trials for patients with gliomas, adoptive immunotherapy with TIL's was studied in a mouse model of primary brain tumors to determine if intracerebral tumors have a similar response. Glioma 261 (GL261) tumors were grown in the subcutaneous space of C57BL/6 mice. After enzymatic digestion, the cells were incubated in vitro with interleukin-2 (IL-2) until a confluent population of T lymphocytes was present. The in vitro efficacy of these TIL's was tested against fresh GL261 targets with a chromium release assay; the in vivo efficacy was tested against GL261 tumors in the liver and against irradiated and nonirradiated GL261 tumors in the brain. Mice received one of the following: intraperitoneal saline; intraperitoneal IL-2 (7500 to 50,000 U three times daily for 5 days); IL-2 plus intravenous TIL's (1 to 3 x 10(7) cells); 10 Gy cranial irradiation; irradiation plus IL-2; or irradiation plus IL-2 plus TIL's. The TIL preparation killed 77% of tumor targets in 4 hours at an effector:target ratio of 100:1. In animals with GL261 tumors in the liver, at 2 weeks there were 93 +/- 37, 128 +/- 45, and 21 +/- 14 liver metastases in the control, IL-2, and IL-2 plus TIL groups, respectively. However, in animals with GL261 tumors in the brain, no treatment group had an increased survival rate compared to the control group. It is concluded that, although TIL and IL-2 immunotherapy can be used effectively to treat brain tumors in vitro and at sites outside the central nervous system, it is ineffective against the same type of tumor in the brain. Different methods of delivery or different combinations of these immunomodulators may be more effective; however, based on these findings, treatment of patients with IL-2 and TIL cannot be recommended until efficacy has been demonstrated in an animal model.

Expression and modulation of major histocompatibility antigens on murine primary brain tumor in vitro

Lysis of tumor cells by activated cytotoxic lymphocytes requires their recognition of antigens associated with major histocompatibility complex molecules. The authors studied the constitutive expression of Class I and Class II major histocompatibility complex antigens on mouse brain-tumor cells and the capacity of different cytokines and cytokine combinations to alter this expression in vitro. Cells from the murine glioma 26 (GL26), glioma 261 (GL261), and ependymoblastoma A (EpA) cell lines were established in monolayer culture and treated for 48 hours with either alpha interferon, gamma interferon, tumor necrosis factor alpha, tumor necrosis factor alpha plus gamma interferon, or interleukin-2. They were then analyzed by flow cytometry for baseline and cytokine-altered major histocompatibility complex expression. All cell lines had a similar constitutive major histocompatibility complex pattern with low Class I antigen expression and no detectable Class II antigen expression. Alpha interferon substantially induced and up-regulated Class I antigen expression, but had no effect on Class II antigen expression. Gamma interferon also stimulated up-regulation of Class I antigen expression, generally doubling the anti-Class I antigen fluorescence of treated cells. Its effect on Class II antigen expression was more extensive. In the GL26 and GL261 cell lines the expression of Class II antigen determinants increased to 12 x and 14 x control values and as many as 75% of cells that had no detectable constitutive expression of Class II antigen expressed this antigen after priming with gamma interferon. The addition of tumor necrosis factor alpha to gamma interferon further increased Class II antigen expression on EpA tumor cells only. Interleukin-2 and tumor necrosis factor alpha alone had no effect on Class I or Class II antigen expression of any cell lines. It is concluded that Class I and Class II antigen expression in mouse glioma cell lines is induced and enhanced after treatment with certain cytokines in vitro. Use of these cell lines to create in situ primary brain tumors in C57BL/6 mice should provide an excellent animal system to study major histocompatibility complex modulation in brain tumor cells and to examine the potential impact of major histocompatibility complex up-regulation on the response of brain tumors to immunotherapy.

Intravascular streaming during carotid artery infusions. Demonstration in humans and reduction using diastole-phased pulsatile administration

Intra-arterial carotid artery chemotherapy for malignant gliomas is limited by focal injuries to the eye and brain which may be caused by poor mixing of the drug with blood at the infusion site. This inadequate mixing can be eliminated in animal models with diastole-phased pulsatile infusion (DPPI) which creates 1-ml/sec spurts during the slow blood flow phase of diastole. Before treatment with intracarotid cisplatin, 10 patients with malignant gliomas were studied to determine whether intravascular streaming occurs after intracarotid infusion in humans, and if so, if it is reduced with DPPI. Regional cerebral blood flow (rCBF) studies were performed by intravenous injection of H2(15)O and positron emission tomography. This was followed by supra- or infraophthalmic internal carotid artery (ICA) injections of H2(15)O with either continuous infusion or DPPI. Local H2(15)O concentration in the brain was determined and the images of radiotracer distribution in the continuous infusion and DPPI studies were compared to the rCBF images. Intravascular streaming of the infusate was identified by a heterogeneous distribution of the infused H2(15)O in brain compared to rCBF. Extensive and variable intravascular streaming occurred in three patients who received infusions into the supraophthalmic segment of the ICA. Some brain areas received up to 11 times the expected radiotracer delivery, while other regions received as little as one-tenth. This streaming pattern was markedly reduced or eliminated by DPPI. In the five patients who received infraophthalmic infusions, a minimally heterogeneous distribution of the infusate was detected. The authors conclude that extensive intravascular streaming accompanies supraophthalmic ICA infusions in patients. The magnitude of streaming can be substantially reduced or eliminated with DPPI. Those who perform intra-arterial infusion should consider using DPPI to assure uniform drug delivery to brain.

Adoptive immunotherapy of intracerebral metastases in mice

Lymphokine-activated killer (LAK) cells are a heterogeneous population of immune effector cells that nonspecifically destroy neoplastic cells but not normal cells. Although parenteral treatment with interleukin-2 (IL-2) alone or a combination of IL-2 and LAK cells reduces tumor load and prolongs survival in mice with pulmonary, peritoneal, or hepatic metastases, the effect of these treatments on brain metastases has not been studied. To determine in an animal model if intracerebral metastases would be protected by the immunologically privileged status of the brain, intracardiac and intravenous injections of 10(5) KHT sarcoma cells were performed in C3H mice to create brain and lung metastases, respectively. The mice were treated with adoptive immunotherapy to determine if efficacy seen in an extracerebral site could be reproduced in the brain, and if histological examination of these brains would reveal a significant degree of lymphocyte infiltration and cytolytic activity. Animals were treated with either parenteral IL-2 (7500 U three times daily on Days 3 to 7 after tumor injection), or IL-2 plus LAK cells (7500 U IL-2 times daily on Days 3 to 7, and 10(8) LAK cells intravenously on Days 3 and 6 after tumor injection), or IL-2 excipient (three times daily on Days 3 to 7 after tumor injection). As compared to control animals, pulmonary metastases on Day 14 after tumor injection were reduced or eliminated in animals treated with either IL-2 or IL-2 plus LAK cells (p less than 0.01). In these same animals, there was no reduction in the number of intracerebral metastases and no evidence of lymphocytic infiltration or cytolytic activity in the brain. This is the first study that reveals an organ-specific resistance to the treatment of metastases with adoptive immunotherapy, and affirms the concern that due to inadequate trafficking of endogenous or exogenous-activated lymphocytes or due to inadequate activation of in situ brain lymphoid precursors, there is no rejection of tumors in the brain. This information suggests that brain metastases in patients with systemic malignancies will not respond to intravenous treatment with LAK cells and IL-2, and that alternative forms of treatment are needed. Furthermore, this modification of a previously existing model of murine brain metastasis provides a method for concurrently evaluating the effectiveness of treatments for intra- and extracranial cancers.

The effect of intravenous interleukin-2 on brain water content

Parenteral treatment with interleukin-2 (IL-2) is effective against certain advanced cancers outside the central nervous system. Prior to commencement of Phase II trials in patients with brain tumors, the neurological and neuroradiological features of 10 patients treated with intravenous administration of repeated doses of IL-2 were studied. Three patients had malignant gliomas, and seven patients had extracranial cancer without evidence of intracranial metastasis. All were treated with intravenous doses of 10(5) U/kg three times daily for up to 5 days. The patients with gliomas received cranial computerized axial tomography (CT) scans before IL-2 therapy was initiated and during the later stages of treatment. The patients with extracranial cancer underwent T2-weighted magnetic resonance (MR) imaging before and later during therapy. After two to 11 doses of IL-2, the patients with gliomas had marked neurological deterioration that was associated with a mild to marked increase in peritumoral edema and mass effect visible on CT scans. With cessation of treatment and appropriate supportive care, all returned to their pretreatment state. The patients with extracranial cancer were either neurologically unchanged or underwent minor transient changes in mental status (lethargy and confusion). In these patients, the MR signal intensity was quantified and compared in eight anatomic regions of interest. In six of the seven patients, there were increases in gray and white matter signal intensity consistent with increased cerebral water content. The percentage changes (means +/- standard error of the means) were 12.6% +/- 7.3% in the gray matter and 17.0% +/- 6.2% in the white matter. This study demonstrates that treatment with a high parenteral dose of IL-2 is not tolerated by patients with gliomas due to increased cerebral edema. In patients with extracranial cancer but no brain disease, parenteral IL-2 induces an increase in the cerebral water content of both gray and white matter.

Implantation of dispersed cells into primate brain

Although several experimental therapies such as dopaminergic cell implantation in parkinsonian models and intratumoral placement of lymphokine-activated killer cells require intracerebral deposition of dispersed cell suspensions, a successful technique of needle implantation of cells into primate brain has not been demonstrated. The authors have sought to establish a stereotaxic technique to predictably deposit dispersed cells in primate brain. Human lymphocytes were cultured in recombinant interleukin-2, labeled with sodium 51 chromate (51Cr), and stereotaxically injected into the frontal white matter of six anesthetized rhesus monkeys. A 10-microliters aliquot of cell suspension (2 X 10(7) cells/ml) was deposited 16 mm deep to the dura at 5 microliters/min via Hamilton No. 22s or 26s needles. Five control aliquots were counted for each injection. Reflux out of the needle track was absorbed on gauze, and the recovered cells were counted. The animals were sacrificed 1 hour after implantation and the brain was removed and sectioned such that the cortex and white matter along the needle track were separate. The tissue sections were then counted. Recovery was expressed as the percentage of total injected radioactivity (cpm) that was present in each brain section. Two additional injected hemispheres were processed for autoradiography and histological study. Cell recovery in the brain (mean +/- standard deviation) was 87.2% +/- 13.9% (3.3% +/- 4.9% in cortex and 83.9% +/- 15.9% in white matter). The autoradiograms and histological examination showed a dense accumulation of radioactivity (cells) at the target site and minimal radioactivity (cells) in the needle track. Accurate intracerebral deposition of dispersed cells in primates was achieved with the technique described. This knowledge permits reliable stereotaxic implantation of cells into the brains of nonhuman primates and humans for investigation and therapy.

Intratumoral LAK cell and interleukin-2 therapy of human gliomas

Adoptive immunotherapy using lymphokine-activated killer (LAK) cells and interleukin-2 (IL-2) offers the possibility of a new treatment for patients with malignant glial tumors. In a clinical trial, the effectiveness of a 5-day treatment cycle of direct intratumoral administration of both LAK cells and IL-2 via a reservoir/catheter system in patients with recurrent malignant gliomas was studied. Ten patients were entered into the study, nine of whom were treated with 15 cycles of LAK cells (0.9 to 21.0 x 10(9) cells) and IL-2 (49 to 450 x 10(3) U/kg). The 10th patient in the study was not treated because of the onset of severe neurological deficits prior to beginning immunotherapy. Of the nine patients treated, one had a partial tumor response to immunotherapy as documented by computerized tomography. Neurological side effects occurred in all patients undergoing treatment and were related to increases in cerebral edema that appeared to be mediated by the immunotherapy. This report demonstrates the present limitations of regional adoptive immunotherapy with LAK cells and IL-2 in the treatment of human glial tumors.

The effect of interleukin-2 on the blood-brain barrier in the 9L gliosarcoma rat model

Carbon-14-labeled aminoisobutyric acid was used to determine local blood-to-tissue transfer constants in 22 Fischer rats with intracerebral 9L gliosarcomas that received either high-dose parenteral interleukin-2 (IL-2) or a control injection. In tumor and peritumoral tissue, the transfer constants in the IL-2-treated animals (89.6 +/- 14.6 and 35.8 +/- 6.0, respectively, mean +/- standard error of the mean) were larger (p less than 0.05) than in control animals (61.4 +/- 6.4 and 14.6 +/- 2.2, respectively). In contrast, in normal frontal and occipital tissue contralateral to the tumor-bearing hemisphere, there was no significant difference between the transfer constants in IL-2-treated and control animals. Furthermore, treatment of animals with IL-2 excipient caused no change in permeability as compared to animals treated with Hanks' balanced salt solution. Parenteral injection of IL-2 increases blood-brain barrier disruption in tumor-bearing rat brain but does not increase the vascular permeability of normal brain. Methods to prevent this increased tumor vessel permeability are required before parenteral IL-2 can be used safely for the treatment of primary or metastatic brain tumors.

Penetration of recombinant interleukin-2 across the blood-cerebrospinal fluid barrier

Recombinant interleukin-2 (rIL-2) is an immunotherapeutic agent with efficacy against certain advanced cancers. The penetration of rIL-2 across the blood-cerebrospinal fluid (CSF) barrier was studied in 12 cancer patients who had no evidence of tumor involvement of the central nervous system. At different times during treatment with intravenous rIL-2, CSF was withdrawn either continuously for 8 to 26 hours via a lumbar subarachnoid catheter (in eight patients) or by a single lumbar puncture (in four). Bioassay showed the appearance of rIL-2 in lumbar CSF 4 to 6 hours after the first intravenous dose, a rise over 2 to 4 hours to a plateau of 3 to 9 U/ml, and clearance to less than 0.1 U/ml by 10 hours after the last dose. An abnormally elevated CSF albumin level in two of the twelve patients indicated alteration of the blood-brain barrier. There were no abnormalities in the CSF glucose level or white blood cell count. The CSF pharmacokinetics contrast with the rapid elimination of rIL-2 from plasma and demonstrate significant blood-CSF barrier penetration. These data support the possibility of achieving CSF levels of rIL-2 that are adequate to maintain activity of lymphokine-activated killer cells after parenteral administration, and argue for rIL-2-associated disruption of the human blood-brain barrier in some patients.

Intravascular streaming and variable delivery to brain following carotid artery infusions in the Sprague-Dawley rat

Intracarotid artery infusions in animals are commonly performed in studies of the blood-brain barrier and in chemotherapy trials. Implicit in the analysis of these experiments is that the infusate will be distributed to the territory of the internal carotid artery in a manner that is proportional to blood flow. Fifteen Sprague-Dawley rats were studied to determine if poor infusate mixing with blood due to intravascular streaming occurred during intracarotid artery drug infusions and if it could be eliminated with fast retrograde infusion. In three experimental groups, a radiolabeled flow tracer--14C-iodoantipyrine (IAP)--was infused retrograde through the external carotid artery into the common carotid artery at slow, medium, and fast rates (0.45, 1.5, and 5.0 ml/min). In a control group, IAP was injected intravenously (i.v.). Local isotope concentrations in the brain were determined by quantitative autoradiography, and the variability of isotope delivery was assessed in the frontoparietal cortex, temporal cortex, and caudate putamen of all animals. Streaming phenomena were manifest in all selected anatomic areas after the slow and medium rates of intraarterial infusion. After fast intracarotid infusion or i.v. injection, there was uniform distribution of isotope in the same brain regions.

Dorsal root entry zone coagulation for intractable sciatica

Chronic back and leg pain which is unresponsive to medical and/or surgical treatment is a common and difficult neurosurgical problem. Twelve patients with this condition underwent dorsal root entry zone coagulation of that region of the conus medullaris which correlated with the pain. Only 2 patients had a favorable result. The implications of this finding are discussed.

Successful treatment of phantom pain with dorsal root entry zone coagulation

We studied 22 patients with amputation due to trauma, gangrene, or cancer. All developed postamputation pain, underwent a dorsal root entry zone (DREZ) procedure, and were followed from 6 months to 4 years after surgery. Overall, only 8 (36%) of these 22 patients had pain relief. However, good results were obtained in 6 (67%) of 9 patients with phantom pain alone, and in 5 (83%) of 6 patients with traumatic amputations associated with root avulsion. Poor results were obtained in patients with both phantom and stump pain, or stump pain alone. The DREZ procedure has a well-defined, but limited role in the treatment of postamputation pain.

Carotid artery mixing with diastole-phased pulsed drug infusion

Focal injury to the brain or retina is a frequent complication of drug delivery to the internal carotid artery (ICA) and may be due to poor mixing of the drug with blood at the infusion site. Rhesus monkeys were studied to determine whether phased drug delivery during diastole from a modified pulsatile angiographic injector would improve drug mixing in vivo. A radiolabeled flow tracer, carbon-14-iodoantipyrine (14C-IAP), was injected into the ICA of three monkeys in 80-msec pulses, each ending at least 50 msec before the end of local diastole. Local isotope concentration in the brain was determined by quantitative autoradiography. The ratio of highest to lowest concentration was 1.86 +/- 0.26 (mean +/- standard deviation) in the frontoparietal cortex, 1.65 +/- 0.42 in the frontoparietal white matter, 1.89 +/- 0.28 in the temporal cortex, and 1.39 +/- 0.17 in the basal ganglia. These results were similar to recordings in three control animals that received intravenous 14C-IAP to demonstrate complete drug mixing (1.37 +/- 0.12, 1.41 +/- 0.11, 1.70 +/- 0.08, 1.22 +/- 0.24, respectively), and contrasted to findings in five animals which received continuous intracarotid infusions to demonstrate standard ICA drug delivery (4.54 +/- 2.07, 2.94 +/- 1.45, 5.43 +/- 3.57, 3.60 +/- 2.90, respectively). Pulsed intra-arterial infusion during diastole provides a technically simple method for improving intravascular drug mixing, and results in drug delivery to tissue capillaries that is proportional to blood flow.

Cushing syndrome: pituitary CT scanning

Proper treatment of patients with Cushing syndrome depends on knowledge of whether the condition derives from a pituitary or adrenal adenoma or an ectopic tumor that secretes adrenocorticotropic hormone (ACTH). Fifty-seven patients with Cushing syndrome were prospectively evaluated to determine whether computed tomography (CT) of the pituitary gland is useful in diagnosing or excluding an ACTH-producing adenoma and in predicting the site of the adenoma within the pituitary gland. Findings on CT scans were normal in 35 of 50 patients with surgically confirmed Cushing disease and in seven patients with ectopic ACTH-producing tumors. Of the 15 patients with Cushing disease for whom CT results were abnormal, eight had macroadenomas and seven had microadenomas. This study demonstrates a low sensitivity (30%) and low diagnostic accuracy (39%) of CT in the detection of ACTH-producing pituitary tumors and indicates the need for alternative methods of confirming the pituitary origin of excessive ACTH secretion in most patients.

Sacrococcygeal rhizotomy for perineal pain

Chronic pain in the perineum is a difficult neurosurgical problem. This article evaluates the effectiveness of sacrococcygeal rhizotomy in 28 patients who had cancer-related pain or coccydynia, underwent rhizotomy, and were followed for an average of 3 years. Good pain relief was obtained in 53% (10 of 19 patients) with malignant pain, as opposed to 22% (2 of 9 patients) with nonmalignant pain. Sacral rhizotomy is a reasonable treatment for cancer-related perineal pain, but it is ineffective for coccydynia and other benign perineal pain problems.

Syringomyelia in a man with sarcoidosis

Sarcoidosis, generally a systemic ailment, uncommonly affects the central nervous system. It only rarely affects the spinal cord alone or in combination with other areas. Syringomyelia has never been associated with sarcoidosis. We report the case of a 32-year-old man with sarcoidosis who presented with surgically verified syringomyelia. The pertinent literature is reviewed. The mechanisms by which sarcoidosis could cause a syrinx are discussed.

Dorsal root entry zone lesions for post-amputation pain

Chronic pain following an amputation may involve the stump, the phantom limb, or both. Operations such as rhizotomy, cordotomy, stump revision, and dorsal column stimulation have been unsuccessful in treating this condition. This study evaluates the effectiveness of dorsal root entry zone (DREZ) coagulation for this pain problem. The authors studied 22 patients with amputations due to trauma, gangrene, or cancer. All developed post-amputation pain, underwent a DREZ procedure, and were followed from 6 months to 4 years after surgery. Overall, only eight (36%) of these 22 patients had pain relief. However, good results were obtained in six (67%) of nine patients with phantom pain alone, and in five (83%) of six patients with traumatic amputations associated with root avulsion. Poor results were obtained in patients with both phantom and stump pain, or stump pain alone. The DREZ procedure has a limited, but definite, place in the treatment of post-amputation pain.

Carotid artery injections in 40- to 99-g Fischer rats: technical note and evaluation of blood flow by various injection techniques

Despite extensive clinical use of brain tumor chemotherapy via the internal carotid artery (ICA), demonstration of efficacy and toxicity screening of ICA chemotherapy in brain tumor models has been limited. A method for performing ICA injections in 40- to 99-g Fischer rats is described, with documentation of its effect upon cerebral blood flow. A 33 gauge cannula was secured into a PE-10 catheter and, after ligation of the external carotid (ECA) and the pterygopalatine arteries, injections were made into the common carotid artery (CCA). The reliability of this method compared to CCA injection with and without ligation of the ECA was evaluated utilizing 15-micrometers 103Ru microspheres. With this technique, 68.3 +/- 11.19% of the microspheres lodged in the brain, compared to 28.9 +/- 21.3% to 32.7 +/- 19.8% for the other techniques (P less than 0.01). With this technique, regional perfusion of brain tumors can be done in the avian sarcoma virus rat glioma model, the D-54 MG human glioma-immunosuppressed rat transplantation model, and any of the large rat brain tumor models. The relevance of this method of experimental regional perfusion for the preclinical assessment of the efficacy and of the toxicity of chemotherapy and immunotherapy via the ICA is discussed.

Intracerebral transplantation of a human glioma line in immunosuppressed rats

A model was developed for in vivo study of the human glioma-derived D-54 MG cell line in the brains of immunosuppressed Fischer 344 rats. The rats were injected with horse anti-rat thymocyte serum before and after intracerebral inoculation with 5 or 10 microliters of a D-54 MG tumor cell suspension. Reproducible mortality distributions were obtained, with deaths occurring 18 to 34 days after intracerebral inoculation. Tumors grew as well circumscribed intracerebral masses with sheets of anaplastic cells, areas of necrosis bordered by concentrated nuclei, and minimal lymphocytic infiltration. Cytogenetic analysis revealed the same general chromosome distribution and markers in the heterotransplanted glioma cells as in the cultured line. Blood-brain barrier disruption was demonstrated by intracerebral tumor staining after intravenous injection of Evans blue dye. The in vivo growth of D-54 MG in immunosuppressed rats provides a reliable experimental model for the study of chemotherapy, immunodiagnosis, and immunotherapy of a human glioma-derived tumor in an animal sufficiently large to evaluate intracarotid or intratumoral injection of therapeutic agents.