Serum antibodies against glycosphingolipids in chronic relapsing experimental allergic encephalomyelitis. Demonstration by ELISA and relation to serum in vivo demyelinating activity.

Sera from guinea pigs with spinal cord-induced chronic relapsing experimental allergic encephalomyelitis (crEAE) were tested for IgG antibodies against glycosphingolipids (GSL; galactocerebroside, ganglioside GM1, sulfatide) by an enzyme-linked immunosorbent assay and for in vivo demyelinating activity by infusion into the lumbosacral subarachnoid space of normal rats. In chronic stage-crEAE sera (40-200 days after sensitization) a high incidence (21/26) and high titers (up to 1:2560) of antibodies against one or more GSL coincided with a high incidence (22/26) of in vivo demyelinating activity. These results suggest an involvement of antibodies against various GSL in the process of demyelination.

Antibodies-restricted heterogeneity in serum and cerebrospinal fluid of chronic relapsing experimental allergic encephalomyelitis.

An animal model which might help to study multiple sclerosis has long been sought. With chronic relapsing experimental allergic encephalitis (EAE), the search seems to have brought hope and evidence of comparable pathology whether concerned with clinical or neuropathological results, but no study of the cerebrospinal fluid (CSF) electrophoretic pattern has been made so far. A new sensitive method enables to study the CSF proteins: unconcentrated CSF proteins after agar gel electrophoresis are stained with silver reagents. The silver technique allows to follow the evolution of the inflammatory reaction in chronic relapsing EAE as well as in the acute form of EAE. This technique provides an additional approach to the study of EAE and an argument in favor of chronic relapsing EAE in guinea pigs as a model for multiple sclerosis.

The role of brain edema in epileptic brain damage induced by systemic kainic acid injection.

Edema formation and blood-brain barrier permeability was studied in animals with epileptic seizures induced by subcutaneous injection of kainic acid. Brain edema was most pronounced between 3 and 24 h after kainic acid injection. It was reflected by massive swelling of perineuronal and perivascular astroglia. Three hours after kainic acid perivascular astroglia swelling resulted in disturbance of local microcirculation in the affected brain areas. In addition, compression of drainage veins by the edematous brain induced focal perivenous hemorrhages similar to herniation damage in human brain edema. Tracer studies with sodium fluorescein, Evans blue, albumin and horseradish peroxidase revealed only a mild increase in the permeability of cerebral vessels, topographically unrelated to areas of brain edema. This finding indicates the presence of cytotoxic brain edema in kainic acid-induced epileptic brain damage. Treatment of brain edema with dexamethasone did not influence the incidence and severity of kainic acid-induced epileptic brain damage. However, in 54% of animals injected with kainic acid, lesions were completely prevented by treatment of brain edema with mannitol. The present results indicate that brain edema plays an important role in the pathogenesis of epileptic brain damage following systemic kainic acid intoxication. It is suggested that in this model of limbic epilepsy the brain edema is due to the massive ionic imbalance elicited in the affected brain regions by the kainic acid-induced persistent neuronal excitation.

Local tumor control and morbidity after one to three fractions of stereotactic external beam irradiation for uveal melanoma.

BACKGROUND AND PURPOSE: To evaluate prospectively local tumor control and morbidity after 1-3 fractions of stereotactic external beam irradiation (SEBI) in patients with uveal melanoma, unsuitable for ruthenium-106 brachytherapy or local resection. MATERIAL AND METHODS: This phase I/II study includes 62 selected patients with uveal melanoma. The mean initial tumor height was 7.8+/-2.8 mm. With the Leskell gamma knife SEBI, 41 patients (66%) were irradiated with two equal fractions of 35, 30 or 25 Gy/fraction, 14 patients (22%) were treated with three fractions of 15 Gy each, and seven patients (11%) with small tumor volumes below 400 mm(3) were treated with one fraction of 45 Gy. The mean total dose was 54+/-8 Gy. The minimal follow-up period was 12 months, and the median follow-up was 28.3 months. Data on radiation-induced side-effects were analyzed with the Cox proportional hazards model for possible risk factors. RESULTS: Local tumor control was achieved in 98% and tumor height reduction in 97%. The mean relative tumor volume reductions were 44, 60 and 72% after 12, 24 and 36 months, respectively. Seven patients developed metastases (11%). Secondary enucleation was performed in eight eyes (13%). Morbidity was significant in tumors exceeding 8 mm in initial height; it was comparable and acceptable in those smaller. In the stepwise multiple Cox model, tumor localization, height and volume, planning target volume (PTV), total dose and patient age were identified as the strongest risk factors for radiation-induced lens opacities, secondary glaucoma, uveitis, eyelash loss and exudative retinal detachment. In this model, the high-dose volume irradiated with more than 10 Gy/fraction was the strongest risk factor for radiation-induced uveitis. CONCLUSIONS: Stereotactic external photon beam irradiation and a total dose of 45-70 Gy delivered in one to three fractions are highly effective at achieving local tumor control in uveal melanoma. Further clinical studies using smaller fraction doses, and consequent smaller high-dose volumes, are justified to optimize dose and fractionation. Fractionated stereotactic irradiation has a challenging potential as an eye-preserving treatment in uveal melanoma.

Histogenesis of demyelinating lesions in the spinal cord of guinea pigs with chronic relapsing experimental allergic encephalomyelitis.

Spinal cord lesions in Hartley guinea pigs with chronic relapsing experimental allergic encephalomyelitis (EAE) were studied by light, transmission and scanning electron microscopy at different stages of the formation of demyelinated plaques. In addition the inflammatory response in the meninges was studied in isolated pia mater preparations separated from the spinal cord surface. In initial chronic lesions in the spinal cord, inflammation was restricted to penetrating parenchymal veins of the spinal cord and meninges. With the formation of large demyelinated plaques in the spinal cord, massive fibrosis of the meninges with infiltration by inflammatory cells was noted in an area covering the surface of the lesion. In plaques which reach the spinal cord surface, inflammatory cells could be seen passing between the pia and the spinal cord substance. In chronic remyelinated lesions, adhesions between meningeal fibroblasts and the astroglial limiting membrane were seen. In addition a topographical correlation between the distribution of spinal cord veins and venules and demyelinated plaques was found. These observations indicate that spinal cord lesions in chronic relapsing EAE are initiated by perivenous inflammation in the parenchyma and the meninges. Plaque formation, especially in spinal cord surface lesions, is additionally enhanced by the entrapment of inflammatory cells in the fibrosed meninges. The exchange of macrophages through the glia-limiting membrane may be responsible for the more rapid debris removal in the spinal cord in comparison with brain lesions in chronic relapsing EAE.

In vivo demyelinating activity of sera from animals with chronic experimental allergic encephalomyelitis. Antibody nature of the demyelinating factor and the role of complement.

Sera from guinea pigs and rats with chronic experimental allergic encephalomyelitis were injected into the cerebrospinal fluid (CSF) of normal recipient rats. Guinea pig sera induced demyelination in the central and (or) peripheral nervous system, whereas injection of rat sera resulted in demyelination in the peripheral nervous system only. Control sera did not induce demyelination. Demyelinating activity in guinea pig sera was confined to the IgG-fraction; in rat sera the IgG- as well as the IgM-fraction were able to induce demyelination. The demyelinating activity was abolished when the sera were absorbed with with sensitising antigen (guinea pig spinal cord tissue) or when immunoglobulins were removed from the sera. When chronic EAE sera from rats were injected into the CSF of rats, complement was not required for the induction of demyeLination. The presence of complement, however, augmented the demyelinating activity. Decomplemented chronic EAE sera from guinea pigs failed to induce demyelination after injection into the CSF of rats. Injection of control and non-demyelinating or demyelinating EAE sera into the subarachnoid space of normal recipient rats induced a weak inflammatory response with increased numbers of large mononuclear cells in the meninges. It is discussed that in vivo a complex interaction of antibodies, complement and effector cells is responsible for induction of demyelination.

Proliferation activity in pituitary adenomas: measurement by monoclonal antibody Ki-67.

The monoclonal antibody (MAb) Ki-67 detects a nuclear antigen expressed by proliferating cells during the entire cell cycle. In contrast to conventional histological techniques, the use of MAb Ki-67 on frozen sections or cytological smear preparations allows direct determination of the growth rate of tumors routinely. Sixty-two pituitary adenomas were investigated by use of the MAb Ki-67 in a two-step avidin-biotin-peroxidase complex technique. The proliferation activity ranged from 0.1 to 2.8%. There was no significant difference between the proliferation and hormonal state of the adenomas. Adenomas for which there was histological evidence of dural infiltration, however, showed a statistically significant higher proliferation activity (P less than 0.05) compared to noninvasive adenomas.

Pituitary adenomas with invasion of the cavernous sinus space: a magnetic resonance imaging classification compared with surgical findings.

We present 25 pituitary adenomas that were confirmed surgically to have invaded the cavernous sinus space. The surgical results are compared with the preoperative magnetic resonance imaging findings. For comparable radiological criteria, we classified parasellar growth into five grades. This proposed classification is based on coronal sections of unenhanced and gadolinium diethylene-triamine-pentaacetic acid enhanced magnetic resonance imaging scans, with the readily detectable internal carotid artery serving as the radiological landmark. The anatomical, radiological, and surgical conditions of each grade are considered. Grades 0, 1, 2, and 3 are distinguished from each other by a medial tangent, the intercarotid line--through the cross-sectional centers--and a lateral tangent on the intra- and supracavernous internal carotid arteries. Grade 0 represents the normal condition, and Grade 4 corresponds to the total encasement of the intracavernous carotid artery. According to this classification, surgically proven invasion of the cavernous sinus space was present in all Grade 4 and Grade 3 cases and in all but one of the Grade 2 cases; no invasion was present in Grade 0 and Grade 1 cases. Therefore, the critical area where invasion of the cavernous sinus space becomes very likely and can be proven surgically is located between the intercarotid line and the lateral tangent, which is represented by our Grade 2. We also measured tumor growth rates, using the monoclonal antibody KI-67, which shows a statistically higher proliferation rate (P < 0.001) in adenomas with surgically observed invasion into the cavernous sinus space, as compared with noninvasive adenomas.

Classic, atypical, and anaplastic meningioma: three histopathological subtypes of clinical relevance.

This study correlates the histopathological classification of meningiomas with clinicopathological features of biological activity. A retrospective evaluation of 1799 surgical specimens of meningiomas from 1582 patients was made. The classic histopathological type, atypical meningiomas defined by increased cellularity and at least five mitotic figures in 10 high-power fields, anaplastic (malignant) meningiomas, and hemangiopericytic or papillary meningiomas were seen in 87.6%, 7.2%, 2.4%, and 2.8% of operations, respectively. The rates of recurrence in surgically treated patients with classic, atypical, anaplastic, and hemangiopericytic or papillary meningiomas were 6.96%, 34.6%, 72.7%, and 68.2%, respectively. The extent of surgery and the tumor size and site were studied in detail in 252 tumors of all histopathological types. Recurrences were rare in classic meningiomas after complete resection, whereas atypical and anaplastic tumors recurred after complete resection much more frequently. Classic meningiomas, hemangiopericytomas, and papillary meningiomas were smaller at surgery than atypical and malignant meningiomas. Atypical and malignant tumors were operated on more often in falcine and lateral convexity regions than were classic meningiomas. To support the authors' subjective categorization by a quantitative parameter related to proliferation, 112 meningiomas comprising all histopathological subtypes were investigated for staining of argyrophilic nucleolar organizer region proteins (Ag-NOR's). The Ag-NOR counts showed significant differences between classic, atypical, and anaplastic tumors but no significant differences between primary and recurrent tumors. Hemangiopericytomas and papillary meningiomas had lower Ag-NOR values than anaplastic meningiomas. A correlation of Ag-NOR numbers with the authors' histopathological scale of malignancy supports the introduction of atypical meningiomas with intermediate biological behavior on the classification scale between classic and anaplastic meningiomas. Overlapping of Ag-NOR numbers among all groups of malignancy may restrict the prognostic value of Ag-NOR counting in the individual case.

Detection of tumor necrosis factor-alpha protein and messenger RNA in human glial brain tumors: comparison of immunohistochemistry with in situ hybridization using molecular probes.

Tumor necrosis factor-alpha (TNF alpha) protein and messenger (m)RNA distribution was studied in biopsy samples of glial brain tumors, using immunohistochemistry and in situ hybridization with molecular probes, to investigate the role of this cytokine in tumor proliferation and immunological host defense. Focal expression of TNF alpha was detected in four of four glioblastomas, one of two anaplastic astrocytomas, and four of five low-grade astrocytomas, regardless of their subtype or grade of malignancy, but in none of the normal peritumoral brain tissues used as controls. The TNF alpha protein and mRNA were present in reactive astrocytes and protoplasmic tumor cells, confined to areas of leukocyte or T-lymphocyte infiltrating, and less pronounced in tumor cells at the edge of necrosis. Additionally, TNF alpha reactivity was found in infiltrating macrophages and perivascular microglia. Immunohistochemistry and in situ hybridization for TNF alpha showed comparable reaction patterns and numbers of TNF alpha-positive cells, even though the sensitivity of in situ hybridization was significantly higher. Quantitative evaluation of TNF alpha protein, TNF alpha mRNA, and leukocyte infiltration revealed a significant positive correlation between the TNF alpha-positive reactive astrocytes and the number of lymphocytes present in corresponding areas. Together, these data lead to the conclusion that TNF alpha in reactive astrocytes and monocytic cells within tumor areas of high leukocyte infiltration and in tumor cells at the border of necrosis may represent one defense pathway of the immune system against tumor proliferation.

TLD array for precise dose measurements in stereotactic radiation techniques.

We developed a new TLD array for precise dose measurement and verification of the spatial dose distribution in small radiation targets. It consists of a hemicylindrical, tissue-equivalent rod made of polystyrene with 17 parallel moulds for an exact positioning of each TLD. The spatial resolution of the TLD array was evaluated using the Leskell spherical phantom. Dose planning was performed with KULA 4.4 under stereotactic conditions on axial CT images. In the Leksell gamma unit the TLD array was irradiated with a maximal dose of 10 Gy with an unplugged 14 mm collimator. The doses delivered to the TLDs were rechecked by diode detector and film dosimetry and compared to the computer-generated dose profile. We found excellent agreement of our measured values, even at the critical penumbra decline. For the 14 mm and 18 mm collimator and for the 11 mm collimator combination we compared the measured and calculated data at full width at half maximum. This TLD array may be useful for phantom or tissue model studies on the spatial dose distribution in confined radiation targets as used in stereotactic radiotherapy.

Shuttle dose at the Vienna Leksell Gamma Knife.

The aim of this study was to determine the shuttle dose for all collimator helmets (4, 8, 14 and 18 mm) of the Gamma Knife, model B, in Vienna, Austria. The additional dose accumulated during the transport of the patient in and out of the treatment position should be considered in the dose planning procedure of multicentre treatment regimens and in fractionated stereotactic Gamma Knife radiotherapy. The GafChromic film study was basically used to determine the shuttle dose of all four collimator helmets. In addition, measurements with an ionization chamber (18 and 14 mm collimator--and, for the 18 mm collimator helmet, TLD dosimetry--were performed in order to confirm the GafChromic film data. The shuttle dose ranged between 99.6 and 183.5 mGy, depending mainly on the size of the collimator and the irradiated isocentres at the half-life activity of Co-60 in a brand new Gamma unit. Our film-generated data were in good correlation with the dose levels obtained with the ionization chamber and the TLD dosimetry, showing a dose difference of less than 0.8%. Since it was possible to verify the shuttle dose even for the 4 and 8 mm collimator helmets, we consider it a non-negligible factor and would advocate the inclusion of the shuttle dose in radiosurgical dose planning.

Radio-opaque markers for stereotactic imaging of uveal melanoma.

In in vitro and in vivo studies, episclerally sutured radio-opaque markers were evaluated as localizers for better determination of the clinical tumour volume prior to stereotactic radio-therapy of uveal melanoma. Four different types of markers were studied in vitro: tantalum marker, 2.5 mm in diameter; ring-shaped markers custom-designed in polymethyl methacrylate (PMMA), 2.6 mm and 3.0 mm in diameter; and barium-impregnated silicone rubber spheres, 2 mm in diameter. In vivo PMMA markers 3.0 mm in diameter and barium-impregnated silicone rubber spheres 2 mm in diameter were used. The best results were obtained with the barium-impregnated silicone rubber spheres both in vitro and in vivo. For the CT-delineation of selected uveal melanomas with either a flat discoid shape or flat tumour extensions or when adjacent serous retinal detachment is present, small episclerally sutured barium-impregnated silicone rubber spheres are useful as localizers for determining the clinical tumour volume.

Beneficial gamma-knife radiosurgery in a patient with Nelson's syndrome.

A 50-year-old female patient with Cushing's disease had undergone transsphenoidal removal of the pituitary adenoma and conventional radiotherapy in 1988. Since no remission was achieved, she underwent bilateral adrenalectomy in May 1989. During out-patient follow-up, she developed signs and symptoms due to invasive Adrenocorticotrophic hormone (ACTH)-producing macroadenoma (Nelson's syndrome) in 1994. ACTH levels at that time were 3400 ng/l. Near-total surgical resection of a 2.0 x 2.5 pituitary tumour which slightly extended laterally into the cavernous sinus was achieved by subfrontal approach in June 1994. However, she rapidly developed a recurrence of her complaints, with a visual field defect inferior-nasal of the left eye, and a second operation was carried out in November 1994. Culture of the tumour's cells revealed significant inhibition of ACTH production by bromocriptine. Adjuvant treatment with this drug therefore was started in November 1994. Because of the rapid recurrence it was decided to treat her with gamma-knife radiosurgery. The dose that was given in January 1995 was 12 Gy to the border and 40 Gy into the centre of the tumour. During a follow-up of more than 2 years, no recurrence, but even a minor reduction of tumour mass was observed by magnetic resonance imaging (MRI). Plasma ACTH levels decreased gradually to levels between 200 and 400 ng/l, and ophthalmologic complaints disappeared. It is concluded that gamma-knife radiosurgery may be a good alternative for patients with Nelson's syndrome who have rapidly recurring disease.

Suction fixation system for stereotactic radiosurgery of intraocular malignancies.

We designed a suction fixation system for the radiosurgical treatment of intraocular malignancies with the Leksell gamma unit (gamma knife). OUr device consists of a circular suction chamber and an adjustable unit to be fixed to the Leksell stereotactic head frame. All components are made of plastic materials in order to avoid artifacts in CT or MRT imaging. A permanent suction of 600 to 800 millibars is provided by a standard vacuum pump, powered by a portable battery. Suction times up to 40 minutes were well tolerated in all cases. In the gamma knife of the Neurosurgical Department at the University of Vienna, we successfully used this device. Up to January 1994 we have performed 19 radiosurgical treatments in 9 patients with large or extra-large uveal melanomas and in one patient suffering from a choroidal metastasis.

Neuroanatomical details under endoscopical view--relevant for radiosurgery?

Both, neuroendoscopy and radiosurgery, are upcoming techniques in neurosurgery and become nowadays more and more important. In planning radiosurgical interventions it is very important to have both, the information about the morphology of the pathology itself, and also a clear understanding from the surrounding structures. Neuroendoscopic techniques gives the possibility to demonstrate well known structures without prior dissection. This paper focuses on these anatomical informations which might be relevant in planning further radiosurgical interventions especially in cases of the vascularization of the cranial nerves and the arachnoid membranes, these structures appears much more complex than described in "common" neuroanatomical textbooks. Endoscopic techniques also better demonstrate the real in vivo relationships and gives so a better understanding for interpreting "planning" MRI and CT scans. We therefore consider that neuroanatomical studies under a neuroendoscopical view are very important and could be very helpful in planning radiosurgical intervensitons.

Intra-operative marking of neuroanatomical details--helpful for radiosurgery?

This report is a list of simple but effective techniques for marking important structures intra-operatively. During the last 2 years in 52 patients intra-operative marking techniques have been used. In 37 cases a small piece of fat has been taken. In 10 patients it was done by a radiopaque Barium impregnated silicon sphere and in 5 patients with a piece of a monofilament suture. Postoperative checks were done by conventional X-ray, computer tomography and Magnetic Resonance Imaging. The indication in all cases was to offer landmarks helpful for planning postoperative radiosurgery. In case of fat and radiopaque Barium impregnated silicone spheres the markings were always well defined and clear in contrast. In those cases where a piece of monofilament suture was used it was impossible to get clear postoperative information. In general there were no intra- or post-operative complications. All markers were well tolerated and no side effects have been observed so far. The advantages and disadvantages of each of these possibilities are described and discussed.

Radiosurgery in the treatment of cerebral AVMs.

Radiosurgery of AVM's is gaining in popularity and is advocated by many for the treatment of lesions less than 3 cm in diameter. During a 17 month period 33 patients with cerebral AVM's were treated with radiosurgery. All regions of the brain were represented in the series including brain stem. A mean follow-up of 10.8 months revealed a 6% rebleed rate and a 9% total complication rate. Multimodality therapy including embolization and surgery is recommended for the treatment of AVM's and radiosurgery is seen as an important adjunctive treatment option.

Microsurgery versus radiosurgery in the treatment of small acoustic neurinomas.

Microsurgical preservation of the facial nerve during removal of acoustic neurinomas can hardly be compared with microsurgery of the eighth cranial nerve. Many more anatomical and pathogenetic factors are involved that need careful consideration. In small neurinomas, of grades I and II, total extirpation of the tumour with preservation of both the facial nerve and segments of the vestibulocochlear nerve not directly involved by the tumour has become a safe and practical technique. In small acoustic neurinomas immediate facial nerve function could be preserved in 88% and "useful hearing" could be preserved in 78%. A number of different types of tumour-cranial nerve relationships could be established in small acoustic neurinomas, showing also the effects of adjusted surgical techniques on the preservation of hearing. Optimal selective separation of cranial nerves from the tumour is only possible through open surgical intervention, while radiosurgery requires the irradiation of the entire tumour/nerve complex.

The need for adjunctive focused radiation therapy in pituitary adenomas.

In pituitary adenomas radiation therapy regardless of the technique should be limited to surgical failures. The delayed onset of beneficial effects and the high rate of pituitary insufficiency have to be weighed against the good surgical and/or medical results in the treatment of these tumours. Unfortunately surgical outcome is almost invariably correlated with invasive growth. Invasiveness is statistically significantly correlated with tumour size, as well as with high proliferation rates, which can be measured by immunohistological methods such as mAB KI-67. Owing to the good results of medical treatment, radiation therapy is usually unnecessary in prolactinomas. Patients with persistent hypersecretion of growth hormone after unsuccessful surgery may represent the ideal candidates for radiation therapy, whereas patients with persistent Cushing's disease need cure for hypercortisolism without delay. In patients with residual tumour due to non functioning adenomas, radiation therapy should only be given if the proliferation rate is high.