Search

Deletion of 1p is associated with histological progression to meningiomas. Detection of this alteration may be a predicting factor for recurrences in this tumor. We present 8 meningiomas from four patients: the original tumor and the first recurrence in one patient, and the first and second recurrences in the other three were studied. We compared results of monosomy 22 and deletion of chromosome 1p with cytogenetic methods and fluorescence in situ hybridization (FISH) analysis obtained from slides of direct preparations, of cultured cells and slides of touch preparations. The cytogenetic study showed normal chromosome 22 and deletion on 1p32 in both samples of one patient; only monosomy 22 in both recurrences in another patient, and normal karyotypes with different non-clonal anomalies in the other tumors. However, with FISH analysis, monosomy 22 in both recurrences of three patients was demonstrated, as well as the loss of 1p in all tumors. These results were more evident in the analysis of direct and touch preparations than in those of cultured cells.

Meningiomas may display benign (grade I), atypical (grade II) and anaplastic (grade III) histopathological findings. The cytogenetic studies strongly suggest that secondary changes (beyond loss of chromosome 22) appear to be associated with more atypical features and with greater clinical aggressivity. We studied 60 tumors from 52 patients. Histopathological features such as nuclear pleomorphism, nucleolar prominence, mitosis, necrosis, cellular density, PCNA labeling index, and karyotype have been evaluated. The distribution in histological grades was: 50% benign, 33% atypical and 17% anaplastic meningiomas. Nuclear pleomorphism and nucleolar prominence showed a progressive increase in grades I, II and III. Multifocal micronecrosis was considered a criterion of malignancy. A significant correlation was observed between PCNA-LI, mitotic index and grades. Complex karyotypes increased progressively: benign (34% of cases), atypical (45% of cases) and anaplastic (70% of cases). The most common numerical alterations were losses of chromosomes 10, 14, 18 and 22. The chromosomes most often involved in structural anomalies were: 1, 4, 7, 14 and 22. Telomeric associations were present in four cases and double minutes in two cases. Prognostic criteria for these tumors have been analyzed on the basis of these data.

Meningiomas may display benign (Grade I), atypical (Grade II) and anaplastic (Grade III) histopathological findings. The cytogenetic studies strongly suggest that secondary changes (moreover loss of chromosome 22) appear to be associated with more atypical features and with greater clinical aggressivity. We studied 60 tumors from 52 patients. Histopathological features such as nuclear pleomorphism, nucleolar prominence, mitosis, necrosis, cellular density, PCNA labeling index, and karyotype have been evaluated. Nuclear pleomorphism and nucleolar prominence showed a progressive increase in Grades I-III. Multifocal micronecrosis was considered a criterion of malignancy. A significant correlation was observed between PCNA-LI, mitotic index and grades. Complex karyotypes increased progressively: benign (34% of cases), atypical (45% of cases) and anaplastic (70% of cases). The most common numerical alterations were losses of chromosomes 10, 14, 18 and 22. The chromosomes most often involved in structural anomalies were: 1, 4, 7, 14 and 22. Telomeric associations was present in four cases and double minutes in two cases. Prognostic criteria for these tumors have been analyzed on the basis of these data.

Since 1995 a group of 57 patients with familial tremor and Parkinson's disease have been operated in two main sets: the first, with 11 cases, with predominant tremor, where the ventro-oralis posterior (Vop) thalamic nucleus was stimulated, and the second, with 44 cases, with mainly rigidity and akinesia, where the globus pallidus internus (GPi) was unilaterally (10 cases) or bilaterally (34 cases) stimulated. In 2 cases, a combined thalamic-pallidal stimulation was achieved. In the last cases, an image fusion software with 3D correlation of MR and CT images and volumetric image matching has been used to correct MRI distortion. In all cases, an Itrell II stimulation system (Medtronic) was implanted. Result analysis shows that Vop stimulation is mostly effective for tremor, and GPi stimulation is better for rigidity and akinesia. Transcortical magnetic stimulation tests suggest that GPi pallidal electrical inhibition increases cortical excitability, as opposed to Vop thalamic stimulation, which implies a different mechanism of action., (Copyright 2000 S. Karger AG, Basel)

We present a new frameless stereotatic system prototype that has been initially validated in functional neurosurgery operations and that makes use of an optical position tracker for image-guided neurosurgery. Several devices for tracking different surgical instruments have been designed and manufactured. These devices include an array of infrared light-emitting diodes that are tracked by three charge-coupled device cameras. The system presents several new approaches for surgery planning. For high-quality 3D images of the patient's anatomy, we have developed a parallel version of a volume-rendering algorithm, thus enabling real-time 3D anatomy manipulation on low-cost PC workstations. In order to test the accuracy of the system, the localization of the target by means of a stereotatic frame has been compared with frameless techniques, obtaining a difference of about 1 +/- 1 mm., (Copyright 2000 S. Karger AG, Basel)

Background: Cytogenetic studies of meningiomas suggest that loss of (or parts of) chromosome 22 is a primary event in the development of these tumors; later on, other chromosomal changes would occur in the caryotypes. All these secondary changes are observed mainly in cases with high clinical aggressivity. However, in a few cases of meningiomas disomy 22 coexists, but with other chromosomic anomalies. We present clinical, histopathological and cytogenetic findings in a group of meningiomas with disomy of chromosome 22., Patients and Methods: We collected 10 meningiomas from nine patients which ages ranged between 28-70 years. Fresh tumoral specimens were divided for histologic examination and cytogenetic study, performed after short-term culture., Results: At microscopic examination 5 tumors were classified as benign meningiomas, four as atypical and one as malignant meningioma. Four cases were recurrent tumors. The cytogenetic studies showed that all tumors presented two chromosomes 22 and other chromosome abnormalities. Losses in chromosomes 4, 7, 10, 14, 16, 17 and 20 were frequent; cytogenetics rearrangements of chromosomes 1, 4, 5, 7, 14, 19 and 22 were frequently involved., Conclusions: In karyotypic evolution of meningiomas, secondary anomalies of chromosomes 1p, 10 and 14 are the most common and appear to be associated with a more aggressive clinical course. In this group of meningiomas with disomy 22, these anomalies were also frequently found, and were related in 50% of cases with atypical or malignant morphologies and of them with recurrent tumors in the 40%.

An experimental study on rats showing the arterial lesions caused by the beams of gamma irradiation used in stereotactic radiosurgery is presented. The common carotid artery of the rat was irradiated with a single narrow-beam of gamma radiation with a maximum dose of 30 and 60 Gy. The results were evaluated at 4, 12 and 24 weeks after irradiation. Several focal changes in the arterial walls were observed in all periods of study with a predominance of hyperplastic (proliferative) alterations at doses of 30 Gy, and hyaline degeneration at doses of 60 Gy. Total occlusion was not observed in any case. In conclusion, vascular hyperplasia is more prominent with the lower doses evaluated.

Medulloblastoma is the most common primitive neuroectodermal tumor (PNET) in children, but is very rare in adults. An isochromosome for the long arms of 17, i(17q), is found in about 30% of pediatric cases. Cytogenetic studies in adults are very scarce; only six cases have been described cytogenetically: three cases had normal karyotype, two were studied partially, and another presented only two clonal structural anomalies: del(9)(q12) and del(11)(q22). We studied the chromosomes from medulloblastoma in a 27-year-old woman and found one hypotetraploid stemline with clonal alterations. In the structural anomalies, chromosomes 3, 9, 12, and i(17q) were involved. Chromosome 9 presented a deletion in the long arm, del(9)(q13), with consequent loss of the 9q13-->qter region. This anomaly was similar to one found in a previous case. We suggest that the partial loss of the long arm of chromosome 9 may be a characteristic change of adult medulloblastoma.

Cytogenetic analyses of 10 cases of recurrent meningiomas growing in culture between 1-10 days are reported, of which seven showed benign morphology, one atypical, and two, malignant features. Normal karyotypes with nonclonal alterations were found in three cases, one case with only monosomy 22, and complex karyotypes in the remaining six. Four cases were hypodiploid, one pseudodiploid, and one hyperdiploid. The chromosomes most often involved in structural rearrangements were 1, 7, and 14 and the losses were chromosomes 7, 10, 14, 15, 18, and 22. Ring chromosome, dicentrics, double minutes, and association between satellites were found in one case. These complex karyotypes with hypodiploidy, structural rearrangements, and other markers in recurrent meningiomas may indicate aggressive tumor characteristics.

25 cases of carotid-cavernous fistulae (CCF) who underwent radiosurgery with a conventional gamma source from 1977 to 1992 are reported. 22 were low-flow, spontaneous CCFs and 3 were high flow fistulae which had undergone a previous trapping. The total dose delivered was 30 to 40 Gy. 91% to patients with low-flow CCF cured after radiosurgery in a mean time of 7.5 months, presenting improvement in a mean time of 2.3 months. Only one of the high-flow fistulae was cured. Follow-up period ranged between 14 years and 15 months (mean: 50 months). No recurrence was recorded in any case. While intravascular embolotherapy is the treatment of choice for high-flow fistulae, stereotactic radiosurgery may be the elective treatment for low-flow CCF.

25 patients with low-flow carotid-cavernous fistula (CCF) underwent radiosurgery between 1977 and 1992. 22 had spontaneous low flow fistulae and 3 traumatic high flow fistulae which had been previously treated with internal carotid trapping. The mean preoperative symptomatic period was 12.2 months (4-24 months). Fistulae were classified according to Barrow's classification. Type T was added for traumatic, high-flow fistulae with flow reduction after internal carotid trapping. 11 cases were of type B, 4 of type C, 7 of type D and 3 of type T. The target point for radiosurgery was calculated from selective internal or external carotid angiograms. Stereotactic radiosurgery was performed with a cobalt source, with 5- to 10-mm collimators. A total dose of 30-40 Gy was delivered in all cases, except 1 posttraumatic case in which the dose was 20 Gy. The follow-up period ranged between 14 years and 15 months (mean: 49.76 months). 20 of the 22 low flow fistulae (90.9%) completely closed in a mean period of 7.5 months (range: 2-20 months) after radiosurgery. Improvement of the symptoms began at a mean period of 2.37 months (range: 0.5-14 months). There were no recurrences, the follow-up period ranging between 14 years and 15 months. 100% of type B CCF closed after a mean period of 5.9 months, 75% of type C closed after a mean period of 12.66 months, and 85.7% of cases of type D closed after a mean period of 8.16 months.(ABSTRACT TRUNCATED AT 250 WORDS)

Based on experimental research, since 1982 until 1991 a series of 11 patients diagnosed as suffering from idiopathic focal epilepsy have been treated with stereotactic radiosurgery. Focus location was determined with cortical electrodes and confirmed by stereotactically placed deep electrodes. Stereotactic radiosurgery was performed with photons from a cobalt source with a dose of 10 to 20 Gy, except in two cases in whom a betatron was used. The results were: complete cessation of seizures in four cases and a significant reduction in the number of seizures in five additional cases. Seizures began to decrease gradually after a period of three months of one year, except in two cases in whom there was an immediate response after treatment. In two cases there was no change. No complication related to the irradiation was recorded. The gradual and delayed effect, obtained with low doses, may favour the hypothesis that non-descructive permanent structural changes, possibly related to the neuronal plasticity phenomenon, constitute the mechanism underlying these facts. Although the number of cases so far is too small, the absence of side-effects may make this bloodless method the one of choice specially in those cases in whom eloquent areas are involved.

The authors report the results of a series of 16 cases of low-grade gliomas in whom radiosurgery was performed. This series started in 1977. All the tumours received a single radiosurgical session (with a mean dose of 21.7 Gy, 5-10 mm. collimator; one patient received two sessions and in another patient two different targets were irradiated in the same session). Prior to radiosurgery, six patients received conventional external fractionated radiotherapy, with two lateral fields of up to 10 x 10 cm. and a mean dose of 55.1 Gy and another six patients with tumours less than 5 cm. in diameter, received stereotactic radiotherapy using four fields of up to 5 x 5 cm. and a mean dose of 53.1 Gy. In both cases, conventional fractionation was used, giving a dose of 1.8 to 2 Gy/day. The tumour disappeared in 8 cases (50%) and shunk or ceased its growth in 5 additional cases (31%). In 3 cases of brainstem gliomas in which the clinical condition was previously very poor there was no evolutional change and the patients eventually died. We conclude that radiosurgery is effective in the treatment of deeply seated low-grade gliomas, where it may become the treatment of choice in the absence of other more definitive choices.

Between 1982 and 1991, 11 patients (4 male, 7 female) ranging in age from 16 to 42 years who had been diagnosed with idiopathic focal epilepsy resistant to medication, were treated with stereotactic radiosurgery. The preoperative symptomatic period was 3-24 years. The process of localizing epileptic focus was based on chronic electrocorticography with flexible electrodes introduced into the subarachnoid space through single burr holes, and left in place during a maximum of 7 days until a clinical seizure was recorded. In most cases the procedure had to be repeated until localization was clear. This process was aided by a computer-assisted automatic analysis procedure. Final confirmation of focus location was done with depth electrode recording in most cases. Stereotactic radiosurgery was performed with a 60Co gamma source using 10 mm collimators, except in two cases in which a betatron was used. The estimated dose was 10-20 Gy at the isocenter. Four of the 11 patients (36%) were medication- and seizure-free after a mean follow-up of 102.5 months. Five patients (45%) presented a reduction of seizures of 98, 89, 86, 75 and 75%, respectively. Two patients did not respond to treatment. Seizure reduction began after a delay period of 2-12 months except in 2 patients and in most cases seizure rate decreased progressively during several months (range: 3-48) postoperatively until stabilization. No complications related to irradiation were recorded. Doses effective for epilepsy are much lower than those for producing cerebral lesions, so the mechanism is not destruction of the focus of the pathways spreading the epileptic activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Previous studies of our group showed that C1-C2 spinal cord stimulation increases carotid and brain blood flow in normal conditions in the goat and dog and it has a beneficial vasomotor effect in a model of vasospasm in the rat. For further clinical application it seemed rational to investigate the possible vascular changes mediated by this technique in experimental brain infarction. To this aim, 45 New Zealand rabbits were used. Brain infarction was produced by bilateral carotid ligation in 15, unilateral microcoagulation of the middle cerebral artery in 15 and by microcoagulation of the vertebral artery at the craniocervical junction in the other 15. One week later, following daily clinical scoring and cortical and posterior fossa blood flow readings by laser Doppler, a period of 120 min of right C1-C2 spinal cord electric stimulation was performed. A mean of 27% increase in previous blood flow recordings was obtained at the right hemisphere and a mean of 32% in the posterior fossa. This procedure was used in 10 patients presenting with various cerebral low perfusion syndromes. Though not constant, an increase in alertness, retention, speech, emotional lability and performance in skilled acts was achieved. No MR changes were observed, though SPECT readings showed an increase in blood flow in the penumbral perilesional area.

Small sized AVMs respond well to stereotactic radiosurgery, while larger AVMs do poorly with stereotactic radiosurgery or stereotactic fractionated radiotherapy. A combination of both methods is proposed for the treatment of these larger lesions.

Since 1982 a series of 11 epileptic patients have been treated with stereotactic radiosurgery. Patients were intracranially recorded with cortical and deep electrodes until the location of the epileptogenic focus was determined. A deep electrode was stereotactically placed at this point to confirm the accuracy of the location. All patients received radiosurgery with a gamma source and a dose of 10 to 20 Gy, except two of them in which a betatron was used. The results were: Total disappearance of the crises and withdrawal of medication: 4 cases (36%). More than 80% reduction of crises: 3 cases (27%). More than 50% reduction of crises: 2 cases (18%). Less than 50% reduction of crises: 2 cases (18%). No complications were observed, even in those cases in which the focus was located near critical areas of the brain. The efficacy of the low doses used accounts for non-destructive mechanisms, probably mediated by a neuronal plasticity phenomenon, as experimental studies suggest. The lack of complications can make this therapeutic approach an alternative to be considered when critical areas are involved.

A total of 14 meningiomas were studied in this report, grouped in different subtypes. The number of NORAg of each was analyzed and quantified. This study analyzes the results obtained as opposed to different subtypes and with clinic and biologic characteristics of patients. Similarly, technical characteristics of silver impregnation method to determine nucleolar organizer regions (NORAg) and its application as a routine method were analyzed. We propose this as a fast and reliable method to analyze of neoplastic proliferative activity.

The good results obtained by stereotactic radiosurgery in arteriovenous malformations has led the authors to expect similar results in low flow carotid-cavernous fistulae. In this paper, 20 cases who underwent radiosurgery with a conventional gamma source are presented. The total dose delivered was 36 to 40 Gy. 90% of the patients were cured after radiosurgery after a mean time of 7 months. Those presenting a mild improvement after a mean time of 2 months and those with a marked improvement after 4 months.

A series of 39 samples were obtained from meningiomas in 28 patients in order to investigate the relationships of the oestrogen receptor (OER) and progesterone receptor (PR) with the tumoural subtype and some histological features. Twenty-one samples were positive (greater than 10 fmole/mg protein), 7 were OER-PR-negative, and 1 was positive in both receptors. Twenty-two samples were considered as syncitial, 7 transitional, 7 fibroblastic and 3 angioblastic. The histological subtype was not found to be significantly related to the presence or absence of PR. Relations were not observed between the progestin receptor and the following histological parameters: cellular pattern, cell density, nuclear polymorphism, mitosis, lymphoplasmacellular infiltrates, degree of vascularization, psammoma bodies and interstitial fibrosis. Only the presence of intratumoural necrosis was significantly related with a low PR levels. However, progesterone binding activity was lower in tumours with numerous psammomas, fibroblastic cell pattern and interstitial fibrosis. The clinical and biological significance of these results is discussed.

Based on the rewarding effect of septal area, therapeutic stimulation of this region has been applied to surgical management of chronic pain. However some basic problems of this technique remain unsolved. Thus the effect of septal stimulation was tested on an experimental model of painful and symbolic stress, comparing the variations in the pituitary-adrenal axis activity, the peripheral catecholamine levels and the structural changes in gastric mucosa and adrenal glands, between the problem and different control groups. The bioelectrical activity of septal area and anterolateral hypothalamus during stimulation were recorded. A decrease in gastric ulceration and plasma cortisol were observed in the septal stimulation group. No direct influence on the catecholaminic system was noted. A facilitation of septal activity and its influence on hypothalamic rythm were found. All these effects were mainly achieved in the posterior perifornical septal region.

The bolus injection test was used to study the intracranial volume pressure relationships in an experimental population of normal and hydrocephalic dogs. Hydrocephalus was developed by means of an intracisternal injection of a kaolin powder solution. Hydrocephalic animals were tested a mean of 15 days after kaolin injection. The intraventricular pressure (ICPo) and amplitude of intraventricular pulse wave (AMPo) were measured at baseline steady-state. Pressure-volume index (PVI) and intracranial compliance (C) were calculated from bolus injection tests. The ICPo (p less than 0.01) and AMPo (p less than 0.001) were much higher in hydrocephalic animals and C decreased significantly (p less than 0.001). There were no statistical differences regarding PVI. A direct linear correlation was found between AMPo and ICPo (p less than 0.001) and between PVI and ICPo (p less than 0.05) but no correlations were found between PVI and AMPo. The regression analysis showed a non-linear correlation between C and ICPo (p less than 0.01) and between C and AMPo (p less than 0.001). The results of our experimental study suggest that: 1) pulse amplitude relates to the intracranial compliance, and 2) the intracranial compliance is a better parameter of the volume-pressure response than PVI.

The clinical symptoms, pathological findings and surgical treatment of a case of primary frontal lobe eosinophilic granuloma are presented. Initially a frontal mass was detected that clinically seemed like a low-growth tumor. After operation, the histological, cytochemical and ultrastructural studies showed positive acid phosphatase, alpha-naftil-esterase, oil-red and PAS reactions of tumoral cells and the presence of rod-shaped bodies in proliferative histiocytes, all which confirmed the pathological diagnosis of eosinophilic granuloma. Other osseous or visceral histiocytosis-X signs were not observed. The patient remains asymptomatic after a postoperative follow-up of 2 years.

An experimental model of kaolin-induced hydrocephalus in the dog was studied in order to evaluate the progress of ventricular dilatation and the communications between the ventricular system and the subarachnoid space. Skull and spine radiological studies were obtained after metrizamide intraventricular injection, and the baseline ventricular pressure and cerebral pulse pressure amplitude were measured in anesthetized animals. Intracranial compliance and resistance to drainage of cerebrospinal fluid were calculated by means of bolus injection test. Light and scanning electron microscope studies were done at different developmental stages of hydrocephalus. With these experimental parameters, two successive phases were seen: an initial acute hypertensive hydrocephalus (H1) with high resistance, low compliance, severe ependymal damage, and subependymal edema; and a late chronic normotensive hydrocephalus (H2) with little resistance increase, normal compliance, epithelial regeneration, and subependymal gliosis. Both the H1 and H2 stages showed an increase in the cerebral pulse pressure amplitude.

The authors propose a hypothesis about the mathematical relationship between the position and intensity of epileptogenic discharge and the potential recorded from an electrocorticographic electrode. A computer program is used to solve the equation and to determine a small area of maximal probability for the focus to be found.

The hemodynamic changes induced by spinal cord stimulation (SCS) have been studied in a group of 20 patients with peripheral vascular pain. The surgical technique consisted of the introduction of 1 or 2 electrodes in the subarachnoid space up to the level of the painful area, for mono or bipolar SCS. Several techniques have been used for evaluation of hemodynamic changes induced by SCS. Peripheral blood flow speed was measured by means of ultrasound Doppler, showing a raised maximum speed during stimulation, and a tendency of the pulse wave to return to normal. Thermography showed a marked increase of temperature in the painful area. Preoperatively, plethysmography showed an absence of the typical flow waveform, whilst postoperative recordings showed a small wave of progressively increasing amplitude. Scintigraphy with 201TI showed an increase in muscular blood flow in previously hypovascularized areas. The mechanism of action of SCS on peripheral blood flow and vascular pain is discussed.

Based on experimental and clinical evidence of central pain produced by hyperactivity of deafferented neurones and associated with irritative foci at thalamic or cortical levels, stereotactic low-dose (10 Gy) radiosurgery has been performed in 3 patients with central pain syndromes. SEEG findings and results of stereotactic radiosurgery on painful conditions are presented and mechanisms of action discussed.

In 17 epileptic patients, most of them with seizures of partial type but with diffuse or focal alternating abnormalities in the electroencephalographic recordings, chronic implantation of subarachnoid electrodes was performed. Through two bicoronal burr-holes and under fluoroscopic control, 13 to 19 insulated monopolar flexible electrodes were introduced in the subarachnoid space, conducting them either to standardized cortical targets, or concentrating them in that area of interest showed by conventional EEG. The electrodes were placed bilaterally and symmetrically, and remained implanted for 10 days. During this period, the activity of multiple foci, the reciprocal dependence between them, its reaction to cortical electric stimulation, barbiturate administration and sleep, were studied. No morbidity was found. Because of the simplicity and safety of this technique, it appears to be a good diagnostic method placed between conventional EEG and stereoelectroencephalography.

An experimental model of cobalt-induced epilepsy was performed on 15 cats. 3 months later, they were irradiated by means of a gamma source with a total target dose of 10 Gy. One month after irradiation all EEG recordings returned to normal, while a control group maintained the epileptiform traces. Histological study of the irradiated foci showed neuronal reafferentation. The action mechanism of ionizing radiation over epileptogenic foci in relation to this reafferentation and neuronal plasticity mechanisms is discussed.

A case of traumatic avulsion of the L-5 and S-1 nerve roots is described. Surgical intervention was undertaken and long-term functional recovery obtained.

Percutaneous epidural stimulation of the low thoracic spinal cord was carried out in 41 patients with pain from peripheral arterial disease of the lower limbs. Results are reported relating to pain, claudication distance, peripheral blood flow, and trophic lesion changes. Following a trial period of stimulation, 37 patients had stimulators permanently implanted. After a mean poststimulation follow-up period of 25 months, substantial pain relief (75% to 100%) was obtained in 29 cases; claudication distance significantly increased in 15 cases; Doppler ultrasound recordings of lower-limb distal arteries showed a tendency toward normalization of pulse-wave morphology, with increase of amplitude in 12 of the 23 patients studied; a rise in skin temperature was also detected by thermography. Distal arterial blood pressure remained unchanged with stimulation. Ischemic cutaneous trophic lesions of less than 3 sq cm healed, but gangrenous conditions were not benefited. A placebo effect or the natural history of the disease can be excluded as the reason for these improvements. It is concluded that spinal cord stimulation is a valid alternative treatment for moderate peripheral arterial disorders when direct arterial surgery is not possible or has been unsuccessful.

Sixty laminectomies were performed in dogs to investigate the prevention of the laminectomy membrane and its side effects. These operations were distributed in six groups of 10, one was a control group, and in the others the bone defect was protected with different materials (Oxicel, Silastic, Dacron, methyl methacrylate, and Kiel bone graft). After a survival of 2 months, suboccipital myelography was performed, immediately after which the animals were sacrificed and the operated spinal slice obtained. The different radiographic densities of the tissues of each slice were calculated and the diverse histological nature identified by hematoxylin and eosin, periodic acid Schiff, Masson's trichrome, and Gomori's reticulin strains. Only the acrylic plastic and the Kiel bone graft prevented expansion of the scar tissue inside the spinal canal and adhesions between the dura and the cicatrical overlying muscles. Therefore, the authors suggest that a solid barrier is necessary to effectively prevent the so-called "laminectomy membrane."

An analysis of the long-term results of 42 patients with epilepsy and behavioural disturbances treated by stereotactic fornicotomy has been carried out. An attempt has been made to classify the indications for this surgical method. Patients must be selected according the following criteria: the lower age groups, severe behavioural disturbances and epileptic symptomatology unchanged by any other form of treatment, normal I,Q. and electroencephalographic demonstration of a temporal lobe epileptic focus. The stereotactic lesion of the fornix was always carried out homo-laterally and was without morbidity and mortality. The results have been satisfactory in 70% of our patients but mainly when aggression was the main feature. The best results are related to a high I.Q. and a short clinical history.

Fourteen cases of single and polimalformative craniosynostosis are presented. A Crouzon's syndrome, and Apert's syndrome and a Carpenter's syndrome are included. On the cranial deformities, 7 cases of scaphocephaly, 4 cases of oxycephaly and 3 cases of acrocephaly were diagnosed. The eye abnormalities, the mental retardation and the intracranial hyperpressure symptomatology were analyzed. A lineal descompresive craniectomy was performed in 10 cases. The applied surgical criterium was the appearing of intracranial hyperpressure. The postoperative results upon the clinical symptomatology and the cranial deformity are commented, showing a real improve of the hyperpressure symptoms in all the cases, a correction of the scaphocephalic defect and a lack of effect on those clinical manifestations resulting from the cerebral damming. Finally, the timing of operation is discussed.

Radiofrequency lesions of the spinothalamic tract in the pons have been made in five patients with pain from malignant disease. In all cases relief from pain in the upper limbs and neck was obtained. No important dysesthesias were reported postoperatively. Findings on stimulation in the target and elsewhere in the pons are described. In one case the lesion was verified on postmortem examination.

Focal irradiation of epileptic foci has been performed in a group of 6 epileptic patients, of whom 2 presented with epilepsy and 4 with epileptic psychoses. The epileptic focus was localized by means of conventional scalp EEG, electrocorticography and stereoelectroencephalography. Radiosurgery was performed by coupling a stereoguide to a 60Co unit using a 10-mm diameter collimator. An estimated dose of 10 Gy was administered. Results are presented and the mechanism of action of radiation discussed.