[Candida albicans cerebral granuloma in an immunocompetent patient. A case report]. / Granulome cérébral àCandida albicans chez un patient immunocompétent. Cas clinique.

We report a case of temporal lobe granuloma caused by Candida albicans in an immunocompetent patient. This 54-year-old patient had experienced headaches and some memory disorders for two to three months before his admission to the neurosurgical department. Cerebral-computer tomography and magnetic resonance imaging showed a single right-temporal lesion with a large peritumoral edema. We operated on the patient via a temporal approach using neuronavigation and resected the lesion. The anatomopathological result and the cultures of the granuloma showed C. albicans species. The patient received antifungal therapy for three months. No predisposing factors or immunosuppression was found. After seven months, he presented an ischemic cerebrovascular accident of the brain stem and then chronic meningitis complicated by hydrocephalus. The patient's condition progressively deteriorated and he died 18 months later in an other department. C. albicans can be found even in the immunocompetent patient, but is seldom observed. Surgery can provide an accurate diagnosis and therapeutic management in the initial phase, completed by antifungal therapy.

[Surgical treatment of cortical and subcortical cavernomas. General principles and personal series of 20 cases treated between 2000 and 2006]. / Traitement chirurgical des cavernomes corticaux et sous-corticaux. Principes généraux et série personnelle de 20 cas opérés entre 2000 et 2006.

The surgical treatment of cortical or subcortical hemispheric cavernomas is founded on a series of questions: Is the cavernoma located in an eloquent or non-eloquent area? Is the cavernoma tangent to the cortex and visible immediately after the dura opening or deep seated in the hemisphere? Does the cavernoma lie in the depth of a sulcus and identifiable on the pretrans-sulcal approach MRI? Will perilesional tissue have to be removed to cure the epilepsy? What is the appropriate technology for each particular case: preoperative functional MRI, angiography, preoperative stereotactic guidance, peroperative ultrasonography, neuronavigation, peroperative neurophysiology and cortical stimulation, preoperative MRI? Based on a personal series of 20 cases operated on between 2000 and 2006, we describe our personal experience.

[Giant extradural epidermoid cyst of the posterior fossa]. / Kyste épidermoïde extra-dural géant de la fosse postérieure.

We report an unusual case of giant extradural epidermoid cyst of the posterior fossa in a 73-year-old man. The patient presented headache and gait disturbance for 3-4 months, cerebellar ataxia, left cerebellar dysmetria, and perturbed balance. The CT-scan showed a huge posterior fossa extradural lesion with a small area of peripheral contrast enhancement. Outcome was good after total resection of the lesion via a suboccipital approach. Pathology reported an epidermoid cyst. Extradural epidermoid cyst is a rare benign tumor of the skull which sometimes can reach considerable size. It is a slow growing lesion and may cause mild neurological deficits. The goal of surgical treatment is total resection of the tumor with its capsule. The long-term prognosis is excellent after successful resection.

[Metabolic imaging for supratentorial oligodendrogliomas]. / Les oligodendrogliomes supra-tentoriels: imagerie métabolique.

Metabolic imaging with positron emission tomography (PET) provides, in neuro-oncology, information complementary to that provided by anatomic imaging obtained with CT-scanner or MRI. Only a few publications have yet reported its use in oligodendroglial tumors. These findings and partial results obtained in ongoing work, suggest some preliminary conclusions: 11C-MET (L-methyl-methionine) is a more appropriate tracer than 18F-FDG (fluoro-deoxy-glucose), in terms of both specificity and sensitivity, for the assessment of patients with this category of tumor. PET/MET allows differentiation between grade II and grade III oligodendrogliomas; better targeting for stereotactic biopsy; more accurate assessment of the post-operative residual tumor; identification of progression from low-grade to anaplastic grade during the disease course; differentiation between recurrence and a post-radiation processes. PET/MET allows, to some extent, prediction of response to radiotherapy; and, probably, to chemotherapy.

[(18)F]-fluoro-L-thymidine PET and advanced MRI for preoperative grading of gliomas.

PURPOSE: Conventional MRI based on contrast enhancement is often not sufficient in differentiating grade II from grade III and grade III from grade IV diffuse gliomas. We assessed advanced MRI, MR spectroscopy and [(18)F]-fluoro-l-thymidine ([(18)F]-FLT) PET as tools to overcome these limitations. METHODS: In this prospective study, thirty-nine patients with diffuse gliomas of grades II, III or IV underwent conventional MRI, perfusion, diffusion, proton MR spectroscopy ((1)H-MRS) and [(18)F]-FLT-PET imaging before surgery. Relative cerebral blood volume (rCBV), apparent diffusion coefficient (ADC), Cho/Cr, NAA/Cr, Cho/NAA and FLT-SUV were compared between grades. RESULTS: Cho/Cr showed significant differences between grade II and grade III gliomas (p = 0.03). To discriminate grade II from grade IV and grade III from grade IV gliomas, the most relevant parameter was the maximum value of [(18)F]-FLT uptake FLTmax (respectively, p < 0.001 and p < 0.0001). The parameter showing the best correlation with the grade was the mean value of [(18)F]-FLT uptake FLTmean (R(2) = 0.36, p < 0.0001) and FLTmax (R(2) = 0.5, p < 0.0001). CONCLUSION: Whereas advanced MRI parameters give indications for the grading of gliomas, the addition of [(18)F]-FLT-PET could be of interest for the accurate preoperative classification of diffuse gliomas, particularly for identification of doubtful grade III and IV gliomas.

Relationships between high oxygen extraction fraction in the acute stage and final infarction in reversible middle cerebral artery occlusion: an investigation in anesthetized baboons with positron emission tomography.

Studies in humans suggest that regions that show maximal increases in brain oxygen extraction fraction (OEF) in the hours following an ischemic episode are those most vulnerable for infarction and are often, although not always, associated with the final site of infarction. To clarify this issue, we followed the hemodynamic and metabolic characteristics of regions with an initially maximally increased OEF and compared them with the ultimately infarcted region in an experimental stroke model. Positron emission tomography (PET) was used to obtain functional images of the brain prior to and following reversible unilateral middle cerebral artery occlusion (MCAO) in 11 anesthetized baboons. To model early reperfusion, the clips were removed 6 h after occlusion. Successive measurements of regional CBF (rCBF), regional CMRO2 (rCMRO2), regional cerebral blood volume, and regional OEF (rOEF) were performed during the acute (up to 2 days) and chronic (> 15 days) stage. Late magnetic resonance imaging (MRI) scans (co-registered with PET) were obtained to identify infarction. Reversible MCAO produced an MRI-measurable infarction in 6 of 11 baboons; the others had no evidence of ischemic damage. Histological analysis confirmed the results of the MRI investigation but failed to show any evidence of cortical ischemic damage. The lesion was restricted to the head of the caudate nucleus, internal capsule, and putamen. The infarct volume obtained was 0.58 +/- 0.31 cm3. The infarcts were situated in the deep MCA territory, while the area of initially maximally increased OEF was within the cortical mantle. The mean absolute rCBF value in the infarct region of interest (ROI) was not significantly lower than in the highest-OEF ROI until 1-2 days post-MCAO. Cerebral metabolism in the deep MCA territory was always significantly lower than that of the cortical mantle; decreases in CMRO2 in the former region were evident as early as 1 h post-MCAO. In the cortical mantle, the rOEF was initially significantly higher than in the infarct-to-be zone. Subsequently, the OEF declined in both regions. The differences in the time course of changes in CMRO2 and OEF between these two regions, with the eventually infarcted area showing earlier metabolic degradation and in turn decline in OEF, presumably underlie their different final outcomes. In conclusion, following MCAO, the region that shows an early maximal increase in the OEF is both topographically and physiologically distinct from the region with final consolidated infarction if reperfusion is allowed at 6 h. This high OEF, although indicative of a threatened condition, is not an indicator of inescapable consolidated infarction and is thus a situation in which therapy could be envisaged. Whether or not it is at risk of infarction and thus constitutes one target for therapy remains to be seen.

Increased expression of transforming growth factor-beta after cerebral ischemia in the baboon: an endogenous marker of neuronal stress?

There has been an increasing interest in recent years in the evaluation of the neuronal and glial responses to ischemic insult. Some cytokines, including transforming growth factor-beta (TGF-beta), that are overexpressed after experimental stroke in rodents are thought to be implicated in the neuronal processes that lead to necrosis. Thus, such cytokines could predict tissue fate after stroke in humans, although data are currently sparse for gyrencephalic species. The current study addressed the expression pattern of TGF-beta1 in a nonhuman primate model of middle cerebral artery occlusion. Focal permanent ischemia was induced for 1 or 7 days in 6 baboons and the following investigations were undertaken: cerebral oxygen metabolism (CMRO2) positron emission tomography studies, magnetic resonance imaging, postmortem histology, and reverse transcription-polymerase chain reaction. The aim of the current study was to correlate the expression of TGF-beta1 to the underlying metabolic and histologic state of the threatened cerebral parenchyma. The authors evidenced increased TGF-beta1 mRNA levels (up to 25-fold) in those regions displaying a moderate (20% to 49%) reduction in CMRO2. The current findings suggest that the greatly enhanced expression of TGF-beta1 in the penumbral zones that surround tissue destined to infarction may represent a robust index of potentially salvageable brain. The current investigation, in the nonhuman primate, strengthens the authors' hypothesis, derived from rodent models, that TGF-beta1 may be involved in the physiopathology of human stroke.

Regional cerebral oxygen consumption, blood flow, and blood volume in healthy human aging.

Using high-resolution positron emission tomography and the oxygen 15 continuous inhalation method, we examined the changes in cerebral metabolic rate of oxygen, blood flow, blood volume, and oxygen extraction fraction as a function of age in 25 optimally healthy, unmedicated volunteers who ranged in age from 20 to 68 years. Subjects were strictly selected for absence of cerebrovascular risk factors, dementia, or mental disorders; they had neither biological nor clinical abnormalities, and no focal anomaly on computed tomographic scan. Regions of interest were determined according to the anatomical structures defined on corresponding computed tomographic scan cuts obtained using a stereotaxic head-positioning method. This same method was also used for positron emission tomographic imaging. There was no significant effect of aging on PaCO2 values, hematocrit, arterial blood pressure, cholesterol and triglyceride levels, and blood glucose levels. In most cerebral cortex gyri, the cerebral metabolic rate of oxygen significantly decreased with age according to a linear pattern, with the same magnitude (about -6% per decade) in all four lobes and on both sides. This effect of age on cortical cerebral metabolic rate of oxygen persisted when the possible influence of cortical atrophy, gender, and head size were partialled out. In contrast, the white matter, deep gray nuclei, thalamus, and cerebellum were not significantly affected. The cerebral blood volume declined with a similar pattern to cerebral metabolic rate of oxygen, while changes in cerebral blood flow were less significant, presumably because of larger variance of data across subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Phase II study of fotemustine in recurrent supratentorial malignant gliomas.

38 adults with recurrent supratentorial malignant gliomas, including glioblastoma multiforme (21), anaplastic astrocytomas (9), probably transformed low-grade astrocytomas (6), pinealoblastoma (1) and non-metastatic tumour of unknown histology (1), were treated with fotemustine 100 mg/m2 intravenously every week for 3 consecutive weeks followed by a 5-week rest period. Maintenance treatment consisted of one infusion every 3 weeks. Patients were divided into three groups according to treatment effect. 10 objective responses (26%) with a median time without progression of 32.7 weeks, 18 stabilisations (47%) and 10 failures (26%) were observed. Pathological findings of the initial primary tumour and neurological functional status were unequally distributed in these groups. Haematological and liver toxicities were mild, delayed, transient and reversible. Thrombocytopenia and leukopenia were more frequent (30%) in patients treated with prior chemotherapy. Fotemustine is a well tolerated active drug in recurrent malignant gliomas with an original and short treatment schedule.

Comparative quantitation of cerebral blood volume: SPECT versus PET.

UNLABELLED: Quantification of cerebral blood volume (CBV) measured by SPECT has been used for evaluation of cerebral hemodynamics in patients with cerebrovascular diseases. The accuracy of such quantification, however, has not been validated with PET. METHODS: CBV was assessed using SPECT and in vitro 99mTc-labeled red blood cells and PET with the 15O steady-state inhalation method and C15O. In 23 patients with carotid artery disease, we measured hemispheric (including cortical and subcortical areas) CBV, and in 11 patients, we measured regional CBV in small cortical regions. We further evaluated the interhemispheric and inter-regional asymmetry of CBV with both methods. RESULTS: Quantitative values of both hemispheric and regional CBV measured by SPECT were significantly correlated with those measured by PET in the same patients. There was a significant correlation between the side-to-side asymmetry of CBV for both methods. CONCLUSION: This study demonstrates usefulness and the accuracy of SPECT for quantitative CBV assessment in comparison with the less widely available PET procedures.

Progressive impairment of brain oxidative metabolism reversed by reperfusion following middle cerebral artery occlusion in anaesthetized baboons.

A better understanding of the temporospatial evolution of ischaemic brain tissue towards necrosis would be of crucial value to establish and validate therapeutic strategies for stroke in man. By means of sequential positron emission tomographic (PET) studies performed through the acute to the chronic stages of infarction, we addressed the question of the effect of 6 h temporary occlusion of the middle cerebral artery (MCAO) on the evolution of the volume of severely hypometabolic tissue in anaesthetized baboons and compared it to that reported previously in permanently occluded baboons. Thirteen anaesthetized baboons underwent serial PET (15O steady-state technique) examinations before and 1, 4, 7, 24-48 h and 15-62 days following transorbital MCAO. Reperfusion, at 6 h post-occlusion, was assessed by Doppler sonography and cerebral blood flow (CBF) values after clip removal. In each baboon, the infarct volume was calculated by standard histological procedures 20-91 days after MCAO. The severely hypometabolic tissue volume, as defined by a threshold of oxidative metabolism, showed a progressive increase for up to 24-48 h in a not dissimilar manner to that found in baboons with permanent occlusion. However, these hypometabolic volumes regressed in the chronic stage (p < 0.05). Permanent and temporary occluded baboons, when taken together, showed a highly significant relationship between histological and chronic hypometabolic volumes (r = 0.84; p < 0.001). Moreover, the final hypometabolic volume where cerebral metabolic rate of oxygen (CMRO2) was below 40% of contralateral metabolism corresponded well to that of histological infarction volume. We conclude that, in anaesthetized baboons, restoration of blood flow will reverse (even if not immediately) the progressive derangement of metabolism after MCAO and markedly limit the final volume of consolidated infarction.)

[11C]L-methionine uptake in gliomas.

Treatment of gliomas remains disappointing in spite of a great number of experimental biological data and of randomized therapeutic studies. This could be partly explained by the inefficiency of our conventional methods to assess the regional metabolism of these tumors. The use of positron emission tomography (PET) brings encouraging possibilities in this field. We report our preliminary experience of measuring regional cerebral methionine uptake with PET after intravenous injection of [11C]L-methionine. Twenty-two patients with histologically confirmed gliomas were studied. An ECAT II positron emission tomograph was used for scanning. The position of the plane was chosen to include a major section of the tumor in the reconstructed brain slice. The protocol required a two-step examination: 1) after injection of 15 to 25 mCi of [11C]L-methionine, 12 scans were performed over a period of 46 minutes; and 2) 18 hours later, regional cerebral blood volume was measured in the same slice after intravenous injection of 2 to 4 mCi of 68GaCl3. The tumoral region of interest was determined as being the area of maximum activity. For each patient we calculated the ratio, R, between the activity in this tumor region of interest and the activity in the contralateral healthy symmetric region of interest which was used as an "internal standard" for the same patient. We correlated the ratio R with the histological grading. In 22 patients, mean values of R were calculated for each tumor: Grade II (n = 5): R = 1.04 +/- 0.27; Grade III (n = 5): R = 1.68 +/- 0.22; and Grade IV (n = 12): R = 2.33 +/- 0.86.(ABSTRACT TRUNCATED AT 250 WORDS)

The in vivo metabolic pattern of low-grade brain gliomas: a positron emission tomographic study using 18F-fluorodeoxyglucose and 11C-L-methylmethionine.

OBJECTIVE: The object of the present study was to identify metabolic differences between low-grade astrocytomas and oligodendrogliomas and to improve their diagnosis and noninvasive assessment, because both types of tumors look very similar from the point of view of clinical and radiological data (as assessed by computed tomography and magnetic resonance imaging). METHODS: Before any aggressive treatment, 22 patients with primary low-grade gliomas (astrocytomas in 12 patients and oligodendrogliomas in 10) were investigated with positron emission tomography for both glucose metabolism (18F-fluorodeoxyglucose) and amino acid uptake (11C-L-methylmethionine). An original software that allows a full metabolic analysis of the tumor region of interest (defined from the T1-weighted magnetic resonance image) and compares tumor tissue uptake tracer concentrations with average healthy tissue values has been implemented for data processing. Heterogeneity of each individual tumor has been taken into account and was expressed in histograms, which provided data about the mean and also extreme and intermediate values of tracer concentrations and the way these values are distributed among the full tumor mass. RESULTS: It has been shown that both tumor types exhibit a glucose hypometabolism (slightly more pronounced with astrocytomas), whereas they strongly differ in methionine uptake, which is high in all oligodendrogliomas and either decreased, normal, or moderately increased in astrocytomas. This latter metabolic difference between both tumor populations may be partially explained by their different cell densities. CONCLUSION: This study suggests that despite similar radiological and clinical presentations, these two kinds of low-grade gliomas are metabolically different and could therefore have specific responses to different therapies. Moreover, their in vivo metabolic follow-up with positron emission tomography should rely on different parameters, depending on their histological type; methionine uptake may be more relevant than glucose metabolism in the follow-up of oligodendrogliomas.

[Percutaneous transluminal angioplasty in atheromatous stenosis of the proximal supra-aortic trunks: the brachiocephalic trunk and the subclavian artery]. / L'angioplastie endoluminale percutanée des sténoses athéromateuses des troncs supra-aortiques proximaux. Tronc artériel brachio-céphalique, artères sous-clavières.

The authors are reporting their experience about percutaneous transluminal angioplasty (PTA) in atheromatous stenosis of proximal supra-aortic arteries. In this series of 17 patients, with a 6-month follow-up, vertigos were the main clinical symptoms (8 cases), and it must be pointed out that 5 of these 8 patients also underwent a proximal angioplasty of one or the two of their vertebral arteries at the same time. Three subclavian steal-syndromes, one arterial insufficiency of an upper limb, one transient cerebral ischaemia, and four asymptomatic cases were also treated by the same procedure. For diagnosis as well as for follow-up, the authors are emphasizing the value of hemodynamic results of Doppler recording. As for the technics itself, it mainly derives from the PTA of the lower limbs arteries. The results in this series appear to be good from an hemodynamic point of view, with neither morbidity nor mortality.

[Diagnosis and prognosis in neuro-oncology: contribution of positron emission tomography]. / Diagnostic et pronostic en neuro-oncologie: apport de la tomographie par émission de positrons (TEP).

Positron emission tomography (PET) assesses the uptake and distribution of a radiopharmaceutics labelling tissue metabolism, in tumour and in presumably healthy brain, respectively. This technique provides data which are complementary from those obtained with anatomical imaging (CT-scanner, MRI) and with histology performed on a biopsy sample. The most frequently used tracers, in neuro-oncology, are 18FDG and 11C-methionine. However, for most of the applications of this technique, the latter tracer appears to be more effective than the former, both from the point of view of sensitivity and specificity. The main applications of PET in clinical neuro-oncology are the following

[Associated vertebral angioma and epidural cavernoma (author's transl)]. / Angiome vertébral associé à un cavernome épidural.

A 27 year old man developed a pyramidal syndrome with hypoesthesia up to the level of D8, over a period of two months. Radiographic examination revealed the presence of an angioma of D8. Selective angiography demonstrated that there was epidural invasion as well as an angioma of the vertebral body, and enabled embolization of the 2 pedicles of the lesion to be performed. This produced only a partial, temporary improvement, and a posterior epidural tumor was found and removed by operation. The histological appearance of the tumor was that of a cavernoma, and rapid and permanent recovery of normal neurological function was obtained after the operation. The authors discuss the pathogenicity of the neurological disorders associated with single bone angiomas, and the problems raised by their treatment.

[Hemodynamic study of obstructive lesions of the internal carotid artery: value of coupled measurement of regional cerebral blood flow and volume]. / Etude hémodynamique des lésions obstructives de l'artère carotide interne: intérêt de la mesure couplée du débit et du volume sanguins cérébraux régionaux.

A study of 130 patients having presented either a transient ischemic attack or a completed stroke, or admitted for an asymptomatic carotid stenosis, allowed the following investigations: CT-scan, doppler, angiography, measurement of the regional cerebral blood flow (rCBF) by the study of 133Xe clearance (Novocerebrograph (R)), and measurement of the regional cerebral blood volume (rCBV) made by gamma emission tomography after autotransfusion of 99m Tc-labeled erythrocytes with an Elscint Apex 415 ECT (R) camera. Our aim was to look in which case a rCBF and/or a rCBV interhemispheric asymmetry was observed, by comparing the previous hemodynamic parameters with clinical, CT-scan and angiographic data. Although a rCBF and/or a rCBV asymmetry appeared more often among patients presenting with infarction than among those of the asymptomatic category, this does not seem specific for any clinical grade. The same statement applies to the comparison between hemodynamic parameters and CT data. The arterial lesions were classified in 4 groups: no stenosis (12 cases), uni or bilateral moderate carotid stenosis (40 cases), unilateral severe carotid stenosis or occlusion (65 cases), bilateral carotid severe stenosis or occlusion (13 cases). We observed a rCBF asymmetry among some patients in the 4 groups, although this was more frequent among the two latter groups. Nevertheless no case of a rCBV asymmetry was observed in the 2 first groups. Such an asymmetry was present in 31 percent of the patients belonging to the two latter groups. In patients of the third group the asymmetry was always due to a relative increase of rCBV beyond the carotid lesion.(ABSTRACT TRUNCATED AT 250 WORDS)

[Endoluminal angioplasty for atheromatous stenoses of supra-aortic trunks. The brachiocephalic arterial trunk, subclavian arteries]. / L'angioplastie endoluminale des sténoses athéromateuses des troncs supra-aortiques. Tronc artériel brachio-céphalique, artères sous-clavières.

The authors are reporting their experience about percutaneous transluminal angioplasty in atheromatous stenosis of proximal supra-aortic arteries. In this series of 12 patients, with an 6 months follow-up, vertigo was the main clinical symptom (6 cases), and it must be pointed out that 5 of these 6 patients also underwent a proximal angioplasty of one or the two of their vertebral arteries at the same time. Two subclavian steal syndromes, one arterial insufficiency of an upper limb, one transient cerebral ischaemia, and two asymptomatic cases were also treated by the same procedure. For diagnosis as well as for follow-up, the authors are emphasizing the value of hemodynamic results of Doppler recording. As for the technics itself, it mainly derives from the PTA of the lower limbs arteries. The results in this series appear to be good from an hemodynamic point of view, with neither morbidity, nor mortality.

[Investigation methods of cerebral perfusion]. / Méthodes d'investigation de la perfusion cérébrale.

Brain energy metabolism is essentially oxydative, through the glycolysis and the Krebs cycle. Brain tissue cannot survive more than a few minutes if the substrate (glucose, for which there is no endogenous reserve) or oxygen supply is abolished. Otherwise, there is a precise matching between perfusion (cerebral blood flow-CBF) and oxydative (oxygen consumption-CMRO2) and glycolytic regional metabolism. When intraarterial pressure is decreased (due to a systemic arterial pressure impairment or an arterial obstructive lesion), CBF is maintained constant through an increase of the pial vessels caliber and therefore an enhancement of the cerebral blood volume (CBV); this is cerebral circulatory autoregulation. In physiologic conditions, any increase of the local metabolic demand (during a motor, sensory, or cognitive activation) is supplied through a local enhancement of perfusion, and reversely. Therefore, the measurement of brain perfusion is useful not only to assess the consequences of cerebrovascular or some other diseases, but also to observe the functions involved in the normal working brain. This measurement is most frequently focused on CBF (flow) parameter, but in some clinical circumstances the access to CBV will be also of major importance for a correct understanding of the physiological or pathophysiological situation. We shall describe the different methods available both in clinical and experimental practice, and shall indicate for each one its characteristics, advantages and pitfalls.

[The ventrolateral position]. / La position ventro-latérale.

AIM: To propose an alternative to the sitting position and the other horizontal positions while maintaining the advantages of the sitting position and assuring maximum safety for the patient particularly with respect to the risk of air embolism. POSITION: The patient is positioned as for the sitting position with the median axis of the posterior cranial fossa prolonging the spinal axis. The head is maintained by a Mayfield head holder and is inclined without force. The patient rests laterally on the apron, the thorax and the lower limbs resting on cushions. The upper limbs rest on the arm rests interdependent with the table facilitating surgical access and rolling movements. DATA: Since 1993, this position was used for 556 patients. For 81.3% of the patients lesions were located in the posterior cranial fossa and for 12.75% in the supratentorial region. Access to the cervical area was achieved for 4.7% of the patients. RESULTS: This position gave us access to the lesions without specific difficulties, irrespective of the patient's morphology. There were no air embolism events and no capnographic anomaly was reported. CONCLUSION: Since discontinuing use of the sitting position in our institution, we have found that the ventrolateral position can replace the sitting position advantageously. It allowed us to approach lesions located in a large area, from the cervical spine to the supratentorial area located behind external auditory meatus, and was compatible with anesthetic and surgical requirements.