The role of surgery when endovascular treatment is considered the first choice therapy for ruptured intracranial aneurysms.

AIM: Nowadays endovascular therapy is more and more considered as first choice treatment for ruptured intracranial aneurysms. The aim of this study was to understand the impact that endovascular treatment (EVT), chosen as first therapeutic strategy, has had in the selection of ruptured intracranial aneurysms submitted to surgery at our Institution and what role neurosurgeons still play in this setting. METHODS: From 1998 to 2002, 272 consecutive patients were treated at the Hospital of Toulouse for ruptured intracranial aneurysms: 222 by embolization and 50 by surgery. The two groups were homogeneous for sex, age and aneurysms multiplicity. RESULTS: The patients of the surgical group had a worst clinical-radiological status at the treatment time than those treated by EVT. Clipping was performed for different reasons: 16% for failure of attempted EVT; 32% for intracranial hematoma requiring surgical evacuation; 30% for aneurysm morphology unsuitable for EVT and 22% for absence of the endovascular operator. Aneurysms of the middle cerebral artery (MCA) represented the main surgical group. The aneurysms judged unsuitable for EVT and addressed to surgery had often a complex morphology representing a challenge also for surgery. Mid-term outcome is significantly better for patients treated by EVT. CONCLUSION: The results show that microsurgery continues to have a role in the treatment of ruptured intracranial aneurysms even when EVT is the first choice. The precarious clinical conditions of the patients submitted to surgery and the frequent complexity of their aneurysms explain their worst outcome. This would advise training dedicated vascular Neurosurgeons to guaranty a high level treatment when EVT is not possible.

Frontoethmoidal meningoencephalocoele repair in Cambodia: outcomes and cost comparisons.

In Cambodia, spina bifida is rare, but frontoethmoidal meningoencephalocoeles (MECs) are common. Mean life expectancy for patients with congenital MECs may be <20 years, but the complex treatment required has not been available in the country until recently. During visits by combined neurosurgical/craniofacial teams from both Germany and France, a method of repair has been developed that is suitable for the local conditions, affordable and has allowed Cambodian surgeons to learn how to successfully treat MECs. The surgical technique and initial results with 30 patients have been described in a previous publication. This paper presents the outcomes of 128 cases and illustrates that it is cost-effective for these patients to be treated in Cambodia.

Motor cortex stimulation for neuropathic pain.

Since the initial publication of Tsubokawa in 1991, epidural motor cortex stimulation (MCS) is increasingly reported as an effective surgical option for the treatment of refractory neuropathic pain although its mechanism of action remains poorly understood. The authors review the extensive literature published over the last 15 years on central and neuropathic pain. Optimal patient selection remains difficult and the value of pharmacological tests or transcranial magnetic stimulation in predicting the efficacy of MCS has not been established. Pre-operative functional magnetic resonance imaging (fMRI), 3-dimensional volume MRI, neuronavigation and intra-operative neurophysiological monitoring have contributed to improvements in the technique for identifying the precise location of the targeted motor cortical area and the correct placement of the electrode array. MCS should be considered as the treatment of choice in post-stroke pain, thalamic pain or facial anesthesia dolorosa. In brachial plexus avulsion pain, it is preferable to propose initially dorsal root entry zone (DREZ)-tomy; MCS may be offered after DREZotomy has failed to control the pain. In our experience, the results of MCS on phantom limb pain are promising. In general, the efficacy of MCS depends on: a) the accurate placement of the stimulation electrode over the appropriate area of the motor cortex, and b) on sophisticated programming of the stimulation parameters. A better understanding of the MCS mechanism of action will probably make it possible to adjust better the stimulation parameters. The conclusions of multicentered randomised studies, now in progress, will be very useful and are likely to promote further research and clinical applications in this field.

Review of language organisation in bilingual patients: what can we learn from direct brain mapping?

Although the majority of people worldwide are bilingual, the brain representation of language in bilingual persons is still a matter of debate. Since the beginning of the studies conducted on bilinguals, most authors denied that learning a new language requires a new semantic processing or the involvement of new cortical areas. In this paper, we review neurosurgical studies using direct electrocortical or subcortical stimulation techniques for brain mapping in bilingual subjects and compare this data with that obtained from other brain mapping methods. The authors focused on the most controversial issue whether multiple languages are represented in common or distinct cerebral areas. Seven direct brain mapping studies from different teams focused on bilingualism and multilingualism. All these studies showed that even if cerebral representation of language in multilingual patients could be grossly located in the same cortical region, it was possible to individualise distinct language-specific areas by direct cortical stimulation in the dominant frontal and temporo-parietal regions. Task- and language-specific sites were also described, demonstrating an important specialisation of some cortical areas. Using subcortical stimulation, some authors were able to find specific white matter tracts for different languages. Finally, all authors recommend in bilingual patients who need brain mapping for neurosurgical purpose to test all languages in which the subjects are fluent.

Cortical intraoperative stimulation in brain tumors as a tool to evaluate spatial data from motor functional MRI.

RATIONALE AND OBJECTIVE: The purpose of this prospective, double-blind study was to correlate motor functional MRI (fMRI) with cortical brain mapping by intraoperative stimulation using 3D reconstructed images of the surface of the brain, and to validate the spatial data of fMRI in patients with brain tumors. METHODS: Fourteen patients with tumors of the rolandic region underwent functional MR mapping of the hand region and subsequently cortical mapping before tumor resection. Data obtained with fMRI and brain mapping were not known previously by the neurosurgeon and by the neuroradiologist, respectively (double-blind study). RESULTS: In each case, the results of direct cortical mapping matched those obtained with fMRI, both positively and negatively, although the extent of the functional activations was larger than the area required to elicit the corresponding movement during intraoperative brain mapping. CONCLUSION: fMRI can be used before surgery to assess motor functional area in patients with rolandic tumors. More studies are needed to validate during surgery the real extent of fMRI activations.

Chronic motor cortex stimulation for phantom limb pain: a functional magnetic resonance imaging study: technical case report.

OBJECTIVE AND IMPORTANCE: Chronic motor cortex stimulation has provided satisfactory control of pain in patients with central or neuropathic trigeminal pain. We used this technique in a patient who experienced phantom limb pain. Functional magnetic resonance imaging (fMRI) was used to guide electrode placement and to assist in understanding the control mechanisms involved in phantom limb pain. CLINICAL PRESENTATION: A 45-year-old man whose right arm had been amputated 2 years previously experienced phantom limb pain and phantom limb phenomena, described as the apparent possibility of moving the amputated hand voluntarily. He was treated with chronic motor cortex stimulation. INTERVENTION: Data from fMRI were used pre- and postoperatively to detect shoulder and stump cortical activated areas and the "virtual" amputated hand cortical area. These sites of preoperative fMRI activation were integrated in an infrared-based frameless stereotactic device for surgical planning. Phantom limb virtual finger movement caused contralateral primary motor cortex activation. Satisfactory pain control was obtained; a 70% reduction in the phantom limb pain was achieved on a visual analog scale. Postoperatively and under chronic stimulation, inhibiting effects on the primary sensorimotor cortex as well as on the contralateral primary motor and sensitive cortices were detected by fMRI studies. CONCLUSION: Chronic motor cortex stimulation can be used to relieve phantom limb pain and phantom limb phenomena. Integrated by an infrared-based frameless stereotactic device, fMRI data are useful in assisting the neurosurgeon in electrode placement for this indication. Pain control mechanisms and cortical reorganization phenomena can be studied by the use of fMRI.

Virtual movements activate primary sensorimotor areas in amputees: report of three cases.

OBJECTIVE: In our multidisciplinary pain clinic, three patients with amputated limbs and with surgical indications for chronic motor cortex stimulation for phantom limb pain were selected for their ability to voluntarily move the missing limb. The sensation of being able to move a missing limb at will occurs quite frequently among traumatic amputees, but the ability to control it sufficiently to perform a functional magnetic resonance imaging (fMRI) examination is more rarely encountered. We used motor fMRI to study these virtual movements. METHODS: In two patients with upper-limb amputations, movements of the stump, the normal hand, and the missing arm were studied. In a third patient with both legs amputated, movements of the stumps and of the missing feet were studied. The fMRI data were analyzed with the Statistical Parametric Map 96 software and reformatted for integration into anatomic slices. RESULTS: Virtual movements of the missing limbs produced contralateral primary sensorimotor cortex and central sulcus activations in the patients with upper-limb amputation. Interhemispheric and bilateral activations were found in the patient with both legs amputated. These activation areas were different from the stump activation areas. Additionally, the significance thresholds chosen to generate the activation maps in virtual movements (although individual) were globally the same as those used to detect motor activation in the normal side of the patients. CONCLUSION: Cortical areas devoted to the missing limb seem to persist for several years after amputation. The precentral activations found in our patients are in agreement with the statement that the neural mechanisms involved in the mental representation of an action and in its execution are the same. Data from fMRI can be used to evaluate phantom limb virtual movements and to study cortical reorganization phenomena that can appear with time or as a result of some therapies. In these patients, fMRI data may be useful in assisting the neurosurgeon in the placement of chronic motor cortex electrodes.

Methodological and technical issues for integrating functional magnetic resonance imaging data in a neuronavigational system.

OBJECTIVE: The aim of this article was to analyze the technical and methodological issues resulting from the use of functional magnetic resonance image (fMRI) data in a frameless stereotactic device for brain tumor or pain surgery (chronic motor cortex stimulation). METHODS: A total of 32 candidates, 26 for brain tumor surgery and six chronic motor cortex stimulation, were studied by fMRI scanning (61 procedures) and intraoperative cortical brain mapping under general anesthesia. The fMRI data obtained were analyzed with the Statistical Parametric Mapping 99 software, with an initial analysis threshold corresponding to P < 0.001. Subsequently, the fMRI data were registered in a frameless stereotactic neuronavigational device and correlated to brain mapping. RESULTS: Correspondence between fMRI-activated areas and cortical mapping in primary motor areas was good in 28 patients (87%), although fMRI-activated areas were highly dependent on the choice of paradigms and analysis thresholds. Primary sensory- and secondary motor-activated areas were not correlated to cortical brain mapping. Functional mislocalization as a result of insufficient correction of the echo-planar distortion was identified in four patients (13%). Analysis thresholds (from P < 0.0001 to P < 10(-12)) more restrictive than the initial threshold (P < 0.001) had to be used in 25 of the 28 patients studied, so that fMRI motor data could be matched to cortical mapping spatial data. These analysis thresholds were not predictable preoperatively. Maximal tumor resection was accomplished in all patients with brain tumors. Chronic motor cortex electrode placement was successful in each patient (significant pain relief >50% on the visual analog pain scale). CONCLUSION: In brain tumor surgery, fMRI data are helpful in surgical planning and guiding intraoperative brain mapping. The registration of fMRI data in anatomic slices or in the frameless stereotactic neuronavigational device, however, remained a potential source of functional mislocalization. Electrode placement for chronic motor cortex stimulation is a good indication to use fMRI data registered in a neuronavigational system and could replace somatosensory evoked potentials in detection of the central sulcus.

Management of hydrocephalus in pediatric patients with posterior fossa tumors: the role of endoscopic third ventriculostomy.

OBJECT: The authors undertook a study to evaluate the effectiveness of endoscopic third ventriculostomy in the management of hydrocephalus before and after surgical intervention for posterior fossa tumors in children. METHODS: Between October 1, 1993, and December 31, 1997, a total of 206 consecutive children with posterior fossa tumors underwent surgery at Hjpital Necker-Enfants Malades in Paris. Excluded were 10 patients in whom shunts had been placed at the referring hospital. The medical records and neuroimaging studies of the remaining 196 patients were reviewed and categorized into three groups: Group A, 67 patients with hydrocephalus present on admission in whom endoscopic third ventriculostomy was performed prior to tumor removal; Group B, 82 patients with hydrocephalus who did not undergo preliminary third ventriculostomy but instead received conventional treatment; and Group C, 47 patients in whom no ventricular dilation was present on admission. There were no significant differences between patients in Group A or B with respect to the following variables: age at presentation, evidence of metastatic disease, extent of tumor resection, or follow-up duration. In patients in Group A, however, more severe hydrocephalus was demonstrated (p < 0.01): the patients in Group C were in this respect different from those in the other two groups. Ultimately, there were only four patients (6%) in Group A compared with 22 patients (26.8%) in Group B (p = 0.001) in whom progressive hydrocephalus required treatment following removal of the posterior fossa tumor. Sixteen patients (20%) in Group B underwent insertion of a ventriculoperitoneal shunt, which is similar to the incidence reported in the literature and significantly different from that demonstrated in Group A (p < 0.016). The other six patients (7.3%) were treated by endoscopic third ventriculostomy after tumor resection. In Group C, two patients (4.3%) with postoperative hydrocephalus underwent endoscopic third ventriculostomy. In three patients who required placement of CSF shunts several episodes of shunt malfunction occurred that were ultimately managed by endoscopic third ventriculostomy and definitive removal of the shunt. There were no deaths; however, there were four cases of transient morbidity associated with third ventriculostomy. CONCLUSIONS: Third ventriculostomy is feasible even in the presence of posterior fossa tumors (including brainstem tumors). When performed prior to posterior fossa surgery, it significantly reduces the incidence of postoperative hydrocephalus. The procedure provides a valid alternative to placement of a permanent shunt in cases in which hydrocephalus develops following posterior fossa surgery, and it may negate the need for the shunt in cases in which the shunt malfunctions. Furthermore, in patients in whom CSF has caused spread of the tumor at presentation, third ventriculostomy allows chemotherapy to be undertaken prior to tumor excision by controlling hydrocephalus. Although the authors acknowledge that the routine application of third ventriculostomy in selected patients results in a proportion of patients undergoing an "unnecessary" procedure, they believe that because patients' postoperative courses are less complicated and because the incidence of morbidity is low and the success rate is high in those patients with severe hydrocephalus that further investigation of this protocol is warranted.

[Importance and limitations of the validation of functional MRI of motor function and language using preoperative cortical stimulation]. / Intérêt et limites de la validation de l'irm fonctionnelle de la motricité et du langage par la stimulation corticale peropératoire.

UNLABELLED: This chapter describes and discusses the value of the localization of functional areas obtained from functional MRI in brain tumor cases. Correlation method is cortical brain mapping by intraoperative stimulation. The experience reported here is focused on the study of motricity and language. METHODS: Twenty two patients with tumors of the rolandic region (n = 16) or in the temporal lobe (n = 6) underwent functional MR mapping and subsequently cortical mapping before tumor resection. The tasks chosen were a flexion and extension of the fingers or a naming task. We used 3D reconstructed images of the surface of the brain to assess intra and post operatively the functional MRI and stimulation data. RESULTS: For the motor correlation, in each case, the results of direct cortical mapping matched those obtained with functional MRI, both positively and negatively, although the extent of the functional activations was larger than the area required to elicit the corresponding movement during intraoperative brain mapping. For the language correlation and for the task chosen, only the results of the precentral areas matched those of functional MRI. CONCLUSIONS: Functional MRI can be used preoperatively to assess motor functional area in patients with rolandic tumors. More studies are needed to validate intraoperatively the language areas and the real extent of functional MRI activations. Finally, the observed discrepancy between functional MRI and cortical stimulation is likely due to the rather profound differences between both techniques, in terms of neurophysiology, practical applications and statistical analysis.

[Somatosensory evoked potentials during surgery of scoliosis: significance of epidural recording]. / Potentiels évoqués somesthésiques au cours de la chirurgie de la scoliose: intérêt du recueil épidural.

PURPOSE OF THE STUDY: To evaluate the usefulness of the epidural recording in scoliosis surgery in children or young adults. MATERIAL AND METHOD: We used somatosensory-evoked potentials in 60 children or young adults in surgical treatment of scoliosis. Somatosensory-evoked potentials were elicited and recorded using a standard method recording of cortical P40 and subcortical P27, simultaneously with the monitoring of spinal cord function using epidural electrode to record the ascending somatosensory volley (by tibial nerve stimulation) at a high thoracic level. RESULTS: The use of subcortical and epidural recording sites for the somatosensory-evoked potentials indicated that a reliable response could be obtained in 96 p. 100 of the patients. Cortical somatosensory-evoked demonstrated a 48 p. 100 false positive rate. DISCUSSION: Epidural recording in scoliosis surgery is safe and reliable. Combined subcortical and epidural recordings are especially useful in patients with neuromuscular scoliosis or with cerebral palsy that may not have reliable cortical potentials.

[Potential neurosurgical damage of rubber bullets. Analysis of 2 pediatric cases]. / Gravité neurochirurgicale potentielle des projectiles "caoutchouc". Analyse de 2 cas pédiatriques.

We present 2 cases of craniocerebral injuries in children caused by rubber bullets. The potential severity of these projectiles is discussed. The first case was an eleven-year-old boy who died a few days after having been injured by a rubber bullet during a riot. He presented with a bi-hemispheric fronto-parietal craniocerebral injury with massive intraventricular hemorrhage. The second case was a fourteen-year-old boy also injured by a similar rubber bullet with an important left fronto-temporal cerebral contusion. These projectiles were composed of a metal cylinder (length: 1.7 cm, diameter: 1.7 cm) covered by a 2 mm layer of rubber. The term "rubber bullet" could give the impression that these projectiles are harmless. But, based on these observations and on the literature, these rubber bullets (like their predecessors) can induce severe, or even fatal craniocerebral injuries.

[French neurosurgery in the Bosnia-Herzegovina conflict]. / Les missions neurochirurgicales françaises dans le conflit en Bosnie-HerzEgovine.

Seven French neurosurgical missions, from June 1994 to December 1996, were sent successively to Bosnia-Herzegovina with the help of a non-governmental organisation Médecins du Monde. The aim of this article is to present the working conditions, make an overall evaluation of the missions and then to draw lessons and discuss the limits. The initial aim of these neurosurgical missions was: i) to provide human and logistic support to the Bosniac teams in the field; ii) to exchange knowledge and help in the training of local young neurosurgeons; iii) to be present as witnesses. The towns of Tuzla and Zenica in Eastern and Central Bosnia respectively were chosen as the missions bases. One hundred five neurosurgical operations were carried out in precarious conditions, particularly concerning anesthesia. The largest number of the operations (52%) concerned standard neurosurgical pathologies, without any direct link to the war but which had been put off or made difficult due to the war. Cranioplasties and peripheric nerve injuries were the main lesions directly related to the war situation which the French missions had to deal with. Actually, war neurosurgical pathologies were very often dealt with in emergency by Bosniac teams in the field hospitals near the front. Previously existing neurosurgical environment, in particular with access to a scanner is an absolute necessity to carry out a good quality neurosurgical mission. Precarious anesthesia and operating conditions require the surgical team to adapt to local conditions, but are not a contra-indication to such missions. Although help in the field can prove useful on occasions, training the resident teams is important. This can be done locally, but additional training in a neurosurgically developed country is fundamental. Missions such as these require relatively major funding (about 150 000 French francs for each of our missions) and suitable infrastructures. Prior to undertaking this type of mission, a neurosurgeon must evaluate local human and equipment needs.

[Practical role of functional MRI in neurosurgery]. / Rôle pratique de l'IRM fonctionnelle en neurochirurgie.

INTRODUCTION: Since its description in the early 1990's, functional magnetic resonance imaging (fMRI) has been used first for research purposes, and after in clinical applications in the field of neurosurgery. The purpose of this article was to critically review the literature on fMRI to achieve a better understanding of the usefulness of fMRI in brain surgery for tumors, epilepsy surgery, and radiosurgery. MATERIAL AND METHODS: Medical literature databases containing peer-review articles dating from 1990 were queried for key words related to fMRI. RESULTS: On 3,065 references scanned for relevance, 256 articles with direct or indirect relationships between fMRI and neurosurgery were analyzed. DISCUSSION: fMRI can be useful in the selection of patients for whom a surgical resection is attempted and could aid in the decision-making whether to operate on a patient who has been previously considered inoperable. fMRI is a useful tool in the decisional scheme of treatment of low-grade astrocytomas or arteriovenous malformations in the rolandic area in intact or slightly impaired patients. fMRI can be repeated in selected patients with slow growing brain tumors or congenital lesions such as AVM to study cortical reorganization phenomena. In epilepsy surgery, the Wada-test could be substituted by fMRI to determine the hemispheric dominance of language. The choice of standardized tasks and a better understanding of analysis problems in the treatment of fMRI images must be achieved before drawing more accurate conclusions on fMRI and brain tumors.

[Presurgical evaluation of cerebral tumors with functional MRI]. / Evaluation pré-chirurgicale des tumeurs cérébrales par IRM fonctionnelle.

PURPOSE: To evaluate the capabilities and the limitations of motor functional magnetic resonance imaging (FMRI) in the presurgical planning of the cerebral tumors located in or near the motor homunculus and to correlate each type of activation with the histologic characteristics of each tumor. MATERIALS AND METHODS: FMRI was performed in 17 patients (14 adults and 3 children), without motor deficit, presenting with various intra cerebral tumors. Three FMRI activation paradigms were used, controlateral to the lesion: ballistic opposition of the fingers, flexion-extension of the foot and click of the tongue. Four patients, without motor deficit, with cerebral tumors far from the motor homunculus were used as control group to look for non specific activations. In all cases, the histopathology of the tumor was known accurately. RESULTS: In 11 patients with infiltrating tumors, the activated areas were clearly displaced. They were often intratumoral and scattered in correlation with the degree of infiltration. Two patients with non infiltrating tumors (meningioma) showed extratumoral shift of the activated areas. Four patients presenting cerebral tumors far from the homunculus motor did not show intratumoral activation. The supplementary motor area and the ipsilateral primary motor cortex were also sometimes activated during the motor tasks. The task of the tongue was often artifacted, probably because of the head motion. CONCLUSIONS: These preliminary results suggest that the histopathologic characteristics of a tumor and especially its microscopic structure plays a role, with others factors, on the motor functional area organization. In a small number of cases, the data obtained from the FMRI could be used intraoperatively, with a neuronavigation system.

Hemangioblastoma of the corpus callosum: A case report and review of the literature on its origin.

A third case of corpus callosum hemangioblastoma (HB) is presented. With no preoperative embolization, surgery was uneventful and the postoperative course was excellent. Based on the literature, we attempted to clarify the histogenesis of HB and to explain why they are exceptional in the supratentorial region in contrast to the posterior cranial fossa. The VHL gene is expressed particularly in Purkinje cells of the cerebellum, but this expression is also possible in supratentorial structures. Its mutation leads to developmental arrest of angioblasts that become potentially neoplastic cells. These CD133-positive pluripotent neoplastic angioblasts, similar to stem cells, may be immature HB in the brain. They also express VEGF, coexpress Epo/EpoR, and are capable of differentiation into primitive vascular structures. This coexpression may not only mediate developmental stagnation, but may also induce HB proliferation. Therefore, HB tumorigenesis may be initiated during embryogenesis and may originate from angiomesenchyma because of the expression of three cell types (stromal cells, pericytes, and endothelial cells) in vimentin. Their capacity for proliferation and differentiation in HB depends on the microenvironment.

Cortical areas involved in Arabic number reading.

OBJECTIVE: Distinct functional pathways for processing words and numbers have been hypothesized from the observation of dissociated impairments of these categories in brain-damaged patients. We aimed to identify the cortical areas involved in Arabic number reading process in patients operated on for various brain lesions. METHODS: Direct cortical electrostimulation was prospectively used in 60 brain mappings. We used object naming and two reading tasks: alphabetic script (sentences and number words) and Arabic number reading. Cortical areas involved in Arabic number reading were identified according to location, type of interference, and distinctness from areas associated with other language tasks. RESULTS: Arabic number reading was sustained by small cortical areas, often extremely well localized (<1 cm(2)). Over 259 language sites detected, 43 (17%) were exclusively involved in Arabic number reading (no sentence or word number reading interference detected in these sites). Specific Arabic number reading interferences were mainly found in three regions: the Broca area (Brodmann area 45), the anterior part of the dominant supramarginal gyrus (Brodmann area 40; p < 0.0001), and the temporal-basal area (Brodmann area 37; p < 0.05). Diverse types of interferences were observed (reading arrest, phonemic or semantic paraphasia). Error patterns were fairly similar across temporal, parietal, and frontal stimulation sites, except for phonemic paraphasias, which were found only in supramarginal gyrus. CONCLUSION: Our findings strongly support the fact that the acquisition through education of specific symbolic entities, such as Arabic numbers, could result in the segregation and the specialization of anatomically distinct brain areas.

Third ventriculocisternostomy in cerebellar haematomas.

BACKGROUND: We prospectively evaluated the role of endoscopic third ventriculocisternostomy in the management of acute obstructive hydrocephalus created by cerebellar hematomas. METHOD: Following a therapeutic diagram based on clinical and radiological signs, endoscopic third ventriculocisternostomy was used to treat hydrocephalus associated with cerebellar hematomas in 8 patients (male: 5, female: 3, mean age: 67 years-old). Causes of cerebellar hemorrhage were spontaneous in 6 cases, traumatic in 1 case, and acute bleeding of a posterior fossa tumor (lung metastasis) in the remaining case. Deeply comatose patients (Glasgow Coma Score between 3 and 5) and patients with signs of brainstem compression were initially excluded from this study. FINDINGS: Overall clinical improvement after third ventriculocisternostomy was achieved in all patients and was associated with the decrease of the ventricle size on follow-up CT scans. One patient who initially had a clot evacuation associated with an external ventricular drainage and persistant hydrocephalus had a successful third ventriculocisternostomy in the post operative course. No complication related to the procedure was noted. INTERPRETATION: In selected patients, third ventriculocisternostomy can be used to treat hydrocephalus associated with posterior fossa hematomas.

Perimetric visual field and functional MRI correlation: implications for image-guided surgery in occipital brain tumours.

OBJECTIVE: To compare the results of visual functional MRI with those of perimetric evaluation in patients with visual field defects and retrochiasmastic tumours and in normal subjects without visual field defect. The potential clinical usefulness of visual functional MRI data during resective surgery was evaluated in patients with occipital lobe tumours. METHODS: Eleven patients with various tumours and visual field defects and 12 normal subjects were studied by fMRI using bimonocular or monocular repetitive photic stimulation (8 Hz). The data obtained were analyzed with the statistical parametric maps software (p<10(-8)) and were compared with the results of Goldmann visual field perimetric evaluation. In patients with occipital brain tumours undergoing surgery, the functional data were registered in a frameless stereotactic device and the images fused into anatomical three standard planes and three dimensional reconstructions of the brain surface. RESULTS: Two studies of patients were discarded, one because of head motion and the other because of badly followed instructions. On the remaining patients the functional activations found in the visual cortex were consistent with the results of perimetric evaluation in all but one of the patients and all the normal subjects although the results of fMRI were highly dependent on the choices of the analysis thresholds. Visual functional MRI image guided data were used in five patients with occipital brain tumours. No added postoperative functional field defect was detected. CONCLUSIONS: There was a good correspondence between fMRI data and the results of perimetric evaluation although dependent on the analysis thresholds. Visual fMRI data registered into a frameless stereotactic device may be useful in surgical planning and tumour removal.