Introduction of magnetoencephalography to stereotactic techniques

Magnetoencephalography (MEG), a noninvasive functional brain mapping technique, was used for preoperative localization of the sensorimotor cortex in patients harboring lesions involving these eloquent regions. Prior to surgery, MEG source locations were transferred onto high-resolution MRI pictures which were then used for preoperative evaluation, risk analysis, and planning. We have developed a process to transform the MEG-derived sensorimotor localization coordinates into the COMPASS stereotactic coordinate system. Thus the MEG-derived functional information is incorporated into the stereotactic database, enabling the simultaneous visualization of functional and anatomical data. This information can be used for the selection of cases and in planning safe approaches for computer-assisted volumetric resections. The integration of MEG and stereotactic neurosurgery also allows a more precise comparison between MEG and intraoperative direct electrocorticographic mapping (ECoG). Seven patients were studied with good correlation between MEG and intraoperative mapping. In 4, the correlation was only based on gross visual comparison between intraoperative identification of the gyrus pattern and MEG photographs. The availability of the MEG coordinates in the stereotactic system, however, allows a more precise correlation between MEG and ECoG. In all 3 patients studied in this manner, the MEG coordinates (pinpointed to a precise cortical representation of a few millimeters) overlapped with ECoG results. In summary, we compared functional MEG data to intraoperative ECoG and conclude that the introduction of MEG into stereotactic neurosurgery can provide precise functional and anatomic information for image-guided surgical planning and resection.     

Preoperative cortical localization with functional MRI for use in stereotactic radiosurgery

Accurate localization of the lesion with respect to functionally significant brain is essential to safe stereotactic radiosurgical dose planning. We report the use of functional MR imaging in 3 patients to identify critical areas of surrounding brain and to provide assistance with dose planning, especially with regard to shaping the peripheral isodose around the lesion. We used a functional MRI system employing a conventional 1.5-tesla MRI unit that can detect decreases in deoxyhemoglobin concentration occurring with performance of specific tasks. Two of the patients had supratentorial arteriovenous malformations and 1 patient had a recurrent parasagittal meningioma. Functional MRI provided information on the location of speech, motor, and sensory cortex in these patients. Radiosurgical dose plans were constructed that kept these cortical areas outside of the 30% isodose curves. We believe that the safety of supratentorial parenchymal radiosurgery will be enhanced by the localization of critical brain regions around the target.     

Pathological changes in surgically resected angiographically occult vascular malformations after radiation

OBJECTIVE: The goal of this study was to evaluate the pathological changes associated with radiation treatment (stereotactic radiosurgery or conventional irradiation) of angiographically occult vascular malformations (AOVMs). METHODS: Eleven patients underwent surgical resection of an AOVM in the mesial temporal lobe, brain stem, thalamus, or basal ganglia after previous radiation treatment. The indications for surgery were recurrent symptomatic bleeding from the lesion in 10 patients and recurrent intractable seizures in 1 patient. Radiation was used as the initial therapy because the risk of surgical resection was deemed too high. Three patients received conventional radiation therapy of 3000 to 5400 rads at an outside institution. One patient received radiosurgery with the gamma knife at another institution using a dose of 15 Gy to the margin. The remaining 7 patients received stereotactic radiosurgery with a helium-ion particle beam. The dose range was from 18 to 26 Gy equivalents. The interval from radiation to surgical resection ranged from 1 to 10 years, with a mean of 3.5 years. These lesions were compared with 10 nonirradiated cavernous malformations. RESULTS: One irradiated lesion was identified pathologically as a true arteriovenous malformation despite being angiographically occult. This lesion did not demonstrate significant changes in the vasculature but did have radiation necrosis of the surrounding brain 5 years after 25 Gy equivalents of helium-ion radiosurgery. Two other specimens were too small to identify the type of vascular malformation adequately. Of the remaining eight malformations identified as cavernous malformations, six showed a combination of marked fibrosis of the vascular channels, fibrinoid necrosis, and ferrugination. However, the fibrinoid necrosis was the only finding unique to the irradiated lesions compared with nonirradiated controls. All the irradiated lesions still had patent vascular channels; none were completely thrombosed. CONCLUSION: Radiosurgery or conventional radiation therapy did not cause histologic vascular obliteration in intracranial AOVMs evaluated 1 to 10 years (mean 3.5 yr) after radiation delivery. It should be recognized that these patients are irradiation failures who may not be representative of all irradiated patients. However, recurrent bleeding from AOVMs may relate to poor radiation response in some patients.     

Correlation of functional magnetic source imaging with intraoperative cortical stimulation in neurosurgical patients

This study compared noninvasive preoperative functional imaging by using magnetoencephalography (MEG) with intraoperative direct cortical stimulation in ten patients undergoing neurosurgery. The goal was to assess the accuracy and reliability of MEG-based functional imaging in these patients as a possible replacement or adjunct for direct cortical stimulation with electrocorticography. Objective comparison of intraoperative mapping with preoperative MEG procedures was achieved by intraoperative recording of mapped cortical locations for motor responses using an interactive image-guided surgical device, the ISG viewing wand, with which mapping points could be marked on a previously acquired (MRI) set. In all ten patients, at least one stimulation site elicited a response during both MEG and intraoperative mapping. The central sulcus ipsilateral to the lesion was only directly visible on high-resolution MRIs in 3/10 cases and equivocally in 2/10. Coregistered with MRI to form magnetic source images (MSIs), MEG predictions of the postcentral gyrus were possible in all 10 cases. In all 10 cases, these were in agreement with intraoperative estimation of the precentral gyrus. Functional mapping of somatosensory cortex was achieved noninvasively in surgical patients by using MSI. The accuracy, compared with cortical stimulation, was always sufficient to define motor and somatosensory strips.     

Combined utility of functional MRI, cortical mapping, and frameless stereotaxy in the resection of lesions in eloquent areas of brain in children

We studied 16 children with lesions in the eloquent brain to determine if the amalgamation of information from functional magnetic resonance imaging (fMRI), frameless stereotaxy, and direct cortical mapping and recording could facilitate the excision of these lesions while minimizing potential neurological deficits. The mean age of the children was 10 years. Fourteen children presented with seizures. All lesions were located in or near eloquent cerebral cortex. fMRI was successful in all patients in delineating the relationship between the lesion and regions of task-activated cortex. The ISG wand was utilized in all cases for scalp and bone flap placement, and for intraoperative localization of the lesion. Direct cortical stimulation or recording of phase reversals with somatosensory evoked potentials helped delineate the central sulcus and language cortex in patients with lesions near the motor or language cortex. Intraoperative electrocorticography (ECoG) was utilized in all patients who presented with seizures to guide the extent of resection of the epileptiform cortex. Ten children had benign cerebral neoplasms, nine of which were totally resected. The other diagnoses included vascular malformations, Sturge-Weber, tuberous sclerosis, Rasmussen's encephalitis, and primitive neuroectodermal tumor. Only 1 patient with a left Rolandic AVM developed a new neurological deficit postoperatively. Thirteen of fourteen patients who presented with seizure disorders were rendered either seizure free or improved in terms of seizure control postoperatively. Follow-up has ranged from 12 to 18 months, with a mean follow-up of 15 months. We conclude that the techniques of fMRI, frameless stereotaxy, direct cortical stimulation and recording can be utilized in sequence to accurately localize intracerebral lesions in eloquent brain, and to reduce the morbidity of resecting these lesions in children.     

Treatment of arteriovenous malformations with stereotactic radiosurgery employing both magnetic resonance angiography and standard angiography as a database

Twenty-one arteriovenous malformations were prospectively evaluated using magnetic resonance angiography and compared with stereotactic angiography. The goals were to establish the feasibility of magnetic resonance angiography, compare it to stereotactic angiography, employ magnetic resonance angiography in follow-up, and semiquantify flow. A correlative evaluation between flow and response to stereotactic radiosurgery was carried out. Phase contrast angiograms were obtained at flow velocities of 400, 200, 100, 60, and 20 cm/sec. The fractionated velocities provided images that selectively demonstrated the arterial and venous components of the arteriovenous malformations. Qualitative assessment of the velocity within the arteriovenous malformations and the presence of fistulae were also determined by multiple velocity images. In addition, 3-dimensional time-of-flight magnetic resonance angiograms were obtained to define the exact size and shape of the nidus. This technique also permitted evaluation of the nidus and feeding arteries for the presence of low flow aneurysms. Correlation between the two imaging modalities was carried out by subjective and semiquantitative estimation of flow velocity and estimation of nidus size. The following velocity parameters were employed: fast, intermediate, slow, and none (arteriovenous malformation obliterated). In 19 of 21 (90.5%) arteriovenous malformations, magnetic resonance angiography was equal or superior to stereotactic angiography for flow quantification and visualization of the nidus. Only 2 of 21 arteriovenous malformations were better demonstrated by stereotactic angiography than by magnetic resonance angiography (failure rate of 9.5%). The nidus size in one case was clearly underestimated by stereotactic angiography and would have resulted in a geographic miss without magnetic resonance angiography. Seven post-radiosurgery arteriovenous malformations were evaluated for follow-up with both magnetic resonance angiography and stereotactic angiography. In 6 of 7 arteriovenous malformations, magnetic resonance angiography response matched stereotactic angiography response. Correlation of flow with outcome was carried out for 14 arteriovenous malformations using magnetic resonance angiography only. Interestingly, all nine arteriovenous malformations with intermediate or slow flow demonstrated partial or complete obliteration; whereas only 3 of 5 fast flow arteriovenous malformations achieved a response with a median follow-up of 10 months. This early analysis suggests that slower flowing arteriovenous malformations may obliterate faster after stereotactic radiosurgery and flow parameters could be employed to predict response. In conclusion, magnetic resonance angiography permits semiquantitative flow velocity assessment and may therefore be superior to stereotactic angiography. An additional advantage of magnetic resonance angiography is the generation of serial transverse images which can replace the conventional CT scan employed for stereotactic radiosurgery treatment planning.(ABSTRACT TRUNCATED AT 400 WORDS)     

Comparison of magnetoencephalography, functional MRI, and motor evoked potentials in the localization of the sensory-motor cortex

To clarify the topographical relationship between peri-Rolandic lesions and the central sulcus, we carried out presurgical functional mapping by using magnetoencephalography (MEG), functional magnetic resonance imaging (f-MRI), and motor evoked potentials (MEPs) on 5 patients. The sensory cortex was identified by somatosensory evoked magnetic fields using MEG (magnetic source imaging (MSI)). The motor area of the hand region was identified using f-MRI, during a hand squeezing task. In addition, transcranial magnetic stimulation localized the hand motor area on the scalp, which was mapped onto the MRI. In all cases, the sensory cortex was easily identified by MSI and the results of MSI correlated well with the findings obtained by the intraoperative recording of somatosensory evoked potentials. In contrast, the motor cortex could not be localized by f-MRI due to either the activated signal of the large cortical vein or the lack of any functional activation in the area of peri-lesional edema. MEPs were also unable to localize the entire motor strip. Therefore, at present, MSI is considered to be the most reliable method to localize peri-Rolandic lesions [corrected].     

Large arteriovenous malformations of the face: aesthetic results with recurrence control

Large facial arteriovenous malformations are problematic for patients because of grotesque disfigurement, risk of rapid enlargement, and life-threatening rupture. Successful treatment of these relentless complex lesions is one of the most difficult challenges facing plastic surgeons. From a series of 300 large facial arteriovenous malformations, 85 patients were treated with embolization and excision; six of these cases (representing six separate anatomic regions: labial, auricular, eyelid, cheek, chin, and occipitoparietal) were selected for review. The purpose of this article was to look critically at the management of these six facial arteriovenous malformations, including patient presentation, angiographic procedures, surgical planning and technique, and postoperative long-term follow-up care. Lessons learned from the six representative cases provide clues for the management of large facial arteriovenous malformations and demonstrate the possibilities of recurrence and their occasionally relentless behavior. The cases show that long-term control of these lesions with acceptable aesthetic results can be achieved. The mainstay of treatment includes the following: (1) selective intra-arterial embolization with fine catheters and direct lesional embolization; (2) judicious resection and reconstruction with local or expanded tissue flaps; and (3) careful follow-up with serial examinations, duplex, and arteriography.     

On the reorganization of sensory hand areas after mono-hemispheric lesion: a functional (MEG)/anatomical (MRI) integrative study

The topography of primary sensory cortical hand area following a monohemispheric lesion (sudden = stroke; progressive = neoplasm) was investigated in relationship with clinical recovery of sensorimotor deficits. Twenty seven patients with monohemispheric lesions were studied in a clinically stabilized condition. Functional informations from magnetoencephalography (MEG) were integrated with anatomical data from magnetic resonance imaging (MRI). MEG localizations of the neurons firing at early latencies in primary sensory cortex after separate stimulation of median nerve, thumb and little fingers of each hand were carried out. Characteristics of cerebral equivalent current dipoles (ECDs) activated by each contralateral stimulation, the 'hand extension' (i.e., the distance in millimetres between ECDs of first and fifth digits), as well as interhemispheric differences of the tested parameters were investigated. Finally, ECDs' locations were integrated with MRI. Lesions involving cortical (C) or subcortical (s.c.) areas receiving sensory input from the hand were often combined to increase interhemispheric asymmetry of the tested parameters (22% for C and 49% for s.c. lesions). This might be due to an activation of neuronal districts which in the affected hemisphere (AH) differ from those normally activated in the unaffected hemisphere (UH) and in the control population. Moreover, the 'hand extension' was enlarged on the AH--more frequently after a SC lesion--mainly due to a medial shift of the little finger ECD, combined to a tendency of both finger ECDs to shift frontally. After a C lesion, responses from the AH were often stronger than normal. Spatial reorganizations were also seen in the UH (7% of C and 14% of SC lesions). 'Hand extension' in the UH was selectively enlarged for the P30m only when combined with a similar enlargement in the AH. Significant interhemispheric asymmetries due to neuronal reorganization in the AH were associated with worse clinical outcomes compared to patients without asymmetries.     

Use of positron emission tomography for presurgical localization of eloquent brain areas in children with seizures

Successful surgical management of a neoplastic or nonneoplastic seizure focus in close proximity to or within eloquent brain areas relies on precise delineation of the relationship between the lesion and functional brain areas. The aim of this series was to validate the usefulness and test the efficacy of noninvasive presurgical PET mapping of eloquent brain areas to predict surgical morbidity and outcome in children with seizures. To identify eloquent brain areas in 15 children (6 female and 9 male; mean age 11 years) with epileptogenic lesions PET images of regional cerebral blood flow were performed following the administration of [(15)O]water during motor, visual, articulation, and receptive language tasks. These images with coregistered magnetic resonance (MR) images were then used to delineate the anatomic relationship of a seizure focus to eloquent brain areas. Additional PET images using [18F]fluoro-2-deoxy-D-glucose (FDG) and [11C]methionine (CMET) were acquired to help localize the seizure focus, as well as characterize the lesion. Patient surgical management decisions were based on PET mapping in combination with coregistered MR images, PET-FDG findings, and the anatomic characteristics of the lesion. At follow-up 1-26 months after surgery, all patients that underwent temporal lobectomy (9 patients) and extratemporal resection (4 patients) for a neoplastic or nonneoplastic seizure focus are seizure-free with minimal postoperative morbidity. Of prime importance, no child sustained a postoperative speech or language deficit. PET imaging was also well tolerated without procedural complications. Based on PET mapping, a nonoperative approach was used for 2 children and a biopsy only was used in one child. When cortical injury involved prenatally determined eloquent cortex, PET demonstrated reorganization of language areas to new adjacent areas or even to the contralateral hemisphere. Integration of anatomical and functional data enhanced the surgical safety, defined optimal surgical approach, delineated the seizure focus from eloquent brain areas, facilitated maximum resection and optimized the timing of surgery, thereby minimizing surgical morbidity while maximizing surgical goals. PET measurements of FDG and CMET uptake were also helpful in localizing the seizure focus and grading the tumors. PET used for brain mapping in children provides the surgeon with strategic preoperative information not readily attainable with traditional invasive Wada testing or intraoperative cortical stimulation. PET mapping may also improve the outcome of extratemporal resections by allowing aggressive seizure focus resection. In addition, serial brain maps may optimize timing for surgical intervention by demonstrating reorganization of eloquent cortex often seen in younger children after cortical injury. Our results suggest that noninvasive presurgical brain mapping has the potential to reduce risk and improve neurologic outcome.     

The clinico-neuropsychological manifestations of arteriovenous malformations of the thalamus

A comprehensive clinical and neuropsychological study was made of 34 patients with thalamic arteriovenous malformations. In the thalamus. Memory disorders were a common abnormality (in 31 of 34 patients). They were modally nonspecific and depended on the site of arteriovenous malformations. With the prevalent ventricular pattern of hemorrhages, memory disorders were accompanied by disorientation and emotional and volitional impairments. Arteriovenous malformation was removed in 12 patients (on the left side in 7 patients and on the right in 5). After surgery there was virtually progression of memory defects in all patients. Speech disorders combining the specific features of lesions in various cortical regions were detected in 5 of 7 patients with left thalamic arteriovenous malformations.     

Intraoperative localization of functional regions in the sensorimotor cortex by neuronavigation and cortical mapping

Surgery of lesions within the central region requires exact intraoperative anatomical orientation and knowledge of the position of functional cortical regions to minimize the surgical trauma and to avoid postoperative neurological deficits. We combined somatosensory evoked potential (SSEP) phase reversal and/or cortical electrical stimulation with neuronavigation in 26 patients for localization and visualization of functional cortical areas and their anatomical site in relation to the lesion. After location of the central sulcus by means of SSEP phase reversal, the precentral gyrus was electrically stimulated to detect functional motor regions. Electrode position was documented, and the functional regions were related to the site of the lesion using a specially developed neuronavigation system. In 11 of 15 patients the central fissure was located with SSEP phase reversal. Electrical stimulation yielded motor evoked potentials in 23 of the total 26 patients. The anatomical site of these functional regions and their relation to the lesion were evaluated with the neuronavigation system. The precentral gyrus, central sulcus, and postcentral gyrus could be identified in all 23 cases. The combination of intraoperative electrophysiological mapping and neuronavigation provides safe and reliable localization of the sensorimotor cortex. This technique is a promising tool to minimize the risk of surgically caused sensory and motor deficits.     

Stereotactic transcranial magnetic stimulation: correlation with direct electrical cortical stimulation

OBJECTIVE: To evaluate stereotactic transcranial magnetic stimulation (TMS) as a tool for presurgical functional mapping of human motor cortex. METHODS: Transcranial magnetic stimulation using a frameless stereotactic system was performed in two patients with tumors near the central sulcus. TMS motor function maps were plotted on the patients' three-dimensional volumetric magnetic resonance imaging data and compared with direct electrical cortical stimulation at surgery with the patient under local anesthesia. RESULTS: Stereotactic TMS was well tolerated by both patients and was consistent with known somatotopic representation of human motor cortex. The results demonstrated a good correlation between the TMS and electrical cortical stimulation maps, with all TMS responses eliciting more than 75% of the maximum motor evoked potential falling within 1 cm of the electrical cortical stimulation site. CONCLUSIONS: Our findings indicate that stereotactic TMS is feasible and can provide accurate noninvasive localization of cortical motor function. It may prove to be a useful method for presurgical planning.     

Mobile fluoroscopic open stereotaxy for MRI-negative angiographic microlesions

The approach to the deep-seated angiographic microlesion is often difficult, particularly when it is not demonstrated by computed tomography (CT) or magnetic resonance imaging (MRI). We have developed a method to localize these lesions for open stereotactic surgery employing mobile fluoroscopy. Prior to craniotomy, the patient's head is fixed in a stereotactic frame in a position optimal for the routine microscopic surgery. Following the injection of contrast media, the location of the lesion is marked on the fluoroscope monitor. Under fluoroscopic control, the scalp is marked using radiopaque pointer on each side of the patient's head so that the scalp marks and the target lesion overlap each other on the fluoroscope monitor. Thus the imaginary line connecting these scalp marks passes through the lesion. An additional pair of scalp marks is obtained by changing the projection angle of the fluoroscope. By simple calculation, the coordinates of the lesion are obtained as the nearest point to these two imaginary lines, each of which connects a pair of scalp marks. After craniotomy, the lesion is approached using an open stereotactic technique. The first patient had an aneurysm 1.5 mm in diameter that arose from the feeder of the arteriovenous malformation. The second patient had a small residual nidus of arteriovenous malformation 1.5 cm in diameter in the deep frontal lobe, not recognizable by CT or MRI because of artifacts from a previous surgery. Both patients were successfully operated by employing the present method. This method requires only a conventional stereotactic frame and a mobile fluoroscope, and provides simple and reliable localization of the small lesions recognizable only by cerebral angiography.     

An analysis of the natural history of cavernous malformations

BACKGROUND: The treatment of cavernous malformations has been controversial. Some reports suggest that surgical resection of the lesion for the prevention of recurrent hemorrhage should not be considered because of low hemorrhagic risk. However, the role of surgery in management of cavernous malformations is undergoing reevaluation. The decision for surgical resection should be based on a careful analysis of the natural history of this lesion, which is not well understood. METHODS: We investigated, retrospectively, the natural history of 108 cavernous malformations in 62 patients. Individual cavernous malformations were divided into four categories on the basis of magnetic resonance (MR) findings. The pattern of clinical and radiologic presentation and outcomes of management were analyzed. RESULTS: The age of the patients ranged from 4-63 years (mean: 32.2 years). Multiple lesions were found in 13 of 62 patients (21%) and two of these patients were siblings. Twenty-five out of 62 patients had suffered recurrent symptoms. The bleeding rate was 2.3%/person/year (1.4%/lesion/year) during 2509.6 patient years. There were no significant differences between the bleeding rates of each type of lesion. During the follow-up period of 12-48 months (mean: 22.4 months), two of 28 patients conservatively treated had recurrent hemorrhages (rebleeding rate: 3.8%/person/year). During the follow-up period of 12-66 months (mean: 21.7 months), recurrent hemorrhages were observed in two of 17 patients with radiosurgery (rebleeding rate: 7.8%/person/year). CONCLUSION: Our study has provided a profile of the natural history of these lesions. Based on our results, we recommend surgical excision of cavernous malformations in those patients with recurrent symptoms or acute progressive symptoms.     

Effects of lesions invading the postcentral gyrus on somatosensory thresholds on the face

Patients with unilateral removals from either the parietal, frontal or temporal lobe and normal control subjects were examined on three tests of tactile sensibility. The patients with surgical excisions from the parietal lobe were subdivided into two groups: those whose lesions invaded the face area in the primary sensory cortex and those whose lesions spared this area. A significant percentage of patients with lesions that invaded the face area had mild to severe sensory deficits on the side of the face contralateral to the lesion. A much smaller number of patients had deficits on the ipsilateral side. Lesions to the face area in the primary sensory cortex were, however, associated with a lower incidence of severe and persistent sensory deficits when compared to previous results on the effects of lesions to the hand area on the sensory capacity of the hand. These results suggest that there is some preservation of sensory function after damage to the face area in the primary sensory cortex, presumably due to the bilateral representation of the face.     

Computed imaging-assisted stereotactic brain biopsy: a risk analysis of 225 consecutive cases

BACKGROUND: Treatment strategies for intracranial mass lesions are most effective when based upon histopathological diagnoses. Image-guided stereotaxy has provided the means to sample tissue from small or deeply seated intraparenchymal lesions with a relatively high degree of safety and accuracy. Although procedural complications are infrequent, devastating neurological sequelae may result from hemorrhage or direct trauma. This study was undertaken to identify factors that may confer an increased risk of morbidity from stereotactic brain biopsy. METHODS: Two hundred twenty-five consecutive computer-assisted stereotactic brain biopsy procedures were reviewed. Patient age averaged 47.4 years (range, 3-84 years); gender ratio was approximately 2:1 (male:female). Pre-existing medical conditions were identified in nearly half of the cohort. 61.3% of biopsied lesions were lobar; the remainder (38.7%) were "deep-seated" (thalamus, basal ganglia, pineal, hypothalamus, cerebellum, brainstem). Glial tumors accounted for the majority (44.4%) of biopsied lesions; metastases (12.9%) and lymphoma (11.6%) were also relatively common. Demographical, anatomical, surgical, and histological data were compiled and putative risk factors for morbidity identified. These variables were then subjected to univariate and logistic regression analyses to determine their significance as independent predictors of operative risk. RESULTS: Twelve patients suffered complications as a consequence of the biopsy procedure (eight from hemorrhage, four from direct trauma). Major morbidity (hemiparesis, aphasia, obtundation) occurred in eight patients (3.6%). Three patients (1.3%) suffered minor morbidity (transient, mild neurological deficits). One operative fatality occurred (0.4%). An increased risk of morbidity was associated with the preoperative use of antiplatelet agents, chronic corticosteroids, deep-seated lesions, malignant gliomas, and a greater number of biopsy attempts (p < 0.05). Factors not conferring increased morbidity included gender, age, pre-existing illness, extracranial malignancy, cardiac disease, hypertension, diabetes, HIV status, and instrument used to procure the specimen. CONCLUSIONS: Complications arising from stereotactic brain biopsy are infrequent but can be disastrous. Operative risk is a function of several independent variables, including lesion properties (location, histology), preoperative pharmacological therapy (corticosteroids, antiplatelet agents), and operative technique. This analysis suggests that the morbidity of stereotactic brain biopsy may be minimized by risk factor modification.     

Dural-pial arteriovenous malformation after sinus thrombosis

BACKGROUND: We report an unusual case of acquired dural-pial arteriovenous malformation (AVM) following sinus thrombosis. CASE DESCRIPTION: Initial angiography performed in a 39-year-old man showed thrombosis of the superior sagittal sinus (SSS) and the right transverse sinus (TS) but no vascular malformations. Follow-up angiography 29 months later revealed recanalization of the SSS and the TS, retrograde cortical venous drainage which suggested that thrombosis of the sinuses probably propagated into the adjacent parietal cortical veins, and development of a dural-pial AVM at or near the site of thrombi in more than one cortical vein. Complete surgical excision of the lesion was accomplished without neurological deterioration. CONCLUSIONS: The present case suggests the possibility that the pial AVM is not only a congenital condition but also may develop as an acquired lesion.     

The clinical assessment of attachment in children under five

Dural arteriovenous malformations (AVMs) are considered to be acquired lesions that develop secondary to venous obstruction, which sometimes happens in head trauma. However, there has been a report of an anterior cranial fossa dural AVM that occurred independently of a history of head trauma, and there has been speculation that these malformations are congenital. The authors recount their experience with a patient who had an anterior cranial fossa dural AVM that was discovered incidentally. The lesion was fed by the bilateral anterior ethmoidal arteries and drained into the superior sagittal sinus via frontal cortical veins. The patient had a history of severe head trauma that had occurred 30 years earlier. This is the first case report in which a previous head trauma is strongly believed to be the cause of an anterior cranial fossa dural AVM. The authors postulate that anterior cranial fossa dural AVMs can develop secondary to a head trauma.     

Fulminant hepatitis complicated by small intestine infection and massive hemorrhage

OBJECT: The purpose of this study was to evaluate the efficacy of noninvasive preoperative functional imaging data used in an interactive fashion in the operating room. The authors describe a method of registering preoperative functional magnetic resonance (fMR) imaging localization of sensorimotor cortex with a frameless stereotactic surgical navigation device. METHODS: The day before surgery, patients underwent blood oxygen level-dependent fMR imaging while performing a finger-tapping motor paradigm. Immediately afterward an anatomical stereotactic MR image was acquired. Raw fMR imaging data were analyzed offline at a separate workstation, and the resulting functional maps were registered to a high-resolution anatomical scan. The fused functional-anatomical images were then downloaded onto a surgical navigation computer via an ethernet connection. At surgery, the brain was exposed in the standard fashion, and the sensorimotor cortex was identified by direct cortical stimulation, the use of somatosensory evoked potentials, or both. This localization was then compared with that predicted by the registered fMR study. Thirteen procedures were performed in 12 patients. The mean registration error was 2.2 mm. The predicted location of motor and/or sensory cortex matched that found on intraoperative mapping in all 12 patients tested. Maximal tumor resection was accomplished in each case and no new permanent neurological deficits resulted. CONCLUSIONS: Compared with conventional brain mapping techniques, fMR image-guided surgery may allow for smaller brain exposures, localization of the language cortex with the patient under general anesthesia, and the mapping of multiple functional sites. The scanning equipment used in this method may be more readily available than for other functional imaging techniques such as positron emission tomography or magnetoencephalography.