摘要:

LONG-TERM SUBDURAL SURFACE cortical cerebral blood flow (CBF) and electrocorticographic monitoring was performed in 12 patients with complex partial seizures. A total of 40 seizures were analyzed. Baseline CBF values from nonepileptic and epileptic temporal lobe (mean ± standard error) were 60.0 ± 1.0 and 50.2 ± 1.8 ml/100 g per minute, respectively (P< 0.05). In general, clinical seizure onset was preceded by a 20-minute preictal CBF increase from baseline in the epileptic temporal lobe. Peak early postictal CBF values of nonepileptic and epileptic temporal lobes were 57.7 ± 13.3 and 89.0 ± 21.7 ml/100 g per minute (P> 0.05) at 5.2 ± 2.2 and 2.4 ± 1.0 minutes (P> 0.05) after clinical seizure onset, respectively. Statistically significant differences between nonepileptic and epileptic temporal lobe CBF were detected at 50 minutes (74.0 ± 14.2 and 37.5 ± 9.2 ml/100 g per minute, respectively;P< 0.05) and 60 minutes (75.6 ± 13.6 and 36.1 ± 8.5 ml/100 g per minute, respectively;P< 0.05) postictal. The data suggest that the optimal times for CBF analysis to differentiate epileptic from nonepileptic temporal lobe are 1) during the interictal period and 2) late (50 to 60 minutes) postictal. The results of this study should improve the understanding of the dynamic cerebral perfusion patterns in the epileptic human brain.

ISSN:0148-396X    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

FOR THE STUDY of pathogenesis and treatment of recurrent trigeminal neuralgia, we performed 31 repeat operations from among 400 patients with trigeminal neuralgia in the past 10 years. Initially, of these 400 patients, 376 underwent microvascular decompression only, and 24 underwent partial sensory rhizotomy with or without microvascular decompression. Fifty-three patients (14%) had recurrences after microvascular decompression, of which 31 patients underwent repeat operations. Among the repeat operations, there was negative exploration in 16 patients (52%), arterial loop compression in 7 (22%), venous compression in 4 (13%), and Teflon compression or adhesion in 4 (13%). Twenty-one patients had early recurrences within 1 year, and 10 patients had late recurrences. Negative exploration and arterial compression were more likely in early recurrence (P= 0.01). Continuing demyelination might occur in patients with negative exploration, even when adequate decompression had been initially performed. Seventy percent of the patients had no recurring pain by way of partial sensory rhizotomy for negative explorations, redecompression of arterial loops, division of offending veins, or lysis and reposition of Teflon. About half of the patients had positive findings that were amenable without rhizotomy in the repeat operations. A repeat operation for failed microvascular decompression is a good choice if the condition of the patient is tolerant.

ISSN:0148-396X    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

THIRTEEN CASES OF intramedullary hemangioblastoma of the spinal cord are reported. The tumors were diagnosed with radiological studies, especially magnetic resonance imaging. Microsurgery was used to achieve gross total removal of the tumors in all cases. Signs and symptoms improved in 84.6% of the patients after surgery. The authors describe the diagnosis and microsurgical techniques for the excision of intramedullary hemangioblastoma of the spinal cord. This disease should be differentiated from hydromyelia, intramedullary ependymoma, and vascular malformation of the spinal cord. Total removal of the tumor is recommended.

ISSN:0148-396X    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

FUNCTIONAL MAGNETIC RESONANCE imaging (FMRI) has detected changes in regional cerebral blood flow and volume in response to motor movements, visual stimuli, and auditory stimuli in each of their respective primary cortices. This experiment was conducted to determine whether signal changes in the somatosensory cortex secondary to tactile stimulation could be demonstrated. The palm of the right hand was periodically stimulated while the subject was undergoing echo-planar imaging with a 1.5-T magnetic resonance scanner equipped with local gradient and radio frequency coils. Sagittal and coronal images of 10- to 15-mm slice thickness were selected to include the postcentral gyrus and surrounding regions. Temporally correlated signal changes of 1% to 5% occurred in the peri-rolandic region in each of six subjects. The time course of signal changes was comparable to that found in other primary sensory and motor cortices. The results provide preliminary evidence of the sensitivity of FMRI to activation of the somatosensory cortex with tactile stimulation and support FMRI as a promising noninvasive technique for study of the functional organization and integrity of the cerebrum.

ISSN:0148-396X    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

THE PURPOSE OF incorporating stereotactic methodology into neurosurgical operations is to achieve a consistently high degree of accuracy in localizing intracranial targets. Therefore, the limits of resolution for the operation are a function of the accuracy of the particular stereotactic frame system. The total clinically relevant error (application accuracy) comprises errors associated with each procedural step, including imaging, target selection, vector calculations, and the mechanical errors of stereotactic frames. To evaluate these parameters, a systematic error analysis was carried out with four commonly used stereotactic devices: the Brown-Roberts-Wells, the Cosman-Roberts-Wells, the Kelly-Goerss COMPASS (modified Todd-Wells), and the Leksell frames. Over 21,500 independent accuracy test measurements were made with 11,000 computed tomograms. The results suggest a potentially significant degree of error in the application accuracy of all stereotactic instruments, which is accentuated by but not entirely due to imaging-associated errors. Clinically encountered levels of weightbearing by stereotactic frames may have a pronounced effect on their mechanical accuracy. Both the reapplication of aiming arc assemblies and the use of phantom base units introduce independent sources of mechanical inaccuracy into stereotactic procedures. The scope of individual error values and their determining factors must be considered with every clinical use of stereotactic frame systems.

ISSN:0148-396X    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

THE DIFFERENT SOURCES of spatial distortion in magnetic resonance images are reviewed from the point of view of stereotactic target localization. The extents of the two most complex sources of spatial distortion, gradient field nonlinearities and magnetic field inhomogeneities, are discussed both qualitatively and quantitatively. Several ways by which the spatial distortion resulting from these sources can be minimized are discussed. The clinical relevance of the spatial distortion along with some strategies to minimize the localization errors in magnetic resonance-guided stereotaxy are presented.

ISSN:0148-396X    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

HYPERICIN, A POLYCYCLIC aromatic dione isolated from plants, is presently being clinically evaluated as an antiviral agent in the treatment of human immunodeficiency virus (HIV) infection. In addition, it is known to be a potent protein kinase C inhibitor. To evaluate its potential as an inhibitor of glioma growth, an established (U87) and low-passage glioma line 93–492 were treated with hypericin in tissue culture for a period of 48 hours after passage. Hypericin inhibited the glioma growth in a dose-related manner, with a marked inhibition of growth in the low-micromolar concentration range (e.g., in line U87 and low-passage line 93–492, a concentration of hypericin of 10 μmol/L produced 62 and 76% decreases in [3H]thymidine uptake, respectively). Because the reported inhibitory effects of protein kinase C are enhanced by visible light, [3H]thymidine uptake was measured in both the presence and the absence of visible light. In glioma line A172, the presence of light slightly increased the inhibitory effect of hypericin. Moreover, an apoptosis (i.e., programmed cell death) assay was performed to determine whether the treatment of glioma cells with hypericin was cytostatic or cytocidal. Cells were harvested, and purified deoxyribonucleic acid (DNA) was analyzed by agarose gel electrophoresis. DNA from cells treated with hypericin for 48 hours exhibited a classical “ladder” pattern of oligonucleosome-sized fragments characteristic of apoptosis. These data suggest that the proven safe drug hypericin may have potential as an antiglioma agent; we suggest clinical trials.

ISSN:0148-396X    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

ELECTRIC SPINAL CORD stimulation (SCS) is widely used as a treatment modality for ischemic pain in peripheral arterial insufficiency. The background for the therapeutic effect may be a temporary inhibition of sympathetically maintained peripheral vasoconstriction. In this series of experiments, the involvement of different types of cholinergic and adrenergic receptor subclasses in the vasodilatory effect was explored in anesthetized rats. The microcirculation in hindlimb skin and hamstring muscle was studied by the laser Doppler technique. The ganglionic blocker hexamethonium as well as the nicotinic receptor antagonist chlorisondamine abolished the effect in both vascular beds, whereas the muscarinic receptor antagonists pirenzepine and atropine were ineffective. Among the adrenergic receptor active compounds, phentolamine, prazosine (an α1-receptor antagonist), and clonidine in high doses suppressed the SCS-induced vasodilation. Yohimbine (an α2-receptor antagonist) did not alter the effect. The β-adrenergic compounds had a differential effect on muscle and skin perfusion. Atenolol, a β1-receptor antagonist, inhibited SCS-induced vasodilation only in the skin, whereas the β2-receptor antagonist butoxamine selectively depressed the muscle response. The vasodilatory effect of SCS in the animal model used here seems to a large extent to be mediated by an inhibitory effect on peripheral vasoconstriction maintained via efferent sympathetic activity involving nicotinic transmission in the ganglia and the postganglionic α1-adrenoreceptors. The involvement of β-receptors seems to be different in skin and muscle, β1being more important for the changes in the skin and β2being more important for those in muscle. The high-intensity antidromic response, earlier believed to explain how SCS exerted its vasodilatory effect, was resistant to cholinergic and adrenergic manipulations and seems to depend on entirely different mechanisms.

ISSN:0148-396X    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

IN THIS STUDY, the penetration of red laser light (632.8 nm) in fresh bovine brain was measured parallel, oblique, and perpendicular to the axis of white matter tracts. The measurements were performed in eight samples with an isotropic light source and detector and were obtained by advancing the detector tip toward the light source in the tissue. A statistically significant difference in the effective attenuation coefficient of the light (μeff) was found between the parallel and perpendicular directions, 0.47 ± 0.06 mm−1and 0.63 ± 0.13 mm−1, respectively (P= 0.005). The measurements taken at an angle of 45 degrees in the same sample resulted in an intermediate μeffof 0.58 ± 0.09 mm−1. These results suggest a preferential guidance of light along the axis of the white matter tracts of the brain.

ISSN:0148-396X    

出版商:OVID    

年代:1994

数据来源: OVID

ISSN:0148-396X    

出版商:OVID    

年代:1994

数据来源: OVID