Vladimír Beneš

Diffusion parameters of the extracellular space in human gliomas

Tumor cell migration through the extracellular space (ECS) might be affected by its pore size and extracellular matrix molecule content. ECS volume fraction α (α = ECS volume/total tissue volume), tortuosity λ (λ2 = free/apparent diffusion coefficient) and nonspecific uptake k′ were studied by the real‐time tetramethylammonium method in acute slices of human tissue. The diffusion parameters in temporal cortical tissue resected during surgical treatment of temporal lobe epilepsy (control) were compared with those in brain tumors. Subsequently, tumor slices were histopathologically classified according to the grading system of the World Health Organization (WHO), and proliferative activity was assessed. The average values of α, λ, and k′ in control cortex were 0.24, 1.55, and 3.66 × 10−3s−1, respectively. Values of α, λ, and k′ in oligodendrogliomas did not significantly differ from controls. In pilocytic astrogliomas (WHO grade I) as well as in ependymomas (WHO grade II), α was significantly higher, while λ and k′ were unchanged. Higher values of α as well as λ were found in low‐grade diffuse astrocytomas (WHO grade II). In cellular regions of high‐grade astrocytomas (WHO grade III and IV), α and λ were further increased, and k′ was significantly larger than in controls. Classic medulloblastomas (WHO grade IV) had an increased α, but not λ or k′, while in the desmoplastic type α and k′ remained unchanged, but λ was greatly increased. Tumor malignancy grade strongly corresponds to an increase in ECS volume, which is accompanied by a change in ECS structure manifested by an increase in diffusion barriers for small molecules. GLIA 42:77–88, 2003.

Prognostic factors in intramedullary astrocytomas: a literature review

Astrocytomas affect a significant portion of patients with intramedullary tumors. These infiltratively growing tumors are treated by a variety of methods—biopsy and decompressive surgery, maximal safe resection, adjuvant oncological therapy. Also, numerous prognostic factors are reported in the literature. Better understanding of factors that influence prognosis may help in treatment planning with the goal of prolonging survival. We have thus undertaken an extensive literature review in order to define factors affecting prognosis. A total of 38 articles were studied. Only tumor grade was consistently reported as the major factor affecting prognosis. The influence of other clinical factors (age, gender, history length, functional status, tumor location or extent, syrinx or cyst presence) can be speculated upon, but cannot be assessed adequately from the available literature. For both low- and high-grade (HG) astrocytomas, maximal safe tumor resection should be the primary treatment objective but is often not feasible in contrast to other intramedullary and spinal neoplasms. Since the biological nature of spinal cord HG glioma is identical to that of the brain, the same treatment algorithm of maximal safe resection followed by concomitant radio- and chemotherapy would be sensible to implement.

One Year Experience with 3.0 T Intraoperative MRI in Pituitary Surgery

A multifunctional surgical suite with intraoperative 3.0 T MRI (ioMRI) has been operating at the Central Military Hospital, Prague since April 2008. Our experiences over the past year and the effect of ioMRI on the extent of pituitary adenoma resection are evaluated. Eighty-six pituitary adenoma resections were performed in 85 patients with ioMRI in the first year of the ioMRI service. Pituitary adenoma suprasellar extension was present in 60 cases, invasion into cavernous sinus in 49 cases, and retrosellar growth in one case. The surgical goal was set before surgery: either a radical resection (49 cases) or a partial resection (37 cases). In the group of patients where a decision for a radical resection was taken the results are as follows: ioMRI confirmed radical resection in 69.4% of the cases; ioMRI disclosed unexpected adenoma residuum and further resection led to radical resection in 22.4%. In the group of patients where a decision for a partial resection was taken, the results are as follows: no further resection was perfomed after ioMRI in 51.3% of the cases and further resection was performed after ioMRI in 48.7% of the cases. ioMRI seems to be a valuable tool to increase the extent of pituitary adenoma resection.

Experience of 500 cases of neurophysiological monitoring in carotid endarterectomy

SummaryBackground. Experience with Intraoperative monitoring using neurophysiological and haemodynamic indices in 500 operations for carotid endarterectomy is reported. Methods. Transcranial Doppler technique (TCD), electroencephalogram (EEG) and bilateral median somatosensory evoked potentials (SEP) were performed. Latency and amplitude of SEP, spectral analysis of EEG signal and blood flow velocity in the medial cerebral artery (MCA) were continuously measured. Findings. After two consecutive drops of N20/P25 complex of more than 50%, a warning was given, and when the decrease continued, an the alarm raised. Abnormal EEG changes, if any, appeared after a significant decrease in the N20/P25 amplitude. A mean blood flow velocity drop below 40% of the reference value after cross clamping was rated as a significant warning event.A warning as a result of a decrease in N20/P25 amplitude occurred in 80 operations (16.0%), after an spectral edge frequency decrease in 2 cases (0.4%) and after a Vmean decrease in 21 cases (4.2%). False negative results were experienced in 2 patients (0.4%). A shunt was inserted in 2.8% of the operations. The overall mortality/morbidity rate was 2.4%. Conclusion. A decrease of more than 50% in the amplitude of the thalamocortical somatosensory evoked potential complex N20/P25 proved to be the most reliable warning of danger of ischaemia during carotid endarterectomy.

Comparison between degree of carotid stenosis observed at angiography and in histological examination

SummaryBackground. The generally accepted indications for carotid endarterectomy are the clinical picture and degree of per cent stenosis of the carotid artery. Despite the fact that stenosis measurement is defined, the methods vary considerably. The correlation of particular methods, especially angiography and duplex sonography, has been repeatedly demonstrated. However, the correlation between any technique and true anatomical stenosis, as evaluated on the surgical specimen, has been only anecdotally reported. Method. During carotid endarterectomy, the atherosclerotic plaque was removed in one piece and subsequently stored and histologically processed. The histological slides were evaluated under an optical microscope, scanned and the slide with maximum stenosis was determined using a planimetric program. Both the minimal lumen area and the area of the whole plaque were measured. The stenosis was calculated using the planimetric method. On the maximum stenosis slice, the minimal diameter and the diameter of the whole plaque were also measured. Angiographic images were scanned and the per cent stenoses were remeasured, according to the NASCET and ECST criteria. In total, of 147 cases, all above-mentioned parameters were obtained. Student’s t tests for paired samples were used to evaluate the results. Findings. The t-tests indicated significant differences between the per cent stenosis as measured on the anatomical specimen and on the angiogram (p<0.05). The results indicate that the angiographic measurement underestimates the degree of in-situ anatomical stenosis. The underestimation was more marked the less the degree of stenosis. Conclusions. Our study finds that per cent stenosis measurement obtained by angiography with NASCET or ECST methods does not reliably reflect the anatomical degree of per cent stenosis, which makes questionable the rigorous following of percentage stenosis using angiography as the sole indicator for carotid endarterectomy in all cases.

The MRI volumetry of the posterior fossa and its substructures in trigeminal neuralgia: a validated study

PurposeOur aim was to determine whether the anatomical configuration of the posterior fossa and its substructures might represent a predisposition factor for the occurrence of clinical neurovascular conflict in trigeminal neuralgia (TN).MethodsWe used MRI volumetry in 18 patients with TN and 15 controls. The volume of the pontomesencephalic cistern, Meckel’s cave and the trigeminal nerve on the clinical and non-affected sides was compared. The reliability has been assessed in all measurements.ResultsThe posterior fossa volume was not different in the clinical and control groups; there was no difference between the affected and non-affected sides when measuring the pontomesencephalic cistern and Meckel’s cave volume either. The volume of the clinically affected trigeminal nerve was significantly reduced, but with a higher error of measurement.ConclusionsWe did not find any association between the clinical neurovascular conflict (NVC) and the size of the posterior fossa and its substructures. MRI volumetry may show the atrophy of the affected trigeminal nerve in clinical NVC.

Clinical characteristics in patients with hippocampal sclerosis with or without cortical dysplasia.

BACKGROUND Mesial temporal lobe epilepsy (MTLE) with hippocampal sclerosis (HS) constitutes a distinct clinical syndrome with variable pathogenesis. Extrahippocampal regions may be affected in MTLE/HS, association with cortical dysplasia is common and temporal polar cortex is frequently involved in seizure onset. Patients with dual pathology may have favourable outcome from the surgery provided that both pathologies are removed. The aim of the study was to review clinical variables of MTLE/HS patients in order to distinguish preoperatively patients with associated microscopic cortical dysplasia in the temporal pole. METHODS A series of 38 patients with the clinical diagnosis of MTLE and histopathologically proven HS were analysed. Patients were divided into two groups on the basis of histopathological finding in the temporal polar cortex: HS associated with malformation of cortical development (group HS+, n = 19) and a group with isolated HS (group HS, n = 19). Demographic, clinical, electrographic and seizure semiology variables were obtained and their prevalence compared between both groups. RESULTS At least one insult was identified in early childhood history of 18 patients in the HS group in comparison to 10 patients in the HS+ group (p < 0.01). Complicated febrile seizures were found in both groups with similar prevalence, the history of early childhood CNS infection prevailed in the HS group (p < 0.01). Absence of aura was reported in HS group only. Patients in the the HS+ group had earlier surgery (p < 0.05) but the seizure outcome was comparable between groups. CONCLUSIONS Microscopic dual pathology is common in MTLE/HS patients. This group of patients is difficult to distinguish preoperatively on the basis of noninvasive electrographic features or ictal clinical semiology. Detailed information regarding the possible precipitating insult in the history may be of critical importance.

Comparison of 3 fusion techniques in the treatment of the degenerative cervical spine disease. Is stand-alone autograft really the "gold standard?": prospective study with 2-year follow-up.

Study Design. A prospective study. Objective. The aim of this study was to compare the 3 different methods of interbody fusion of the cervical spine—autograft in stand-alone technique, autograft with anterior plate, and polyetheretherketone cage supported by anterior plate. The clinical and radiological data obtained were analyzed and discussed. Summary of Background Data. Although degenerative cervical spine disease has been treated by an anterior approach for more than 50 years, there is not one generally accepted operative approach. There is a very low-quality evidence of little or no difference in pain relief between each of the techniques. Iliac crest autograft still seems to be the “gold standard” for interbody fusion. Methods. Prospective study collecting clinical and radiological data of 81 patients undergoing anterior cervical interbody fusion, in which the interbody fusion of 1 or 2 motion segments from C3 to C7 was done by any of the 3 techniques–-stand-alone insertion of autograft (group 1: 28 patients), autograft and anterior plate (group 2: 18 patients), and polyetheretherketone cage filled with beta-tricalcium phosphate and plate (group 3: 29 patients). Patients were followed for 2 years after surgery. Results. Significant interaction of relative height in the segment and time was found (P < 0.001). The values of the relative height of stand-alone autograft dropped below 95% of initial height and the values of the other 2 groups remained above 105%. Significant interaction of time and group was found for Cobb S angles (P < 0.001). Values of group 1 decreased substantially and remained significantly lower than values of other 2 groups. Fusion rate was 100% in all groups. Neck Disability Index group and time interaction was found (P = 0.023). During postoperative follow-up, group 1 scored in all controls higher than the other 2 groups, but differences were not significant. Visual analogue scale showed effect of time (P < 0.001). This was due to a smaller improvement of patients in group 1 during the whole follow-up in comparison with the other 2 groups. Highest proportion of unsatisfied patients was in group 1 compared with the other 2 groups after 2 years (P = 0.034). Conclusion. Significantly worse radiological and clinical results after 2 years of follow-up were achieved using stand-alone autograft technique in comparison with autograft supported by anterior plating similarly as in comparison with cage implant and anterior plating. Using artificial fusion substrate together with plate and cage can offer the same clinical and radiological results such as iliac autograft and plating. Anterior plating seems to be an important factor influencing the postoperative cervical spine alignment and also the clinical outcome.

Accuracy of angiography and Doppler ultrasonography in the detection of carotid stenosis: a histopathological study of 123 cases

SummaryBackground. A prospective study was performed comparing the accuracy of digital subtraction angiography (DSA) and Doppler ultrasonography (DUS) stenosis findings with measurements on histological specimens.Method. DSA and DUS were used to evaluate carotid stenosis and were compared with measurements on histological specimens. Intact carotid plaques from 123 cases were removed in one piece during surgery. The specimens were histologically processed and examined in transverse sections. The smallest inner and correlating outer diameters were measured and the extent of stenosis was calculated. Carotid artery stenoses were compared and statistics done. Specimens in symptomatic cases were divided into 3 groups: stenosis 30–49% (Group 1), stenosis 50–69% (Group 2) and stenosis 70–99% (Group 3). Specimens in asymptomatic cases were divided into two groups: stenosis ≤59% (Group A) and stenosis ≥60% (Group B).Findings. Wilcoxon paired tests revealed significant differences between DSA, DUS and measurements on histological specimens. In severe stenoses only, no significant difference was observed between stenosis measurement according to the European Carotid Surgery Trial (ECST) angiography methodology and measurements on histological specimens. The most pronounced differences were found between angiography methodology of the North American Symptomatic Carotid Endarterectomy Trial (NASCET) and measurements on histological specimens. When investigating how often preoperative measurement classified stenosis into the same Group of stenoses as postoperative measurement, DUS was the most accurate diagnostic tool.Conclusions. This study confirmed our previous results, i.e., angiography underestimates the degree of carotid artery stenosis. DUS seems to be more accurate in classifying stenoses into different groups to the extent of narrowing of the carotid arteries. These results make the position of angiography in diagnostic algorithm of carotid stenoses investigations even more questionable.

Cognitive functions before and 1 year after surgical and endovascular treatment in patients with unruptured intracranial aneurysms

Background and purpose. This prospective study investigated whether surgery or endovascular treatment for unruptured intracranial aneurysms (UIAs) affects cognitive functions. Methods. Four neuropsychological variables from an Auditory Verbal Learning Test (overall capacity of verbal memory and delayed recall) and a Trail Making Test (psychomotor speed and cognitive flexibility) were investigated before and 1 year after treatment for UIAs in 65 patients < 61 years of age. This cohort consists of 15 men and 50 women aged 15–60 (mean age 44.9) years. Results. Group-rate analysis showed a non-significant increase in post-treatment scores in the four neuropsychological variables. In addition, no significant differences were found between the surgical clipping (SC) and endovascular coiling (EC) group. Event-rate analysis demonstrated that two patients from the EC and one from the SC group developed cognitive impairment after treatment. Conclusions. Surgical and endovascular repair for UIAs do not impair cognition in patients without postoperative restrictions in lifestyle.