[Dutch Collaborative Epilepsy Surgery Program: reduction of seizures, operative complications and tapering of medication in 338 patients, 1973-1998]

OBJECTIVE

To determine the results of surgical treatment in patients with drug-resistant epilepsy, referred to the Dutch Epilepsy Surgery Program, who were treated in the University Medical Centre Utrecht, the Netherlands, in the period January 1973-December 1998.

DESIGN

Retrospective descriptive.

METHOD

A total of 338 patients were operated on; 269 underwent temporal lobe resection, 41 extratemporal resection, 12 a functional hemispherectomy and 10 callosotomy. Six patients were treated with vagus nerve stimulation. For seven of the patients no follow-up data was available.

RESULTS

After a minimum follow-up of 1 year class I or class II results (in accordance with the University of California in Los Angeles classification (UCLA) where class I = seizure-free and class II < or = 3 seizures per year) were obtained in 91% of patients who underwent temporal lobe resections, 67% of patients who underwent extratemporal resections, 81% of patients who underwent functional hemispherectomy and 10% of patients who underwent anterior callosotomy. In five of these patients an improvement in their behaviour occurred. Of the 6 patients who underwent vagus nerve stimulation only I experienced a beneficial seizure reduction (UCLA class III). Transient physical complications occurred in 4% of the patients treated and permanent damage in 1%. Postoperative psychiatric complications occurred almost exclusively following temporal resections; in 11% of which 7% de novo. After 4 postoperative years this had decreased to 5%. In a group of 143 patients who were seizure-free for 2 or more years, post-surgery medication was tapered in 75 cases, stopped in 33 cases and remained unchanged in 35 cases. The relapse rate following a tapering or stopping of the medication was 30% and with unchanged medication 17%. Although the majority of patients were once again seizure-free upon restarting the medication, a significant number continued to experience seizures.

CONCLUSION

For a number of carefully selected epilepsy patients with intractable seizures, surgery is a successful treatment with few serious complications.

Ionotropic and metabotropic glutamate receptor protein expression in glioneuronal tumours from patients with intractable epilepsy

Glioneuronal tumours are an increasingly recognized cause of chronic pharmaco-resistant epilepsy. In the present study the immunocytochemical expression of various glutamate receptor (GluR) subtypes was investigated in 41 gangliogliomas (GG) and 16 dysembryoplastic neuroepithelial tumours (DNT) from patients with intractable epilepsy. Immunocytochemistry with antibodies specific for ionotropic NR1, NR2A/B (NMDA) GluR1, GluR2 (AMPA), GluR5-7 (kainate), and metabotropic mGluR1, mGluR2-3, mGluR5, mGluR7a subtypes demonstrated in both GG and DNT the presence of an highly differentiated neuronal population, containing subunits from each receptor class. More than 50% of tumours contained a high percentage of neuronal cells immunolabelled for NMDA, AMPA and kainate receptor subunits. A high percentage of neurones showed strong expression of NR2A-B, which co-localized with NR1. Group I mGluRs (mGluR1 and mGluR5) were highly represented in the neuronal component of the tumours. Immunolabelling for several GluRs was also present in the glial component. Increased expression of mGluR2-3, mGluR5 and GluR5-7 was observed in reactive astrocytes in the perilesional zone compared to normal cortex. The neurochemical profile of glioneuronal tumours, with high expression of specific GluR subtypes, supports the central role of glutamatergic transmission in the mechanisms underlying the intrinsic and high epileptogenicity of these lesions.

The value of electrophysiology results in patients with epilepsy and vigabatrin associated visual field loss

PURPOSE

To determine the value of electrophysiological findings in patients with temporal lobe epilepsy and to relate these findings to the amount of concentric contraction of the visual field and the use of vigabatrin.

METHODS

Electro-retinograms and electro-oculograms were done on 30 patients, operated for temporal lobe epilepsy. The patients were divided into three groups: (A) concentric contraction of the visual field associated with a history of vigabatrin medication (15 patients), (B) normal visual field with vigabatrin use (11 patients) and (C) normal visual field without vigabatrin medication (4 patients).

RESULTS

Electrophysiological abnormalities were found in 50% of the patients in group A. The Arden ratio of the EOG was lowered in 57%. Abnormalities in the ERG were found: b-wave implicit time photopic F was prolonged (50%), b-wave amplitudes scotopic B (53%), C (73%) and G (50%) and photopic H (50%) were diminished. The amount of visual field loss and the total dose of vigabatrin used, showed only slight correlation with the ERG and EOG. The use of vigabatrin during the ERG and EOG recording in group A, gave a higher b-wave amplitude scotopic G in 64% of cases. The a-wave implicit times scotopic G (73%) and photopic G (59%) and H (73%) were shortened in group B.

CONCLUSION

EOG was abnormal in 57% in group A. ERG abnormalities could only be found in 50% of group A, mainly in the inner retina. Since also the total dose of vigabatrin and the amount of visual field loss did not really show a correlation with the electrophysiological findings and results of literature are not unanimous, electrophysiology does not appear at present to be a good method to detect patients with, or at risk of, vigabatrin associated visual field loss. Regularly performed visual field examination remains the cornerstone in screening.

Expression of brain-derived neurotrophic factor and tyrosine kinase B receptor proteins in glioneuronal tumors from patients with intractable epilepsy: colocalization with N-methyl-D-aspartic acid receptor

Recent evidence suggests that brain-derived neurotrophic factor (BDNF) and its tyrosine kinase B (TrkB) receptor, in addition to promoting neuronal survival and differentiation, modulates synaptic transmission by increasing N-methyl-D-aspartic acid receptor (NMDAR) activity. Overexpression of BDNF may, then, interfere with normal brain function, causing increased excitability. We have examined the immunohistochemical expression of BDNF, full-length TrkB receptor and the NMDAR subunit 1 and subunit 2A/B proteins (NMDAR1 and NMDAR2A/B) in glioneuronal tumors (gangliogliomas, GG, n = 40; dysembryoplastic neuroepithelial tumors, DNT, n = 15), from patients with chronic intractable epilepsy. The great majority of tumors studied were positive for all markers examined, supporting the high level of neurochemical differentiation of these lesions. BDNF and TrkB immunoreactivity (ir) was mainly observed in the neuronal component of the tumors. In GG, more than 90% of tumors contained very intense BDNF-ir ganglion cells. Double labeling confirmed the presence of BDNF-ir and TrkB-ir in neurons which contained NMDAR1. NMDAR2A/B intensely labeled abnormal neurons in both GG and DNT and co-localized with NMDAR1. The presence of BDNF and its receptor in the neuronal component of GG and DNT may suggest a role for this neurotrophin in the development of these lesions, preventing the death of abnormal neuronal cells. In addition, since these neurons contain both NMDAR1 and NMDAR2A/B subunits, the BDNF-TrkB pathway may also contribute through a modulation of glutamatergic transmission to the intrinsic epileptogenicity of glioneuronal tumors.

A grading system for hippocampal sclerosis based on the degree of hippocampal mossy fiber sprouting

In patients suffering from temporal lobe epilepsy (TLE) a highly variable degree of hippocampal sclerosis (HS) can be observed. For standard neuropathological evaluation after hippocampal resection, neuronal cell loss in the hippocampal subareas is assessed (Wyler score 0-4) [Wyler et al. (1992) J Epilepsy 5: 220-225]. Other marked morphological changes in the sclerotic hippocampus are gliosis and loss of mossy fibers in the hilus and mossy fiber sprouting in the supragranular layer. In this study we quantified changes in mossy fiber density using Timm's stain in resected hippocampal tissue from patients with various degrees of sclerosis. We found that tissue specimens from patients without sclerosis (W0) show almost no mossy fiber sprouting. Patients with moderate sclerosis show sprouting without fiber loss in the hilus, whereas specimens from patients with severe sclerosis show sprouting as well as fiber loss in the hilus. Thus, analysis of mossy fiber abundance in hilus and supragranular layer by the rapid and simple Timm's stain is a sensitive measure for hippocampal sclerosis. It provides a reliable rapid tool for neuropathological evaluation, even if the tissue only contains dentate gyrus due to the sectioning procedure.

Glioneuronal tumors and medically intractable epilepsy: a clinical study with long-term follow-up of seizure outcome after surgery

The present study intends to identify factors that predict postoperative clinical outcome in patients with gangliogliomas (GG) and dysembryoplastic neuroepithelial tumors (DNT). We evaluated the medical records of 45 patients with GG and 13 patients with DNT, treated surgically between 1985 and 1995. We assessed several clinical and histopathological features and analyzed the data statistically. At 5 years postoperatively, 63% of patients with GG and 58% of patients with DNT were seizure-free (Engel's class I). Younger age at surgery (P<0.01 for GG and P<0.05 for DNT), total resection (P<0.01 for GG), shorter duration of epilepsy (P<0.01), absence of generalized seizures (P<0.01 for GG; P<0.05 for DNT) and absence of epileptiform discharge in the post-operative EEG (P<0.01 for GG; P=0.01 for DNT) predicted a better postoperative seizure outcome. Tumor recurrence with malignant progression occurred in eight histologically benign GG and two anaplastic GG and was associated which older age at surgery (P=0.01) and subtotal resection of the tumor (P<0.01). Our results indicate that a prompt diagnosis, relatively soon after seizure onset, followed by complete resection of glioneuronal tumors provides the best chance for curing epilepsy and preventing their malignant transformation.

Localization of implanted EEG electrodes in a virtual-reality environment

In the planning of epilepsy surgery procedures, intracranial electrodes are implanted in a significant fraction of the patients. Accurate localization of the individual electrode contacts with respect to the brain cortex is imperative. Because the manual tracking of an EEG electrode in a CT scan in a slice-by-slice fashion is cumbersome and subjective, the goal of this study was to develop an easier and more accurate way to localize implanted EEG electrodes. In this paper, we present our solution in the form of a virtual-reality environment with interactive tools to assist the clinician with EEG localization. With the help of a high-quality and fast volume renderer, a view is created of the inside of the patient's skull to obtain an overview of the electrodes in relation to the cortical structures. Depth, grid, and reed electrodes are characterized semi-interactively using different methods. For depth electrodes, the contacts (which are not visible in the CT scan) are derived by measuring off the theoretical distance between the contact and the end of the electrode from the central axis produced by a three-dimensional (3D) line tracker. For grid electrodes, the contacts are visible in a CT, so the 3D view is merely used to find the contacts and to resolve the overlap of grids with other grids, tail wires, or bone ridges. For reed electrodes, the contacts, which are again not visible in this case, are calculated from a line model fitted to the positions of lead markers. After letting the user place artificial spheres on the lead markers and wire, a B-spline is fitted to the spheres' centers to estimate the positions of the contacts. The approach was evaluated by applying it to CT scans of seven patients. It appeared that the method is generally applicable (even crossing electrodes or electrodes with gaps were correctly characterized), and that the display via 3D views and slices is so good that manual placement of spheres performed as well as semi-automatic placement. From computer experiments, it appeared that the final localization error in the position of EEG contacts could be estimated to lie in the order of the dimensions of one voxel.

[Vigabatrin: balancing effectiveness vs. (irreversible) visual field loss as a side effect]

The antiepileptic drug vigabatrin causes an asymptotic concentric contraction of the visual field in 30 to 40% of the patients. The visual field loss seems to be correlated with the cumulative dose of vigabatrin and is not reversible. The cause of this field loss is located in the inner retina (the horizontal and/or amacrine cells). The exact mechanism is still unknown. Though abnormalities in electrophysiology and colour vision are found, regular visual field examination remains the cornerstone in detecting visual field loss. A careful judgement has to be made in individual patients before starting or continuing vigabatrin medication.

Long term changes in the visual fields of patients with temporal lobe epilepsy using vigabatrin

AIM

To study the long term changes in the concentric contraction of the visual field in patients with temporal lobe epilepsy on vigabatrin medication.

METHODS

Repeated Goldmann visual field examinations were compared in 27 patients with drug resistant temporal lobe epilepsy and concentric contraction of the visual field. Two groups were studied: 16 patients who had already stopped vigabatrin medication before surgery and 11 patients who continued vigabatrin medication.

RESULTS

Concentric contraction of the visual field did not change in 16 patients who stopped vigabatrin before the first examination; there was slight but significant progress in visual field loss in 11 patients who continued the use of vigabatrin.

CONCLUSION

Long term follow up of concentric contraction in this selected group of patients indicates that vigabatrin associated visual field loss is not reversible and that progression is possible when vigabatrin is continued.

Glutamate and gamma-aminobutyric acid content and release of synaptosomes from temporal lobe epilepsy patients

During surgical intervention in medically refractory temporal lobe epilepsy (TLE) patients, diagnosed with either mesial temporal lobe sclerosis (MTS)- or tumor (T)-associated TLE, biopsies were taken from the anterior temporal neocortex and the hippocampal region. Synaptosomes, isolated from these biopsies were used to study intrasynaptosomal Ca(2+) levels ([Ca(2+)](i)), and glutamate and gamma-aminobutyric acid (GABA) contents and release. All synaptosomal preparations demonstrated a basal [Ca(2+)](i) of about 200 nM, except neocortical synaptosomes from MTS-associated TLE patients (420 nM). K(+)-induced depolarization resulted in a robust increase of the basal [Ca(2+)](i) in all preparations. Neocortical synaptosomes from TLE patients contained 22.9 +/- 3.0 nmol glutamate and 4.6 +/- 0.5 nmol GABA per milligram synaptosomal protein, whereas rat cortical synaptosomes contained twice as much glutamate and four times as much GABA. Hippocampal synaptosomes from MTS-associated TLE patients, unlike those from T-associated TLE patients, contained about 70% less glutamate and 55% less GABA than neocortical synaptosomes. Expressed as percentage of total synaptosomal content, synaptosomes from MTS-associated TLE patients exhibited an increased basal and a reduced K(+)-induced glutamate and GABA release compared to rat cortical synaptosomes. In MTS-associated TLE patients, only GABA release from neocortical synaptosomes was partially Ca(2+)-dependent. Control experiments in rat synaptosomes demonstrated that at least part of the reduction in K(+)-induced release can be ascribed to resection-induced hypoxia in biopsies. Thus, synaptosomes from MTS-associated TLE patients exhibit a significant K(+)-induced increase in [Ca(2+)](i), but the consequent release of glutamate and GABA is severely impaired. Our data show that at least part of the differences in glutamate and GABA content and release between human biopsy material and fresh rat tissue is due to the resection time.

The wada test: prediction of focus lateralization by asymmetric and symmetric recall

PURPOSE

The intracarotid amytal test is commonly used as a predictor of memory dysfunctioning after anterior temporal lobe resection (ATL) for intractable epilepsy. Asymmetry in memory scores can provide focus lateralizing information. In this study the predictive value of a set of Wada test parameters was analyzed, including patients with symmetrical memory scores.

METHODS

The Wada test was carried out in 226 patients undergoing ATL (94 L, 132 R). Data were collected on item recognition (five items), story recall, amytal dose, presentation time, EEG and arterial filling of amytal. A logistic regression analysis was performed on these data in order to find a set of variables which could best predict the side of seizure onset.

RESULTS

The analysis yielded four variables, i.e. both memory scores, story recall after right-sided injection and presentation time of stimuli after left-sided injection which could correctly predict seizure lateralization in 85% of the cases. Misclassification was lower for right foci than for left foci. Seizure outcome was four times more favourable in the correctly classified patients.

CONCLUSIONS

The results suggest that prediction of focus lateralization in temporal lobe epilepsy can be fairly exact even if left/right memory scores are equal. Performing the Wada test with only five memory items keeps the time window of active amytal short enough and gives accurate information about contralateral temporal lobe functioning. The classification scheme can be useful in predicting a lowered chance of seizure freedom.

Concentric contraction of the visual field in patients with temporal lobe epilepsy and its association with the use of vigabatrin medication

PURPOSE

To describe concentric visual field loss found in the presurgical evaluation of patients with drug-resistant temporal lobe epilepsy and relate the findings to potential causative factors.

METHODS

A series of 157 consecutive patients with drug-resistant temporal lobe epilepsy, who had been selected for neurosurgical treatment, was examined in a study set up as a prospective investigation of their visual fields, to document the loss of visual field resulting from surgery. Pre-as well as postoperative visual field examinations were performed following a standard protocol using static and kinetic perimetry. As a number of patients appeared to have an unexplained concentric visual field contraction in the presurgical examination, a relation with potentially causative factors was analyzed in a cross-sectional study of all these patients. Correlations were sought with duration and severity of the seizure disorder, underlying pathology as indicated by magnetic resonance imaging (MRI) and demonstrated by pathology, any type of antiepileptic drug (AED) ever prescribed, and gender.

RESULTS

In this cross-sectional analysis of 157 consecutive patients who were candidates for surgery for temporal lobe epilepsy, absolute concentric contraction of the visual field of 10 to 30 degrees was found in the presurgical examination in 20 (17%) of 118 patients who had ever used vigabatrin (VGB) and in none of 39 who had not had this medication. This difference was significant (p = 0.004). In addition, men [15 (21%) of 72] were significantly more often affected (p = 0.007) than women [five (6%) of 85]. The degree of visual field loss, as indicated by the Esterman grid, showed a positive correlation with the duration of VGB medication. There was no correlation of visual field contraction with a history of meningitis as potential cause of the epilepsy, duration of the epilepsy, status epilepticus in the medical history, or histologic abnormality of the brain tissue removed. Ophthalmologic examination of the patients with concentric contraction revealed no abnormalities. None of the patients with concentric contraction complained spontaneously of their visual field loss.

CONCLUSIONS

VGB medication is a causative factor in concentric visual field loss. Visual field examination of patients using VGB should be seriously considered.

Non-linear analysis of intracranial human EEG in temporal lobe epilepsy

OBJECTIVE

Intracranial EEG recordings from patients suffering from medically intractable temporal lobe epilepsy were analyzed with the aim of characterizing the dynamics of EEG epochs recorded before and during a seizure and comparing the classification of the EEG epochs on the basis of visual inspection to the results of the numerical analysis.

METHODS

The stationarity of the selected EEGs was assessed qualitatively. The coarse-grained correlation dimension and coarse-grained correlation entropy were used for the non-linear characterization of the EEG epochs.

RESULTS

High-pass filtering was necessary in order to make the majority of the epochs appear stationarity beyond a time scale of about 2 s. It was found that the dimension of the ictal EEGs decreased with respect to the epochs containing ongoing (interictal) activity. The entropy of the ictal recordings however increased. A scaling of the entropy was applied and it was found that the scaled entropy of the ictal EEG decreased, consistent with the increased regularity of the ictal EEG. The coarse-grained quantities discriminated well between EEG epochs recorded prior to and during seizures at locations displaying ictal activity and classification improved by including the linear autocorrelation time in the analysis.

CONCLUSIONS

It is concluded that ictal and non-ictal EEG can be well distinguished on the basis of non-linear analysis. The results are in good agreement with the visual analysis.

Language area localization with three-dimensional functional magnetic resonance imaging matches intrasulcal electrostimulation in Broca's area

In this study, intraoperative electrocortical stimulation mapping (ioESM), the current gold standard for the localization of critical language areas, is compared with functional magnetic resonance imaging (fMRI) in a 14-year-old girl with medically intractable epilepsy caused by a tumor in the region of Broca's area. Prior to the operation, four different fMRI tasks that target inferior frontal language areas were applied. Prior to the resection, ioESM as well as fMRI detected no language areas at the exposed cortical area. After removal of the tumor, a unique opportunity presented itself, where ioESM could be performed in the depth of a now exposed and intact gyrus. One specific locus that was indicated to be a critical language area by multiple-task fMRI was targeted. IoESM selectively confirmed the location of this language area to within an estimated 3 mm. We propose that the combined use of different fMRI tasks increases the sensitivity and specificity for the detection of essential language areas.

Characterization of neocortical and hippocampal synaptosomes from temporal lobe epilepsy patients

To investigate epilepsy-associated changes in the presynaptic terminal, we isolated and characterized synaptosomes from biopsies resected during surgical treatment of drug-resistant temporal lobe epilepsy (TLE) patients. Our main findings are: (1) The yield of synaptosomal protein from biopsies of epilepsy patients was about 25% of that from rat brain. Synaptosomal preparations were essentially free of glial contaminations. (2) Synaptosomes from TLE patients and naive rat brain, quickly responded to K(+)-depolarization with a 70% increase in intrasynaptosomal Ca(2+) ([Ca(2+)](i)), and a 40% increase in B-50/GAP-43 phosphorylation. (3) Neocortical and hippocampal synaptosomes from TLE patients contained 20-50% of the glutamate and gamma-aminobutyric acid (GABA) contents of rat cortical synaptosomes. (4) Although the absolute amount of glutamate and GABA released under basal conditions from neocortical synaptosomes of TLE patients was lower than from rat synaptosomes, basal release expressed as percentage of total content was higher (16.4% and 17.3%, respectively) than in rat (11.5% and 9. 9%, respectively). (5) Depolarization-induced glutamate and GABA release from neocortical synaptosomes from TLE patients was smaller than from rat synaptosomes (3.9% and 13.0% vs. 21.9% and 25.0%, respectively). (6) Analysis of breakdown of glial fibrillary acid protein (GFAP) indicates that resection time (anoxic period during the operation) is a critical parameter for the quality of the synaptosomes. We conclude that highly pure and viable synaptosomes can be isolated even from highly sclerotic human epileptic tissue. Our data show that in studies on human synaptosomes it is of critical importance to distinguish methodological (i.e., resection time) from pathology-related abnormalities.

MR contribution in surgery of epilepsy

The contribution of MR imaging in patients with drug-resistant epilepsy considered for surgical therapy is discussed. In this review we focus on: (a) focal abnormalities (mesial temporal sclerosis, focal migration disorders, hamartomatous lesions and low-grade tumours, phakomatosis and vascular malformations) associated with therapy-resistant partial epilepsy, requiring resective surgery; (b) abnormalities leading to generalized seizures that require more drastic surgical procedures, such as callosotomy and functional hemispherectomy; and (c) localisation of implanted depth-electrodes.

[No adverse effects on intelligence 6 years after surgery for epilepsy]

OBJECTIVE

To evaluate the long-term effects of epilepsy surgery on intelligence.

DESIGN

Prospective descriptive.

METHOD

The group included 20 patients of the Instituut voor Epilepsiebestrijding, Heemstede, and the Epilepsiecentrum Kempenhaeghe, Heeze, the Netherlands, who suffered from medication-resistant epilepsy originating from the temporal lobe, in 9 patients from the left lobe (mean age: 33.1 years), in 11 from the right one (34.6 years). The epilepsy focus was removed surgically (Academic Hospital, Utrecht). The scores on the 'Wechsler adult intelligence scale' (WAIS) were determined before the operation and 6 months, 2 years and 6 years after operation.

RESULTS

The mean WAIS IQs before operation were: verbal IQ (VIQ): 111.8 and performance IQ (PIQ): 117.7 in the group treated on the left and VIQ: 113.5 and PIQ: 112.4 in the group treated on the right. The mean gains 6 years after operation were 0.8 and 2.6 VIQ-points and 8.7 and 8.5 PIQ-points respectively. In the patients operated on the left the difference between VIQ and PIQ was significant 2 and 6 years after operation. The increase in IQs remained within what could be expected in retests. Only for the VIQ of patients treated on the left was a smaller retest effect found.

CONCLUSION

These figures show that in the long term epilepsy surgery does not have an adverse outcome on the intelligence.

Relevance of temporal lobe white matter changes in hippocampal sclerosis. Magnetic resonance imaging and histology

RATIONALE AND OBJECTIVES

To evaluate the diagnostic relevance of ipsilateral atrophy of the collateral white matter in the parahippocampal gyrus (ACWMp) and temporal lobe gray/white matter demarcation loss (GWDL) on magnetic resonance imaging in patients with histologically confirmed hippocampal sclerosis. In the second part of this investigation, histologic specimens were analyzed to find an explanation for GWDL.

METHODS

Retrospective visual assessment of hippocampal signal intensity and size and of ACWMp and GWDL was performed using 4- to 5-mm coronal T2-weighted spin-echo magnetic resonance images of 80 patients with histologically proven hippocampal sclerosis and of 30 age-matched controls without epilepsy. Frequency of occurrence and likelihood ratios of ACWMp and GWDL were calculated and their contribution to the diagnosis of hippocampal sclerosis was assessed, particularly in patients with no or restricted hippocampal abnormalities (either high signal or smaller size) on magnetic resonance imaging. The second part of the study involved the morphologic histologic assessment of neocortical temporal lobe specimens of all patients. Myelin density was evaluated in specimens of a subgroup of six patients with hippocampal sclerosis and GWDL on MRI and six patients with hippocampal sclerosis without GWDL.

RESULTS

ACWMp was found in 68% and GWDL in 65% of patients with hippocampal sclerosis on magnetic resonance imaging. Both features had an infinite positive likelihood ratio. Sixty-two patients (77.5%) had concomitant hippocampal signal increase and smaller size. Eighteen patients (22.5%) had no or restricted hippocampal abnormalities on magnetic resonance imaging. When using ACWMp and GWDL as additional diagnostic parameters, 13 of these 18 patients were more unambiguously diagnosed as having hippocampal sclerosis. No significant morphologic differences were found between GWDL-positive and GWDL-negative specimens. A significantly lower average myelin stain was found in the white matter of the GWDL-positive group compared to the GWDL-negative group.

CONCLUSIONS

ACWMp and GWDL can improve the visual diagnosis of hippocampal sclerosis, particularly in patients with no or restricted hippocampal abnormalities. These results suggest that loss of myelin may be the underlying cause of GWDL in association with hippocampal sclerosis.

Comparison of combined versus subdural or intracerebral electrodes alone in presurgical focus localization

PURPOSE

The yield of subdural versus intracerebral electrodes for ictal localization remains a point of controversy. We assessed the relative sensitivity of these two types of electrodes per case.

METHODS

Eighty-three intracranial recordings obtained from 82 patients were retrospectively reviewed to establish which type of electrode performed best in which patients and which seizure types.

RESULTS

Sixty (73%) of 82 patients had temporal lobe seizure onsets, eight frontal, nine widespread or multifocal/multilobar or both, whereas in five, seizure onset was not localized. Exclusive use of intracerebral electrodes would have been sufficient for accurate localization of the seizure-onset zone in all 35 patients with strictly mesial temporal seizure onsets. In only 20 (57%) of these 35 patients, the same decision would have been reached with exclusive use of subdural electrodes. In widespread neocortical and mesial temporal seizures (n = 25), yield of both electrode types was at about the same level, but neither was sufficient to identify the zone of ictal onset on its own. In frontal or multilobar seizures (n = 22), yield of subdural electrodes was slightly better then that of the intracerebral electrodes, but was not sufficient in all cases.

CONCLUSIONS

This study indicates that, depending on the characteristics of the seizure disorder, exclusive use of either intracerebral or subdural electrodes may easily result in erroneous diagnosis because of insufficient sampling of the brain. These findings are in contrast with other studies emphasizing the high yield of reliable EEG findings in evaluations with a single type of electrode and corroborate the results of one of our previous studies.

Effect of valproic acid on sodium currents in cortical neurons from patients with pharmaco-resistant temporal lobe epilepsy

In a selected group of temporal lobe epilepsy patients with seizures refractory to pharmacological treatment, pharmacological seizure control can be attained by surgical resection of the epileptic zone. We investigated to what extent pharmaco-resistance is reflected in a reduced response at the cellular level, in neurons acutely isolated from the temporal cortex resected in 20 patients. We studied the effect of valproic acid (VPA) on the transient sodium current, measured under whole-cell voltage-clamp conditions. We compared neurons from patients with temporal lobe sclerosis (S) with neurons from patients without hippocampal sclerosis (nS) and compared hippocampal CA1 neurons (CA) with neocortical neurons (NC). We could not detect differences in the voltage dependence and kinetics of sodium current activation and inactivation in any of the group comparisons. VPA shifted the voltage dependence of steady-state inactivation (expressed as V(h,i) in a Boltzmann fit) to more hyperpolarized levels. The shift induced by 2 mM VPA was -5.1 +/- 0.7 mV in CA-S (n = 13), -5.1 +/- 0.7 mV in CA-nS (n = 25), -4.3 +/- 0.5 mV in NC-S (n = 17) and -4.9 +/- 0.5 mV in NC-nS (n = 16) The relation between concentration and voltage shift had an EC50 of 1.4 +/- 0.2 mM VPA (n = 16) and a maximal shift of 9.6 +/- 0.9 mV. We conclude that pharmaco-resistance in these patients is not associated with a changed modulation of the sodium current by VPA. Results are discussed in the light of a reduced sodium current modulation by carbamazepine in CA1 neurons of patients with hippocampal sclerosis and of similar observations in the kindling model of epileptogenesis.

Intracranial EEG seizure-offset termination patterns: relation to outcome of epilepsy surgery in temporal lobe epilepsy

PURPOSE

Studies using stereo-EEG (SEEG) and electrocorticography (ECoG) should not only identify a patient's epileptogenic zone, but also should provide prognostic information for surgical outcome. In this respect, seizure-offset patterns have so far been the subject of only one study, in which they were shown to be associated with poor outcome when recorded over cortical areas outside the temporal lobe of seizure onset. To clarify whether seizure-offset patterns are reliable in predicting seizure outcome, we studied SEEG/ECoG in a similar group of patients with temporal lobe epilepsy (TLE).

METHODS

SEEG/ECoG records of 44 patients with refractory TLE were analyzed. The areas of seizure termination were classified as ipsilateral or contralateral (mesial and/or lateral) temporal, (temporal and) frontal, and diffuse/bilateral. Patients were classified with respect to seizure outcome as either seizure-free (UCLA class 1a) or not seizure free (UCLA class 2-4); both groups were correlated with specific seizure-offset categories using Fisher's exact probability test and analysis of variance (ANOVA).

RESULTS

Of the 44 patients, the majority (n = 36) had at least part of their seizure offsets in the ipsilateral temporal lobe, whereas 8 patients manifested no seizure offsets in this lobe. Only 9 patients (20%) showed exclusive offsets in the ipsilateral temporal lobe. No statistically significant difference was evident between patients with all seizure offsets in the ipsilateral temporal lobe and those with offsets elsewhere. Similarly, no statistically significant difference was evident between patients with a diffuse seizure offset and those with seizure offsets of a different category.

CONCLUSIONS

Seizure-offset patterns in SEEG/ECoG are unreliable in predicting seizure outcome after resective activity surgery for TLE.

Nonlinear dynamics of epileptic seizures on basis of intracranial EEG recordings

PURPOSE

An understanding of the principles governing the behavior of complex neuronal networks, in particular their capability of generating epileptic seizures implies the characterization of the conditions under which a transition from the interictal to the ictal state takes place. Signal analysis methods derived from the theory of nonlinear dynamics provide new tools to characterize the behavior of such networks, and are particularly relevant for the analysis of epileptiform activity.

METHODS

We calculated the correlation dimension, tested for irreversibility, and made recurrence plots of EEG signals recorded intracranially both during interictal and ictal states in temporal lobe epilepsy patients who were surgical candidates.

RESULTS

Epileptic seizure activity often, but not always, emerges as a low-dimensional oscillation. In general, the seizure behaves as a nonstationary phenomenon during which both phases of low and high complexity may occur. Nevertheless a low dimension may be found mainly in the zone of ictal onset and nearby structures. Both the zone of ictal onset and the pattern of propagation of seizure activity in the brain could be identified using this type of analysis. Furthermore, the results obtained were in close agreement with visual inspection of the EEG records.

CONCLUSIONS

Application of these mathematical tools provides novel insights into the spatio-temporal dynamics of "epileptic brain states". In this way it may be of practical use in the localization of an epileptogenic region in the brain, and thus be of assistance in the presurgical evaluation of patients with localization-related epilepsy.

Assessment of the preferred plane and sequence in the depiction of mesial temporal sclerosis using magnetic resonance imaging

RATIONALE AND OBJECTIVES

Definition of optimal magnetic resonance (MR) scanning plane and conventional MR sequence for the detection of mesial temporal sclerosis (MTS).

METHODS

Coronal and axial T2-weighted images and axial T2-weighted images parallel to the long axis of the hippocampus (APLAH) and coronal inversion recovery (IR) images were obtained in patients with medically intractable temporal lobe epilepsy in their phase 1 preoperative evaluation. Thirty-three consecutive MR scans were reviewed by a panel of three radiologists. Twenty-three patients had MR abnormalities consistent with MTS, and ten scans were normal. To assess the best single scanning technique, another group of three radiologists, who were masked to all patient data, individually assessed the different planes and sequences of the 33 studies presented separately in a random fashion. For each plane and sequence, the likelihood (L) ratio for the correct diagnosis was determined separately.

RESULTS

For all planes considered separately, a likelihood ratio of 4.4 was optimal for the coronal T2-weighted images. The likelihood ratio of APLAH T2 was 2.2; of axial T2, 3.9; of coronal IR, indefinite because of 100% specificity.

CONCLUSIONS

For the assessment of MTS, coronal T2-weighted images were considered the best single scanning technique.

Is 11C-flumazenil PET superior to 18FDG PET and 123I-iomazenil SPECT in presurgical evaluation of temporal lobe epilepsy?

OBJECTIVE

To determine the contribution of 18FDG PET, 11C-flumazenil PET, and 123I-iomazenil SPECT to the presurgical evaluation of patients with medically intractable complex partial seizures.

METHODS

Presurgical evaluation was performed in 23 patients, who were considered candidates for temporal lobe resective surgery (14 females and nine males with a median age of 34 (range 13 to 50) years). The presurgical diagnosis was based on seizure semiology as demonstrated with ictal video recording, ictal and interictal scalp EEG recordings, and MRI.

RESULTS

Eighteen patients had convergent findings in clinical semiology, interictal and ictal EEG with scalp and sphenoidal electrodes, and MRI that warranted surgery without depth EEG (DEEG). In five patients with insufficient precision of localisation, DEEG with intracerebral and subdural electrodes was performed. MRI showed abnormalities in 22 out of 23 patients. Of these 22, 18 had mesial temporal sclerosis. This was limited to the mesial temporal lobe in four and more widespread in the temporal lobe in 14 patients. In one patient only enlargement of the temporal horn was found and in three others only white matter lesions were detected. 18FDG PET showed a large area of glucose hypometabolism in the epileptogenic temporal lobe, with an extension outside the temporal lobe in 10 of 23 patients. Only in one of these patients DEEG showed extratemporal abnormalities that were concordant with a significant extratemporal extension of hypometabolism in 18FDG PET. 18FDG PET was compared with the results of scalp EEG: in none of the patients was an anterior temporal ictal onset in scalp EEG related to a maximum hypometabolism in the mesial temporal area. By contrast, the region of abnormality indicated by 11C-flumazenil PET was much more restricted, also when compared with DEEG findings. Extension of abnormality outside the lobe of surgery was seen in only two patients with 11C-flumazenil and was less pronounced compared with the intratemporal abnormality. Both 18FDG PET and 11C-flumazenil PET reliably indicated the epileptogenic temporal lobe. Thus these techniques provide valuable support for the presurgical diagnosis, especially in patients with non-lesional MRI or non-lateralising or localising scalp EEG recordings. In those patients in whom phase 1 presurgical evaluation on the basis of classic methods does not allow a localisation of the epileptogenic area, PET studies may provide valuable information for the strategy of the implantation of intracranial electrodes for DEEG. Previous studies have suggested that 11C-flumazenil binding has a closer spatial relationship with the zone of ictal onset than the area of glucose hypometabolism, but this study suggests rather that the decrease in the 11C-flumazenil binding simply reflects a loss of neurons expressing the benzodiazepine-GABA receptor. 11C-flumazenil PET did not prove to be superior to 18FDG PET.

CONCLUSION

In 21 patients sufficient material was obtained at surgery for a pathological examination. In 17 mesial temporal sclerosis, in one an oligodendroglioma grade B, in another a vascular malformation and in two patients no abnormalities were found. Although all 21 patients with pathological abnormality showed hypometabolic zones with 18FDG PET and a decreased uptake in 11C-flumazenil binding, there was no strong correlation between pathological diagnosis and functional abnormal areas in PET. Grading of medial temporal sclerosis according to the Wyler criteria showed no correlation with the degree of hypometabolism in either 18FDG or 11C-flumazenil PET. The interictal 123I-iomazenil SPECT technique was highly inaccurate in localising the lobe of surgery.

Inhibitors of protein tyrosine phosphorylation reduce the proliferation of two human glioma cell lines

Epidermal growth factor (EGF) and platelet-derived growth (PDGF) are suggested to be involved in the proliferation of human gliomas. We examined the effects of these growth factors on two human malignant glioma cell lines. Treatment of the A172 glioblastoma and the Hs683 glioma cell line with EGF and PDGF resulted in the tyrosine autophosphorylation, and hence activation, of the respective growth factor receptors. In addition, both cell lines responded to EGF and PDGF with increased deoxyribonucleic acid (DNA) synthesis. Because the intrinsic protein tyrosine kinase activity of this class of growth factor receptors is indispensable for their functioning, we tested the effects of specific protein tyrosine kinase inhibitors on growth factor-induced DNA synthesis and glioma cell proliferation. Genistein inhibited both EGF- and PDGF-stimulated autophosphorylation of the receptors and induction of DNA synthesis. However, genistein seemed to be cytotoxic to the cells. The tyrphostins RG 50875 and RG 13022 dose-dependently inhibited DNA synthesis induced by EGF, PDGF, and serum. RG 13022 completely blocked the EGF- and PDGF-induced DNA synthesis at a concentration of 50 mumol/L. The tyrphostins showed no selectivity in blocking either EGF or PDGF signaling. With concentrations up to mumol/L, no cytotoxic side effects of the tyrphostins were observed. Both tyrphostins also inhibit serum-driven cell growth in a dose-dependent manner. These results support the hypothesis that activated protein tyrosine kinase receptors are involved in the proliferation of A172 and Hs683 glioma cells. Selective inhibitors of protein tyrosine kinases, therefore, might have the potential to contribute to the treatment of growth factor-dependent gliomas.

Fast spin-echo MR of contact points on implanted intracerebral stainless steel multicontact electrodes

A three-dimensional fast spin-echo MR technique is proposed for locating contact points on implanted intracerebral multicontact electrode bundles, Coronal or sagittal reformatting shows the entire trajectory of the electrode bundles. The contract points are clearly visible owing to the absence of coating material associated with a slightly larger susceptibility artifact. Potentially, this technique may preclude postimplantation thin-section CT, with its associated high radiation dose.

Temporal lobe epilepsy: the various MR appearances of histologically proven mesial temporal sclerosis

PURPOSE

To determine the frequency of appearance of various MR signs in mesial temporal sclerosis, to determine the optimal scanning planes for their visualization, and to propose a histologic explanation for the diminished demarcation between gray and white matter in the temporal lobe, a frequent MR finding in patients with mesial temporal sclerosis.

METHODS

MR scans of 14 surgically treated patients with epilepsy and histologically proven mesial temporal sclerosis were assessed for the presence of six features: feature 1, high signal intensity in the hippocampus; 2, reduced hippocampal size; 3, ipsilateral atrophy of the hippocampal collateral white matter; 4, enlarged temporal horn; 5, reduced gray-white matter demarcation in the temporal lobe; and 6, decreased temporal lobe size.

RESULTS

Feature 1 was present in 14 patients and was best appreciated on the T2-weighted images in planes parallel to the long axes of the hippocampi. Feature 2, present in 12 patients, and feature 6, present in 9 patients, were optimally seen in the coronal planes and on the inversion-recovery sequences in particular. Feature 3, present in 12 patients, was optimally seen on the coronal T2-weighted images. Feature 4, seen in 11 patients, was equally well seen in all planes (transverse, coronal, and parallel to the long axes of the hippocampi). Feature 5, seen in 10 patients, was best appreciated on the T2-weighted images in the planes of the long axes of the hippocampi. Histologic investigation of the temporal lobe white matter in the 10 patients with feature 5 demonstrated on the MR scan showed abnormalities in 7 cases. Oligodendroglia cell clusters were found in 6, with concomitant corpora amylacea in 1 case and perivascular macrophages with pigment a sole finding in another case.

CONCLUSION

Of the six features found in cases of mesial temporal sclerosis on MR, increased hippocampal signal intensity is the most consistent. A decreased gray-white matter demarcation in the temporal lobe parenchyma is also a frequent feature of this disease. A combination of multiple scanning planes results in an optimal demonstration of lesions.

Functional neurosurgery in the treatment of epilepsy in The Netherlands. Aspects of presurgical evaluation and the contribution of subdural and stereotactically implanted depth electrodes in the Dutch Workgroup for Functional Surgery

In the Netherlands all patients who are considered candidates for surgical treatment of their epilepsy are referred to the Dutch Workgroup for Functional Neurosurgery. Resective neurosurgery in partial epilepsy is a focus of special interest of national health authorities. Annually 15-20 patients can now be operated upon. Presurgical evaluation includes a.o. 18/FDG PET. For depth-EEG recording a specially designed method of "Combined Subdural and Depth-EEG Recording" is used which has been described previously. 70 patients underwent depth-EEG recording with the combined method. In 4.2% of the patients there were transient complications, in 1.4% there was a possibly permanent slight neurological deficit caused by the method. Fifty-six patients were evaluated at least one year after their surgical treatment (median follow-up 3 years). In the frontal lobe group comprising 9 patients 56% were seizure-free, 76% benefited from the treatment. In the temporal lobe group with 47 patients 68% were seizure-free and 92% benefited. No patient deteriorated from the resection. Permanent morbidity was nil.

Regional brain glucose metabolism in patients with complex partial seizures investigated by intracranial EEG

We performed interictal 18F-2-fluoro-2-deoxy-D-glucose positron emission tomography (18FDG-PET) studies in 57 patients with complex partial epilepsy (CPE), not controlled by medical treatment and considered for surgical resection of their epileptic focus. A precise localization of the epileptic focus was obtained in 37 of these patients with a combination of subdural and depth electrodes. We visually inspected the metabolic images; we also measured glucose consumption in a number of brain regions and compared the values with those obtained in 17 normal controls. Eighty-two percent of the 57 patients had an area of glucose hypometabolism on the 18FDG-PET images. Six patients had a frontal epileptic focus, 3 of them had a frontal lobe hypometabolism. Twenty-six patients had a unilateral temporal lobe focus and all of them displayed a temporal lobe hypometabolism. The asymmetry was more pronounced in the lateral temporal cortex (-20%) than in the mesial part of the temporal lobe (-9.6%). In each cortical brain region on the side of the epileptic focus (except the sensorimotor cortex), glucose consumption rate was lower than in the contralateral region or than in controls. No differences could be found between patients with a seizure onset restricted to the hippocampus and patients with a seizure onset involving the hippocampus and the adjacent neocortex. Divergent metabolic patterns were obtained in 5 patients with bilateral temporal seizure foci. Combined with other non invasive techniques (EEG, neuroradiology), PET contributes increasingly to the selection of patients with CPE who could benefit from surgical treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Protein tyrosine kinases in human brain and gliomas

Tyrosine kinase activity was determined in neonatal and adult human brain, oligodendrogliomas, and astrocytomas. The astrocytomas were divided into low- (grade I and grade II) and high-grade (grade III and grade IV) tumors. We measured the tyrosine kinase activity in the cytosolic and membrane fraction using poly(glutamic acid:tyrosine, 4:1) as an artificial substrate. The cytosolic activity in oligodendrogliomas (n = 7), low-grade astrocytomas (n = 7), and neonatal brain (n = 1) was increased, on average, two- to fourfold compared with that in normal adult brain (n = 14). The cytosolic activities of high-grade astrocytomas (n = 11) were in approximately the same range as found in normal adult brain. The absence of an increase in cytosolic activity in high-grade astrocytomas compared with adult brain is likely due to the occurrence of necrosis in these tumors. In contrast to the cytosolic activity, no differences were found in the membrane-bound activity. By fast protein liquid chromatography, at least three forms of cytosolic protein tyrosine kinase could be separated, which eluted at 0, 115, and 210 mM NaCl. In most cases the highest amount of activity eluted at 210 mM NaCl. However, in oligodendrogliomas, high-grade astrocytomas, and neonatal brain, more activity eluted at 115 mM NaCl than in normal adult brain (p = 0.043). Nevertheless, protein tyrosine kinases from all three peaks contributed to the elevated levels of total cytosolic activity of oligodendrogliomas and low-grade astrocytomas.

Combined use of subdural and intracerebral electrodes in preoperative evaluation of epilepsy

For intracranial recording of partial seizures considered to originate from one of the temporal or frontal lobes, the team in the Utrecht Academic Hospital has used subdural, multicontact, flexible electrodes since 1972. These are introduced through bilateral, frontocentral trephine holes and are manipulated under fluoroscopy to cover most of the cerebral convexity. It became evident that in many patients, additional placements to record from intracerebral structures were indispensable. Therefore, using the same trephine holes, an additional 2 to 4 depth electrodes were stereotactically implanted in the mesial temporal and/or frontal structures, as appropriate. An extensive intra- and extracerebral spatial representation of the epileptogenic zone was thus obtained. We report here the methods for manufacturing and applying these electrodes and our clinical experience with 28 patients. The results obtained so far stress the value of combining subdural and depth electroencephalographic monitoring in the presurgical selection of patients suffering from medically refractory complex partial seizures. By miniaturizing the electrodes, extensive areas of the brain can be investigated without craniotomy or multiple burr holes.

Quantitative analysis of 18/FDG-PET in the presurgical evaluation of patients suffering from refractory partial epilepsy. Comparison with CT, MRI, and combined subdural and depth. EEG

CT, MRI, 18/FDG-PET and Depth. EEG, performed with subdural and depth electrodes were part of the presurgical evaluation in 22 patients. Statistical analysis of 18/FDG-PET was performed to compare cerebral utilization of glucose to that of normal age matched controls. The findings of CT, MRI, and quantitative analysis of PET are compared with those of ictal Depth. EEG. A positive correlation between CT and Depth. EEG was obtained in 23% of the patients and between MRI and Depth. EEG. in 50%. For both imaging techniques a negative correlation was found in 5%. Regional abnormalities were found with quantified PET in 95% of the patients and were concordant with Depth. EEG. for side of onset in 77% of the patients and for lobe of onset in 59%. A possibly false localising PET result for lobe of onset was obtained in 8 patients (36%). Limitations of PET were most apparent in patients with regional mesiolimbic or bilateral seizure onset. A favourable outcome of surgery was associated usually with positive convergence of both methods. PET may be a valuable contribution to the research and management of partial complex epilepsy, but at present cannot be considered a reliable alternative to invasive EEG methods in patients without clear unilateral focus localization on surface EEG.

Enolase isoenzymes in human cerebral metastasis

gamma-Enolase [one of the three possible subunits of the dimeric enzyme enolase (EC 4.2.1.11)] has been reported as a marker for human neurons, neuroendocrine cells and tumors derived from these cells. In recent years, however, its presence has been reported in nonneuronal tumors. For employment in the histopathologic diagnosis of tumors of the nervous system, exact knowledge of the enolase isoenzyme patterns occurring in these tumors is a prerequisite. In human gliomas, the presence of varying quantities of gamma-enolase has been demonstrated. The present study examines the enolase isoenzyme pattern in human cerebral metastases of various primary progeny, using electrophoresis of tumor tissue extracts as well as immunohistochemistry. Additionally, a number of primary tumors of nonneuroepithelial tissue was examined by immunohistochemistry. The presence of gamma-enolase was demonstrated in a significant number of brain metastases. A relation between enolase isoenzyme pattern and survival after operation for brain metastasis could not be found. For histopathologic diagnosis of tumors of the adult human central nervous system, analysis of the enolase isoenzyme pattern is not reliable.

Production and characterization of monoclonal antibodies against human type K pyruvate kinase

K-type pyruvate kinase was purified from human kidney by immunoadsorbant chromatography. Monoclonal antibodies secreting hybridomas were made using conventional techniques. Two clones were established which produced antibodies against K-type not cross-reacting with the other pyruvate kinase isoenzymes, named the M, L and R-types. The specificity of the monoclonal antibodies was proven by enzyme-linked immunosorbent assay, immunoprecipitation and immunoblotting experiments. The M- and K-isoenzymes are produced from the same gene probably by alternative splicing, and all differences between both enzymes originate from one exon coding for 45 amino acids (Noguchi et al. J. Biol. Chem. 261, 13807-13812 (1986]. The monoclonal antibodies are specific for K-type under denaturing conditions. Thus, it is likely that these antibodies recognize (a) continuous epitope(s), of which at least some amino acids are coded in the K-specific exon. The monoclonal antibodies could be successfully used in immunohistochemical studies. Neurons and astrocytes in brain, Kupffer cells in liver, connective tissue cells and vascular smooth muscle cells showed immunoreactivity. However, striated muscle cells in skeletal muscle and heart and hepatocytes were not immunoreactive. Other types of glial cells, e.g., oligodendrocytes and microglia, so far studied, showed no reaction either.

Discrimination between neuronal and glial cell tumours by pyruvate kinase electrophoresis

Pyruvate kinase is a tetrameric enzyme, of which different isozymes are known (M, K and L). In normal human brain of adults mainly the M4 type is found with little or none of type K4 or the hybrid K3M. In gliomas of adults as well as in children a shift in the synthesis of isozymes of pyruvate kinase occurs from the M-towards the K-type. In these tumours the hybrid K2M2 is not expressed. In gliomas of children only a spur of K2M2 is found. There exists a peculiar difference in isozyme distribution of pyruvate kinase between gliomas on the one hand and neuro-, retino- and medulloblastomas on the other. In the latter group of tumours often the whole isozyme set is observed and in all cases the hybrids K2M2 and KM3 are found. These findings provide enzymological criteria for the discrimination of neuronal tumours from glial-cell tumours.

Experiences in psycho-surgery in The Netherlands

The authors report on their experiences in 54 cases operated upon for various psychiatric diseases including compulsive neurosis, depression, anxiety, tension and in some of this group also automutilation; intractable temporal lobe epilepsy and aggressive behaviour; aggressive behaviour and minor epileptic problems; severe mental retardation, restlessness, automultilation and in some of this group also aggression. Operative procedures have been fronto-basal lesions according to Knight and Bridges, as well as lesions in the cingulum, the paracingular white matter, the anterior part of the radiation of the corpus callosum and the basal frontal region, using the technique of Crow. Amygdalotomy and thalamotomy was performed for epilepsy, aggression and automutilation in the mentally retarded patients. Because of the small number of patients and the variety of different diseases and techniques no statistically valid analysis of the results is possible.

Subunit composition, regulatory properties, and phosphorylation of phosphofructokinase from human gliomas

In this study, we investigated the alterations in the activity, subunit profile, and kinetic regulatory properties of phosphofructokinase (PFK) from human gliomas compared with those from normal human brain. Gliomas showed a decrease in the enzyme activity as compared to normal brain. This decrease in PFK activity was accompanied by a relative increase in the expression of the liver type subunit of PFK. The enzymes from the tumor and normal brain showed no significant differences in their affinity toward the substrate fructose 6-phosphate. However, tumor and normal brain PFK showed major differences with respect to their behavior towards citrate and fructose 2,6-bisphosphate. The enzyme from the gliomas was less sensitive to citrate inhibition. More importantly, the enzyme from the tumor was more sensitive to the activation by fructose 2,6-bisphosphate. In addition, we found that in gliomas the L-type subunit could be phosphorylated, most probably by a cyclic AMP-independent protein kinase. This phosphorylation could not be detected in normal human brain. It is proposed that the preferential expression of the liver type subunit by undifferentiated cancer cells may be explained in terms of the unique regulatory properties of this isozyme.

Enolase isoenzymes in human gliomas

Gamma-enolase (one of the three possible subunits of the dimeric enzyme enolase (EC 4.2.1.11)) has been reported as a marker for human neurons. Studies investigating the presence of gamma-enolase in human gliomas have given conflicting results, but a definite finding is important for further studies of the biology of these tumors and the possible use of gamma-enolase as a marker for tumors originating in nervous tissue or for neuronal damage. Using electrophoresis of tumor tissue extracts as well as immunohistochemistry the authors have demonstrated the presence of gamma-enolase in human gliomas. Analysis of the gamma-enolase content in the plasma of patients with brain neoplasms further revealed that, although this enzyme may be present in the tumor itself, its concentration in blood is not a reliable marker for a tumor of the human central nervous system.

Isozyme pattern of enolase of childhood tumors

Retinoblastoma, neuroblastoma, and medulloblastoma have many common features, clinical as well as histologic; a common embryonic origin has been suggested. The authors studied the electrophoretic pattern of enolase (EC 4.2.1.11) in these tumors. All tumors were characterized by the presence of three types of enolase, designated as alpha alpha, alpha gamma and gamma gamma. The latter is supposed to be the neuron-specific enolase. Normal adult brain and adult retina show the same set of isozymes (alpha alpha, alpha gamma and gamma gamma). In contrast, gliomas of childhood, tumors originating from the supportive tissue of the central nervous system, are characterized mainly by the presence of the alpha alpha dimer and a small amount of the alpha gamma hybrid. The results of this report support the hypothesis of a common embryonic origin of retinoblastoma, neuroblastoma, and medulloblastoma.

Glycolytic enzymes from human neuroectodermal tumors of childhood

In this study pyruvate kinase, hexokinase and aldolase are investigated in two types of embryonal tumors, neuroblastomas and medulloblastomas; the results are compared with similar studies in gliomas. The activities of hexokinase and pyruvate kinase are significantly decreased in neuroblastomas. In neuroblastoma and medulloblastoma all five forms of pyruvate kinase (K4, K3M, K2M2, KM3 and M4) are present. In contrast, the gliomas investigated are characterized by the presence of mainly K4 and a little K3M. In neuroblastomas, medulloblastomas and gliomas, hexokinase type I is present; in addition, hexokinase type II is present in two medulloblastomas. Aldolase A is the predominant isozyme in all tumors investigated; this is in contrast with normal nervous tissue. It can be concluded that the isozyme characteristics especially of pyruvate kinase from neuroblastomas and medulloblastomas are comparable with similar findings in retinoblastoma; these findings support the hypothesis that these three tumors have a common embryonic origin.

Spontaneous spinal epidural haematoma. Etiological considerations

Four cases with the typical clinical picture of spinal epidural haematoma are reported. The exact cause of the haemorrhage is generally unknown. A survey is presented of the various causative factors as put forward in the literature so far. The authors point out the possible etiology of this entity and emphasize the need for routine histological examination.

Panmedullary ependymoma with multiple cysts complicated by fatty deposits in the proximal spinal cord

The authors describe a case of panmedullary ependymoma presenting with multiple cysts complicated by fatty deposits in the spinal cord from C6 to D2 as demonstrated by CT-scanning. To the authors' best knowledge the combination of these features have not been described previously. The radiological, operative and histological findings are discussed and compared with those of other panmedullary spinal cord tumours such as astrocytomas.

Isoenzymes of creatine kinase in extracts of various parts and regions of the human central nervous system

The distribution of isoenzymes of creatine kinase (EC 2.7.3.2.) was investigated by agarose gel electrophoresis of extracts of selected parts and regions of the human central nervous system. Besides the major brain isoenzyme BB, we demonstrated the presence of three other creatine kinase isoenzyme forms. The distribution of creatine kinase isoenzymes depending strongly on the region from which the biopsy was taken. We found substantial amounts of the MB isoenzyme in extracts of the dura from the cauda equina of the two adults examined.

Isoenzymes of creatine kinase in extracts of various parts and regions of the human central nervous system

The distribution of isoenzymes of creatine kinase (EC 2.7.3.2.) was investigated by agarose gel electrophoresis of extracts of selected parts and regions of the human central nervous system. Besides the major brain isoenzyme BB, we demonstrated the presence of three other creatine kinase isoenzyme forms. The distribution of creatine kinase isoenzymes depending strongly on the region from which the biopsy was taken. We found substantial amounts of the MB isoenzyme in extracts of the dura from the cauda equina of the two adults examined.

Isoenzymes of creatine kinase in extracts of various parts and regions of the human central nervous system

The distribution of isoenzymes of creatine kinase (EC 2.7.3.2.) was investigated by agarose gel electrophoresis of extracts of selected parts and regions of the human central nervous system. Besides the major brain isoenzyme BB, we demonstrated the presence of three other creatine kinase isoenzyme forms. The distribution of creatine kinase isoenzymes depending strongly on the region from which the biopsy was taken. We found substantial amounts of the MB isoenzyme in extracts of the dura from the cauda equina of the two adults examined.