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R G Sola

Publications and source records attributed to R G Sola.

At least 19 recordsLinked to original sources
PubMed2004

Microanatomy of the dysplastic neocortex from epileptic patients.

Focal cortical dysplasia (FCD) is a pathology that is characterized by the abnormal development of the neocortex. Indeed, a wide range of abnormalities in the cortical mantle have been associated with this pathology, including cytoarchitectonic alterations and the presence of dysmorphic neurons, balloon cells and ectopic neurons in the white matter. FCD is commonly associated with epilepsy, and hence we have studied the ultrastructure of cortical tissue resected from three subjects with intractable epilepsy secondary to cortical dysplasia to identify possible alterations in synaptic circuitry, using correlative light and electron microscopic methods. While the balloon cells found in this tissue do not appear to receive synaptic contacts, the ectopic neurons in the white matter were abnormally large and were surrounded by hypertrophic basket formations immunoreactive for the calcium-binding protein parvalbumin. Furthermore, these basket formations formed symmetrical (inhibitory) synapses with both the somata and the proximal portion of the dendrites of these giant ectopic neurons. A quantitative analysis revealed that in the dysplastic tissue, the density of excitatory and inhibitory synapses was different from that of the normal adjacent cortex. Both increases and decreases in synaptic density were observed, as well as changes in the proportion of excitatory and inhibitory synapses. However, we could not establish a common pattern of changes, either in the same patients or between different patients. These results suggest that cortical dysplasia leads to multiple changes in excitatory and inhibitory synaptic circuits. We discuss the possible relationship between these alterations and epilepsy, bearing in mind the possible limitations that preclude the extrapolation of the results to the whole population of epileptic patients with dysplastic neocortex.

Adult↗
PubMed2003

Histopathology and reorganization of chandelier cells in the human epileptic sclerotic hippocampus.

Impairment of GABA-mediated inhibition is one of the main hypotheses invoked to explain seizure activity, both in experimental models and in human epilepsy. We have studied the distribution and the neurochemical characteristics of certain GABAergic circuits in the normal and epileptic human sclerotic hippocampal formation. We have focused our attention mainly on chandelier cells because, together with basket cells, they are considered to have powerful effects on spike generation. Chandelier cells represent a unique type of interneuron whose axon terminals (Ch-terminals) form synapses with the axon initial segments of cortical pyramidal cells and granular cells of the dentate gyrus. Different neurochemical subpopulations of chandelier cells have been identified by immunocytochemistry, mainly in the neocortex. Markers for Ch-terminals include the GABA transporter 1 (GAT-1), the polysialylated form of the cell-surface glycoprotein neural cell adhesion molecule (PSA-NCAM) and the calcium-binding proteins parvalbumin (PV) and calbindin D-28k (CB). In the normal hippocampal formation, GAT-1- and PV-immunoreactive (-ir) Ch-terminals were identified in the granular and polymorphic layers of the dentate gyrus, in the strata pyramidale and oriens of the CA fields, and in the pyramidal layer of the subicular complex. In addition, and in contrast to the hippocampus and dentate gyrus, subsets of Ch-terminals in the upper pyramidal layer of the normal subiculum express CB and PSA-NCAM. The sclerotic hippocampus of epileptic patients presented an impressive morphological and neurochemical reorganization of Ch-terminals and basket formations. This was apparent in the dentate gyrus and hippocampal formation, but not in the subiculum, which appeared to remain unaltered. Principally, numerous and more complex PV- and CB-ir Ch-terminals, as well as dense PV-ir basket formations, appeared in some hippocampal segments, whereas in other regions there was a lack of labelled elements. These changes varied considerably not only between different patients, but also within different hippocampal fields in a given patient. In general, the changes were not correlated with the clinical characteristics or degree of histopathological alterations observed in the patients, such as granular cell dispersion, neuron loss and proliferation of mossy fibres. However, some surviving neurons in the regions adjacent to the areas of neuron loss were consistently innervated by dense basket formations and complex Ch-terminals. These results indicate that, in the human epileptic hippocampus, GABAergic circuits are more highly modified than previously thought. When considered along with other extrahippocampal alterations, we suggest that these changes are important in the pathophysiology of temporal lobe epilepsy associated with hippocampal sclerosis.

Adolescent↗
PubMed2002

[Magnetic resonance in dural post-puncture headache in patient with cerebrospinal fluid hypotension].

Magnetic resonance imaging (MRI) has allowed us to establish a set of radiologic signs associated with intracranial hypotension syndrome. Findings are partly influenced by cerebral displacement. Intracranial hypotension syndrome is characterized by a decrease in cerebrospinal fluid (CSF) pressure to less than 60 mm H2O associated with occipital headache radiating to the frontal and temporal zones. For diagnostic purposes, the most common cause is anesthetic or therapeutic dural puncture, although spontaneous CSF leakage can occur. CSF protein and lymphocyte counts may be high, while the cranial meninges biopsy is normal. MRI images may show a descended brain, taking the start of the sylvian aqueduct and the location of the cerebellar amygdalae as points of reference; diminished size of the subarachnoidal cisterns and occasionally of the cerebral ventricles; meningeal enhancement from increased uptake of the contrast solution; subdural hygromas and hematomas; and pituitary enlargement. Paraspinal fluid and dilated epidural veins may be observed. Radiologic images and clinical signs are related. When CSF pressure is very low, there is greater meningeal enhancement, subdural collection and cerebral displacement. Findings gradually disappear as symptoms diminish. The signs and symptoms that might develop during intracranial hypotension syndrome vary according to the brain structure that might be affected during descent, repositioning and the traction of anchoring structures. MRI allows the degree of cerebral and spinal involvement to be ascertained, to predict whether resolution of the clinical picture will be early or late and to visualize the effect of approaches to reducing CSF leakage.

Anesthesia, Spinal↗
PubMed2001

Changes in the colocalization of glutamate ionotropic receptor subunits in the human epileptic temporal lobe cortex.

Double-labeling immunocytochemical techniques and confocal microscopy were used to quantify possible differences in the degree of colocalization of glutamate ionotropic receptor subunits between non-spiking and spiking neocortex removed from temporal lobe epileptic patients. Spiking neocortex was characterized by laminar-specific changes in the number of cells immunoreactive for NMDAR1, GluR2/3 and GluR5/6/7 subunits, as well as the percentage of cells which colocalized various combinations of these receptors. These changes may lead to profound modifications in the functioning of excitatory synaptic circuits in spiking cortex.

Adult↗
PubMed2001

Neuropathological findings in a patient with epilepsy and the Parry-Romberg syndrome.

PURPOSE: The Parry-Romberg syndrome is an unusual disorder frequently associated with epilepsy. The origin of this disease, and the cause of epilepsy, are unknown. This study is the first reported case of the Parry-Romberg syndrome, with intractable temporal lobe epilepsy, in which detailed microanatomic analyses have been performed on resected brain tissue obtained after surgical intervention. METHODS: Standard histopathologic methods and correlative light and electron microscopy, combined with immunocytochemical techniques, were used to study in detail the synaptic microorganization of the resected hippocampal formation. RESULTS: After surgery, the patient was seizure free (follow-up period of 4 years and 7 months). The resected temporal lobe showed a variety of dramatic microanatomic alterations (small groups of ectopic cells, neuronal loss, gliosis, and activated microglial cells) in mesial structures, including the entorhinal cortex, subiculum, and dentate gyrus. At the electron-microscopic level, we found that in the dentate gyrus, the number of synapses in the cell-sparse region adjacent to the ectopic mass of neurons was almost twice that found in the molecular and polymorph cell layers, indicating the intrusion of neuritic processes and synapse formation. In addition, the symmetrical axosomatic synapses characteristically found on granule cells, which are likely derived from gamma-aminobutyric acid (GABA)ergic inhibitory basket cells, were not observed. CONCLUSION: The complete seizure relief after surgery suggests that the pacemaker region(s) of seizure activity were within the resected tissue. However, we do not know which of the multiple neuropathologic findings reported here were the primary cause of seizure activity. Nevertheless, the changes found in the dentate gyrus circuitry appear to be among the most important alterations that would lead to epilepsy.

Adult↗
PubMed1998

Local changes in GTP-binding protein immunoreactivities in human epileptogenic neocortex.

The relative levels of guanine nucleotide-binding protein alpha-subunits Gi1alpha, Gi2alpha, Gi3alpha, Go(alpha), Gs(alpha), and Gx/z(alpha) were measured in neocortex removed at surgery from patients with intractable temporal lobe epilepsy. Immunoreactivity was quantified using specific polyclonal antisera against the Galpha-subunits according to the Laurell "rocket" immunoelectrophoresis technique. We compared the G protein contents of spiking (active) and nonspiking (nonactive) cortical regions, based on intraoperative electrocorticography, within the same and different patients. There were no clear trends for lower or higher levels of G-protein subtypes to be found in the samples of protein extracts from nonspiking regions as compared to spiking regions. However, comparison of paired samples of spiking and nonspiking cortex within the same patient demonstrated that levels of certain G-protein subtypes were either increased or decreased in all patients. This indicates that cortical regions with enhanced neuronal activity may produce microzonal alterations in the levels of G proteins. Moreover, our results suggest that high levels of Gi1alpha and low levels of the other G-protein subtypes appear to be associated with a greater susceptibility to maintaining spiking activity.

Adult↗
PubMed1998

[Microvascular decompression in the treatment of essential trigeminal neuralgia].

INTRODUCTION AND OBJECTIVE: We pretend to evaluate the surgical procedure and clinical results of microvascular decompression (MVD) of 21 patients suffering from essential trigeminal neuralgia between 1989 and 1997. PATIENTS AND METHODS: Selection criteria included: ineffectiveness of pharmacological treatment, good general condition, more than five years life expectancy, and do not have undergone ablative-lesive surgical procedures before. RESULTS: After a post-surgical follow-up of between three months and three years, it was obtained a 100% success rate of immediate pain relief, with only a 14.2% recurrence. There were no sequels as those typically found in lesive techniques as paresthesias and dysesthesias, painful and/or corneal anaesthesia and motor disorders. There were no deaths, although there were three cases of post-surgical complications. CONCLUSIONS: To evaluate the long-term results of different surgical techniques in the treatment of the essential trigeminal neuralgia is outstanding the patients satisfaction rate, which not only depends on pain relief and absence of recurrence, but also and very specially on the neurological deficiencies following the procedure. So, we consider that MVD is the most effective technique both in symptoms relief and neural functions and structures preservation, even though the possibility of appearance of complications following any major surgery.

Adult↗
PubMed1997

Loss of inhibitory synapses on the soma and axon initial segment of pyramidal cells in human epileptic peritumoural neocortex: implications for epilepsy.

The peritumoural neocortex removed from epileptic patients represents an important region for research because of its possible relationship to the generation, maintenance, and propagation of seizures. The peritumoural neocortex removed from an epileptic patient showing a regrowth of an anaplastic astrocytoma was examined in detail using immunocytochemistry for gamma-aminobutyric acid, glutamic acid decarboxylase, parvalbumin, nonphosphorylated neurofilament protein, glial fibrillary acidic protein, and histocompatibility antigen HLA-DR. The patterns of immunostaining were compared with the cytoarchitecture and myeloarchitecture in adjacent sections, and with the patterns of immunostaining observed in normal control neocortex. Furthermore, quantitative electron microscopy was used to compare the synaptic densities of presumptive excitatory and inhibitory synapses between regions showing different grades of cytoarchitectural and neurochemical alterations in the peritumoural neocortex, and to compare these regions with normal neocortex. A variety of changes in synaptic circuits in the peritumoural neocortex was found, but it appears that neurons within the less abnormal-looking regions were involved in altered synaptic circuits that might contribute to epileptic activity. In these regions, the most prominent change was the loss of inhibitory synapses on the soma and axon initial segment of pyramidal cells, but numerous excitatory synapses were present on their dendrites that would make these neurons hyperexcitable. However, the most abnormal regions histologically were likely a primary zone for progression of the tumour, with many surviving neurones, but which received and formed very few synapses; thus, they were probably unrelated to the initiation, maintenance, or propagation of seizures.

Adult↗
PubMed1997

[When should the pre-operative study of epileptic patients be carried out?].

There is great controversy as to the best moment for the preoperative study of patients with intractable epilepsy. In this study we attempt to give an answer to this question based on a review of the literature and personal experience. First various problems are analyzed: the epilepsy-lesion relationship; kinds of treatment and types of epilepsy: the concept of curative or palliative surgery, surgical syndromes, how long epilepsy has been present and the age of the patient at the time of operation. With these factors in mind we attempt to analyze the clinical situations and determine in each cases the optimum time to carry out any possible surgical treatment as a complement or 'part' of the medical treatment of these patients as a whole.

Age Factors↗
PubMed1996

Inhibitory neurons in the human epileptogenic temporal neocortex. An immunocytochemical study.

Immunocytochemical methods were used to study alterations in inhibitory neuronal circuits in human neocortex resected during surgical treatment of intractable temporal epilepsy associated or not with brain tumours. The epileptogenic cortex was characterized and divided into spiking or non-spiking zones by intraoperative electrocorticography (ECOG). The resected cortex was cut into blocks, sectioned and stained immunocytochemically for visualization of glutamic acid decarboxylase (GAD), the calcium-binding protein, parvalbumin (PV) and glial fibrillary acidic protein (GFAP). A variety of alterations in cortical neuronal circuits as revealed by immunocytochemical and histological methods were found. Similar alterations in inhibitory neuronal circuits appear to occur independently of the primary epileptogenic site and pathology associated with epilepsy, which suggests that there is possibly a common basic underlying mechanism that leads to seizure activity. These changes were apparently unrelated to ECOG findings at surgery, which bring into question the value of the use of interictal epileptic discharges recorded by ECOG to guide cortical resections. The most conspicuous and common change was the loss of chandelier cells. The finding that these cells are among the most vulnerable types of GABAergic interneurons in the epileptogenic temporal cortex indicates that they might be of great functional importance, since the axon terminals of chandelier cells are likely to exert powerful regulation of impulse generation in cortical pyramidal cells. Therefore, these cells might represent a key component in the aetiology of human epilepsy.

Adolescent↗
PubMed1996

[Anatomo-functional localization in cerebral cortex. Application of imaging systems as a guide for resection of cortical lesions].

The stereo-encephalography of Talairach (SEG) makes it possible to obtain an individualized anatomofunctional map, based on the proportion of the telencephalum with an inter-commissurual line CA-CP. The aim of this paper was to design a method for the preparation of these maps, without need for the use of stereotactic equipment, and to apply this to the anatomofunctional localization of cortico-subcortical lesions. With the aid of a CAD programme (AUTOCAD v. 11), the images obtained using magnetic resonance (MR), with visualisation of the CA-AP line, skull X-ray (Rx) and cerebral angiograph (ADS) were superimposed. This was subsequently squared, as suggested by Talairach, permitting comparison between the maps (by standardization of the CA-CP line at 25 mm.) or with a stereotactic map. A total of 104 patients were studied, divided into three groups: A. Control 10 patients with slight HSA, with no ADS pathology. B. Resection of the lesion. 38 patients with vascular lesions (30) or benign tumours of less than 3mm (8). C. Epilepsy. 56 patients with drug-resistant epilepsy, with or without a visible lesion on RM (26 and 30 patients respectively). Outstanding amongst the results obtained were: confirmation of the close relationship of the telencephalum with the CA-AP line. Using our method there was great precision in superimposing anatomical structures. There was an error of less than 0.5cm in superimposing the corpus callosum and the pericallosum artery or Galen's vein. This made it possible for us (in group B) to localize subcortical lesions larger than 1cm without using a stereotaxic guide. In these cases we were guided by the cortical venous pattern which led to the lesion. In group C, use of these maps allowed us to obtain a functional surgical document exactly the same as the anatomofunctional maps of the SEG of Talairach.

Adult↗
PubMed1994

Microzonal decreases in the immunostaining for non-NMDA ionotropic excitatory amino acid receptor subunits GluR 2/3 and GluR 5/6/7 in the human epileptogenic neocortex.

Potential alterations in glutamate-utilizing excitatory circuits in resected human epileptogenic frontal and temporal neocortex were investigated by using immunocytochemical methods to visualize receptor subunits which comprise the AMPA/kainate (GluR2/3) and kainate (GluR5/6/7) receptor subtypes. Examination of the patterns of immunostaining in regions of neocortex that were identified as spiking and non-spiking based on intraoperative electrocorticography revealed dramatic, microzonal decreases in immunoreactivity for the receptor subunits examined. The patches of decreased immunostaining for GluR2/3 and for GluR5/6/7 were often coincident with respect to each other. However, such abnormal regions were not necessarily correlated with any particular electrocorticographically defined regions nor any overtly abnormal cytoarchitectural features in adjacent Nissl-stained sections. Moreover in many but not all cases, the focal regions of decreased receptor subunit immunoreactivity coincided with small patches of decreased parvalbumin immunoreactivity a calcium-binding protein which labels a subpopulation of powerful inhibitory GABAergic interneurons. These results indicate that in the human epileptogenic neocortex there may be alterations in particular excitatory and/or inhibitory synaptic systems at small, multiple neocortical foci, and that these alterations are found mostly in the same regions. We suggest that these alterations may contribute to the initiation and/or propagation of seizure activity.

Adolescent↗
PubMed1979

Epicranial plexiform neurofibroma.

Epicranial plexiform neurofibroma is a rare presentation of neurofibromatosis. Two such cases are presented in which epicranial tumors constituted isolated manifestations of the disease except for skin pigmentation. Tumor development began at two and three months of age respectively; one case showed a calvarian bony defect associated with the tumor.

Female↗
PubMedDate not supplied

[A study of the motor and sensory cortex using functional magnetic resonance: tasks of active and passive movement].

INTRODUCTION AND OBJECTIVE: The objective of this study was to locate the rolandic area (pre- and post-central) by means of functional magnetic resonance imaging (FMRI) and define its correspondence on a Talairach map, whilst active and passive movements of the dominant hand were performed. MATERIAL AND METHODS: Ten healthy volunteers were found, 6 men and 4 women, of an average age of 26 years (range 22-33). Two appropriate tasks were designed: one involving active and one passive movement. The examination was carried out using a 1.5 Tesla (General Electric) MRI apparatus. An echo-sequence of planar echo-gradient (BOLD technique) was used, making sagittal and axial planes, parallel to the AC-PC line (anterior commissure-posterior commissure). Subsequently an anatomofunctional Talairach map was drawn for each subject, to include the information obtained on FMRI. RESULTS: In all subjects central activity was detected in the rolandic area during the tasks involving selected active and passive movements. Overlap was seen between the pre- and post-rolandic areas with both types of tasks. CONCLUSION: There is good correlation between the image obtained of motor-sensory activity in the rolandic zone and the Talairach anatomofunctional map.

Adult↗
PubMedDate not supplied

[Neuropsychology and cognitive deterioration in epilepsy].

OBJECTIVE: To carry out a critical evaluation of the international literature on the neuropsychology of epilepsy. The variables which lead to cognitive deterioration in epilepsy and the effect on cognition of different treatments available (pharmacological and surgical). DEVELOPMENT: We evaluate the influence of different neurological variables on the higher functions (aetiology, age of onset, type of crises, duration of illness, frequency and anti-epileptic drugs). We also describe the cognitive functions most affected in epilepsy (memory, attention, executive function, language). Studies of the surgery of epilepsy show that this may lead to both beneficial and undesirable effects on cognition. CONCLUSIONS: The variables which in general most affect higher functions are the duration of the illness and the frequency and types of crises. The commonest neuropsychological effects are those of memory deficit. These studies show that neuropsychological studies should be done from the time of onset of the disorder. Finally, from the surgical point of view, young patients with considerable crisis reduction or free of crises, with moderate preoperative deterioration of memory have the greatest possibility of post-operative improvement in cognition. Older persons with intact cognitive function and major surgical resection have more possibilities of post-surgical deterioration.

Anticonvulsants↗
PubMedDate not supplied

[Magnetoencephalography: a new functional diagnostic technique for the neurosciences].

INTRODUCTION AND OBJECTIVES: We present a review on the technical, methodological and clinical advances in the functional study of the brain by means of magneto-encephalography. We look back the milestones of its historical development, through the work of the major research groups on this field and through our group's works and database (including doctoral thesis). Discussion on the neurophysiological and biomagnetism basis is provided as well as description of technical developments in superconducting detectors (SQUID, Superconducting Quantum Interference Device), signal processing, enhancement of noise-signal ratio and dipole modeling. DEVELOPMENT: The need for brain functional studies has led to newer imaging procedures (functional magnetic resonance, PET, SPECT, etc.). Their spatial and temporal resolution and invasivity are compared to that of magneto-encephalography. Current equipment, up to 306 whole-head channels, may accurately detect cortical and subcortical activity. Apart from the physiological activity, it may be applied to a number of conditions: epilepsy (ictal, interictal and presurgical); dementia, movement disorders, stroke, eloquent cortex delimitation prior to tumour or lesion resection; learning disabilities and foetal studies. CONCLUSIONS: Magnetoencephalography provides with an excellent temporal, very good spatial resolution, acquires in real-time, without references and minimal interference. It entails a great advance in the diagnostic approach in neurosciences.

Brain↗
PubMedDate not supplied

[Evaluation of epilepsy surgery].

INTRODUCTION: Neuropsychology is a discipline included in the neurosciences which, over the past twenty years, has shown its value in the assessment and rehabilitation of cognitive functions in different disorders. In particular, in epilepsy it has permitted the description of the different factors which affect cognitive deterioration; permitted the establishment of profiles of cognitive deterioration and also the evaluation of the adverse effects of some anti-epileptic drugs on cognition. DEVELOPMENT: In this paper we confirm the value of neuropsychology in an Epilepsy Unit and describe different procedures for evaluation, as well as the cognitive consequences of the surgery of epilepsy.

Anticonvulsants↗