thiopental and Epilepsy--Temporal-Lobe

Topics: Amobarbital; Bemegride; Cerebral Cortex; Electric Stimulation; Electrodes; Electrodes, Implanted; Electroencephalography; Epilepsies, Partial; Epilepsy; Epilepsy, Temporal Lobe; Humans; Methohexital; Neurosurgery; Pentylenetetrazole; Photic Stimulation; Respiration; Sleep; Thiopental

Intracranial pressure (ICP) is a major neurological parameter in animals and humans. ICP is a function of the relationship between the contents of the cranium (brain parenchyma, cerebrospinal fluid, and blood) and the volume of the skull. Increased ICP can cause serious physiological effects or even death in patients who do not quickly receive proper care, which includes ICP monitoring. Epilepsies are a set of central nervous system disorders resulting from abnormal and excessive neuronal discharges, usually associated with hypersynchronism and/or hyperexcitability. Temporal lobe epilepsy (TLE) is one of the most common forms of epilepsy and is also refractory to medication. ICP characteristics of subjects with epilepsy have not been elucidated because there are few studies associating these two important neurological factors. In this work, an invasive (ICPi) and the new minimally invasive (ICPmi) methods were used to evaluate ICP features in rats with chronic epilepsy, induced by the experimental model of pilocarpine, capable of generating the main features of human TLE in these animals.

Topics: Animals; Anticonvulsants; Brain; Chronic Disease; Disease Models, Animal; Epilepsy; Epilepsy, Temporal Lobe; Hippocampus; Intracranial Pressure; Magnetic Resonance Imaging; Male; Muscarinic Agonists; Organ Size; Pilocarpine; Rats; Rats, Wistar; Thiopental

Five patients were subjected to a thiopental fast activation test, recording with implanted depth electrodes in two patients and at electrocorticography in 3 patients. A burst-suppression pattern was seen focally in each patient, while adjacent regions in that hemisphere and in the contralateral hemisphere had continuous activity. Although detected in depth electrodes, this pattern was not seen with simultaneous scalp electrode recording. This focal pattern correlated with the presence of a pathological abnormality on histologic examination in all patients. It is postulated that the appearance of a focal burst-suppression pattern during a thiopental fast activation test implies the presence of underlying structural abnormality.

Topics: Adult; Cerebral Cortex; Electroencephalography; Epilepsy, Temporal Lobe; Humans; Stereotaxic Techniques; Temporal Lobe; Thiopental

Thiopental-induced EEG beta activity was analyzed both visually and by computer in 33 patients with complex partial epilepsy. Studies were done in 16 patients with depth electrodes in limbic structures and 17 patients with scalp and sphenoidal electrodes. The percentage of drug-induced change in beta activity was quantified by computer using spectral analysis. The statistical significance of asymmetries between homologous sites in the amount of change was determined. The spatial distribution of significant asymmetries was used for localization and compared with the results of independent visual analysis of the thiopental EEG. Concordance between computer and visual evaluation occurred in 10 of 17 scalp/sphenoidal and 10 of 16 depth electrode tests. The accuracy of visual and computer localization was determined by comparing them with locus of itcal EEG onset, interictal spikes, and positron emission tomography. In scalp/sphenoidal studies, computer analysis indicating asymmetry appeared more likely to correlate with independent clinical criteria than visual analysis. In depth studies the reverse appeared to be true. Scalp/sphenoidal tests yielded positive results in 25-30% of patients whereas depth electrode tests were positive in 50-70% of patients. The results indicate that computer analysis of surface thiopental tests is an accurate and useful supplement to visual evaluation of these tests.

Topics: Brain; Computers; Electroencephalography; Epilepsy, Temporal Lobe; Humans; Thiopental

Criteria for anterior temporal lobectomy, performed on seven patients with partial complex seizures, were derived from a battery of fourteen presurgical tests. Seven tests were routine studies aimed at identifying a focus of epileptic excitability, while seven were designed to reveal areas of focal functional deficit. Conflicting information was frequently obtained from the tests of epileptic excitability, suggesting that it is probably inaccurate to view patients with partial complex seizures as having a single epileptogenic focus. Presurgical evaluation must therefore be aimed at identifying the focus most responsible for the patient's habitual seizures. Tests of focal functional deficit provided useful nonconflicting confirmatory information in each of the seven patients studied. The most reliable information was obtained from depth electrode implantation, and this procedure should be considered essential except when all evidence of surface-recorded epileptic excitability, including ictal onset, and evidence of focal functional deficit agree.

Topics: Adult; Amobarbital; Brain; Electroencephalography; Epilepsy, Temporal Lobe; Female; Humans; Male; Memory, Short-Term; Middle Aged; Radiography; Stereotaxic Techniques; Telemetry; Temporal Lobe; Thiopental; Tomography, Emission-Computed

In 17 epileptic patients, most of them with seizures of partial type but with diffuse or focal alternating abnormalities in the electroencephalographic recordings, chronic implantation of subarachnoid electrodes was performed. Through two bicoronal burr-holes and under fluoroscopic control, 13 to 19 insulated monopolar flexible electrodes were introduced in the subarachnoid space, conducting them either to standardized cortical targets, or concentrating them in that area of interest showed by conventional EEG. The electrodes were placed bilaterally and symmetrically, and remained implanted for 10 days. During this period, the activity of multiple foci, the reciprocal dependence between them, its reaction to cortical electric stimulation, barbiturate administration and sleep, were studied. No morbidity was found. Because of the simplicity and safety of this technique, it appears to be a good diagnostic method placed between conventional EEG and stereoelectroencephalography.

Topics: Electric Stimulation; Electrodes, Implanted; Electroencephalography; Epilepsy; Epilepsy, Temporal Lobe; Follow-Up Studies; Humans; Sleep; Stereotaxic Techniques; Thiopental; Trephining

The diagnostic value of sphenoidal electrode EEG recordings in patients with seizures characteristic for epilepsy with complex partial symptomatology was assessed in a study comprising 404 patients; 71.3% of the patients had seizures with automatisms and amnesia, and 28.7% had psychic seizures with subjective phenomena such as hallucinations and illusions. A total of 59.6% of the patients had diagnostic EEG changes in routine waking or sleep EEG. In sphenoidal EEG recording including thiopenthone activation, diagnostic changes were found in 40.5% of the patients without specific changes in waking or sleep EEG, the chance of a positive finding being more than five times higher in patients with automatisms than patients with psychic seizures. Apart from cases where surgical treatment of temporal lobe epilepsy is considered, sphenoidal electrode EEG recording, including intravenous thiopenthone activation, should be performed in patients with seizure phenomena raising suspicion of epilepsy with complex partial symptomatology but where waking and sleep EEGs fail to demonstrate specific abnormalities.

Topics: Electrodes; Electroencephalography; Epilepsy, Temporal Lobe; Evaluation Studies as Topic; Humans; Sphenoid Bone; Thiopental

Electroencephalographic activity and extracellular discharges from neurons in deep temporal lobe structures were recorded from fine wire microelectrodes chronically implanted in seven psychomotor epileptic patients for diagnostic localization of seizure foci. In four patients, inhalation of 80 per cent nitrous oxide resulted in loss of consciousness without change in firing rates of temporal lobe neurons (n = 22). In all seven patients, thiopental (400 or 200 mg, iv) decreased limbic neuronal firing rates (n = 38) until the return of wakefulness. In only three of these patients, however, did the firing rates of the neurons (n = 19) decrease significantly (P less than .05). Thiopental suppression of unit activity was not related to systemic hypoxia. This study demonstrates that anesthetic induction with nitrous oxide-oxygen does not significantly affect the firing of neurons in various regions of the human limbic system, which may explain the incidence of patient awareness reported when nitrous oxide-oxygen is administered alone. Thiopental depresses the firing of limbic neurons, and this may account in part for the temporary confusion and amnesia often manifested by patients recovering from the effects of thiopental.

Topics: Adolescent; Adult; Epilepsy, Temporal Lobe; Humans; Limbic System; Neural Conduction; Neurons; Nitrous Oxide; Synaptic Transmission; Thiopental

Topics: Adult; Barbiturates; Brain Mapping; Electroencephalography; Epilepsy, Temporal Lobe; Hippocampus; Humans; Male; Synaptic Transmission; Thiopental

Topics: Adolescent; Adult; Electroencephalography; Epilepsy, Temporal Lobe; Hippocampus; Humans; Middle Aged; Pentylenetetrazole; Personality Disorders; Sclerosis; Temporal Lobe; Thiopental

Topics: Amygdala; Animals; Cerebral Cortex; Electroencephalography; Epilepsy, Temporal Lobe; Hippocampus; Injections, Intravenous; Rabbits; Thiopental; Urethane