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PubMed1987

Effects of anterior temporal lobectomy on cognitive function.

Sixty-three patients with intractable partial complex epilepsy were treated by anterior temporal lobectomy for seizure control. Psychometric studies before and after operation documented cognitive function and evaluated the effects of operation on cognition. The mean follow-up period was 7.7 months. Sixty-two of 63 patients had improved seizure control; 49 (78%) were seizure free. Operation had different effects on cognitive abilities in those with right vs. left temporal lobe excisions. Although both groups maintained summary IQ scores in the average range, after operation the left temporal group was less efficient on language-dependent cognitive tasks, particularly those that involved complex learning and memory. In contrast, persons who had right temporal ablations were either unchanged or slightly better cognitively after operation. Future research and clinical evaluations should focus on the components of the learning and memory processes when the ramifications of temporal lobe ablations on cognitive function are studied.

Adult↗
PubMed1993

Complex partial epileptic signs as a continuum from normals to epileptics: normative data and clinical populations.

Over a 10-year period, a total of 447 men and 624 women between 18 and 61 years of age were administered an inventory whose items describe experiences that are similar to those evoked by electrical stimulation of the temporal lobes. Empirically determined factors contained experiences of sensory enhancement, affective-dissociation, ego alien intrusions, and literary emphasis. Using this population as a reference, T scores for these clusters were calculated for special normal populations (poets, drama students, false pregnancies) and for clinical groups (post-traumatic stress, anxiety-depersonalization, exotic dissociations, and complex partial epilepsy). Whereas only mild elevations (50 < T < 65) in indicators of temporal lobe signs and symptoms were noted in the special groups, moderate (65 < T < 75) and severe (T > 79) elevations were noted in the clinical populations.

Adult↗
PubMed1991

Does inter-subject variability in cortical functional organization increase with neural 'distance' from the periphery?

In mapping the functional anatomy of the human brain, anatomical variability is a recurring concern. The degree to which the functional organization of any one subject or group of subjects is more generally predictive is largely unknown. We have previously reported that the inter-subject variability of primary visual, somatosensory and motor cortices is small (4-8 mm). Many have suggested, however, that higher-order brain areas will be considerably more variable. For this reason we assessed the anatomical variability of several brain areas participating in language perception and production. In 10 anatomically normal subjects undergoing evaluation for partial complex epilepsy we applied a previously described battery of lexical tasks; intra-subject image averaging was used to minimize the effects of variations in response magnitude. We found inter-subject anatomical variability to be uniformly consistent, with no appreciable effect of distance from the neural periphery.

Adolescent↗
PubMed1992

Magnetoencephalographic localization of epileptic cortex--impact on surgical treatment.

A 24-channel, planar, superconducting quantum interference device gradiometer, sampling a fourth of the head surface over brain tissue, was used to determine the site of an epileptic focus in a 36-year-old woman with intractable complex partial epilepsy. The other presurgical findings appeared divergent: a large arachnoid cyst over the right parietal convexity, dissimilar interictal electroencephalographic patterns, and several neuropsychological dysfunctions. The equivalent current sources of magnetoencephalographic spikes were in the right posterior temporal region of the cortex, 4 cm apart from the cyst. Surgical exploration of the area pinpointed by magnetoencephalography revealed a pachygyric patch of cortex displaying focal discharges on the electrocorticogram. After resection, a dramatic reduction of seizures occurred. The good agreement between electrocorticography and magnetoencephalography warrants future investigation of multichannel magnetoencephalography as a potential alternative to invasive presurgical recordings.

Adult↗
PubMed1992

Adenosine: a potential mediator of seizure arrest and postictal refractoriness.

Adenosine is a potent inhibitory neuromodulator and has been proposed as an endogenous anticonvulsant. Depth electrodes modified to include a microdialysis probe were implanted for 10 to 16 days in the hippocampi of 4 patients with intractable complex partial epilepsy to test the hypothesis that during seizures extracellular adenosine reaches levels that may depress epileptiform activity. Samples were collected bilaterally at 3-minute intervals before, during, and after a single, spontaneous-onset seizure in each patient. All seizures commenced in one hippocampus and propagated to the contralateral hippocampus. Extracellular adenosine levels increased by 6- to 31-fold with the increase significantly greater in the epileptogenic hippocampus. During seizures, levels of adenosine in the dialysate reached concentrations as high as 2.5 microM, reflecting extracellular concentrations of approximately 65 microM. Adenosine at concentrations of 40 to 50 microM depresses epileptiform activity in vitro, so the levels we report may suppress seizure activity in vivo. Moreover, adenosine levels remain elevated above basal values for the entire 18-minute postictal period. These data support the role of adenosine in mediating seizure arrest and postictal refractoriness and suggest that treatments which facilitate adenosine may be effective in preventing seizures.

Adenosine↗
PubMed1998

Altered hippocampal kainate-receptor mRNA levels in temporal lobe epilepsy patients.

This study determined whether hippocampal kainate (KA) receptor mRNA levels were increased or decreased in temporal lobe epilepsy patients compared with nonseizure autopsies. Hippocampal sclerosis (HS; n = 17), nonsclerosis (non-HS; n = 11), and autopsy hippocampi (n = 9) were studied for KA1-2 and GluR5-7 mRNA levels using semiquantitative in situ hybridization techniques, along with neuron densities. Compared with autopsy hippocampi, HS and non-HS cases showed decreased GluR5 and GluR6 hybridization densities per CA2 and/or CA3 pyramid. Furthermore, HS patients demonstrated increased KA2 and GluR5 hybridization densities per granule cell compared with autopsy hippocampi. These findings indicate that chronic temporal lobe seizures were associated with differential changes in hippocampal KA1-2 and GluR5-7 hybridization densities that vary by subfield and pathology group. In temporal lobe epilepsy patients, these results support the hypothesis that pyramidal cell GluR5 and GluR6 mRNA levels are decreased as a consequence of seizures, and in HS patients granule cell KA2 and GluR5 mRNA levels are increased in association with aberrant fascia dentata mossy fiber sprouting and/or hippocampal neuronal loss.

Adult↗
PubMed2002

Gamma-Knife radiosurgery of mesiotemporal tumour epilepsy observations and long-term results.

PURPOSE: The efficacy of radiosurgery in cases of mesiotemporal tumours associated with long standing epilepsy has not clearly been documented up to now. The authors present a retrospective analysis of 19 cases treated by Gamma-Knife radiosurgery (GKRS) for mesiotemporal tumour epilepsy. METHODS: Between 1992 and 1997 19 patients (12 male and 7 female) with a mean age of 31 years (5-72) and mesiotemporal tumour-induced epilepsy of a mean duration of 8.6 years (0.9-28) were treated by GKRS. All tumours were within the mesiotemporal structures and the pathohistology proven by biopsy or resective procedure revealed 15 (79%) low grade astrocytomas, 3 (16%) gangliogliomas and 1 (5%) cavernoma. Beside tumour control, the main aim of GKRS was alleviation of epilepsy by irradiating the presumed epileptic foci outside the tumour volume. The 50% isodose volumes surrounding the tumours measured a mean of 6.2 ccm (1.1-18 ccm). Doses given at marginal isodoses ranged from 12 to 30 Gy (mean 17.3 Gy). The outcome with respect to epileptic seizures was evaluated by the Engel classification. RESULTS: After a follow-up (FU) of 1.7 to 9.7 years (mean 6.5 years) 11 patients (57.9%) were significantly ameliorated (Engel I and Engel II), 7 patients (36.8%) worthwhile improved (Engel III) and 1 patient (5.3%) unchanged. In 11 patients (58%) radiosurgically induced image changes were seen on MRI. INTERPRETATION: Although microsurgical approach guided by electrocorticography (EcoG) is the state of art for treatment of mesiotemporal tumour epilepsy, GKRS can be used as a non-invasive, safe and effective alternative to resective surgery for selected cases.

Adolescent↗
PubMed1994

Dual-isotope autoradiographic measurement of regional blood flow and benzodiazepine receptor availability following unilateral middle cerebral artery occlusion.

Single-photon emission tomography (SPET) imaging in patients with complex partial epilepsy has shown that the seizure focus is characterized by both decreased interictal blood flow and decreased uptake of the benzodiazepine (BZ) receptor tracer iodine-123 iomazenil. The purpose of this study was to examine the confounding effect of decreased flow on iomazenil uptake. The left middle cerebral artery of four rats was occluded, and the animals were simultaneously injected with 25 microCi of iodine-125 iomazenil and 500 microCi of the blood flow tracer [123I]iofetamine (N-isopropyl-p-iodoamphetamine). All rats, including two sham, were sacrificed 1 h after injection, a time when uptake of both agents is nearly maximal. Control experiments showed that arterial occlusion for 1 h did not affect the total number of BZ binding sites. Using a dual autoradiographic technique, the uptake of both [123I]iofetamine and [125I]iomazenil was measured in more than 200 regions showing variable levels of reduced flow and expressed as a percentage of the contralateral homotypic area. The straight line fit of % [125I]iomazenil (y axis) versus % [123I]iofetamine (x axis) in all 200 regions had a slope of 0.74. Insofar as the rat is an accurate model of human subjects with epilepsy, these studies suggest that decreased flow to the epileptogenic focus will linearly exacerbate the decrease in uptake secondary to neuropathologic loss of BZ receptors. Thus, for localization of seizure focus, a single SPET image of [123I]iomazenil in an epileptic patient may have greater sensitivity than a comparable blood flow image, because the former is enhanced by both decreased flow and a loss of BZ receptors.

Amphetamines↗
PubMed1996

Suppression of background brain activity influence in localizing epileptic spike sources from biomagnetic measurements.

The origin of inter-ictal epileptic activity can be localized from the magnetoencephalogram (MEG) using the Equivalent Current Dipole (ECD) as a source model. One problem with such localizations is that in many patients, the localization of an epileptic spike source becomes inaccurate because the epileptic spikes are superimposed by pathologic brain rhythmic activities. This paper proposes to use the spatial coherence of the measured magnetic field caused by the measured magnetic field to suppress its influence in the ECD localization. In the method proposed here, the covariance matrix, which expresses the spatial coherence of the rhythmic magnetic field, is first calculated using a data portion where no spikes exist and rhythmic slow waves are evident. Then, ECD localization is performed by minimizing the least-squares cost function modified by the covariance matrix. Experiments using a computer generated ECD field and rhythmic slow waves measured from a patient suffering from complex partial epilepsy prove the basic effectiveness of the method proposed. Localizations of actual spike sources in the same clinical data are performed, and results indicating the effectiveness of the proposed method are obtained.

Brain↗
PubMedDate not supplied

Brain imaging during seizure: ictal brain SPECT.

The role of single photon computed tomography (SPECT) in presurgical localization of medically intractable complex partial epilepsy (CPE) in children is reviewed. 99mTechnetium Neurolite, a newer lipophylic agent with a high first pass brain extraction and little or no redistribution is injected during a seizure, while the child is monitored with a video recording and continuous EEG and SPECT imaging is performed in the next 1-3 hours with the images representing regional cerebral profusion at the time of injection. On SPECT studies performed with radiopharmaceutical injected during a seizure, ictal focus is generally hypervascular. Other findings on ictal brain SPECT include hypoperfusion of adjacent cerebral cortex and white matter, hyperperfusion of contralateral motor cortex, hyperperfusion of ipsilateral basal ganglia and thalamus, brain stem and contralateral cerebellum. Ictal brain SPECT is non-invasive, cost effective and highly sensitive for localization of epileptic focus in patients with intractable CPE.

Brain↗
PubMed1998

[Asystolic seizures].

Epileptic seizures may alter autonomic functions. This is especially the case with complex focal seizures (of temporal lobe origin) and grand mal. Most frequently, such seizures cause ictal tachycardia, sometimes tachypnea, probably caused by the propagation of epileptic discharges to autonomic cerebral structures. Ictal bradycardia and asystole are rare phenomena. However, they may be life threatening. Their differentiation from primary cardiac arrest is possible by the use of ictal EEG and ECG registration. Postictal serum prolactin measurement does not differentiate syncope from seizure. However, a postictal increase of creatine kinase is only measured after epileptic seizures and not after syncope. Treatment of such epileptic seizures includes an optimization of anticonvulsant drug therapy and the implantation of a cardiac demand stimulator. There is growing evidence that ictal asystole is a cofactor in sudden unexplained death in epileptic patients.

Adult↗
PubMed1996

Melanotic astrocytoma.

A case of pigmented pilocytic astrocytoma (WHO grade I) incidentally found in a right temporopolar lobectomy specimen is reported. The patient, a 41-year-old woman, underwent surgery because of long-standing complex partial epilepsy of presumed post-traumatic origin. Using immunohistochemistry and electron microscopy, the tumor was shown to be composed of astrocytes without evidence of neurosecretory or melanocytic differentiation. The cytoplasmic pigment was identified as neuromelanin by its histochemical staining properties and ultrastructure. Although rare cases of ependymoma, subependymoma, choroid plexus papilloma and ganglioglioma with melanogenesis are on record, no melanotic astrocytoma has been described so far.

Adult↗
PubMed2006

Impaired baroreflex function in temporal lobe epilepsy.

Changes of cardiovascular function are frequent in temporal lobe epilepsy (TLE). The baroreflex - the most important reflex for cardiovascular stability - has not been studied systematically in TLE. We evaluated cardiovascular variability and baroreflex function in TLE. In 22 TLE patients and 20 controls, we continuously monitored heart rate (HR) and blood pressure (BP). Time-domain parameters were derived from recordings at rest and from standard cardiovascular reflex tests. Spectral analysis determined sympathetic and parasympathetic modulation of HR and BP in the low (LF-power) and high frequency range (HF-power). We calculated the relative LF- and HF-powers of HR in relation to the sum of LF- and HF-powers. LF/HF-ratio of HR was assessed as a parameter of sympatheticovagal balance. LF-transfer function gain between BP and HR determined baroreflex function.Time-domain parameters did not differ between TLE patients and controls. Spectral analysis showed decreased absolute LF- and HF-powers but increased relative LF-power and LF/HF-ratio of HR in TLE. LF-transfer function gain between BP and HR was reduced in TLE (p<0.05). The reduction of absolute LF- and HF-powers indicates decreased total autonomic variability in TLE. However, increased relative LF-power and LF/HF-ratio of HR in TLE show a relative increase of sympathetic tone. Most importantly, we demonstrate an impaired baroreflex function in TLE. These cardiovascular autonomic abnormalities may contribute to cardiac arrhythmia in TLE.

Adult↗
PubMed1984

Hypoglycemic activation of focal abnormalities in the EEG of patients considered for temporal lobectomy.

EEGs were recorded in 22 patients with medically refractory complex partial epilepsy undergoing presurgical evaluation and 11 age-matched controls while subjected to moderate levels of hypoglycemia to determine if changes activated were predictive of underlying pathology. Five patients had fasting EEGs showing focal abnormalities not seen in the non-fasting state. With hypoglycemia, EEG tracings in normal individuals showed diffuse background slowing, whereas 7 of 22 patients developed focal temporal changes, including focal spike and focal slow wave activation. The development of focal changes correlated well with clinical data concerning underlying focal pathology; focal abnormalities were not evoked in patients with multifocal disease. Hypoglycemic activation of the EEG may be a useful technique for predicting the presence of pathology in patients considered for anterior temporal lobectomy.

Adult↗
PubMed1986

Interictal spike-wave complexes in the human medial temporal lobe: typical topography and comparisons with cognitive potentials.

Ten of 16 patients with complex partial epilepsy displayed an interictal spike-slow wave sequence with characteristic morphology and depth voltage topography. This 'typical slow wave' (TSW) lasted 300-600 msec, was usually largest and negative in the anterior hippocampus, and positive in the amygdala. Simultaneous recordings from ipsilateral cingulate, supplementary motor, orbitofrontal, and lateral temporal cortices, as well as from the contralateral medial temporal lobe (MTL), revealed only small, apparently volume-conducted, wave forms. Simultaneously recorded multiunit activity within the focal MTL was profoundly inhibited during the TSW. The TSW propagated to the scalp, producing a large widespread positivity. A large endogenous potential with similar latency range and task correlates as the scalp-P3 was recorded from the MTL to infrequent tones in a simple discrimination task. This 'depth-P3' had very similar polarity and relative amplitude across MTL sites, as was observed for the TSW at the same electrode contacts. However, at more superficial intracranial sites, the TSW was relatively smaller than the P3. Similarly, from MTL to surface, the P3 was found to decrement about half as much as the TSW decrements. This evidence suggests that the surface P3 is generated, but in part only, by the MTL.

Adolescent↗
PubMed1989

Profiles of instant heart rate during partial seizures.

Instant heart rate (R-R intervals) can be readily studied during spontaneous seizures recorded with ambulatory cassette AEEG/AECG techniques. Ninety-three seizures were recorded in 32 patients with complex partial epilepsy. Instant R-R interval plots showed that 74% of seizures were associated with a dominant tachycardia, the most characteristic features of which were the initial steep acceleration phase at seizure onset and the wide fluctuations in heart rate ('exaggerated sinus arrhythmia') which occurred during and immediately after the seizure. Five percent of seizures were associated with a dominant but transient phase of heart rate slowing during or towards the end of the seizure. Nineteen percent of seizures showed equivocal or negative ictal effects on the heart rate and rhythm despite unequivocal AEEG seizure discharges. Conversely, other patients had characteristic heart rate changes despite equivocal AEEG abnormality. The heart rate profiles showed striking seizure-to-seizure similarities when multiple fits were recorded in the same patient. Ratemeter profiles may be clinically useful to locate epileptic seizures in long duration records; they can help to locate seizures which are either inaccurately timed or poorly identified by the event marker, or not clearly associated with definite AEEG changes. The secondary cardiac effects of epilepsy may be misdiagnosed if their primary cerebral origin is not suspected.

Adult↗