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PubMed1996

Properties of a delayed rectifier potassium current in dentate granule cells isolated from the hippocampus of patients with chronic temporal lobe epilepsy.

PURPOSE: Properties of potassium outward currents were investigated in human hippocampal dentate gyrus granule cells from 11 hippocampal specimens obtained from patients with temporal lobe epilepsy (TLE) during resective surgery. METHODS: Dentate granule cells were isolated enzymatically and outward currents analyzed by using the whole-cell configuration of the patch-clamp method. Hippocampal specimens were classified neuropathologically with respect to severe segmental cell loss, gliosis, and axonal sprouting (Ammon's horn sclerosis, AHS), or the presence of a focal lesion in the adjacent temporal lobe. RESULTS: A delayed rectifier outward current (IK), but not an A-type potassium current (IA) or inwardly rectifying potassium currents, was observed in all cells. The average current density of IK, the time-dependent decay of IK, and the resting membrane characteristics were not significantly different between patients with and without AHS. The voltage of half-maximal activation V1/2(act) was 5.4 +/- 1.8 mV in AHS compared with -2.9 +/- 1.8 mV in lesion-associated epilepsy (NS). In contrast, V1/2(inact) was shifted in a hyperpolarizing direction in AHS (-67.7 +/- 0.6 mV) compared with that in hippocampi not showing AHS (-47.7 +/- 2.6 mV; p = 0.0017). CONCLUSIONS: The altered steady-state voltage-dependence of IK may result in abnormal excitability of dentate granule cells in AHS and exert a marked influence on input-output properties of the dentate gyrus.

Adult↗
PubMed1996

Postictal alteration of sodium content and apparent diffusion coefficient in epileptic rat brain induced by kainic acid.

PURPOSE: We studied temporal changes of brain sodium and apparent diffusion coefficient (ADC) in a temporal lobe epilepsy (TLE) rat model using kainic acid (KA). METHODS: In situ three-dimensional 23Na magnetic resonance imaging (MRI) and proton diffusion-weighted imaging (DWI) were used. KA at a dose of 10 mg/kg body weight and 12 adult Sprague Dawley rats weighing 228-318 g (268 +/- 25 g) were used. RESULTS: Twenty-four hours after KA injection, magnetic resonance (MR) visible sodium levels increased in both the pyriform cortex (+90%) and amygdala (+68%) and increased insignificantly in the hippocampus (+18%) and caudate-putamen (12%). The ADC in the pyriform cortex showed a -9% decrease at 5 h postictally, reaching -30% at 24 h, whereas in the amygdala decreases were -8 and -26% respectively. A significant decrease in ADC (-7%) in the hippocampus was also observed 24 h postically. Seven days later, sodium increases persisted, whereas ADC returned to normal level. CONCLUSIONS: The increase in MR visible sodium, associated with the decrease in ADC is consistent with the hypothesis that sequential seizures caused an increase in sodium influx and perturbation of membrane ion homeostasis, which eventually evolved into an irreversible phase of cellular edema, with increased MR visible intracellular sodium and decreased ADC. Return of ADC to near-control level and persistent high sodium level at 7 days may be explained by the increase in extracellular space and tissue necrosis.

Amygdala↗
PubMed1996

Hippocampal cell distributions in temporal lobe epilepsy: a comparison between patients with and without an early risk factor.

Neuronal cell distributions were measured for anterior and posterior locations in the hippocampi of epilepsy patients who were seizure-free after temporal lobectomy. Patients were divided into two groups, those with an early risk factor, defined as a neurologic insult occurring in the first 4 years of life, and those with no early risk factor. Early-risk patients had lower hilar cell densities, lower granule cell densities, and fewer granule cells per millimeter, a measured related to total granule cell number, than to early risk patients. Moreover, each risk group had different anteroposterior density gradients for granule cells and hilar cells. These differences in cell distribution may arise from different patterns of cell loss of cell migration in the dentate gyrus during development. In the early-risk group, there was also a distinction between patients with a history of febrile convulsions without CNS infection and patients with a history of meningitis or encephalitis. These two subgroups had similar numbers of granule cells, However, the meningitis/encephalitis subgroup exhibited a wider granule cell layer, suggesting that the granule cell layer was more dispersed. Our results support the hypothesis of a predominantly anterior hippocampal insult in temporal lobe epilepsy (TLE). In nonepileptic hippocampus, the ratio of putatively excitatory granule neurons to putatively inhibitory hilar neurons is highest in the anterior hippocampus. This ratio may explain in part why the anterior hippocampus is more prone to cell loss and seizures.

Adult↗
PubMed1996

Significance of simple partial seizures in temporal lobe epilepsy.

We determined how localization of simple partial seizures (SPS) correlated with localization of complex partial seizure (CPS) in scalp/sphenoidal EEG and assessed prognosis after temporal lobe resective surgery in patients with an ictal correlate of SPS in scalp/sphenoidal EEG recordings. EEGs were recorded with the 10-20 system of electrode placement and supplemented with sphenoidal electrodes. Between 1985 and 1992, 183 patients with temporal lobe epilepsy (TLE) reported an aura (SPS) during inpatient monitoring; all were eligible for inclusion in our study. The EEGs during SPS showed ictal changes in 51 patients (28%, 117 SPS). Forty-four patients had unilateral temporal interictal spikes (IIS), and SPS and CPS always arose from the same region. Seven patients had bitemporal interictal spikes; SPS colocalized with CPS in 4 patients (57%), SPS were contralateral to CPS in 2 patients, and 1 patient had bilateral independent CPS but unilateral SPS. SPS accompanied by EEG ictal changes conveyed a favorable prognosis in patients who underwent epilepsy surgery. Scalp/sphenoidal recorded IIS but were less reliable in identifying the location of CPS onset in patients with bitemporal spikes.

Adult↗
PubMed1996

Implications of seizure termination location in temporal lobe epilepsy.

Where propagating symptomatic seizures terminate has not been studied, but might provide insight into mechanisms of seizure termination as well as localization of epileptogenic tissue. We investigated location of seizure termination in 50 refractory temporal lobe epilepsy (TLE) patients who had intracranial EEG recording of spontaneous seizures and subsequent temporal lobe resection with > 1-year follow-up. Only seizures that had onset in the resected temporal lobe were included. Location of the electrical termination for each seizure in each patient was categorized as diffuse, localized to the onset location, or localized elsewhere. The proportion of all seizures in each patient in each category was analyzed with respect to the outcome of surgery. Outcome was classified as seizure-free or persistent seizures. Diffuse seizure termination was noted equally frequently in both outcome groups. However, the 27 patients without seizures postoperatively had a significantly greater proportion of seizures with termination in the onset location (67%) than did the 23 patients with persistent seizures (36%, p < 0.01). The seizure-free patients also had a significantly lower proportion of seizures with localized termination elsewhere than the onset site (13%) than did patients with persistent seizures (45%, p < 0.005). Localization of the site of termination of seizures of focal origin to cortical regions other than the onset is associated with a poorer surgical prognosis. This observation raises the possibility of additional abnormal epileptogenic cortical regions with impaired seizure-terminating capabilities.

Adolescent↗
PubMed1996

Intracartotid amobarbital procedure memory performance and age at first risk for seizures distinguish between lateral neocortical and mesial temporal lobe epilepsy.

PURPOSE: To determine whether intracarotid amobarbital procedure (IAP) memory-performance asymmetries and early risk factors for epilepsy distinguish between lateral neocortical temporal lobe epilepsy (LNTLE) and mesiobasal temporal lobe epilepsy (MBTLE). METHODS: We studied 10 patients with LNTLE and 22 with MBTLE. All LNTLE patients showed (a) presence of temporal neocortical lesion or lateral seizure onset by intracranial recording, and (b) absence of mesial temporal sclerosis (MTS) by histopathologic analysis. All patients with MBTLE showed (a) video-scalp EEG seizures consistent with mesial TLE, and (b) presence of unilateral MTS by histopathologic analysis. All patients had good surgical outcomes (Engel I or II). Unilateral IAP memory performance was defined as percentage of memory items presented during hemispheric anesthesia that was recognized after recovery. IAP asymmetry scores were the differences in memory performance after right and left injections. RESULTS: Mean memory-asymmetry scores were significantly lower in the LNTLE than in the MBTLE group. An IAP memory asymmetry of < 25% correctly classified seven of 10 patients with LNTLE, and an asymmetry of > or = 25% correctly classified 18 of 22 patients with MBTLE. Age at first risk for epilepsy was significantly younger in those with MBTLE than in those with nonlesional LNTLE. Results suggest that both IAP memory performance and age at first risk can help distinguish between MBTLE and LNTLE.

Adult↗
PubMed1997

Temporal changes in proton MRS metabolites after kainic acid-induced seizures in rat brain.

PURPOSE: In situ 1H-magnetic resonance spectroscopy (MRS) was used to study temporal metabolic changes in a rat model of temporal lobe epilepsy (TLE) by using kainic acid (KA). METHODS: Rat brains were scanned at the level of the hippocampal body for MRS measurements. Relative ratios of N-acetyl groups (NA: N-acetylaspartate and N-acetylaspartyl glutamate), choline, and lactate (Lac) over creatine (Cr) were calculated. RESULTS: NA/Cr ratios increased significantly during the ictal phase. During the postictal and interictal phases, the NA/Cr ratio decreased. There was a significant and prolonged increase of the lactate/Cr ratio in the hippocampi of rats that started 1 h after the onset of KA-induced seizure activity and persisted up to 24 h after the injection. The prolonged lactate/Cr increase in an area susceptible to neuronal damage (e.g., hippocampus) correlated with the onset of seizure activity but remained elevated thereafter. CONCLUSIONS: The ictal and early postictal increase in lactate ratios may reflect increased cellular activity and metabolism resulting from KA excitotoxicity. Assuming that the changes in NA/Cr ratios are due to NAA increase, we speculate that an activation of the N-acetylaspartylglutamate (NAAG) dipeptidase pathway may explain the ictal increase in NA/Cr ratios. The late postictal decrease in NA/Cr ratios is a reflection of KA-induced neuronal cell loss.

Animals↗
PubMed1997

Identification of frontal lobe epileptic foci in children using positron emission tomography.

PURPOSE: Presurgical evaluation for intractable frontal lobe epilepsy (FLE) is difficult and invasive, partly because anatomic neuroimaging studies with computed tomography (CT) and magnetic resonance imaging (MRI) typically do not show a discrete lesion. In adult patients with FLE, functional neuroimaging of glucose metabolism with positron emission tomography (PET) is less sensitive in detecting focal metabolic abnormalities than in temporal lobe epilepsy (TLE). Comparable data on children with FLE are not available. METHODS: We used high-resolution PET scanning of glucose metabolism to evaluate 13 children (age 17 months to 17 years; mean age 9.5 years) with intractable FLE being considered for surgical treatment. Only children with normal CT and MRI scans were included. RESULTS: Hypometabolism including the frontal lobe was evident in 12 of the 13 children, was unilateral in 11 of 13, and was restricted to the frontal lobe in 8 of 13. One child showed bilateral frontal cortex hypometabolism and another had an ictal PET scan demonstrating unilateral frontal cortex hypermetabolism surrounded by hypometabolism. Additional hypometabolic areas outside the frontal cortex were observed in 5 children in parietal and/or temporal cortex. Localization of seizure onset on scalp EEG was available in 10 children and corresponded to the location of frontal lobe PET abnormality in 8. However, in 4 of the 10 children, the extent of hypometabolism exceeded the epileptogenic region indicated by ictal EEG. In 2 of the 13 children, the abnormality evident on EEG was more extensive than that evident on PET. In the remaining 3 children for whom only interictal EEG data were available, the PET foci did not correspond in location to the interictal EEG abnormalities. In 11 of the 13 children, the presumed region of seizure onset in the frontal lobe, as based on analysis of seizure semiology, corresponded to the locations of frontal lobe glucose metabolism abnormalities. CONCLUSIONS: Although high-resolution PET appears to be very sensitive in localizing frontal lobe glucose metabolic abnormalities in children with intractable FLE and normal CT/MRI scans, the significance of extrafrontal metabolic disturbances requires further study; these may represent additional epileptogenic areas, effects of diaschisis, seizure propagation sites, or secondary epileptogenic foci.

Adolescent↗
PubMed1997

Usefulness of ictal and interictal 99mTc ethyl cysteinate dimer single photon emission computed tomography in patients with refractory partial epilepsy.

PURPOSE: Ictal perfusion single photon emission computed tomography (SPECT), using HMPAO, has been shown to localize epileptic foci in approximately 90% of studies. Unfortunately, HMPAO decomposes rapidly, precluding the performance of ictal studies. Ethyl cysteinate dimer (ECD) is a SPECT perfusion agent recently approved by the Food and Drug Administration. After preparation, this compound is stable for approximately 6 h. facilitating the performance of ictal studies. METHODS: In a prospective, open-label, uncontrolled, non randomized study, we evaluated the potential benefits of the use of 99mTc-ECD SPECT for lateralization of the epileptic focus. Ten consecutive adult epilepsy surgery candidates were studied with ictal and interictal 99mTc-ECD SPECT. RESULTS: The mean delay between seizure onset and ictal SPECT injection was 23.2 s. The mean seizure duration was 84.1 s. Ictal studies agreement between the epilepsy focus and area of hyperperfusion was evident in 8 of 10 cases. In one case, SPECT was lateralized in a patient with bilateral temporal lobe epilepsy (TLE); however, hyperperfusion was observed on the same side of that particular seizure. In another case, there was location disagreement. Interictal SPECT showed focal hypoperfusion in three cases. CONCLUSIONS: 99mTc-ECD proved to be an optimal tracer for ictal studies. Although this is a small series, the results of ictal and interictal findings using 99mTc-ECD are similar to those reported with 99mTc-HMPAO. Because 99mTc-ECD has a longer decomposition time, true ictal studies are easier to obtain. This new tracer will probably allow the use of ictal SPECT to become widely accepted in most epilepsy centers.

Adult↗
PubMed1998

Correlation between interictal regional cerebral blood flow and depth-recorded interictal spiking in temporal lobe epilepsy.

PURPOSE: Single photon emission computed tomography (SPECT) is used as an adjunctive method in preoperative localization of epileptic foci. In temporal lobe epilepsy (TLE), interictal hypoperfusion is observed in 60-70% of cases. Correlation with ictal EEG changes is observed in approximately 50-60% of cases. Relationships with interictal EEG have been studied less. We compared interictal SPECT data obtained in 20 patients with their interictal intracerebral electrical activity recorded by depth electrodes to evaluate a potential relationship. METHODS: We studied 20 sequential patients whose clinical, surface, and depth EEG data indicated seizure originating in the temporal lobe and who had interictal [99mTc]hexamethylpropylene amine oxime (HMPAO)-SPECT stereo-EEG (SEEG). Intracerebral electrodes were placed according to the patient's profile. The interictal extent of epileptiform activity allowed delineation of the irritative zone. Interictal spike frequency was also analyzed semiquantitatively. Visual and numerical SPECT analysis was performed blind to SEEG data. RESULTS: Interictal hypoperfusion was observed in 16 patients, involving the epileptogenic temporal lobe in 14. Except for 1 patient who manifested lateral temporal hypoperfusion corresponding to a mass lesion, two distinctive patterns of hypoperfusion were noted: (a) mesial hypoperfusion (5 patients), and (b) global temporal hypoperfusion (8 patients). In 8 patients, hypoperfusion had also extended into the adjacent cortex. Temporal mesial hypoperfusion was associated with spiking limited to the mesial structures, whereas global temporal hypoperfusion or hypoperfusion extending beyond the temporal lobe was associated with a similar topographic pattern of spikes. CONCLUSIONS: Comparison between SPECT and SEEG data collected in the interictal phase indicated that the extent of the hypoperfused area correlated topographically with that of the underlying irritative zone.

Adolescent↗
PubMed1998

Longitudinal quantitative hippocampal magnetic resonance imaging study of adults with newly diagnosed partial seizures: one-year follow-up results.

PURPOSE: We wished to establish whether hippocampal changes occur in 1 year in adults with newly diagnosed partial seizures and, if so, to identify possible causes and mechanisms. METHODS: Thirty-six adult patients with newly diagnosed partial seizures underwent a magnetic resonance imaging (MRI) scan of the brain including hippocampal volume and T2 relaxation time (HCT2) measurement and had a follow-up quantitative MRI scan approximately 1 year after the baseline MRI scan. RESULTS: At baseline, 4 patients (11%) had hippocampal sclerosis (HS), 4 (11%) had abnormalities other than HS, and 28 had a normal MRI scan (78%). Twenty-three patients (64%) had recurrent seizures in the period between the two MRI scans. One of the 4 patients with HS, who had daily seizures, had significantly increased HCT2 values on follow-up, possibly reflecting progressive hippocampal damage. None of the 32 patients with MRI findings other than HS at baseline progressed to HS on follow-up. However, 2 of the 32 patients had significant hippocampal changes, probably related to resolution of inflammatory swelling or edema after seizures were controlled. CONCLUSIONS: Subtle changes in hippocampi can occur in 1 year in adults with newly diagnosed partial seizures, which could be due to resolution of edema after seizure control or to hippocampal changes associated with frequent and daily seizures. Follow-up of the studied cohort for several years will be required to settle the question of whether progressive hippocampal damage occurs in temporal lobe epilepsy (TLE).

Adolescent↗
PubMed1999

The prognosis for control of seizures with medications in patients with MRI evidence for mesial temporal sclerosis.

PURPOSE: Mesial temporal sclerosis (MTS) is the most common and important pathology in temporal lobe epilepsy (TLE), and its presence in magnetic resonance imaging (MRI) scans is strongly correlated with a successful surgical outcome. Despite the general assumption that patients with MTS respond poorly to medication, the long-term prognosis for such patients has not yet been investigated. We studied the overall clinical prognosis of patients with MTS and analyzed the factors related to the degree of medical responsiveness. METHODS: Case patients were actively followed up at the Yonsei Epilepsy Clinic in Seoul, Korea, for >2 years. A structured interview and a thorough clinical evaluation were conducted. MRI scans, at the field strength of 1.0 or 1.5 Tesla, were performed with T1- and T2-weighted coronal and axial spin-echo images. All coronal slices were < or = 5-mm thick with no gap. Two neurologists and one radiologist determined the presence of MTS in MRIs by visual analysis. RESULTS: The MTS group consisted of 104 patients. Of these, 26 (25%) were completely controlled with adequate therapy, and 40 (38%) were intractable, despite aggressive anticonvulsant polytherapy. The remaining 37% had their seizure frequencies reduced by > or = 50%, but were not seizure free. The age of seizure onset was significantly younger in the intractable group than in the well-controlled group. Patients with a history of febrile convulsions or with epileptiform discharges in their electroencephalogram (EEG) had poorer seizure control (p < 0.05) than those who did not. Among the 16 patients who had no previous treatment, five (31%) became seizure free, and two were intractable. CONCLUSIONS: Not all patients with MTS are medically intractable; 25% of the patients in our study achieved complete control while receiving medication. Poor seizure control was related to an early age of seizure onset, a history of febrile convulsions, and epileptiform discharges on the EEG.

Adolescent↗
PubMed1999

Effects of incorporating memory confidence ratings and language handicap modifications on intracarotid amobarbital procedure (Wada test) memory asymmetry scores.

PURPOSE: Intracarotid amobarbital procedure (IAP) memory asymmetry scores are often considered in determining lateralization of temporal lobe seizure foci. Additionally, these scores sometimes influence treatment plans for epilepsy surgery candidates. We examined the effects of two scoring modifications on IAP asymmetry scores: incorporating memory confidence ratings (MC), and use of a language handicap (LH) (i.e., adding a point to the memory score with anesthetization of the language-dominant hemisphere), both of which could be applied to most IAP protocols despite variations in testing methods among epilepsy surgery programs. METHODS: Sixty-nine consecutive unilateral temporal lobe epilepsy (TLE) patients with subsequent good surgical outcomes (Engel I or II) underwent bilateral IAP testing. Confidence ratings were obtained for all memory responses. The incorporation of confidence ratings and the application of a language handicap for dominant-hemisphere injections were applied to memory asymmetry scores in all combinations, resulting in four scoring methods. Results of the four methods were compared with respect to the proportion of patients lateralized accurately by each method. RESULTS: No patients were falsely lateralized with any method. Percentage of patients correctly lateralized with each scoring method is shown in Table 2. The results obtained with MC and with MC + LH (67% and 64% of patients accurately lateralized, respectively) were significantly better than results obtained with LH (55%, p<0.05). No other differences were significant. CONCLUSIONS: Although not statistically superior to standard methods, these results suggest that incorporating memory confidence ratings into IAP protocols may increase the likelihood of obtaining asymmetry scores that accurately lateralize to the hemisphere of seizure onset. In contrast, inclusion of a language handicap for scores obtained with the language-dominant ICA injection were not helpful and may even decrease the probability of obtaining clinically useful lateralizing data. These scoring modifications can be applied to most IAP protocols.

Adult↗
PubMed1999

NMDA-receptor activity visualized with (S)-[N-methyl-11C]ketamine and positron emission tomography in patients with medial temporal lobe epilepsy.

PURPOSE: To determine whether neurochemical activation of the N-methyl-D-aspartate (NMDA) receptor-gated ion channel shows quantitative changes, measured as binding of 11C-labeled (S)-[N-methyl]ketamine, in patients with medial temporal lobe epilepsy (MTLE). METHODS: Eight patients with MTLE who were evaluated regarding epilepsy surgery underwent positron emission tomography (PET) with (S)-[N-methyl-11C]ketamine. The presurgical investigations included magnetic resonance imaging (MRI), PET with 18F-fluoro-deoxyglucose (18FDG), and seizure monitoring by using video-EEG. The uptake of (S)-[N-methyl-11C]ketamine in the temporal lobe of ictal onset was compared with the contralateral side and correlated to changes in regional glucose metabolism measured by PET with 18FDG. RESULTS: (S)-[N-methyl-11C]ketamine rapidly reached the brain, and high radioactivities were measured in the striatum, thalamic nuclei, and cortical regions. Overall the brain uptake and regional binding potentials of (S)-[N-methyl-11C]ketamine were similar to measurements observed previously in healthy controls. However, 20 min after administration, when blood flow influence was negligible, a side-to-side comparison revealed a 9-34% reduction of tracer radioactivity in the temporal lobes of ictal onset. At earlier times, the differences in binding potentials were less pronounced, 9-21%. The magnitude and distribution of the reduction were similar to the metabolic pattern seen on PET scans with 18FDG. CONCLUSIONS: Radioactivity uptake of intravenously administered (S)-[N-methyl-11C]ketamine was reduced in temporal lobes of ictal in patients with TLE. This may reflect reduced NMDA-receptor density, reduced perfusion, focal atrophy, or other factors.

Adult↗
PubMed1999

Correlations between granule cell dispersion, mossy fiber sprouting, and hippocampal cell loss in temporal lobe epilepsy.

PURPOSE: Correlations between granule cell dispersion (GCD), collateral mossy fiber (MF) sprouting, and hippocampal cell loss were studied to assess the relation between GCD and synaptic reorganization in the dentate gyrus of patients with epilepsy. METHODS: Twenty specimens from patients with medically intractable temporal lobe epilepsy (TLE) were studied along with two control specimens. GCD was considered to be present when the stratum granulosum was wider than 120 microm, the close apposition between the granule cell (GC) soma was lost, and GCs were scattered in the molecular layer (ML). Patterns of MF sprouting were differentiated as wide or narrow according to the area of neo-Timm's staining in the ML. GC loss and volumetric cell-density decreases in the different subfields were assessed. RESULTS: MF sprouting was observed in 16 (80%) and GCD in nine (45%) cases. A significant correlation was found between MF sprouting and cell loss in all the subfields except the cornu Ammonis field 2 (CA2). A wide band of MF sprouting was associated with severe cell loss. Cases with GCD had a wide band of MF sprouting and also a higher degree of cell loss than cases without GCD. CONCLUSION: GCD is associated with a specific pattern of MF sprouting, but cell loss was found to be a major determinant for MF reorganization.

Adult↗
PubMed1999

Gamma knife surgery for mesial temporal lobe epilepsy.

PURPOSE: Gamma knife radiosurgery (GK) allows precise and complete destruction of chosen target structures containing healthy and/or pathologic cells, without significant concomitant or late radiation damage to adjacent tissues. All the well-documented radiosurgery of epilepsy cases are epilepsies associated with tumors or arteriovenous malformations (AVMs). Results prompted the idea to test radiosurgery as a new way of treating epilepsy without space-occupying lesions. METHODS: To evaluate this new method, we selected seven patients with drug-resistant "mesial temporal lobe epilepsy" (MTLE). The preoperative evaluation program was the one we usually perform for patients selected for microsurgery of TLE [video-EEG analysis of seizures, foramen ovale electrode recording, magnetic resonance imaging (MRI) positron emission tomography (PET) scan, neuropsychological testing]. In lieu of microsurgery, the amygdalohippocampectomy was performed by using GK radiosurgery. RESULTS: Morphologic (MRI) signs of destruction of the target took place at 9 months after GK surgery. Since the treatment day, the first patient has been seizure free. Seizure improvement came more gradually for the following patients, and complete cessation of seizures occurred around the tenth month (range, 8-15 months). MRI shows that the amygdaloentorhinohippocampal target was selectively injured. No significant side effect (except one case of homologous quadrantanopia) or morbidity and no mortality was observed. The current follow-up is 24-61 months, and all (but one) patients are seizure free. CONCLUSIONS: This initial experience proves clearly the short-to middle-term efficiency and safety of GK for MTLE surgery. These results need further confirmation of long-term efficiency, but the introduction of GK surgery into epilepsy surgery can reduce dramatically its invasiveness and morbidity.

Adult↗
PubMed2000

Proton magnetic resonance spectroscopic imaging studies in patients with newly diagnosed partial epilepsy.

PURPOSE: To assess whether the N-acetyl aspartate (NAA) to creatine ratio (NAA/Cr) is abnormally low at the onset of epilepsy and whether successful treatment of seizures with antiepileptic drugs is sufficient for normalization of NAA/Cr. PATIENTS AND METHODS: Proton magnetic resonance spectroscopic imaging (1H-MRSI) was used to measure NAA/Cr in temporal lobes of eight patients with newly diagnosed epilepsy before or soon after starting medication. Six patients had follow-up 1H-MRSI examinations 7 months later. Clinical pattern of the seizures and the EEG findings suggested partial seizures in all and TLE in five patients. None of the patients had lesional epilepsy according to magnetic resonance imaging. RESULTS: Initial 1H-MRSI of the temporal lobes showed significantly low NAA/Cr values in five of eight patients. Five of six patients who had follow-up 1H-MRSI were seizure-free after using medication; the remaining patient did not take medication and continued to experience occasional auras. Wilcoxon rank sign comparison of NAA/Cr on initial 1H-MRSI examination and follow-up 1H-MRSIs showed no significant difference (Z = 135, p = 0.893, 2-tailed) for five seizure-free patients. CONCLUSIONS: Neuronal dysfunction is present at an early stage of the epileptic process. NAA/Cr recovery in seizure-free patients controlled with antiepileptic drugs is less evident, compared with successful surgical treatment. Thus, absence of seizures is not necessarily coupled with NAA/Cr improvement and observed variable response warrants further investigation.

Adult↗
PubMed2000

Limitations in the medical treatment of cryptogenic or symptomatic localization-related epilepsies of childhood onset.

We retrospectively examined 169 patients who had cryptogenic or symptomatic localization-related epilepsies (LRE) and were followed-up for more than 5 years. The probability of seizure control was 0.13 during the first year of treatment, 0.25 during the first 5 years, and 0.09 during the second and third 5 years. No patients who continued to have intractable seizures for 15 years became free of seizures. The onset of LRE at the age of 3 years or less, seizure cluster, mesial temporal sclerosis (MTS), and temporal lobe epilepsy (TLE) were significantly associated with a poor seizure control. If an antiepileptic drug (AED) failed to control seizures, probability of seizure control by the next drug was low, in particular in patients in whom more than 4 AEDs have already been tried, and seizure control could not be expected after a trial of 6 AEDs. A tentative indication of epilepsy surgery for LRE of childhood onset may be 5 years of poor seizure control and/or failure of four AEDs.

Adolescent↗