Subtle hippocampal malformation: importance in febrile seizures and development of epilepsy.
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This study was designed to explore the feasibility of PET using [11C](R)-PK11195 as an in vivo marker of activated microglia/brain macrophages for the assessment of neuroinflammation in Rasmussen's encephalitis (RE). [11C](R)-PK11195 PET was carried out in four normal subjects, two patients with histologically confirmed RE, and three patients with clinically stable hippocampal sclerosis and low seizure frequency. Binding potential maps showing specific binding of [11C](R)-PK11195 were generated for each subject. Regional binding potential values were calculated for anatomically defined regions of interest after coregistration to and spatial transformation into the subjects' own MRI. In one patient with RE who underwent hemispherectomy, the resected, paraffin-embedded brain tissue was stained with an antibody (CR3/43) that labels activated human microglia. Whereas specific binding of [11C](R)-PK11195 in clinically stable hippocampal sclerosis was similar to that in normal brain, patients with RE showed a focal and diffuse increase in binding throughout the affected hemisphere. In RE, [11C](R)-PK11195 PET can reveal in vivo the characteristic, unilateral pattern known from postmortem neuropathologic study. PET imaging of activated microglia/brain macrophages offers a tool for investigation of a range of brain diseases where neuroinflammation is a component and in which conventional MRI does not unequivocally indicate an inflammatory tissue reaction. [11C](R)-PK11195 PET may help in the choice of appropriate biopsy sites and, further, may allow assessment of the efficacy of antiinflammatory disease-modifying treatment.
OBJECTIVE: To assess intellectual functioning (IQ) in 54 children and adolescents with intractable epilepsy who later underwent cortical resection due to unilateral malformations of cortical development acquired in utero. METHODS: Lesion type was classified into circumscribed mass lesions and diffuse cortical dysplasia based on histopathologic analysis of surgical tissue. Cortical dysplastic lesions were further graded as mild, moderate, or severe according to specific microscopic features. Laterality of lesion was determined through neurologic examination and electrophysiologic and neuroradiologic procedures. Classification of lesion type was corroborated by its significant relationship with other disease-related variables known to be related to clinical severity (age at seizure onset, age at resection, and extent of lesion). RESULTS: Analyses of covariance revealed that circumscribed lesions had a less deleterious effect on nonverbal IQ than did diffuse cortical dysplasia, after controlling for age at seizure onset and extent of lesion. This effect was also found on verbal IQ measures, but only in subjects with right-sided lesions. Subjects with left-sided lesions performed significantly more poorly on verbal IQ measures than those with right-sided lesions. Additionally, younger age at onset and greater extent of lesion were associated with poorer cognitive outcome. CONCLUSIONS: Cortical dysplasia and early left hemisphere lesions have a significantly worse impact on cognitive functioning than circumscribed lesions or right hemisphere developmental lesions in children with epilepsy.
BACKGROUND: Zonisamide is a sulfonamide antiepilepsy drug with sodium and calcium channel-blocking actions. Experience in Japan and a previous European double-blind study have demonstrated its efficacy against partial-onset seizures. METHODS: A randomized, double-blind, placebo-controlled trial enrolling 203 patients was conducted at 20 United States sites to assess zonisamide efficacy and dose response as adjunctive therapy for refractory partial-onset seizures. Zonisamide dosages were elevated by 100 mg/d each week. The study design allowed parallel comparisons with placebo for three dosages and a final crossover to 400 mg/d of zonisamide for all patients. The primary efficacy comparison was change in seizure frequency from a 4-week placebo baseline to weeks 8 through 12 on blinded therapy. RESULTS: At 400 mg/d, zonisamide reduced the median frequency of all seizures by 40.5% from baseline, compared with a 9% reduction (p = 0.0009) with placebo treatment, and produced a > or =50% seizure reduction (responder rate) in 42% of patients. A dosage of 100 mg/d produced a 20.5% reduction in median seizure frequency (p = 0.038 compared with placebo) and a dosage of 200 mg/d produced a 24.7% reduction in median seizure frequency (p = 0.004 compared with placebo). Dropouts from adverse events (10%) did not differ from placebo (8.2%, NS). The only adverse event differing significantly from placebo was weight loss, though somnolence, anorexia, and ataxia were slightly more common with zonisamide treatment. Serum zonisamide concentrations rose with increasing dose. CONCLUSION: Zonisamide is effective and well tolerated as an adjunctive agent for refractory partial-onset seizures. The minimal effective dosage was 100 mg/d, but 400 mg/d was the most effective dosage.
Hippocampal malformations in patients with epilepsy usually are reported in the context of widespread cortical malformations. Isolated hippocampal malformations are more rarely identified in MRI studies with little documentation of their pathologic appearance. Postmortem examination revealed abnormal position and complex convolutional malformations isolated to the hippocampal formation in an adult with temporal lobe epilepsy in whom MRI demonstrated bilateral hippocampal abnormalities.
BACKGROUND: A hypotonic-hyporesponsive episode (HHE) is the sudden onset of hypotonia, hyporesponsiveness, and pallor or cyanosis that occurs within 48 hours after childhood immunizations. This syndrome has been primarily associated with pertussis-containing vaccines administered to children <2 years of age, and has been estimated to occur once every 1750 diphtheria-tetanus-pertussis (DTwP) vaccinations. Previous studies of HHE were limited by small numbers of cases and, sometimes, by limited details of the event. OBJECTIVES: To characterize a large number of HHE cases reported to the Vaccine Adverse Event Reporting System (VAERS), to assist clinicians in identifying HHE, and to assist researchers in investigating the risk factors, cause, and pathogenesis of this syndrome. METHODS: More than 40,000 VAERS reports received between 1996 and 1998 were screened for HHE by a computer algorithm and reviewed, and a telephone follow-up questionnaire was administered to the witness of HHE. RESULTS: There were 215 HHE cases, all nonfatal. The median age of onset of HHE was 4.0 months (range: 1.1-107 months). Over half of the reports (53%) concerned females. The median birth weight was 3. 36 kg (range: 1.27-4.96 kg); 4.7% had a birth weight <2500 g. The median interval between vaccination and HHE was 210 minutes (range: 1 minute-2 days). Among children with HHE who were <24 months of age, the episode occurred within 5 minutes in only 8.5%, compared with 66.7% of children with HHE >24 months of age. There were no relevant findings regarding family medical history or the mothers' gestational history. Nearly all of the children (98.6%) returned to their prevaccination state according to the telephone questionnaire; median time to return was 6 hours (range: 1 minute- 4 months). The 3 children reported as not returning to their prevaccination state all had VAERS reports submitted after they developed conditions (autism, complex partial epilepsy, and developmental delays with infantile spasms) that are not known to be causally associated with immunization. The vast majority of children (93%) with HHE received a pertussis-containing vaccine, either diphtheria-tetanus-acellular pertussis (DTaP, 28%), DTwP (11%), or diphtheria-tetanus-pertussis-Haemophilus influenzae type b (DTwP-HIB, 61%). During the HHE episode, 90.1% of the children had pallor and 49% had cyanosis. Because of the HHE event, 6.8% of children had had all vaccines withheld as of the date of the interview. Of the remainder, 66.5% of children have had 1 or more subsequent vaccinations or vaccine components withheld, and 26.7% have not had any subsequent vaccinations withheld. Only 1 child was reported to have had a repeat episode of HHE, occurring after hepatitis B vaccination. From 1996 to 1998, the number of HHE reports decreased from 99 to 38, when the predominant pertussis vaccine administered to infants changed from whole-cell to acellular. CONCLUSION: This study represents the largest published case series of children with HHE and supports the generally benign, self-limited, nonrecurrent nature of this syndrome. Although HHE has been less frequently reported to VAERS after increased use of DTaP, HHE does occur after the administration of DTaP and other nonpertussis-containing vaccines. Although most parents and pediatricians withheld the pertussis component of subsequent vaccinations, many did not, with no reported adverse events occurring in the children after the subsequent immunizations. Restricting the definition of HHE to a more narrow age range (eg, <2 years of age) is also proposed because most of the older children probably experienced vasovagal syncope rather than HHE within 5 minutes of immunization.
Seizures associated with temporal lobe tumors may rarely manifest as episodic aggressive behavior. We describe 2 cases involving pediatric patients who presented with histories of unusually aggressive and antisocial behavior. Magnetic resonance imaging identified right mesial temporal lobe masses in both patients. After craniotomy for tumor removal, both patients were seizure-free and had marked reductions in their aggressive behavior. Tumors in the temporal lobe may be associated with behavioral problems, including aggression and rage attacks, which can be alleviated with surgical intervention. It is important to distinguish this subgroup of pediatric patients from those with alternative diagnoses such as attention-deficit/hyperactivity disorder or oppositional defiant disorder.
PURPOSE: To review the clinical and neurophysiological data of 21 patients with epilepsy due to temporal lobe tumors and who had undergone evaluation and surgery at the Hospital das Clínicas da Universidade de São Paulo. The aim of this study was to investigate whether the occurrence of a mirror focus was influenced either by certain clinical factors or if the surgical outcome was influenced by the presence of a mirror focus. METHOD: We included these 21 patients who had undergone at least one interictal electroencephalogram in the pre- and post-surgical periods. They had had a minimum follow-up of one year. RESULTS: Eight patients had mirror focus (Group 1) and 13 did not (Group 2). The mean age at seizure onset, duration of epilepsy disorder and total number of seizures did not vary statistically between the two groups of patients. Generalized tonic-clonic seizures occurred more frequently in the mirror focus group. All, but one patient, with a mirror focus were seizure free at follow- up. The mirror focus disappeared in all eight patients in the post-surgical electroencephalogram. In this group, the patient who was not seizure - free had a seizure recorded in his post-surgical electroencephalogram with seizure onset ipsilateral to the resected tumor. The patients who were not seizure-free had either been submitted to an incomplete resection of the tumor or showed evidence of associated cortical dysplasia. CONCLUSION: The occurrence of mirror focus is not a contraindication to surgery even when interictal epileptiform activity predominates contralaterally to the tumor and neither when seizures appear to arise from the mirror focus on scalp EEG. Good surgical outcome is expected despite EEG findings that may conflict with tumor location.
The traditional view of opioids held that the individual opioid agonists shared the same mechanism of action, differing only in their potency and pharmacokinetic properties. However, recent advances in opioid receptor pharmacology have made this view obsolete. Distinguishing features of the synthetic opioid agonists are related, at least in part, to variation in affinity and intrinsic efficacy at multiple opioid receptors. Respiratory depression is the opioid adverse effect most feared by anaesthesiologists. Specific kappa-receptor agonists produce analgesia with little or no respiratory depression. There are a number of commercially available kappa-receptor partial agonist drugs, the so-called agonist-antagonist or nalorphine-like opioids, which appear to have a limited effect on breathing. Within the series of fentanyl analogues there are differences in behaviour towards particular opioid receptors and there is evidence for subtle differences in respiratory depressant effects. Pethidine (meperidine) causes histamine release and myocardial depression, while the fentanyl analogues do not. Pethidine has atropine-like effects on heart rate, while fentanyl analogues reduce heart rate by a vagomimetic action. Severe bradycardia or even asystole is possible with fentanyl analogues, especially in conjunction with the vagal stimulating effects of laryngoscopy. Fentanyl analogues often produce minor reductions in blood pressure, and occasionally severe hypotension by centrally mediated reduction in systemic vascular resistance. Muscle rigidity and myoclonic movement occurs frequently during induction of anaesthesia with larger doses of opioids. Fentanyl and alfentanil have been reported to produce localised temporal lobe electrical seizure activity in patients with complex partial epilepsy. There are probably fewer biliary effects with agonist-antagonist opioids than the agonist opioids. The mechanism of adverse effects after spinal administration is distinctly different for morphine, which is very water soluble, compared with more lipid-soluble opioids. The systemic absorption of morphine after intrathecal or epidural administration is very slow, resulting in long duration of analgesia and low plasma concentrations, while lipid-soluble opioids are rapidly absorbed into the circulation and redistributed to the brain. The serotonin syndrome may result from coadministration of pethidine, dextromethorphan, pentazocine or tramadol with monoamine oxidase inhibitors (MAOIs) or selective serotonin (5-hydroxytryptamine; 5-HT) reuptake inhibitors (SSRIs). There are clinically important interactions between opioids and hypnosedatives, resulting in synergistic effects on sedation, breathing and blood pressure.
The delta(2)- 1,2,3- triazoline anticonvulsants (TRs) may be considered as representing a unique class of "built-in" heterocyclic prodrugs where the active "structure element" is an integral part of the ring system and can be identified only by a knowledge of their chemical reactivity and metabolism. Investigations on the metabolism and pharmacology of a lead triazoline, ADD17014 suggest that the triazolines function as "prodrugs" and exert their anticonvulsant activity by impairing excitatory amino acid (EAA) L-Glutamate (L-Glu) neurotransmission via a unique "dual-action" mechanism. While an active primary beta-amino alcohol metabolite from the parent prodrug acts as an N-methyl-D-aspartate (NMDA)/MK -801 receptor antagonist, the parent triazoline impairs the presynaptic release of L-Glu. Various pieces of theoretical reasoning and experimental evidence have led to the clucidation of the dual-action mechanism. Based on the unique chemistry of the triazolines, and their metabolic pathways, biotransformation products of TRs were predicted to be the beta-amino alcohols V and VA, the alpha-amino acid VI, the triazole VII, the aziridine VIII and the ketimine IX. In vivo and in vitro pharmacological studies of the TR and potential metabolites, along with a full quantitative urinary metabolic profiling of TR indicated the primary beta-amino alcohol V as the active species. It was the only compound that inhibited the specific binding of [3H]MK-801 to the MK-801 site, 56% at 10 micro M drug concentration, but itself had no anticonvulsant activity, suggesting TR acted as a prodrug. Three metabolites were identified; V was the most predominant (45.7 +/- 7.6) % of administered drug, with lesser amounts of VA, (17.3 +/- 5.1) % and very minor amounts of aziridine VIII (4.0 +/- 0.02)%. Since only VIII can yield VA, its formation indicated that the biotransformation of TR occurred, at least in part, through aziridine. No amino acid metabolite was detected, which implied that no in vivo oxidation of V or oxidative biotransformation of TR or aziridine by hydroxylation at the methylene group occurred. While triazoline significantly decreased Ca(2+) -dependent, k(+)-evoked L-Glu release (83% at 100 micro M drug concentration ), some triazolines showed an augmentation of 50-63%, in the Cl(-) channel activity, a useful membrane action that reduces the excessive L-Glu release that occurs during epileptic seizures. The high anticonvulsant activity of TRs in a variety of seizure models including their effectiveness in the kindling model of complex partial seizures may be due to their unique dual-action mechanism whereby the TR and V together effectively impair both pre- and postsynaptic aspects of EAA neurotransmission; thus the TRs have clinical potential in the treatment of complex partial epilepsy which is refractory to currently available drugs. Since there is strong evidence that L-Glu plays an important role in human epilepsy as well as in brain ischemia/stroke, and since the TRs act by inhibiting EAA neurotransmission, it was logical to expect that the anticonvulsant TRs may evince beneficial therapeutic potential in cerebral ischemia resulting from stroke as well. And indeed, several TRs, when tested in the standard gerbil model of global ischemia did evince remarkable ability to prevent neuronal death.
The intracranial spatiotemporal distributions of brainstem auditory evoked potentials were analyzed in two patients with epilepsy to study the dipole directions of waves III and V, previously found to have a horizontal and a vertical dipole, respectively. Depth electrodes were implanted bilaterally into the frontal and temporal lobes of these patients, the targets including the amygdala and hippocampus which are close to the upper pons and midbrain. Recordings around the upper pons and from the subcortical area downwards along the dorsal aspect of the upper pons indicated that waves III and V are constructed of mixed dipoles, wave III also having a vertical dipole segment and wave V also a horizontal one. These results suggest that several neural activities from the upper pons to midbrain contribute to the generation of waves III and V.
An 8-year-old girl presented with coexistence of ganglioglioma and cortical dysplasia manifesting as intractable epilepsy. Preoperative computed tomography demonstrated a small calcified lesion in the left frontal lobe which was not diagnosed as ganglioglioma. Magnetic resonance imaging also failed to demonstrate positive evidence of ganglioglioma or cortical dysplasia. A calcified tumor and the surrounding epileptogenic areas were resected under electrocorticography (ECoG) guidance. Histological examination revealed coexistence of ganglioglioma and cortical dysplasia. The patient became seizure-free after surgery. Resection of the ganglioglioma together with the adjacent epileptogenic area under intraoperative ECoG guidance is important to achieve a successful surgical result in patients with ganglioglioma.
Transient and very localized geophysical forces are hypothesized to be a major source of phenomena that have been traditionally labelled as haunts and poltergeists. They would be generated by increasing tectonic stresses and would display electromagnetic and gravitational characteristics. Materials would be influenced according to their physical properties. Dielectric materials would respond differently from conductors. Organic semiconductors, of which the human being is an important subcategory, would be affected as well. The conspicuous overlaps between (non-convulsive) complex partial epilepsy and many episodes of poltergeists and haunts are expected in light of the direct stimulation of the observer's brain by the transient, intense magnetic fields and the liability of temporal lobe structures. Implications and some general predictions for the distribution of these phenomena in time and space are discussed.
The relationships of background EEG to epileptiform discharge development were studied in 9 epileptic patients having generalized spike and wave complexes (SWCs) with a maximum at the frontal location on either side. The instantaneous power spectrum of EEGs at F3, F4, C3, C4, P3, P4, O1, O2, T3 and T4 was estimated with wavelet transform. Subsequently, the similarity of power spectra between SWCs and background EEG was determined by use of Kullback-Leibler information and artificial neural network in each patient. Both similarity measures revealed that EEG patterns similar to SWCs occurred in the background activity just before SWCs at frontal locations. These findings suggested that these SWC-like EEG events occurred as poorly developed epileptiform discharges buried in the background activity.
The authors reviewed 149 patients who underwent standard anterior temporal lobectomies for intractable complex partial epilepsy with a mean follow-up period of 5 years. Quantitative analyses of hippocampal neuron loss showed that all patients had some cell loss compared to control hippocampi obtained at autopsy. The average hippocampal cell loss was categorized as severe (greater than 30% of autopsy control levels) or mild. Analysis of hippocampal and extrahippocampal pathologies showed that in 109 cases (73%, the hippocampal lesion group) hippocampal cell loss was mild in 17 cases (16%) and severe in 92 cases (84%); in the remaining 40 cases (27%, the extrahippocampal structural lesion group) hippocampal cell loss was mild in 24 cases (60%) and severe in 16 (40%). The first index of surgical outcome was worthwhile seizure reduction, which occurred in 94 cases (86%) with mild or severe hippocampal lesions and in 33 cases (82%) with extrahippocampal pathology. In the hippocampal lesion group, worthwhile seizure reduction occurred in 90% of cases with severe and in only 65% of cases with mild hippocampal cell loss (p = 0.015). In the extrahippocampal pathology group, worthwhile seizure was not statistically different, whether hippocampal cell loss was severe (94% of cases) or mild (75% of cases). The second index of surgical outcome was the occurrence of residual seizures in the patients with worthwhile seizure reduction, which would indicate remaining epileptogenic tissue. In the hippocampal lesion group, the incidence of residual seizures was not statistically different whether hippocampal cell loss was severe (24% of cases) or mild (45% of cases). However, in the extrahippocampal pathology group, residual seizures occurred in 53% of cases with severe cell loss (dual pathology) but in only 11% of cases with mild cell loss (p = 0.025). Worthwhile seizure reduction can be predicted by the presence of either severe hippocampal cell loss or an extrahippocampal structural lesion. However, residual seizures more frequently follow in cases with a combination of both (extrahippocampal pathology associated with severe hippocampal cell loss, or dual pathology), suggesting that epileptogenic tissue more likely extends outside the boundaries of a standard temporal lobectomy.
The indications for the risks and outcome of reoperation for medically refractory temporal lobe epilepsy have not been well documented. A retrospective review is presented of 40 patients who underwent reoperation on the temporal lobe for recurrent seizures. The mean patient age at the first operation was 22 +/- 7 years (+/- standard deviation). Electrocorticography during the first operation showed interictal epileptic abnormalities from surface electrodes in 97% of the cases and from depth electrodes in the mesiotemporal structures in 38%. The seizures recurred with the same pattern within 6 months after the first operation in 60% of patients and within 2 years in 90%. Postoperative neuroimaging studies showed residual mesiotemporal structures in all cases. The mean time between the two operations was 5.5 +/- 5 years and the mean patient age at the second operation was 28 +/- 8 years. The second operation involved focal resection of the mesiotemporal structures in 30 cases. The mean postoperative follow-up period was 4.8 +/- 2.7 years (range 2 to 11 years). After the second operation, 63% of the patients were seizure-free or had rare seizures (one or two per year). There were no permanent neurological complications. Patients who did not benefit from reoperation had electroencephalographic abnormalities in multiple brain areas. Reoperation for temporal lobe epilepsy effectively controls seizures in the majority of patients, and the procedure is safe if rigorous technical rules are observed. More complete resection of mesiotemporal structures during the first operation, even in the absence of intraoperative electrographic abnormalities, could prevent the need for reoperation in defined cases.
OBJECT: Unilateral resection of the hippocampus and amygdala can be used to treat medically intractable mesial temporal lobe seizures. To date seizure outcome and the extent of cognitive morbidity have been unknown in children following the transparahippocampal variation of selective amygdalohippocampectomy (TSA), which prompted the present prospective study. METHODS: Preoperative examinations and outcomes in 22 consecutive children and adolescents who underwent TSA were studied. Cognitive and psychological morbidity were assessed using standard neuropsychological instruments. The authors evaluated relationships between seizure control and cognitive morbidity and 13 and nine clinical variables, respectively. Seizure control was achieved in 11 (65%) of 17 patients (>2 years follow up). Among 13 clinical variables, the only preoperative finding that had a significant bearing on seizure control was the presence of unilateral hypometabolism, which could be observed on [18F]fluorodeoxyglucose-positron emission tomography scans (p<0.001). Patients with seizure control showed significant improvements in verbal and full scale intelligence quotients (both p = 0.05). Patients with longer preoperative durations of seizures exhibited more cognitive impairment that persisted postoperatively. Cognitive outcome analysis based on nine clinical factors revealed no significant difference in cognitive parameters postoperatively, except that significant improvement occurred in rote verbal memory scores among patients who underwent right-sided TSA (p = 0.01). Individually, 81% of the children achieved significant improvement in at least one of seven cognitive parameters, and 52% had stable or improved scores in all parameters. CONCLUSIONS: The results indicate that TSA is a safe effective approach for the treatment of medically intractable mesial temporal lobe seizures in children with minimum effect on cognitive morbidity. Given that the literature suggests that children suffer progressive cognitive morbidity from persistent seizures, the results of this study support early surgical intervention for this group of children.
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