Quantitative Evaluation of Medial Temporal Lobe Morphology in Children with Febrile Status Epilepticus: Results of the FEBSTAT Study.

BACKGROUND AND PURPOSE: The pathogenesis of febrile status epilepticus is poorly understood, but prior studies have suggested an association with temporal lobe abnormalities, including hippocampal malrotation. We used a quantitative morphometric method to assess the association between temporal lobe morphology and febrile status epilepticus. MATERIALS AND METHODS: Brain MR imaging was performed in children presenting with febrile status epilepticus and control subjects as part of the Consequences of Prolonged Febrile Seizures in Childhood study. Medial temporal lobe morphologic parameters were measured manually, including the distance of the hippocampus from the midline, hippocampal height:width ratio, hippocampal angle, collateral sulcus angle, and width of the temporal horn. RESULTS: Temporal lobe morphologic parameters were correlated with the presence of visual hippocampal malrotation; the strongest association was with left temporal horn width (P < .001; adjusted OR, 10.59). Multiple morphologic parameters correlated with febrile status epilepticus, encompassing both the right and left sides. This association was statistically strongest in the right temporal lobe, whereas hippocampal malrotation was almost exclusively left-sided in this cohort. The association between temporal lobe measurements and febrile status epilepticus persisted when the analysis was restricted to cases with visually normal imaging findings without hippocampal malrotation or other visually apparent abnormalities. CONCLUSIONS: Several component morphologic features of hippocampal malrotation are independently associated with febrile status epilepticus, even when complete hippocampal malrotation is absent. Unexpectedly, this association predominantly involves the right temporal lobe. These findings suggest that a spectrum of bilateral temporal lobe anomalies are associated with febrile status epilepticus in children. Hippocampal malrotation may represent a visually apparent subset of this spectrum.

Phenomenology of prolonged febrile seizures: results of the FEBSTAT study.

BACKGROUND: Febrile status epilepticus (FSE) has been associated with hippocampal injury and subsequent mesial temporal sclerosis and temporal lobe epilepsy. However, little is known about the semiology of FSE. METHODS: A prospective, multicenter study of the consequences of FSE included children, aged 1 month through 5 years, presenting with a febrile seizure lasting 30 minutes or more. Procedures included neurologic history and examination and an MRI and EEG within 72 hours. All information related to seizure semiology was reviewed by three epileptologists blinded to MRI and EEG results and to subsequent outcome. Inter-rater reliability was assessed by the kappa statistic. RESULTS: Among 119 children, the median age was 1.3 years, the mean peak temperature was 103.2 degrees F, and seizures lasted a median of 68.0 minutes. Seizure duration followed a Weibull distribution with a shape parameter of 1.68. Seizures were continuous in 52% and behaviorally intermittent (without recovery in between) in 48%; most were partial (67%) and almost all (99%) were convulsive. In one third of cases, FSE was unrecognized in the emergency department. Of the 119 children, 86% had normal development, 24% had prior febrile seizures, and family history of febrile seizures in a first-degree relative was present in 25%. CONCLUSIONS: Febrile status epilepticus is usually focal and often not well recognized. It occurs in very young children and is usually the first febrile seizure. Seizures are typically very prolonged and the distribution of seizure durations suggests that the longer a seizure continues, the less likely it is to spontaneously stop.

Effects of gamma hydroxybutyric acid on inhibition and excitation in rat neocortex.

The mechanism by which the sedative and amnestic recreational drug gamma hydroxybutyric acid (GHB) acts is controversial. Some studies indicate that it acts at its unique receptor, while others demonstrate effects mediated through the GABAB receptor. We examined the effect of GHB on evoked GABAA receptor-mediated mono- and polysynaptic inhibitory postsynaptic currents (IPSCs) as well as on N-methyl-d-aspartate (NMDA) and AMPA-mediated excitatory postsynaptic currents (EPSCs) in layers II/III pyramidal cells of the frontal cortex of rat brain. One millimolar (mM) GHB suppressed monosynaptic IPSCs by 20%, whereas polysynaptic IPSCs were reduced by 56%. GHB (1 mM) also produced a significant suppression of NMDA-mediated EPSCs by 53% compared with 27% suppression of AMPA-mediated EPSCs. All effects of GHB on IPSCs and EPSCs were reversed by the specific GABAB antagonist CGP 62349, but not by the GHB receptor antagonist (2E)-5-hydroxy-5,7,8,9-tetrahydro-6H-benzo[a][7]annulen-6-ylidene ethanoic acid. Consistent with a presynaptic site of action, GHB reduced the frequency but not the amplitude of AMPA receptor-mediated mEPSCs and had no effect on postsynaptic currents evoked by direct application of NMDA. Finally, even though GHB appeared to be acting at presynaptic GABAB receptors, GHB and the GABAB agonist baclofen appeared to have opposite potencies for depression of NMDA- vs. AMPA-mediated EPSCs. GHB showed a preference for depressing NMDA responses while baclofen more potently suppressed AMPA responses. The suppression of NMDA more than AMPA responses by GHB at intoxicating doses may make it attractive as a recreational drug and may explain why GHB is abused and baclofen is not.

Lithium-gadolinium-borate as a neutron dosemeter.

Lithium-gadolinium-borate (LGB) dispersed as microcrystals within the plastic scintillator BC-490 is a promising material for accurate neutron dosimetry in mixed n/gamma fields. Spectral information > 1 MeV is obtained by capture gating proton recoil events in the plastic scintillator to subsequent capture in (6)Li. Below 1 MeV, isolated capture events in either gadolinium or (6)Li give energy information in this region. Discrimination based on capture gating is used to reject false coincidences due to gamma rays or incorrectly gated neutron events. A detailed Monte Carlo model has been created in MCNPX that predicts the energy response of the LGB spectrometer in the capture-gated mode of operation. X-ray microtomography has been performed on the detector in order to obtain the LGB microcrystal distribution within the plastic scintillator, and this is incorporated into the model. The way in which the calculated response functions can be included in an unfolding procedure is outlined.

Human herpesvirus 6 limbic encephalitis after stem cell transplantation.

Central nervous system complications are common in stem cell transplant recipients, but selective involvement of the medial temporal area is unusual. The 5 patients reported here presented after stem cell transplantation with increased hippocampal T2 signal on magnetic resonance imaging and increased hippocampal glucose uptake on [F-18]fluorodeoxyglucose-positron emission tomography (FDG-PET) associated with short-term memory loss, insomnia, and temporal lobe electrographic seizure activity. The initial scalp electroencephalograms (EEGs) failed to detect seizure activity in these patients, although the memory dysfunction along with the magnetic resonance imaging and FDG-PET findings suggested subcortical seizure activity. However, extended EEG monitoring revealed repetitive temporal lobe electrographic seizure activity. Follow-up MRIs in 2 patients and postmortem findings on 1 patient suggested that hippocampal sclerosis had developed following the clinical syndrome. Cerebrospinal fluid studies revealed the presence of human herpesvirus 6, variant B, DNA in all of 3 patients who had lumbar punctures. Immunohistochemical staining for the P41 and P101 human herpesvirus 6 protein antigens showed numerous immunoreactive astrocytes and neurons in the hippocampus of 1 of the patients who died from other causes. Because of its subtle clinical presentation, this syndrome may be underrecognized, but can be diagnosed with appropriate magnetic resonance imaging techniques, EEG monitoring, and cerebrospinal fluid viral studies.

Seizure outcome after temporal lobectomy for temporal lobe epilepsy: a Kaplan-Meier survival analysis.

OBJECTIVE: To determine seizure outcome and its predictors in patients with medically refractory temporal lobe epilepsy (TLE) after temporal lobectomy (TL). BACKGROUND: TL is the most common surgical procedure performed in adolescents and adults for the treatment of medically refractory TLE. Seizure outcome has been reported extensively during the first few postoperative years, but little is known beyond that time. METHODS: The authors analyzed seizure outcome in 79 patients who underwent TL for epilepsy at the Duke University Medical Center from 1962 through 1984. Patients with less than 2 years of follow-up and degenerative disorders were excluded. Predictors of seizure outcome were analyzed using Kaplan-Meier survival analyses. RESULTS: The mean follow-up was 14 years (range, 2.1 to 33.6 years). Using Engel's classification, 65% of patients were class I, 15% were class II, 11% were class III, and 9% were class IV. At least one postoperative seizure occurred in 55% of subjects. The majority of recurrences (86%) took place within 2 years of surgery. Later recurrences tended not to lead to medical intractability. Higher monthly preoperative seizure frequency was associated with poor seizure outcome. A seizure-free state at 2 years was found to be a better predictor of long-term outcome than the 6-, 12-, and 18-month landmarks. CONCLUSIONS: TL provides sustained, long-term benefit in patients with medically refractory TLE. Seizure-free status at 2 years from the time of surgery is predictive of long-term remission.

GABAB-Receptor-mediated currents in interneurons of the dentate-hilus border.

GABA(B)-receptor-mediated inhibition was investigated in anatomically identified inhibitory interneurons located at the border between the dentate gyrus granule cell layer and hilus. Biocytin staining was used to visualize the morphology of recorded cells. A molecular layer stimulus evoked a pharmacologically isolated slow inhibitory postsynaptic current (IPSC), recorded with whole cell patch-clamp techniques, in 55 of 63 interneurons. Application of the GABA(B) receptor antagonists, CGP 35348 (400 microM) or CGP 55845 (1 microM) to a subset of 25 interneurons suppressed the slow IPSC by an amount ranging from 10 to 100%. In 56% of these cells, the slow IPSC was entirely GABA(B)-receptor-mediated. However, in the remaining interneurons, a component of the slow IPSC was resistant to GABA(B) antagonists. Subtraction of this antagonist resistant current from the slow IPSC isolated the GABA(B) component (IPSC(B)). This IPSC(B) had a similar onset and peak latency to that recorded from granule cells but a significantly shorter duration. The GABA(B) agonist, baclofen (10 microM), produced a CGP 55845-sensitive outward current in 19 of 27 interneurons. In the eight cells that lacked a baclofen current, strong or repetitive ML stimulation also failed to evoke an IPSC(B), indicating that these cells lacked functional GABA(B) receptor-activated potassium currents. In cells that expressed a baclofen current, the amplitude of this current was approximately 50% smaller in interneurons with axons that projected into the granule cell dendritic layer (22.2 +/- 5.3 pA; mean +/- SE) than in interneurons with axons that projected into or near the granule cell body layer (46.1 +/- 10.0 pA). Similarly, the IPSC(B) amplitude was smaller in interneurons projecting to dendritic (9.4 +/- 2.7 pA) than perisomatic regions (34.3 +/- 5.1 pA). These findings suggest that GABA(B) inhibition more strongly regulates interneurons with axons that project into perisomatic than dendritic regions. To determine the functional role of GABA(B) inhibition, we examined the effect of IPSP(B) on action potential firing and synaptic excitation of these interneurons. IPSP(B) and IPSP(A) both suppressed depolarization-induced neuronal firing. However, unlike IPSP(A), suppression of firing by IPSP(B) could be easily overcome with strong depolarization. IPSP(B) markedly suppressed N-methyl-D-aspartate but not AMPA EPSPs, suggesting that GABA(B) inhibition may play a role in regulating slow synaptic excitation of these interneurons. Heterogeneous expression of GABA(B) currents in hilar border interneurons therefore may provide a mechanism for the differential regulation of excitation of these cells and thereby exert an important role in shaping neuronal activity in the dentate gyrus.

Febrile convulsions and mesial temporal sclerosis.

Patients with intractable temporal lobe epilepsy and mesial temporal sclerosis often have histories of severe febrile convulsions as infants. Diagnostic advances made possible by magnetic resonance imaging have shown that very prolonged febrile convulsions may produce hippocampal injury and that focal cortical dysgenesis may play a role in the etiology of febrile convulsions, mesial temporal sclerosis, and temporal lobe epilepsy.

Magnetic resonance imaging evidence of hippocampal injury after prolonged focal febrile convulsions.

Magnetic resonance imaging (MRI) was performed after complex febrile convulsions (CFCs) in 27 infants. Definite MRI abnormalities were seen in 6 of the 15 infants with focal or lateralized CFCs and in none of the 12 infants with generalized CFCs. In 2 of the 6 infants with lateralized CFCs and abnormal MRIs, the MR images showed preexisting bilateral hippocampal atrophy consistent with the history of perinatal insults in these infants. However, the remaining 4 infants with MRI abnormalities and lateralized CFCs had significantly longer seizures than other infants and had MRI changes suggesting acute edema with increased hippocampal T2-weighted signal intensity and increased volume predominantly in the hippocampus in the hemisphere of seizure origin. Of those with acute edema, 1 had electrographical seizure activity recorded in the temporal region and another had a choroid fissure cyst displacing the affected hippocampus; both infants had follow-up MRIs showing that hippocampal atrophy had developed. These patients demonstrate that prolonged and focal CFCs can occasionally produce acute hippocampal injury that evolves to hippocampal atrophy. Finally, evidence of preexisting hippocampal abnormalities in several infants and electrographical temporal lobe seizure activity in 1 suggests the possibility that CFCs actually originated in the temporal lobes in some patients.

Involvement of cAMP-dependent protein kinase in mu-opioid modulation of NMDA-mediated synaptic currents.

We have previously reported dual effects of mu-opioids on N-methyl-D-aspartate (NMDA)-receptor-mediated synaptic events in the hippocampal dentate gyrus: an indirect facilitating effect via suppression of GABAergic interneurons (disinhibition) and a direct inhibitory effect in the presence of gamma-aminobutyric acid-A (GABA(A)) antagonists. The cellular mechanism underlying the inhibitory effect of mu-opioids remains to be determined. In the present study we examine the role of adenosine 3',5'-cyclic monophosphate (cAMP)-dependent protein kinase (PKA) in mu-opioid-induced inhibition of NMDA currents in rat hippocampal slices. NMDA-receptor-mediated excitatory postsynaptic currents (NMDA EPSCs) were evoked by stimulating the lateral perforant path and were recorded from dentate granule cells with the use of whole cell voltage-clamp techniques in the presence of the GABA(A) antagonist and a non-NMDA type of glutamate receptor antagonist. Two selective mu-agonists, [N-MePhe3, D-Pro4]-morphiceptin and [D-Ala2, N-MePhe4, Gly-ol5]-enkephalin, induced dose-dependent inhibition of NMDA EPSCs in a concentration range of 0.3-10 microM. This inhibitory effect could be completely reversed by the opioid antagonists naloxone or prevented by a selective mu-antagonist cyprodime, but was not affected by removal of Mg2+ from the external perfusion medium. Intracellular application of pertussis toxin (PTX) into the granule cell via whole cell recording pipettes completely prevented mu-opioid-induced reduction in NMDA currents, suggesting that a postsynaptic mechanism involving PTX-sensitive G proteins might be responsible for the inhibitory action of mu-opioids. Further studies were conducted to identify the intracellular messengers that coupled with G proteins and transduced the effect of mu-opioids in granule cells. The adenylate cyclase activator forskolin was found to enhance NMDA-receptor-mediated synaptic responses and to reverse the inhibitory effect of mu-opioids. Sp-cAMPS, a specific PKA activator, also enhanced NMDA EPSCs, whereas the PKA inhibitor Rp-cAMPS reduced NMDA EPSCs and occluded further inhibition of the current by mu-opioids. These findings strongly suggest that NMDA receptor function is subject to the modulation by PKA, and that mu-opioids can inhibit NMDA currents through suppression of the cAMP cascade in the postsynaptic neuron. Combined with our previous findings, the present results also indicate that mu-opioids can modulate NMDA-receptor-mediated synaptic activity in a complex manner. The net effect of mu-opioids in the dentate gyrus may depend on the interplay between its disinhibitory action, which facilitates NMDA-receptor-mediated responses, and its inhibitory action on the cAMP cascade.

Interneurons of the dentate-hilus border of the rat dentate gyrus: morphological and electrophysiological heterogeneity.

Interneurons located near the border of the dentate granule cell layer and the hilus were studied in hippocampal slices using whole-cell current clamp and biocytin staining. Because these interneurons exhibit both morphological and electrophysiological diversity, we asked whether passive electrotonic parameters or repetitive firing behavior correlated with axonal distribution. Each interneuron was distinguished by a preferred axonal distribution in the molecular layer or granule cell layer, and four groups could be discerned, the axons of which arborized in (1) the granule cell layer, (2) the inner molecular layer, (3) the outer molecular layer, and (4) diffusely in the molecular layer. In our sample, interneurons with axons arborizing diffusely in the molecular layer were most frequent, and those with axons restricted to the granule cell layer were least frequent. Resting potential, input resistance, time constant, electrotonic length, and spike frequency adaptation (SFA) were not significantly different among the four groups, and the variability in SFA between cells with similar axonal distributions was striking. Clear differences in action potential morphology and afterhyperpolarizations, however, emerged when nonadapting interneurons were compared with those exhibiting SFA. Interneurons exhibiting SFA had characteristically broader spikes, progressive slowing of action potential repolarization during repetitive firing, and slow afterhyperpolarizations that distinguished them from nonadapting interneurons. We propose that the variability in repetitive firing behavior and morphology exhibited by each of these interneurons makes each interneuron unique and may provide a high level of fine tuning of inhibitory control critical to information processing in the dentate.

Clinical and electroencephalographic correlates in Rasmussen's encephalitis.

PURPOSE: Rasmussen's encephalitis (RE) is a progressive childhood disease characterized by unilateral brain dysfunction, seizures, and inflammatory histopathology. Converging lines of evidence suggest that an autoimmune process is important in the pathogenesis of RE. METHODS: Two patients with pathologically confirmed RE and increased levels of circulating glutamate receptor subunit (GluR3) antibodies were studied prospectively before, during, and after trials of plasmapheresis (PEX) and other immunomodulation. Frequency, duration, and intensity of clinical seizures were directly correlated with the abundance of interictal epileptiform activity on serial EEGs. RESULTS: Serial EEGs in these patients suggest that early in the course of RE interictal epileptiform activity is localized to the affected hemisphere and that disease progression is associated with increasingly frequent bilaterally synchronous and contralateral epileptiform activity. CONCLUSIONS: The clinical and EEG parameters of epileptogenesis were transiently diminished by PEX, which suggests that circulating factors induce dose-dependent, reversible epileptogenic effects in some patients with RE.

Hippocampal long-term potentiation and spatial learning in the rat: effects of GABAB receptor blockade.

This series of experiments assessed the role of GABAB receptors in the induction of long-term potentiation in the dentate gyrus in vivo, and spatial learning and memory in three different tasks. In urethane-anesthetized rats, the GABAB receptor antagonist CGP 46381 was injected intraperitoneally at a dose which effectively suppressed GABAB-mediated paired pulse disinhibition. Theta-burst stimulation reliably produced long-term potentiation in control rats. However, GABAB receptor blockade significantly suppressed the induction of long-term potentiation in the dentate gyrus. To compare the results of the long-term potentiation experiments with behavior, we assessed the performance of rats on several spatial learning and memory tasks in the presence of CGP 46381. We found that the working memory performance of highly trained rats on the eight-arm radial maze was unaffected by CGP 46381. There was also no effect of GABAB receptor blockade on learning in the eight-arm maze using a five-trial repeated acquisition paradigm. However, when we tested spatial learning in naive rats using a mildly stressful water maze task, we found that CGP 46381 substantially impaired both the latency to find the platform and the path-length travelled in the maze during acquisition. CGP 46381-treated rats took longer to learn the location of the escape platform and travelled a greater distance over the acquisition trials. These data demonstrate that GABAB receptor blockade results in a suppression of hippocampal long-term potentiation in vivo and impairs spatial learning in a task where stress may be a component of performance.

Fast spin-echo, magnetic resonance imaging-measured hippocampal volume: correlation with neuronal density in anterior temporal lobectomy patients.

To assess the value of magnetic resonance imaging (MRI)-measured hippocampal volume in the detection of hippocampal sclerosis, we studied 28 patients undergoing anterior temporal lobectomy for medically intractable mesial temporal lobe epilepsy. Hippocampal volumetry and visual analysis of T2 signal change were performed using fast spin-echo T2-weighed MRI. Quantitative neuronal density measurements were performed in the resected hippocampal specimens. There was a significant correlation between MRI-measured absolute hippocampal volume (AHV) and neuronal density in CA1, CA2, and CA3 subfields (p < 0.0001, p < 0.01, and p < 0.05, respectively). Differential hippocampal volume (side-to-side volume difference) failed to detect bilateral atrophy in three patients, but the bilateral hippocampal atrophy was recognized by considering AHV in these patients. This study suggests that MRI-measured AHV can be of value in elevating patients with mesial temporal lobe epilepsy, especially when there is no side-to-side difference in hippocampal volumetry.

Depression of LTP in rat dentate gyrus by naloxone is reversed by GABAA blockade.

Long-term potentiation (LTP) of the lateral perforant path (LPP) to dentate granule cell (DGC) synapse is suppressed by the opioid antagonist, naloxone, and thus appears to be dependent upon the release of endogenous opioids from the LPP. It has been suggested that endogenous opioids enhance LTP by depressing GABAA inhibition. As one test of this hypothesis, we determined whether blockade of GABAA inhibition would alleviate the naloxone block of LTP in the LPP. Consistent with the hypothesis that endogenous opioids enable LTP by disinhibition of the DGCs, naloxone no longer blocked LTP in the presence of the GABAA antagonist, bicuculline methiodide. Furthermore, although blockade of mu receptors suppressed LTP of the slope of the population excitatory potential (pEPSP), blockade of both mu and delta opioid receptors was needed to suppress LTP of both the pEPSP and the orthodromic population spike (OPS).

Endogenous opioids regulate long-term potentiation of synaptic inhibition in the dentate gyrus of rat hippocampus.

Long-term potentiation (LTP) of excitatory transmission in the hippocampus has been extensively studied as a synaptic model of learning and memory. Here we report a new form of LTP in which inhibitory synaptic signals are potentiated following tetanic stimulation of an opioid-containing excitatory pathway in the presence of opioid antagonists. The lateral perforant path (LPP) was stimulated at the dentate outer molecular layer of hippocampal slices. Evoked synaptic currents were recorded from dentate granule cells using whole-cell voltage-clamp techniques. A high-frequency stimulus train (100 Hz, 1 sec) delivered to the LPP in the presence of naloxone (1 microM) was found to induce a long-lasting potentiation (20 min to 2 hr) in the amplitude of gamma-aminobutyric acidA (GABAA) receptor-mediated inhibitory postsynaptic currents (IPSCs) of granule cells. Such a potentiation was not observed when tetanizing the LPP in control medium. Naloxone-revealed LTP of LPP-evoked IPSCs did not depend upon the presence of granule cell discharge, and was not accompanied by potentiation of mossy fiber-evoked IPSCs, indicating that feedforward, but not feedback, inhibitory circuits were involved. Induction of this LTP could be completely blocked by the N-methyl-D-aspartate (NMDA) receptor antagonist D-2-amino-5-phosphonopentanoic acid (D-APV). However, it was not significantly affected by hyperpolarization of granule cells. These results suggest that LTP may occur at the excitatory synapses between LPP terminals and GABAergic interneurons, rather than at the inhibitory synapses between interneurons and granule cells. Further examination using selective opioid antagonists demonstrated that blocking delta, but not mu and kappa, receptors is critical for inducing LTP of IPSCs in granule cells.

GABAB receptors modulate synaptically-evoked responses in the rat dentate gyrus, in vivo.

We assessed the effects of systemically injected baclofen, a GABAB agonist, on single and paired-pulse responses in the dentate gyrus of urethane-anesthetized rats, in vivo. Baclofen (10 mg/kg) significantly increased the duration of single excitatory responses. This increase was blocked by the GABAB receptor antagonist, CGP 35348, indicating that baclofen was acting through GABAB receptors. To determine the mechanism underlying this increase in response duration, the NMDA antagonist, D-2-amino-5-phosphonopentanoic acid (D-APV), was administered intracerebroventricularly (i.c.v.) after baclofen. D-APV by itself had no effect on the duration of the population excitatory post-synaptic potential (EPSP). However, when infused after baclofen, D-APV blocked the baclofen induced increase in EPSP duration. This indicates the prolonged EPSP duration caused by baclofen resulted from an enhancement of an NMDA receptor mediated component of the response. We then examined the effect of baclofen on population responses to paired stimuli. Baclofen attenuated paired-pulse inhibition of population spike amplitudes at a 25 ms interstimulus interval. CGP-35348 reduced the effect of baclofen on paired-pulse inhibition, indicating that baclofen suppressed paired-pulse inhibition by acting on GABAB receptors. In contrast to its disinhibitory effect at the 25 ms interval, baclofen had an inhibitory effect on responses evoked at a 150 ms interstimulus interval. Under control conditions, we observed that when stimuli were delivered 150 ms apart, both the EPSP duration and population spike amplitude evoked by the second stimulus were enhanced. Baclofen suppressed this enhancement.(ABSTRACT TRUNCATED AT 250 WORDS)

Magnetic resonance imaging evidence of hippocampal sclerosis in progression: a case report.

A 32-month-old child presented in status epilepticus (SE) involving the left side of the body. Fast spin-echo magnetic resonance imaging (FSE-MRI) with hippocampal volumetry performed < or = 24 h after the seizure showed increased T2 signal of the right hippocampus, but no atrophy. Complex partial seizures (CPS) appeared at age 33 months, and three more episodes of SE occurred between 33 and 37 months of age. Follow-up FSE-MRI at 34 and at 45 months of age demonstrated progressive hippocampal atrophy with resolution of the increased T2 signal. Her CPS became intractable and, at age 51 months, she underwent right temporal lobectomy. In the ensuing 5 months, she has had only one major motor seizure. This case demonstrates that acute increased hippocampal T2 signal intensity can occur soon after SE and hippocampal sclerosis (HS) may become evident within months in the setting of recurrent early childhood SE. This observation may support the hypothesis that early childhood SE can lead to HS. Furthermore, this case suggests that years of temporal lobe CPS may not be necessary for development of HS.

Neuronal migration disorders: positron emission tomography correlations.

We analyzed the interictal [18F]fluoro-2-deoxy-D-glucose positron emission tomography (PET) findings of 17 epileptic patients with neuronal migration disorders (NMDs). Fifteen patients had abnormal PET findings, i.e., focal hypometabolism in 9 patients and displaced metabolic activity of normal gray matter in 6. All 15 patients had magnetic resonance imaging (MRI) abnormalities; however, PET abnormality assisted in the identification of NMDs on MRI in 3 patients. Two patients with negative MRI also had negative PET studies. PET hypometabolism appeared to correlate with severity of neuronal dysgenesis or temporal lobe involvement, or both. Displaced metabolic activity of gray matter is regarded as a unique interictal [18F]fluoro-2-deoxy-D-glucose-PET finding in NMD. This study demonstrates variable metabolic patterns in NMD and that PET may be a useful complement to MRI in the evaluation of NMD.