A controversial question: Can morphometry and clinical history be enough to diagnose hippocampal dysplasia?

The presence of dysmorphic neurons with strong cytoplasmatic accumulation of heavy non-phosphorylated neurofilament is crucial for the diagnostics of focal cortical dysplasia type II (FCDII). While ILAE's classification describes neocortical dysplasias, some groups have reported patients with mesial t abnormal neurons in the hippocampus of mesial temporal lobe epilepsy. Here we report a patient with such abnormal neurons in the hippocampus and compared it with previous reports of hippocampal dysplasia. Finally, we discuss the need for diagnostic criteria of hippocampal dysplasia.

Granule cell dispersion is associated with hippocampal neuronal cell loss, initial precipitating injury, and other clinical features in mesial temporal lobe epilepsy and hippocampal sclerosis.

PURPOSE: To characterize a 10-year series of patients with mesial temporal lobe epilepsy (MTLE) and unilateral hippocampal sclerosis (HS) and determine the histopathological characteristic of the association between granule cell dispersion (GCD) and hippocampal neuronal loss. METHODS: The study included 108 MTLE/HS patients. Histopathological analyses were performed in NeuN-stained hippocampal sections for HS pattern, neuronal density, dentate gyrus (DG) pathology, and granule cell layer width. Statistical tests investigated the association between DG pathologies and HS patterns, as well as the correlation of DG width with total hippocampal and subfield-specific neuronal densities. RESULTS: Fifty-six patients (51.9%) presented right HS. All the four ILAE HS patterns were represented (90 Type 1, 11 Type 2, 2 Type 3, and 5 no-HS). Sixty-seven patients (62.0%) presented GCD, 39 (36.1%) normal DG, and 2 (1.9%) narrow DG. GCD was associated with initial precipitating injury, higher numbers of monthly focal seizures and lifetime bilateral tonic-clonic seizures, longer epilepsy duration, and older age at surgery. GCD was prevalent in all HS patterns, except for Type 2 (81.8% normal versus 18.2% GCD, p = 0.005). GCD was associated with total hippocampal and subfield-specific neuronal loss, except for CA1. DG width correlated with total hippocampal (r = -0.201, p = 0.037) and CA4 neuronal densities (r = -0.299, p = 0.002). Patients with HS Type 1 had better surgical outcomes, with 51 (61.4%) seizure-free in the first year post-surgery. CONCLUSIONS: This study confirmed that seizure control in MTLE/HS patients submitted to surgical treatment is comparable worldwide. Moreover, histopathological analyses showed an association between GCD and hippocampal neuronal loss, especially in the CA4 subfield.

Neurocysticercosis and pharmacoresistant epilepsy: possible role of calcified lesions in epileptogenesis.

Neurocysticercosis is a neglected and usually poverty-related disease of high public importance. The mechanisms by which the calcified lesions cause epilepsy are not known, but have been attributed to residual perilesional gliosis or an inflammatory process. This case shows that an inflammatory response to a calcified granuloma may be associated with the development of epilepsy. The increase in glutamate and kinin B1 (pro-epileptogenic) receptors added by reduced expression of kinin B2 (anti-epileptogenic) receptors may explain the chronic epileptogenesis associated with the lesion, corroborating the hypothesis of inflammatory mechanisms involved in the pathophysiology of epilepsy in these patients.

Prognosis of Juvenile myoclonic epilepsy with eye-closure sensitivity.

PURPOSE: Eye closure sensitivity (ECS) has been described as a reflex trait in juvenile myoclonic epilepsy (JME). However, there is no consensus regarding its significance on prognosis. The aim of this study is to clarify the long-term impact of ECS documented by a clinical interview and a video-EEG neuropsychological protocol (VNPP) in a series of 133 JME patients. METHODS: Data from 22 JME patients with ECS confirmed by a VNPP (Group 1) were compared with those of 20 JME patients without any reflex traits (Group 2). They were followed for a mean of 8.21 years (SD=±5.044). The frequency of seizures was assessed using a diary. Except for photosensitivity (PS), any other reflex traits occurrence, drugs/alcohol abuse intake, noncompliance, and Jeavons syndrome, were considered exclusion criteria. RESULTS: Group 1 had a lower age at epilepsy onset (p = 0.028), higher incidence of febrile seizures (13.6%), and familial history of epilepsy (p = 0.023). Only 18.2% had self-perception of eyelid myoclonia (EM) (kappa coefficient = 0.193), which persisted in 77.3% of patients. Limb myoclonia, tonic-clonic seizures (TCS) and/or myoclonic-tonic-clonic seizures (MTCS), as well as absences were more frequent (p = 0.015; p = 0.013; p = 0.011, respectively) in Group 1. PS did not influenced frequency of EM (p = 1.0), absences (p = 0.648), or TCS/MTCS (p = 0.934). Psychiatric comorbidities were not different between groups. CONCLUSIONS: ECS is related to a worse outcome regarding control of all seizure types, persistence of EM, and higher frequency of limb myoclonia, as well as the total number of TCS and/or MTCS.

The impact of epilepsy duration in a series of patients with mesial temporal lobe epilepsy due to unilateral hippocampal sclerosis.

PURPOSE: To evaluate if the duration of epilepsy influences MRI volumes of the hippocampus, amygdala, parahippocampal gyrus, entorhinal cortex and temporal pole of both hemispheres and epileptogenic hippocampus neuronal cell density and dentate gyrus granular cells distribution in patients with refractory mesial temporal lobe epilepsy due to hippocampal sclerosis (MTLE/HS). METHODS: Seventy-seven patients with refractory MTLE/HS submitted to surgery were included. Histopathological analysis included: (1) quantitative: hippocampal subfields and total estimated hippocampal cell density (HCD), thickness of the dentate gyrus - normal, thinning or dispersion; (2) qualitative: type of HS and granule cells pathology in the dentate gyrus (normal, neuronal cell loss, dispersion and bilamination). Automated MRI-derived measurements from bilateral temporal structures (hippocampus, amygdala, parahippocampal gyrus, temporal pole, entorhinal cortex) were obtained for 58 subjects. Histopathological and imaging findings were compared with data from specimens obtained in autopsies of age-matched individuals and living controls, respectively, and the data were adjusted for the age at epilepsy onset and the frequency of focal impaired awareness seizures/month. RESULTS: Forty-two (54.5%) patients presented right HS. The greater the duration of epilepsy, the smaller the total estimated HCD (p = 0.025; r = -0.259). Patients with a normal distribution of the granular cells had a shorter epilepsy duration than those with dispersion (p = 0.018) or thinning (p = 0.031). A reduced ipsilateral hippocampal volume (r = -0.551, p = 0.017) and a smaller hippocampal asymmetry index (r = -0.414, p = 0.002) were correlated to a longer epilepsy duration. The estimated HCD was correlated to the volume of the ipsilateral hippocampus (r = 0.420, p = 0.001). CONCLUSION: Our study showed an increasing atrophy of the ipsilateral hippocampus in patients with a longer epilepsy duration. Our data suggest that this reduction in hippocampal volume is related to neuronal loss. Besides that, we also showed an increased probability of exhibiting an abnormal distribution of the granular cells in the dentate gyrus in patients with longer epilepsy duration.

Praxis-induced myoclonia: From the neurophysiologist to the patient perspective.

PURPOSE: To characterize semiology and EEG features of praxis-induced (PI) myoclonia and to describe the subjective perception of juvenile myoclonic epilepsy (JME) patients with this reflex trait. METHODS: Patients with JME who presented myoclonia during a Video-EEG Neuropsychological Protocol were selected. We analyzed the semiology of upper limbs myoclonia and the ictal EEG patterns on Video-EEG. We explored the subjective aspects of PI by performing a semi-structured interview to each patient. RESULTS: 15 patients experienced 59 upper limbs myoclonia. Jerks were more frequently asymmetric or unilateral (32/59); a bilaterally symmetric pattern of all myoclonia was observed in only five patients. Ictal pattern was polyspike-wave (PSW) in 31/59 myoclonic seizures and spike-and-wave (SW) in 28/59. Six patients started perceiving myoclonia while learning a new skill or practicing a previously learned skill in a more stressful context. For most patients, PI-myoclonia were a source of anxiety. PI persisted despite antiepileptic medications in 10 patients. CONCLUSIONS: Electroclinical features of PI-myoclonia were more heterogeneous than traditionally described. Ictal pattern of SW was almost as frequent as classical PSW. Patients described the influence of learning new skills and anxiety on PI. Their subjective perception let us understand the impact of this reflex trait.

Efficacy and safety of a video-EEG protocol for genetic generalized epilepsies.

INTRODUCTION: Video-EEG has been used to characterize genetic generalized epilepsies (GGE). For best performance, sleep recording, photic stimulation, hyperventilation, and neuropsychological protocols are added to the monitoring. However, risks and benefits of these video-EEG protocols are not well established. The aim of this study was to analyze the efficacy and safety of a video-EEG neuropsychological protocol (VNPP) tailored for GGE and compare its value with that of routine EEG (R-EEG). METHODS: We reviewed the VNPP and R-EEG of patients with GGE. We considered confirmation of the clinical suspicion of a GGE syndrome and characterization of reflex traits as benefits; and falls, injuries, psychiatric and behavioral changes, generalized tonic-clonic (GTC) seizures, and status epilepticus (SE) as the main risks of the VNPP. RESULTS: The VNPPs of 113 patients were analyzed. The most common epileptic syndrome was juvenile myoclonic epilepsy (85.8%). The protocol confirmed a GGE syndrome in 97 patients and 62 had seizures. Sleep recording had a provocative effect in 51.2% of patients. The second task that showed highest efficacy was praxis (39.3%) followed by hyperventilation (31.3%). Among the risks, 1.8% had GTC seizures and another 1.8%, SE. Eighteen percent of patients had persistently normal R-EEG, 72.2% of them had discharges during VNPP. Generalized tonic-clonic seizures, myoclonic status epilepticus, and repeated seizures were the main risks of VNPP present in 6 (5.31%) patients while there were no complications during R-EEG. CONCLUSIONS: The VNPP in GGE is a useful tool in diagnosis and characterization of reflex traits, and is a safe procedure. Its use might preclude multiple R-EEG exams.

Expression of praxis induction on cortical excitability in juvenile myoclonic epilepsy.

OBJECTIVE: This study aimed to evaluate the effects of praxis induction on sensorimotor cortical and transcallosal excitability in juvenile myoclonic epilepsy (JME). METHODS: A total of 36 subjects (18-62years) were included. The JME group was screened by video-electroencephalography neuropsychological protocol and divided into JME without praxis induction [JME-WI (n=12)], JME with praxis-induced seizures or epileptiform discharges [JME-PI (n=10)], and healthy controls (n=14). Motor and somatosensory cortical excitability and transcallosal pathways were evaluated through single-pulse transcranial magnetic stimulation (sTMS) and somatosensory evoked potentials (SEPs). RESULTS: Motor and transcallosal excitabilities tested with sTMS were not different in the motor-dominant or non-dominant hemisphere among groups. Significant differences were found in cortical SEP amplitudes in the P27 component of the non-dominant hemisphere (p=0.03, Cohen's d=0.98), N35 in the dominant hemisphere (p=0.04, Cohen's d=0.96), and P27-35 interpeak amplitude in both somatosensory cortices of the JME-PI group (p=0.03, Cohen's d=0.96; p=0.02, Cohen's d=1.05) when compared with healthy controls. Giant SEPs were observed in two (16.7%) and five (50%) patients of the JME-WI and JME-PI groups, respectively. Cortical latencies did not reveal differences. CONCLUSIONS: Praxis induction was associated with enhanced excitability in the somatosensory cortex of JME patients. SIGNIFICANCE: These findings may help clarifying the less favorable therapeutic response in the JME-PI group and indicate identifying praxis induction as an important determinant in differentiating between JME patients.

Cognitive performance in juvenile myoclonic epilepsy patients with specific endophenotypes.

PURPOSE: Juvenile myoclonic epilepsy (JME) is a heterogeneous syndrome in which seizures can be precipitated not only by non-specific factors, such as sleep deprivation and stress, but also by specific stimuli, such as photic stimuli, eye-closure, praxis, and language. The presence of these reflex traits may indicate the hyperexcitability of different cortical areas, which may be reflected in patients' neuropsychological deficit profile. The objective of our study is to investigate the possible relations between JME endophenotypes and patients' cognitive performance. METHODS: 61 JME patients were divided into four groups: no reflex traits (group 1, 20 patients); praxis induction (group 2, 13); eye-closure and/or photosensitivity (group 3, 17); and a combination of different reflex traits (group 4, 11). Neuropsychological performance was compared between JME subgroups. 60 healthy controls were used to calculate z-scores. Patients also underwent psychiatric assessment. We controlled the clinical variables, e.g. age at epilepsy onset, frequency of myoclonic seizures, total and sedative drug load, setting them as covariables for the ANOVA analysis. RESULTS: Praxis induction was more common in males (p=0.018) and groups with reflex traits (2, 3, and 4) presented higher rates of persistent myoclonia, polytherapy, clonazepam use (group 3), and more frequent psychiatric comorbidities. Group 4 patients performed worse in Trail Making Test B than the patients in group 1. These findings were independent of clinical variables. CONCLUSION: JME patients with a combination of praxis induction and eye-closure/photosensitivity had greater executive dysfunction, revealing an association between reflex ictogenic mechanisms and cognitive performance.

Phenotyping juvenile myoclonic epilepsy. Praxis induction as a biomarker of unfavorable prognosis.

PURPOSE: Juvenile myoclonic epilepsy (JME) is a heterogeneous syndrome with seizures presenting typical fluctuation in diurnal cycle and relation with awakening. Few publications have approached clinical expressions of praxis induction (PI) in the nosology of JME as well as its impact on outcome. The aim of this study is to characterize PI as the only reflex trait in JME and its relation with prognosis. METHOD: JME with PI reported on a questionnaire and confirmed by video-EEG testing (Group 1, 20 patients) were compared with JME without any reflex epileptic trait (Group 2, 25 patients) and followed for a mean of 7.82 years (SD=3.98). Circadian distribution and frequency of seizures were assessed in a diary. Patients also had psychiatric evaluation. RESULTS: Prevalence of PI was 20/133 (15%) JME patients, and was predominant in males (1.5 male: 1 female; OR 13; p=0.042). Among Group 1 patients, only 2/20 presented seizures exclusively in the morning (p=0.013), and none, exclusively on awakening (p<0.001). PI patients had worse prognosis regarding control of myocloni (p=0.02) and absences (p=0.01); only 7/20 (35.0%) could be treated with VPA in monotherapy (p=0.01). At the last follow-up, 2/20 (10.0%) of Group 1 and 10 (40.0%) of Group 2 patients were free of all three seizure types (p=0.02). Even though relative risk of stress as a precipitant of seizures increased 3.82 times in Group 1, psychiatric comorbidities were not different between groups. CONCLUSION: PI reflex trait in JME is related to seizures without preferential circadian occurrence and reduced response to antiepileptic drugs.

Blinking and eyelid myoclonia: Characteristics and correlations of eyelid movements.

PURPOSE: Eyelid myoclonia (EM) is considered a seizure type and has been described in several epileptic conditions. Previous studies reported that EM are precipitated only by slow eye closure, but little is known about the characteristics of blinking in patients with EM seizures and differences in precipitation of EM by different kinds of eye closure. We analyzed by video-EEG the characteristics of blinking and eye closure in these patients. METHOD: Twenty patients with EM had a video-EEG protocol with eyelid sensors. Semiology and rate of blinking and EM were analyzed. Statistical analysis was performed and p-values <0.05 were considered significant. RESULTS: Seventeen cases (mean age 20.7, range 3-35) were women, 10 had EM as the main seizure type and between the others, all, but one, had criteria to Juvenile Myoclonic Epilepsy. All patients presented EM, 18 spontaneously during awake, 10 on eye closure and one only during intermittent photic stimulation. EM assumed the form of flicker, flutter or jerk, accompanied by generalized discharges, spiky posterior alpha, theta rhythm or absence of any EEG abnormality. Analysis of the characteristics of blinking had no statistics differences between patients and healthy subjects. The rate of blinks and EM increased during speech and decreased during reading. EM never occurred during blinking or in the dark. CONCLUSIONS: Despite normal physiology of blinking, EM can manifest as jerk, flicker or flutter, with or without EEG abnormalities and independently of IPS, suggesting that eye closure sensitivity seems to include both, a motor and a visual component.

Hippocampal atrophy and memory dysfunction in patients with juvenile myoclonic epilepsy.

Juvenile myoclonic epilepsy (JME) is a well-defined idiopathic generalized epilepsy (IGE) syndrome, being the most common IGE in adults and accounting for 5-11% of patients with epilepsy. While neuropsychological and neuroimaging studies have discussed the thalamofrontal dysfunction as the major pathophysiologic mechanism of JME, investigation on memory is scarce in patients with JME, with lack of objective assessments addressing common complaints and daily difficulties such as recalling telephone numbers, messages to pass on, and taking antiepileptic drugs regularly. The aim of this study was to objectively assess memory deficits in a group of patients with JME using neuropsychological examination combined with structural MRI of the hippocampi. After informed consent, a cohort of 56 consecutive patients with JME (29 males; mean age ± SD = 26.5 ± 9.01 years; range = 14.0-55.0 years) was included. The control group consisted of 42 healthy volunteers (18 males; mean age ± SD = 31.0 ± 8.54 years; range=20.0-56.0 years) without a family history of neuropsychiatric disorders. Patients and controls were submitted to a MRI and to a neuropsychological assessment, and comparisons between groups were performed, as well as a correlation study between hippocampal atrophy and neuropsychological performance in a group of patients with JME. The level of statistical significance was set at p<0.05. Significant hippocampal atrophy among patients with JME was observed, which was correlated with memory dysfunctions. The present findings reinforce the existence of functional-anatomic ictogenic networks that are not limited to frontal lobes, providing further support towards the concept of 'system epilepsies' in JME.

Modulation of epileptiform EEG discharges in juvenile myoclonic epilepsy: an investigation of reflex epileptic traits.

PURPOSE: Previous studies have suggested that cognitive tasks modulate (provoke or inhibit) the epileptiform electroencephalography (EEG) discharges (EDs) in patients with juvenile myoclonic epilepsy (JME). Their inhibitory effect was found to be especially frequent (64-90%). These studies arbitrarily defined modulation as a >100% increase or >50% decrease of the EDs compared with baseline, which may not sufficiently distinguish from spontaneous fluctuations. The aim of our study was to assess the modulation of EDs and the precipitation of myoclonic seizures by cognitive tasks and by conventional provocation methods, taking into account also the spontaneous fluctuation of EDs. METHOD: Sixty patients with JME underwent video-EEG recordings including 50-min baseline, sleep, hyperventilation, intermittent photic stimulation (IPS), and cognitive tasks. To account for spontaneous fluctuations of the EDs we divided the baseline period into 5-min epochs and calculated the 95% confidence interval for the baseline EDs in each patient. Modulation was assumed when the number of EDs during any 5-min test period was outside the 95% confidence interval. KEY FINDINGS: Using the arbitrary method, our results were similar to previous publications: Cognitive tasks seemed to inhibit the EDs in 94% of the patients, and to provoke them in 22%. However, when the spontaneous fluctuations were accounted for, inhibition was found in only 29% of the patients and provocation in 18%. A nonspecific effect of any cognitive task seemed to account for the observed significant inhibition in two-thirds of the cases, but was observed in only one of the patients with significant provocation. Photoparoxysmal response was observed in 23% of the patients. When accounting for the spontaneous occurrence of EDs, IPS had provocative effect in 10% of the patients. Hyperventilation and sleep had provocative effect on EDs to an extent similar to the cognitive tasks (hyperventilation: 22%; sleep: 18%). The conventional provocation methods tended to be more efficient in patients who were not seizure free. Myoclonia were recorded most often during the cognitive tasks (10 patients). SIGNIFICANCE: Spontaneous fluctuations of EDs account for most of the previously described inhibitory effect of the cognitive tasks. The provocative effect of the cognitive tasks is task-specific, whereas the inhibitory effect seems to be related to cognitive activation in general.

Physiological and electroencephalographic responses to acute exhaustive physical exercise in people with juvenile myoclonic epilepsy.

Although the available evidence suggests that exercise may positively affect epilepsy, whether this effect is applicable to different types of epilepsy has not been established. Physiological responses during rest, acute physical effort, and a recovery period were studied by concomitant analysis of cerebral electric activity using EEGs in subjects with juvenile myoclonic epilepsy (JME) and healthy controls. In addition, level of habitual physical activity, body composition, and 1 week of actigraphy monitoring data were evaluated. Twenty-four subjects (12 with JME and 12 controls) participated in this study. Compared with the control group, the JME group had a significantly lower V˙O(2) at rest (13.3%) and resting metabolic rate (15.6%). The number of epileptiform discharges in the JME group was significantly reduced during the recovery period (72%) compared with the resting state. There were no significant differences between the JME and control groups in behavioral outcomes and sleep parameters evaluated by actigraphy monitoring. The positive findings of our study strengthen the evidence for the benefits of physical exercise for people with JME.

Voxel-based morphometry evaluation of patients with photosensitive juvenile myoclonic epilepsy.

We aim to investigate structural brain abnormalities in juvenile myoclonic epilepsy (JME) patients with photosensitivity (PS). Sixty JME patients, 19 (32%) of whom were photosensitive, were submitted to 1.5T magnetic resonance voxel-based morphometry (VBM). The control group (CTL) consisted of 30 sex-matched healthy volunteers. JME patients with (JME-PS) and without (JME-NPS) PS did not differ in their duration of disease, treatment or seizure control. VBM revealed significantly reduced bilateral gray matter volume (GMV) in thalami, insula cortices and cerebellar hemispheres; while significantly increased GMV was observed in the right superior frontal, orbitofrontal and medial frontal gyri of the JME group compared to CTL. JME-PS had reduced bilateral GMV of visual cortices when compared with CTL; while it was not seen among JME-NPS patients. Reduced left hippocampus and left inferior frontal gyrus volume was observed among JME-PS compared with JME-NPS. This study demonstrates structural abnormalities beyond the limits of the frontal lobes and provides evidence for the role of the occipital cortex in human PS, reinforcing the existence of functional-anatomic ictogenic networks in JME and the concept of 'system epilepsies'.

Provocative and inhibitory effects of a video-EEG neuropsychologic protocol in juvenile myoclonic epilepsy.

PURPOSE: Studies suggest that higher cognitive functions could precipitate seizures in juvenile myoclonic epilepsy (JME). The present study aimed to analyze the effects of higher mental activity on epileptiform discharges and seizures in patients with JME and compare them to those of habitual methods of activation. METHODS: Seventy-six patients with JME (41 female) underwent a video-EEG (electroencephalography) neuropsychologic protocol (VNPP) and habitual methods of activation for 4-6 h. RESULTS: Twenty-nine of the 76 (38.2%) presented provocative effect, and inhibition was seen in 28 of 31 (90.3%). A mixed effect was observed in 11 (35.5%), and 30 patients (39.5%) suffered no effect of VNPP. Action-programming tasks were more effective than thinking in provoking epileptiform discharges (23.7% and 11.0% of patients, respectively, p = 0.03). Inhibitory effect was observed equally in the various categories of tasks, except in mental calculation, which had a higher inhibitory rate. Habitual methods of activation were more effective than VNPP in provoking discharges. Anxiety disorders were diagnosed in 24 of 58 patients (41.4%); anxious patients had greater discharge indexes and no significant inhibitory effect on VNPP. DISCUSSION: Praxis exerted the most remarkable provocative effect, in accordance with the motor circuitry hyperexcitability hypothesis in JME. Inhibitory effect, which had no such task specificity, might be mediated by a widespread cortical-thalamic pathway, possibly involving the parietal cortex. The frequent inhibitory effect found under cortical activation conditions, influenced by the presence of anxiety, supports nonpharmacologic therapeutic interventions in JME.

Magnetic resonance spectroscopy reveals an epileptic network in juvenile myoclonic epilepsy.

PURPOSE: To investigate the cerebral metabolic differences between patients with juvenile myoclonic epilepsy (JME) and normal controls and to evaluate to what extent these metabolic alterations reflect involvement of an epileptic network. METHODS: Sixty patients with JME were submitted to multi-voxel proton spectroscopy (1H-MRS) at 1.5 T over medial prefrontal cortex (MPC), primary motor cortex (PMC), thalamus, striatum, posterior cingulate gyrus (PCG), and insular, parietal, and occipital cortices. We determined ratios for integral values of N-acetyl-aspartate (NAA) and glutamate-glutamine (GLX) over creatine-phosphocreatine (Cr). The control group (CTL) consisted of 30 age- and sex-matched healthy volunteers. RESULTS: The NAA/Cr ratio, a measure of neuronal injury, was reduced in PMC, MPC, and thalamus among patients. In addition, they had an altered GLX/Cr ratio, which is involved in excitatory activity, on PMC, MPC, and PCG, where it was reduced, whereas it was increased on insula and striatum. Multiple regression analysis revealed the strongest correlation between thalamus and MPC, but the thalamus was also correlated with insula, occipital cortex, and striatum among patients. Lower NAA/Cr was observed with advancing age and duration of epilepsy, regardless of frequency of seizures and antiepileptic drug therapy in thalamus and frontal cortex. DISCUSSION: The identification of a specific network of neurochemical dysfunction in patients with JME, with diverse involvement of particular structures within the thalamocortical circuitry, suggests that cortical hyperexcitability in JME is not necessarily diffuse, supporting the knowledge that the focal/generalized distinction of epileptogenesis should be reconsidered. Furthermore, evidence is provided toward progressive neuronal dysfunction in JME.