Cortico-muscular and cortico-cortical coherence changes resulting from Perampanel treatment in patients with cortical myoclonus

OBJECTIVE

To investigate the mechanisms by which Perampanel (PER) reduces the severity of action myoclonus, we studied on MEG signals the changes occurring in cortico-muscular coherence (CMC) and cortico-cortical connectivity in patients with progressive myoclonus epilepsies.

METHODS

The subjects performed an isometric extension of the hand; CMC and cortico-cortical connectivity were assessed using autoregressive models and generalized partial-directed coherence. The contralateral (Co) sensors showing average CMC values >0.7 of the maximum (set to 1) were grouped as central (C) regions of interest (ROI), while adjacent sensors showing CMC values >0.3 were grouped as Surrounding (Sr) ROIs.

RESULTS

Under PER treatment, CMC decreased on Co C and Sr ROIs, but also on homologous ipsilateral (Ip) ROIs; out-degrees and betweenness centrality increased in Co ROIs and decreased in Ip ROIs. The flow from Ip to Co ROIs and from activated muscles to Ip C ROI decreased.

CONCLUSION

The improvement of myoclonus corresponded to decreased CMC and recovered leadership of the cortical regions directly involved in the motor task, with a reduced interference of ipsilateral areas.

SIGNIFICANCE

Our study highlights on mechanisms suitable to treating myoclonus and suggests the role of a reduced local synchronization together a better control of distant synaptic effects.

Different patterns of movement-related cortical oscillations in patients with myoclonus and in patients with spinocerebellar ataxia

OBJECTIVE

To assess whether different patterns of EEG rhythms during a Go/No-go motor task characterize patients with cortical myoclonus (EPM1) or with spinocerebellar ataxia (SCA).

METHODS

We analyzed event-related desynchronization (ERD) and synchronization (ERS) in the alpha and beta-bands during visually cued Go/No-go task in 22 patients (11 with EPM1, 11 with SCA) and 11 controls.

RESULTS

In the Go condition, the only significant difference was a reduced contralateral beta-ERS in the EPM1 patients compared with controls; in the No-go condition, the EPM1 patients showed prolonged alpha-ERD in comparison with both controls and SCA patients, and reduced or delayed alpha- and beta-ERS in comparison with controls. In both conditions, the SCA patients, unlike EPM1 patients and controls, showed minimal or absent lateralization of alpha- and beta-ERD.

CONCLUSIONS

EPM1 patients showed abnormal ERD/ERS dynamics, whereas SCA patients mainly showed defective ERD lateralization.

SIGNIFICANCE

A different behavior of ERS/ERD distinguished the two patient groups: the pattern observed in EPM1 suggests a prominent defect of inhibition occurring in motor cortex contralateral to activated segment, whereas the pattern observed in SCA suggested a defective lateralization attributable to the damage of cerebello-cortical network, which is instead marginal in patients with cortical myoclonus.

Early effect of dalfampridine in patients with MS: A multi-instrumental approach to better investigate responsiveness

BACKGROUND

4-aminopyridine (4-AP) is a potassium-channel blocker able to enhance walking speed in MS improving the action potentials of demyelinated axons on which internodal potassium channels are exposed.

OBJECTIVE

to study early 4-AP effect with clinical, subjective, neurophysiological and neuroradiological tools.

METHODS

Clinical (Timed 25-Foot Walk - T25FW, Timed Up-And-Go - TUG), subjective (MS Walking Scale-12 - MSWS-12), neurophysiological (Motor Evoked Potentials - MEPs) and imaging (Diffusion Tensor Imaging - DTI) evaluations were performed before (T0) and after (T1) 14days of 4-AP treatment. MEPs were recorded from Abductor Hallucis of both legs. A Tract-Based-Spatial-Statistics (TBSS) was performed on DTI.

RESULTS

We found a significant difference between T0 and T1 for T25FW, TUG, MSWS-12 (p≤0.001) in the whole patients' sample (23 subjects, median EDSS 6.0) and decrease of Central Motor Conduction Time and increase of mean Amplitude (Amp) at T1 (p=0.008 and p=0.006). We also recorded a significant difference of T25FW, TUG, MSWS-12 and Amp in clinical responder (CR) patients (CR: amelioration >20% at T25FW). TBSS showed a significant Mean and Radial Diffusivity reduction in the corticospinal tracts (p<0.05) of the whole group of patients; this reduction was also found in the CR subgroup.

CONCLUSION

Neurophysiological and neuroradiological parameters were modified in MS patients treated with 4-AP, and most of them reported a subjective improvement of their motor performances after treatment. The use of clinical, subjective, neurophysiological and neuroradiological tools could help to better explore MS patients responsiveness to 4-AP.

The impact of chorionicity and type of conception on maternal-neonatal outcome in twin pregnancies

PURPOSE OF INVESTIGATION

To evaluate the maternal and neonatal outcomes in twin pregnancies according to chorionicity (monochorionic (MC) versus dichorionic (DC) and type of conception [spontaneously conceived (SC) versus assisted reproduction technology (ART)].

MATERIALS AND METHODS

A retrospective study of 196 twin pregnancies admitted to the Department of Gynecology, Obstetrics and Urology of the University of Rome Sapienza, from January 2008 to April 2013.

RESULTS

There were 55 MC and 141 DC twin pregnancies (82 SC and 59 ART). MC twin pregnancies had a higher incidence of preterm birth (p < 0.008), twin-twin transfusion syndrome (TTTS) (p < 0.021), and intrauterine growth restriction (IUGR) (p < 0.05). MC pregnancies had lower neonatal birth weight (p < 0.05), and lower Apgar score. ART DC pregnancies had a higher incidence of preterm delivery (p < 0.05).

CONCLUSIONS

MC twin pregnancy is associated with higher risk of adverse maternal and perinatal outcomes. In the DC subgroup, ART is associated to a higher incidence of preterm delivery.

Effect of L-5HTP and drugs acting on serotonin metabolism in various myoclonic syndromes

Ten patients affected by various myoclonic syndromes were tested with drugs acting on cerebral serotonin metabolism and with clonazepam (CZP). After L5HTP or serotonergic drugs administration a clear cut improvement was observed in the 2 patients affected by Ramsay-Hunt syndrome, while the patients with myoclonic epilepsy have shown no effect (3 cases) or negative response (1 case). Methysergide was active only in 1 patient affected by progressive erratic myoclonus who had a striking worsening of clinical picture. The main side effects observed were: gastrointestinal distress (L5HTP--4 patients, fenfluoramine--2, quipazine--1, methysergide--2) and cutaneous rash (quipazine--1 case). These results support the possible implication of the serotonergic system in the pathogenesis of myoclonus other than post-anoxic.

Management of hydrosalpinx before IVF: a literature review

Hydrosalpinx has a detrimental effect on the outcome of in vitro fertilization (IVF). Surgical intervention such as salpingectomy or tubal occlusion before IVF improves the outcome of IVF, but these procedures are often contraindicated in women with dense pelvic adhesions. Thus, it is worthwhile to search minimally invasive alternative therapies. The main objective of this review is to assess and compare the value of all the therapeutic options for hydrosalpinx before IVF. The results of the following procedures were compared: the laparoscopic treatments (salpingectomy/proximal tubal occlusion), the hysteroscopic insertion of device achieving tubal occlusion, the tuberous sclerosis and the aspiration of hydrosalpingeal fluid at the time of IVF procedure. Laparoscopic surgical treatment should be considered for all women with hydrosalpinx before IVF. Whenever laparoscopy is not recommended, hysteroscopic insertion of device seems the most effective option for management of hydrosalpinx before IVF.

Significance of multiple neurophysiological measures in patients with chronic disorders of consciousness

OBJECTIVE

The aim of this study was to verify the value of multiple neurophysiological tests in classifying disorders of consciousness (DOCs) in patients in a chronic vegetative or minimal consciousness state categorised on the basis of the Coma Recovery Scale (CRS).

METHODS

The study included 142 patients, all of whom underwent long (18h) EEG-polygraphic recordings including one night. The EEG was scored using the Synek scale and sleep patterns using an arbitrary scale. Absolute total power and relative EEG power were evaluated in different frequency bands. Multimodal evoked potentials (EPs), including auditory event-related potentials, were also evaluated and scored.

RESULTS

The most information came from the combined multimodal EPs and sleep EEG scores. A two-step cluster analysis based on the collected information allowed a satisfactory evaluation of DOC severity. Spectral EEG properties seemed to be significantly related to DOC classes and CRS scores, but did not seem to make any significant additional contribution to DOC classification.

CONCLUSIONS

Multiple electrophysiological evaluations based on EEG, sleep polygraphic recordings and multimodal EPs are helpful in assessing DOC severity and residual functioning in patients with chronic DOCs.

SIGNIFICANCE

Simple electrophysiological measures that can be easily applied at patients' bedsides can significantly contribute to the recognition of DOC severity in chronic patients surviving a severe brain injury.

Music and emotion: an EEG connectivity study in patients with disorders of consciousness

Human emotion perception is a topic of great interest for both cognitive and clinical neuroscience, but its electrophysiological correlates are still poorly understood. The present study is aimed at evaluating if measures of synchronization and indexes based on graph-theory are a tool suitable to study and quantify electrophysiological changes due to emotional stimuli perception. In particular, our study is aimed at evaluating if different EEG connectivity patterns can be induced by pleasant (consonant) or unpleasant (dissonant) music, in a population of healthy subjects, and in patients with severe disorders of consciousness (DOCs), namely vegetative state (VS) patients. In the control group, pleasant music induced an increase in network number of connections, compared with the resting condition, while no changes were caused by the unpleasant stimuli. However, clustering coefficient and path length, two indexes derived from graph theory, able to characterise segregation and integration properties of a network, were not affected by the stimuli, neither pleasant nor unpleasant. In the VS group, changes were found only in those patients with the less severe consciousness impairment, according to the clinical assessment. In these patients a stronger synchronization was found during the unpleasant condition; moreover we observed changes in the network topology, with decreased values of clustering coefficient and path length during both musical stimuli.Our results show that measures of synchronization can provide new insights into the study of the electro physiological correlates of emotion perception, indicating that these tools can be used to study patients with DOCs, in whom the issue of objective measures and quantification of the degree of impairment is still an open and unsolved question.

Clinical and molecular characterization of diffuse large B-cell lymphomas with 13q14.3 deletion

BACKGROUND

Deletions at 13q14.3 are common in chronic lymphocytic leukemia and are also present in diffuse large B-cell lymphomas (DLBCL) but never in immunodeficiency-related DLBCL. To characterize DLBCL with 13q14.3 deletions, we combined genome-wide DNA profiling, gene expression and clinical data in a large DLBCL series treated with rituximab, cyclophosphamide, doxorubicine, vincristine and prednisone repeated every 21 days (R-CHOP21).

PATIENTS AND METHODS

Affymetrix GeneChip Human Mapping 250K NspI and U133 plus 2.0 gene were used. MicroRNA (miRNA) expression was studied were by real-time PCR. Median follow-up of patients was 4.9 years.

RESULTS

Deletions at 13q14.3, comprising DLEU2/MIR15A/MIR16, occurred in 22/166 (13%) cases. The deletion was wider, including also RB1, in 19/22 cases. Samples with del(13q14.3) had concomitant specific aberrations. No reduced MIR15A/MIR16 expression was observed, but 172 transcripts were significantly differential expressed. Among the deregulated genes, there were RB1 and FAS, both commonly deleted at genomic level. No differences in outcome were observed in patients treated with R-CHOP21.

CONCLUSIONS

Cases with 13q14.3 deletions appear as group of DLBCL characterized by common genetic and biologic features. Deletions at 13q14.3 might contribute to DLBCL pathogenesis by two mechanisms: deregulating the cell cycle control mainly due RB1 loss and contributing to immune escape, due to FAS down-regulation.

Event-related potential (ERP) markers of melodic processing: The N2 component is modulated by structural complexity, not by melodic 'meaningfulness'

Previous studies have demonstrated that the event-related potential (ERP) evoked by a note shows substantial differences depending on whether the note is part of a melodic context or presented in an unstructured repetition. In particular, the N2 component has been found to have considerably increased latency and a more frontal topography for notes presented in a melody. An open question is whether such effect is related to the 'meaningfulness' of a note sequence, that is due to the formation of abstract melodic entities, rather than more simply an indicator of cognitive load associated with processing a structurally-complex sequence as opposed to an unstructured repetition. In this study, we addressed this issue by recording ERPs from 10 healthy non-musicians listening to eight one-part unfamiliar tonal melodies and eight sequences of random notes. The two stimuli were matched for distribution of pitch, intervals and note duration as well as for entropy of the time-series of pitch and duration. While tonal melodies were rated more meaningful (p<0.001) and pleasant (p<0.001) by all participants, no effects were found for the N2 component amplitude (p> or =0.8) and latency (p=0.2). Combined with previous findings, this indicates that the N2 evoked by each individual note responds to the structural complexity of the note sequence, i.e., to the presence of pitch and duration changes, but not to higher-level processing related to the formation of abstract melodic entities. In contrast, we found that the amplitude of the P2 component was marginally (p=0.04) elevated for random notes as compared to tonal melodies. This may be related to attentional modulation, or more specifically to associative components of auditory processing.

SCARB2 mutations in progressive myoclonus epilepsy (PME) without renal failure

OBJECTIVE

Mutations in SCARB2 were recently described as causing action myoclonus renal failure syndrome (AMRF). We hypothesized that mutations in SCARB2 might account for unsolved cases of progressive myoclonus epilepsy (PME) without renal impairment, especially those resembling Unverricht-Lundborg disease (ULD). Additionally, we searched for mutations in the PRICKLE1 gene, newly recognized as a cause of PME mimicking ULD.

METHODS

We reviewed cases of PME referred for diagnosis over two decades in which a molecular diagnosis had not been reached. Patients were classified according to age of onset, clinical pattern, and associated neurological signs into "ULD-like" and "not ULD-like." After exclusion of mutations in cystatin B (CSTB), DNA was examined for sequence variation in SCARB2 and PRICKLE1.

RESULTS

Of 71 cases evaluated, 41 were "ULD-like" and five had SCARB2 mutations. None of 30 "not ULD-like" cases were positive. The five patients with SCARB2 mutations had onset between 14 and 26 years of age, with no evidence of renal failure during 5.5 to 15 years of follow-up; four were followed until death. One living patient had slight proteinuria. A subset of 25 cases were sequenced for PRICKLE1 and no mutations were found.

INTERPRETATION

Mutations in SCARB2 are an important cause of hitherto unsolved cases of PME resembling ULD at onset. SCARB2 should be evaluated even in the absence of renal involvement. Onset is in teenage or young adult life. Molecular diagnosis is important for counseling the patient and family, particularly as the prognosis is worse than classical ULD.

Analysis of the host pharmacogenetic background for prediction of outcome and toxicity in diffuse large B-cell lymphoma treated with R-CHOP21

Knowledge on the impact of pharmacogenetics in predicting outcome and toxicity in diffuse large B-cell lymphoma (DLBCL) is scant. We tested 106 consecutive DLBCL treated with R-CHOP21 for 19 single nucleotide polymorphisms (SNPs) from 15 genes potentially relevant to rituximab-CHOP (R-CHOP) pharmacogenetics. Associations of SNPs with event-free survival (EFS) and toxicity were controlled for multiple testing. Genotypic variants of nicotinamide adenine dinucleotide phosphate (NAD(P)H) oxidase p22phox (CYBA rs4673) and alpha1 class glutathione S-transferase (GSTA1 rs3957357) were independent predictors of EFS (CYBA rs4673 TT genotype: HR 2.06, P=0.038; GSTA1 rs3957357 CT/TT genotypes: HR 0.38, P=0.003), after adjusting for International Prognostic Index (IPI). CYBA rs4673 and GSTA1 rs3957357 also predicted outcome in DLBCL subgroups by IPI. Impact of SNPs on toxicity was evaluated in 658 R-CHOP21 courses utilizing generalized estimating equations. NCF4 rs1883112 was an independent predictor against hematologic (odds ratios (OR): 0.45; P=0.018), infectious (OR: 0.46; P=0.003) and cardiac toxicity (OR: 0.37; P=0.023). Overall, host SNPs affecting doxorubicin pharmacodynamics (CYBA rs4673) and alkylator detoxification (GSTA1 rs3957357) may predict outcome in R-CHOP21-treated DLBCL. Also, NCF4 rs1883112, a SNP of NAD(P)H oxidase p40phox, may have a function in protecting against hematologic and nonhematologic toxicity. These results highlight the need to improve characterization of the host genetic background for a better prognostication of DLBCL.

Progressive myoclonic ataxia with intrathecal immune activation in six patients

In six patients with slowly progressive sporadic cerebellar ataxia and cortical multifocal action myoclonus, cerebrospinal fluid (CSF) IgG index was persistently very high (1.2-6.7) and numerous oligoclonal bands were detected. Progressive cognitive impairment and MRI cerebellar and cerebral atrophy were observed. No serum antibodies were found. Various degenerative, metabolic, inflammatory and systemic diseases were excluded. The cerebellum may be the main target of a degenerative or immune process and releases antigens that, enhancing a compartmentalised (auto)immune response, as suggested by the persistent intrathecal activation, could lead to further cerebellar damage. As the frequency of CSF oligoclonal banding in myoclonic ataxia is unknown, our patients' disease might represent a hitherto unreported entity or a subset of progressive myoclonic ataxia.

Genetic diagnosis in Lafora disease

Lafora disease (LD) can be diagnosed by skin biopsy, but this approach has both false negatives and false positives. Biopsies of other organs can also be diagnostic but are more invasive. Genetic diagnosis is also possible but can be inconclusive, for example, in patients with only one heterozygous EPM2A mutation and patients with apparently homozygous EPM2B mutations where one parent is not a carrier of the mutation. We sought to identify occult mutations and clarify the genotypes and confirm the diagnosis of LD in patients with apparent nonrecessive disease inheritance. We used single nucleotide polymorphism, quantitative PCR, and fluorescent in situ hybridization analyses. We identified large EPM2A and EPM2B deletions undetectable by PCR in the heterozygous state and describe simple methods for their routine detection. We report a coding sequence change in several patients and describe why the pathogenic role of this change remains unclear. We confirm that adult-onset LD is due to EPM2B mutations. Finally, we report major intrafamilial heterogeneity in age at onset in LD.

Phosphorylation of sodium channels mediated by protein kinase-C modulates inhibition by topiramate of tetrodotoxin-sensitive transient sodium current

BACKGROUND AND PURPOSE

Topiramate is a novel anticonvulsant known to modulate the activity of several ligand- and voltage-gated ion channels in neurons. The mechanism of action of topiramate, at a molecular level, is still unclear, but the phosphorylation state of the channel/receptor seems to be a factor that is able to influence its activity. We investigated the consequences of phosphorylation of the sodium channel on the effect of topiramate on tetrodotoxin (TTX)-sensitive transient Na(+) current (I(NaT)).

EXPERIMENTAL APPROACH

I(NaT) was recorded in dissociated neurons of rat sensorimotor cortex using whole-cell patch-clamp configuration.

KEY RESULTS

We found that topiramate (100 microM) significantly shifted the steady-state I(NaT) inactivation curve in a hyperpolarized direction. In neurons pre-treated with a PKC-activator, 1-oleoyl-2-acetyl-sn-glycerol (OAG; 2 microM), the net effect of topiramate on steady-state I(NaT) inactivation was significantly decreased. In addition, OAG also slightly shifted the I(NaT) activation curve in a hyperpolarized direction, while perfusion with topiramate had no effect on the parameters of I(NaT) activation.

CONCLUSIONS AND IMPLICATIONS

These data show that PKC-activation can modulate the effect of topiramate on I(NaT). This suggests that channel phosphorylation in physiological or pathological conditions (such as epiliepsy), can alter the action of topiramate on sodium currents.

Spectral and bispectral analysis of the EEG rhythms in basal conditions and during photic stimulation

The aim of the present study is the quantification of the relationships and the phase coupling among spectral peaks in the EEG signal at different sites of the scalp. 10 normal subjects underwent the study. The multi-channel EEG signal was recorded during basal conditions and during photic stimulation. The stimulation frequency (SF) has been chosen related to the single subject's spontaneous alpha rhythm (SF = alpha, SF = 2alpha, SF = alpha/2) and not related to the alpha rhythm (SF = 14 Hz). Spectral and bispectral analysis put into evidence that, in basal conditions, with closed eyes, the spontaneous alpha rhythm is generated by independent oscillators in the occipital and frontal regions. In addition the beta rhythm in the spectra seems an harmonic component linked to the former one. During photic stimulation the spontaneous alpha rhythm is drastically decreased, and the harmonics are lowered, while frontal and occipital responses seem to synchronize. In addition the frontal lobe seems able to generate sub-harmonics which could be related to the genesis of generalized seizures in predisposed subjects.

Movement-related desynchronization-synchronization (ERD/ERS) in patients with Unverricht-Lundborg disease

We studied changes in event-related desynchronization/synchronization (ERD/ERS) patterns in patients with Unverricht-Lundborg disease (ULD), presenting with prominent action myoclonus. We analyzed the movement-related ERD/ERS in alpha and beta frequency bands in 15 patients using self-paced finger extension as a motor paradigm and we compared the results with those obtained in 12 healthy volunteers. In all ULD patients, alpha- and beta-ERD regularly occurred with onset and location similar to that found in healthy controls, but the desynchronization of alpha activity was significantly greater than in controls (C3: -64.4+/-9.8% vs. -49.7+/-14.8%; p=0.004). Moreover, in the patients, both alpha- and beta-ERD spread toward frontal electrodes. In controls, the post-movement beta-ERS regularly occurred; it was absent in eight patients with severe action myoclonus, while, in seven patients with mild or moderate myoclonus, the beta-peak was significantly smaller with respect to that measured in controls (55.6+/-15.1% vs. 153.9+/-99.8%, p=0.006). The failure of beta-ERS well-correlated with motor impairment resulting from action myoclonus, whereas SSEPs and long-loop reflexes performed to detect signs of cortical hyperexcitability showed inconsistent changes. In ULD patients, ERD/ERS changes indicate an increased activation of motor cortex during movement planning and a great reduction of post-excitatory inhibition of motor cortex. The changes involving beta-ERS had a significant relationship with the functional disability in individual patients and might play a pathogenic role in the motor dysfunction.

Layer-specific properties of the persistent sodium current in sensorimotor cortex

We evaluated the characteristics of the persistent sodium current (I(NaP)) in pyramidal neurons of layers II/III and V in slices of rat sensorimotor cortex using whole cell patch-clamp recordings. In both layers, I(NaP) began activating around -60 mV and was half-activated at -43 mV. The I(NaP) peak amplitude and density were significantly higher in layer V. The voltage-dependent I(NaP) steady-state inactivation occurred at potentials that were significantly more positive in layer V (V(1/2): -42.3 +/- 1.1 mV) than in layer II/III (V(1/2): -46.8 +/- 1.6 mV). In both layers, a current fraction corresponding to about 25% of the maximal peak amplitude did not inactivate. The time course of I(NaP) inactivation and recovery from inactivation could be fitted with a biexponential function. In layer V pyramidal neurons the faster time constant of development of inactivation had variable values, ranging from 158.0 to 1,133.8 ms, but it was on average significantly slower than that in layer II/III (425.9 +/- 80.5 vs. 145.8 +/- 18.2 ms). In both layers, I(NaP) did not completely inactivate even with very long conditioning depolarizations (40 s at -10 mV). Recovery from inactivation was similar in the two layers. Layer V intrinsically bursting and regular spiking nonadapting neurons showed particularly prolonged depolarized plateau potentials when Ca2+ and K+ currents were blocked and slower early phase of I(NaP) development of inactivation. The biexponential kinetics characterizing the time-dependent inactivation of I(NaP) in layers II/III and V indicates a complex inactivating process that is incomplete, allowing a residual "persistent" current fraction that does not inactivate. Moreover, our data indicate that I(NaP) has uneven inactivation properties in pyramidal neurons of different layers of rat sensorimotor cortex. The higher current density, the rightward shifted voltage dependency of inactivation as well the slower kinetics of inactivation characterizing I(NaP) in layer V with respect to layer II/III pyramidal neurons may play a significant role in their ability to fire recurrent action potential bursts, as well in the high susceptibility to generate epileptic events.

hERG1 channels are overexpressed in glioblastoma multiforme and modulate VEGF secretion in glioblastoma cell lines

Recent studies have led to considerable advancement in our understanding of the molecular mechanisms that underlie the relentless cell growth and invasiveness of human gliomas. Partial understanding of these mechanisms has (1) improved the classification for gliomas, by identifying prognostic subgroups, and (2) pointed to novel potential therapeutic targets. Some classes of ion channels have turned out to be involved in the pathogenesis and malignancy of gliomas. We studied the expression and properties of K⁺ channels in primary cultures obtained from surgical specimens: human ether a gò-gò related (hERG)1 voltage-dependent K⁺ channels, which have been found to be overexpressed in various human cancers, and human ether a gò-gò-like 2 channels, that share many of hERG1's biophysical features. The expression pattern of these two channels was compared to that of the classical inward rectifying K⁺ channels, IRK, that are widely expressed in astrocytic cells and classically considered a marker of astrocytic differentiation. In our study, hERG1 was found to be specifically overexpressed in high-grade astrocytomas, that is, glioblastoma multiforme (GBM). In addition, we present evidence that, in GBM cell lines, hERG1 channel activity actively contributes to malignancy by promoting vascular endothelial growth factor secretion, thus stimulating the neoangiogenesis typical of high-grade gliomas. Our data provide important confirmation for studies proposing the hERG1 channel as a molecular marker of tumour progression and a possible target for novel anticancer therapies.

Unilateral frontal lobe epilepsy affects executive functions in children

Very few studies to date have investigated the neuropsychological changes detectable in children suffering from frontal lobe epilepsy (FLE). The aim of the present study was to assess the effects of FLE on cognitive and executive functions in childhood. The sample includes 17 children with a frontal epileptogenic focus (10 right and 7 left), with no evidence of anatomical brain damage. These subjects were assessed by means of a battery of tests to investigate executive functioning. The results emphasised the presence of selective impairments of frontal lobe functions without evidence of deficits in global intellectual functioning. No side-specific deficits were detected, while an earlier onset of epilepsy and the duration of the disorder, but not the seizures frequency, were found to correspond with more severe deficits in some specific frontal lobe functions.

FVEPs in Creutzfeldt–Jacob disease: waveforms and interaction with the periodic EEG pattern assessed by single sweep analysis

OBJECTIVE

To characterise flash visual evoked potentials (FVEPs) in 20 patients with Creutzfeldt-Jacob disease (CJD), and assess the relationships between spontaneous EEG patterns and the responses to individual stimuli.

METHODS

We analysed the shape and time course of periodic sharp wave complexes (PSWCs) and responses to 1 Hz flashes. In nine patients, we applied an algorithm based on an autoregressive model with exogenous input (ARX) to estimate responses to individual random flashes and their interaction with PSWCs.

RESULTS

The FVEPs included P1 and N1 components in all patients, and the P2 peak in 18. Eight patients showed giant FVEPs (N1-P2>60 V), all of whom had an MM polymorphism in codon 129 of the prion protein gene; in seven cases, the presence of giant FVEPs correlated with a prominent and almost continuous periodic EEG pattern. Giant N1-P2 abnormally spread on the anterior scalp regions, and had a different waveform distribution from that of the PSWCs. In five patients with a normal or slightly enlarged average N1-P2 amplitude, single sweep (ARX) analysis revealed a period of relative refractoriness following individual PSWCs. In four patients with 'giant' FVEPs, the individual responses occurred regardless of the interval between the stimulus and previous PSWC, but their amplitude had an inverse relationship with the interval length.

CONCLUSIONS

Giant responses to flash stimuli are a common finding in CJD patients (40% of our cases). Single sweep ARX analysis showed that PSWCs were followed by a period of partial refractoriness, which prevented most of the individual responses to flashes, but not giant FVEPs. The association between prominent spontaneous paroxysms and giant FVEPs suggests that both are due to a common hyperexcitable change favouring neuronal synchronisation.

SIGNIFICANCE

Our data contribute to clarifying the debated problem of the occurrence of giant FVEPs in CJD and their relationships with the spontaneous periodic EEG pattern.

Sensorimotor cortex excitability in Unverricht–Lundborg disease and Lafora body disease

Objective: To investigate whether Unverricht–Lundborg disease (ULD) and Lafora body disease (LBD) can be differentiated on the basis of their neurophysiologic profiles.

Methods: Somatosensory evoked potentials (SSEPs), long-loop reflexes (LLRs), and the influence of conditioning nerve stimulation on the motor potentials evoked by transcranial stimulation in 8 patients with LBD and 10 patients with ULD were investigated.

Results: Both groups showed sensorimotor cortex hyperexcitability, but their electrophysiologic profiles were different. Enlarged P25 to N33 SSEP components and enhanced LLRs were common in the ULD patients, whereas medium-latency “giant” SSEP components and less consistently enhanced LLRs were more frequently found in the patients with LBD. Cortical relay time was extremely brief in ULD but varied in LBD. Conditioning somatosensory stimuli differently affected motor cortex excitability, leading to early facilitation in ULD and delayed and prolonged facilitation in LBD.

Conclusions: Patients with Unverricht–Lundborg disease (ULD) and Lafora body disease (LBD) have different electrophysiologic profiles. The ULD findings point to an aberrant subcortical or cortical loop (possibly short-cutting the somatosensory cortex) that is involved in generating the prominent action myoclonus characterizing the disorder. The LBD findings highlight sustained hyperexcitability of the sensorimotor cortex in response to afferent stimuli, which fit with a more severe impairment of inhibitory mechanisms.

Protein-kinase C-dependent phosphorylation inhibits the effect of the antiepileptic drug topiramate on the persistent fraction of sodium currents

We investigated the interference of protein-kinase C (PKC)-dependent Na(+) channel phosphorylation on the inhibitory effect that the antiepileptic drug topiramate (TPM) has on persistent Na(+) currents (I(NaP)) by making whole cell patch-clamp and intracellular recordings of rat sensorimotor cortex neurons. The voltage-dependent activation of I(NaP) was significantly shifted in the hyperpolarizing direction when PKC was activated by 1-oleoyl-2-acetyl-sn-glycerol (OAG). TPM reduced the peak amplitude of I(NaP), but it did not counteract the OAG-induced shift in I(NaP) activation. Firing property experiments showed that the firing threshold was lowered by OAG. TPM was unable to counteract this effect, which may be due to OAG-dependent enhancement of the contribution of subthreshold I(NaP). These data suggest that PKC activation may limit the effect of the anticonvulsant TPM on the persistent fraction of Na(+) currents. The channel phosphorylation that may occur in cortical neurons as a result of physiological or pathological (e.g. epileptic) events can modulate the action of TPM on Na(+) currents.

Movement-activated myoclonus in genetically defined progressive myoclonic epilepsies: EEG-EMG relationship estimated using autoregressive models

OBJECTIVE

To study electroencephalography-electromyography (EEG-EMG) relationships in patients with different forms of progressive myoclonic epilepsies (PME).

METHODS

EEG-EMG auto-spectra, coherence and phase functions were estimated by means of bivariate and time varying autoregressive (AR) models in 15 patients: 8 with Unverricht-Lundborg, 4 with Lafora body disease, and 3 with sialidosis.

RESULTS

The coherence spectra of the EMG epochs including action myoclonus and contralateral frontocentral EEG derivations showed a main beta peak (average coherence: 0.60-0.79) in all patients, regardless of the type of PME. The time lag from cortex to muscle was 13.0-21.3 ms. Significantly, coherent gamma activity was consistently found only in the 3 patients with sialidosis; the most heterogeneous results were obtained in the patients with Lafora disease, who showed a more complex coherence profile. Periods of normal muscle contractions, which could be recorded in patients with Unverricht-Lundborg PME, were characterised by the presence of an EEG-EMG beta coherence peak on the same frequency as in the case of action myoclonus, but with a lower coherence value.

CONCLUSIONS

AR models were capable of describing EEG-EMG relationships in patients with PME, and indicated that coherent cortical and EMG beta oscillations are crucially involved in the generation of myoclonus. Moreover, they could detect the uneven spectral profiles characterising the different forms of PME.

Morphological organization of somatosensory cortex in Otx1(-/-) mice

Knock-out Otx1 mice show brain hypoplasia, spontaneous epileptic seizures and abnormalities of the dorsal region of the neocortex. We investigated structural alterations in excitatory and inhibitory circuits in somatosensory cortex of Otx1(-/-) mice by immunocytochemistry using light, confocal and electron microscopy. Immunostaining for non-phosphorylated neurofilament SMI311 and subunit 1 of the NMDA receptor - used as markers of pyramidal neurons - showed reduced layer V pyramidal cells and ectopic pyramidal cells in layers II and III of the mutant cortex. Immunostaining for calcium-binding proteins calbindin, calretinin and parvalbumin - markers of non-overlapping types of GABAergic interneurons - showed no differences between wild-type and knock-out cortex for calbindin and calretinin neurons, while parvalbumin neurons were only patchily distributed in Otx1(-/-) cortex. The pattern of positivity of the GABAergic marker glutamic acid decarboxylase in Otx1(-/-) cortex was also altered and similar to that of parvalbumin. GABA transporter 1 immunoreactivity was greater in Otx1(-/-) than wild-type; quantitation of structures immunoreactive for this transporter in layer V showed that they were increased overall in Otx1(-/-) but the density of inhibitory terminals on pyramidal neurons in the same layer labeled with this transporter was similar to that in wild-type mice. No differences in the distribution or intensity of the glial markers GABA transporter 3 or glial fibrillary acidic protein were found. The defects found in the cortical GABAergic system of the Otx1(-/-) mouse can plausibly explain the cortical hyperexcitability that produces seizures in these animals.

Brain maturational aspects relevant to pathophysiology of infantile spasms

Infantile spasms (IS) are so typically associated with West syndrome that the term IS, properly referred to as a seizure type, is currently used synonymously with this severe infantile epilepsy. This chapter reviews some clinical and experimental observations relevant to IS pathophysiology with particular regard to maturational aspects that may account for IS age-related expression. Neither the cortical nor the brain stem generator hypotheses account for all the clinical features of IS. It is suggested that IS are generated whenever a cortical discharge is able to influence some archaic circuit located putatively in the brain stem through either an excitatory or a disinhibitory mechanism. This may occur with the highest probability during a developmental window in which IS typically occur, when N-methyl-D-aspartate (NMDA) transmission is particularly facilitated due a reduced sensitivity of NMDA receptors to the Mg2+ block. Interestingly, in this age range (0-18 postnatal day in rat), flexion spasms can be elicited experimentally by NMDA administration. These data provide an important key to further investigating IS pathophysiology, thus allowing us to design more effective strategies aimed at counteracting this harmful infantile epilepsy.

Involvement of CDC25Mm/Ras-GRF1-dependent signaling in the control of neuronal excitability

Ras-GRF1 is a neuron-specific guanine nucleotide exchange factor for Ras proteins. Mice lacking Ras-GRF1 (-/-) are severely impaired in amygdala-dependent long-term synaptic plasticity and show higher basal synaptic activity at both amygdala and hippocampal synapses (Brambilla et al., 1997). In the present study we investigated the effects of Ras-GRF1 deletion on hippocampal neuronal excitability. Electrophysiological analysis of both primary cultured neurons and adult hippocampal slices indicated that Ras-GRF1-/- mice displayed neuronal hyperexcitability. Ras-GRF1-/- hippocampal neurons showed increased spontaneous activity and depolarized resting membrane potential, together with a higher firing rate in response to injected current. Changes in the intrinsic excitability of Ras-GRF1-/- neurons can entail these phenomena, suggesting that Ras-GRF1 deficiency might alter the balance between ionic conductances. In addition, we showed that mice lacking Ras-GRF1 displayed a higher seizure susceptibility following acute administration of convulsant drugs. Taken together, these results demonstrated a role for Ras-GRF1 in neuronal excitability.

Cortical myoclonus in Janz syndrome

OBJECTIVE

To evaluate the characteristics of EEG paroxysms and the relationship between EEG spikes and ictal myoclonic jerks in patients with juvenile myoclonic epilepsy (JME).

METHODS

Six patients with a typical form of JME entered the study and underwent computerized polygraphic recordings. In each patient, the inter-peak spike interval was measured on repeated EEG bursts, and jerk-locked back averaging was performed on ictal epochs using a time window including the 100 ms before and the 100-200 ms after the point at which the jerk-related EMG potential diverged from baseline.

RESULTS

In all cases, the myoclonic jerks were associated with polyspike waves (PSW) complexes. The frequency of repeated spikes within the PSW complex ranged from 16 to 27 Hz. Jerk-locked averaging revealed a positive-negative EEG transient with maximal amplitude on the frontal leads, which preceded the myoclonic jerk by 10.25+/-0.96 ms. A delay of 9.50+/-1.73 ms was measured between the jerk-locked positive peak detected on the frontal EEG leads of the two hemispheres; a comparable time lag was observed between the onset of myoclonic jerks in the two deltoid muscles.

CONCLUSIONS

Our data suggest that the ultimate mechanism responsible for ictal myoclonic jerks in JME is largely similar to that sustaining cortical myoclonus in more severe pathological conditions such as progressive myoclonus epilepsies, despite the different pathogenic substrate and triggering mechanisms.

Potentially epileptogenic dysfunction of cortical NMDA- and GABA-mediated neurotransmission in Otx1-/- mice

Knockout Otx1 mice present a microcephalic phenotype mainly due to reduced deep neocortical layers and spontaneous recurrent seizures. We investigated the excitable properties of layer V pyramidal neurons in neocortical slices prepared from Otx1-/- mice and age-matched controls. The qualitative firing properties of the neurons of Otx1-/- mice were identical to those found in wild-type controls, but the proportion of intrinsically bursting (IB) neurons was significantly smaller. This is in line with the lack of the Otx1 gene contribution to the generation and differentiation of neurons destined for the deep neocortical layers, in which IB neurons are located selectively in wild-type rodents. The pyramidal neurons recorded in Otx1-/- mice responded to near-threshold electrical stimulation of the underlying white matter, with aberrant polysynaptic excitatory potentials often leading to late action potential generation. When the strength of the stimulus was increased, the great majority of the Otx1-/- neurons (78%) responded with a prominent biphasic inhibitory postsynaptic potential that was significantly larger than that observed in the wild-type mice, and was often followed by complex postinhibitory depolarizing events. Both late excitatory postsynaptic potentials and postinhibitory excitation were selectively suppressed by NMDA receptor antagonists, but not by AMPA antagonists. We conclude that the cortical abnormalities of Otx1-/- neocortex due to a selective loss of large projecting neurons lead to a complex rearrangement of local circuitry, which is characterized by an excess of N-methyl-d-aspartate-mediated polysynaptic excitation that is counteracted by GABA-mediated inhibition in only a limited range of stimulus intensity. Prominent postsynaptic inhibitory potentials may also act as a further pro-epileptogenic event by synchronizing abnormal excitatory potentials.

Labeling of rat neurons by anti-GluR3 IgG from patients with Rasmussen encephalitis

The authors report the immunocytochemical localization in rat brain of affinity-purified anti-GluR3 (glutamate receptor) antibodies from two patients with Rasmussen encephalitis (RE) and from immunized rabbits. The distribution of immunolabeling was similar using antibodies from rabbits and patients with RE. No electrophysiologic responses were elicited from acutely dissociated kainate-responsive neurons isolated from rat brain when these antibodies were applied. These findings show that anti-GluR3 antibodies purified from patients with RE bind to specific regions of the CNS but do not act through an excitotoxic mechanism.

Epileptic phenotypes associated with mitochondrial disorders

OBJECTIVE

To define the clinical and EEG features of the epileptic syndromes occurring in adult and infantile mitochondrial encephalopathies (ME).

METHODS

Thirty-one patients with recurrent and apparently unprovoked seizures associated with primary ME were included in the study. Diagnosis of ME was based on the recognition of a morphologic, biochemical, or molecular defect.

RESULTS

Epileptic seizures were the first recognized symptom in 53% of the patients. Many adults (43%) and most infants (70%) had nontypical ME phenotypes. Partial seizures, mainly with elementary motor symptoms, and focal or multifocal EEG epileptiform activities characterized the epileptic presentation in 71% of the patients. Generalized myoclonic seizures were an early and consistent symptom only in the five patients with an A8344G mitochondrial DNA point mutation with classic myoclonus epilepsy with ragged red fibers (MERRF) syndrome or "overlapping" characteristics. Photoparoxysmal EEG responses were observed not only in patients with typical MERRF, but also in adult patients with ME with lactic acidosis and strokelike episodes (MELAS), or overlapping phenotypes, and in one child with Leigh syndrome.

CONCLUSIONS

Epilepsy is an important sign in the early presentation of ME and may be the most apparent neurologic sign of nontypical ME, often leading to the diagnostic workup. Except for those with an A8344G mitochondrial DNA point mutation, most of our patients had partial seizures or EEG signs indicating a focal origin.

Electroencephalographic features in a series of patients with neuronal ceroid lipofuscinoses

We report the electroencephalographic (EEG) features of 22 patients with neuronal ceroid lipofuscinoses (NCL) who were referred to the Neurological Institute of Milan between 1984 and 1998. The EEG data were reviewed, taking into account the different forms of NCL on the basis of age at onset, clinical features and morphological appearance. The study group included patients with infantile NCL (one case), late-infantile NCL (ten cases), juvenile NCL (seven cases) and adult NCL (four cases). We looked for the presence of homogeneous EEG features associated with these different forms, particularly in the early phases of the disease. Our data indicate that the EEG characteristics of late-infantile NCL and of the myoclonic form of adult NCL are quite distinctive, and that their particular spontaneous epileptiform anomalies and response to intermittent light stimulation can be considered relevant diagnostic clues at an early disease stage.