Photosensitive epilepsy: spectral and coherence analyses of EEG using 14Hz intermittent photic stimulation.

OBJECTIVE: To evaluate the EEG recorded in photosensitive idiopathic generalised epilepsy (IGE) patients at rest and during 14Hz IPS, frequency capable of inducing photoparoxysmal responses (PPRs). METHODS: Power spectrum density and coherence profiles were estimated using a block autoregressive parametric model (AR) in 28 patients and 22 controls. RESULTS: At rest, the intra- and inter-hemispheric coherence spectra showed a significantly larger number of coherence peaks in the gamma band in patients with respect to controls. During intermittent photic stimulation (IPS), coherent gamma activity is mainly presented as IPS frequency harmonics; moreover, the patients' mean coherence values significantly increased. In six patients re-evaluated with IPS after putting on glasses with Z1 blue lens (which counteracts PPR) the spectral and coherence profiles tended to return to the resting ones. CONCLUSIONS: Patients are endowed with inherited EEG hyper-synchrony as shown by the large number of coherence peaks detectable under resting conditions, whereas IPS enhances intra- and inter-hemispheric mean coherence values in the gamma band. The persistence of alpha activity peaks during IPS in most controls but not in patients suggests that the alpha generating network plays a significant role in counteracting PPR. SIGNIFICANCE: Both gamma and alpha EEG generators are involved in the PPR generation and in the widespread synchronisation characterising the IGE-associated photosensitivity.

A novel phenotype of sporadic Creutzfeldt-Jakob disease.

An atypical case of sporadic Creutzfeldt-Jakob disease (CJD) is described in a 78-year-old woman homozygous for methionine at codon 129 of the prion protein (PrP) gene. The neuropathological signature was the presence of PrP immunoreactive plaque-like deposits in the cerebral cortex, striatum and thalamus. Western blot analysis showed a profile of the pathological form of PrP (PrP(Sc)) previously unrecognised in sporadic CJD, marked by the absence of diglycosylated protease resistant species. These features define a novel neuropathological and molecular CJD phenotype.

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.

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.

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.

Spectral properties of EEG fast activity ictal discharges associated with infantile spasms.

OBJECTIVE: The aim of this study was to evaluate the characteristics of the ictal EEG event accompanying infantile spasms. METHODS: Quantitative analysis was used, based on the application of a bivariate autoregressive (AR) parametric model; autospectra, coherence, phase functions and inter-hemispheric time differences were estimated on homologous EEG channels in 18 infants presenting with either cryptogenic or symptomatic West syndrome. RESULTS: The AR analysis of the 500 ms EEG epochs preceding spasm onset revealed the presence of a short discharge of fast activity restricted to a narrow frequency band in 13 of the 18 cases included in the study. The fast discharge peaked at 17.5+/-2.1 Hz, with rather low inter-hemispheric coherence values (0.52+/-0.17) and asymmetric amplitude on homologous EEG derivations. It persisted briefly after spasm onset, reaching a higher coherence value (0.71+/-0.16). The inter-hemispheric time difference, estimated in those cases with the coherence values significantly different from zero, ranged from 9.1 to 14.3 ms (11.4+/-1.9) in the epoch preceding spasm onset. CONCLUSION: The data obtained from the analysis of the ictal EEG events, compared with clinical and interictal EEG features, indicate that an asymmetric EEG pattern (mainly consisting of a rhythmic burst of fast activity) consistently preceded both symmetric and asymmetric spasms, thus suggesting a localized cortical origin of the ictal discharge giving rise to the spasms.

Infantile neuroaxonal dystrophy: clinical spectrum and diagnostic criteria.

OBJECTIVE: To present clinical, neurophysiologic, and neuroradiologic findings in 13 patients with infantile neuroaxonal dystrophy (INAD), focusing on aspects that assist early diagnosis. BACKGROUND: Clinicopathologic diagnostic criteria for INAD were delineated by Aicardi and Castelein in 1979, but atypical cases are reported frequently and little is known of the diagnostic utility of MRI. METHODS: The authors reviewed the clinical, neurophysiologic, and MRI findings of 13 patients who met the diagnostic criteria for INAD. RESULTS: Symptoms onset was between 6 months and 2 years of age. In nine patients the clinical course was typical, with rapid motor and mental deterioration; in four patients progression was slower and the clinical picture was different. Electromyographic (EMG) signs of chronic denervation, fast rhythms on EEG and abnormal visual evoked potentials were observed in all patients during the disease course. Cerebellar atrophy with signal hyperintensity in the cerebellar cortex on T2-weighted images were the most characteristic MRI findings; hypointensity in the pallida and substantia nigra was also observed in two patients. alpha-N-acetyl-galactosaminidase activity on leukocytes was normal in the 10 patients tested. CONCLUSIONS: EMG and MRI abnormalities are the earliest and most suggestive signs of INAD, which has a clinical and radiologic spectrum that is broader than reported previously.

Partial seizures associated with antiphospholipid antibodies in childhood.

We report antiphospholipid antibody positivity in three of a consecutive series of 23 children presenting partial epileptic seizures. There was no clinical or serological evidence of systemic lupus erythematosus or other connective-tissue disease. Neither computed tomography nor magnetic resonance imaging revealed ischemic alteration. The presence of antiphospholipid antibodies in 3/23 children may indicate that immune-mediated neuronal damage could be a pathogenetic mechanism for partial epilepsy.

Neuronal ceroid-lipofuscinosis: a clinical and morphological study of 19 patients.

We report on clinical, electrophysiological, neuroradiological, and morphological data from 19 patients with different types (late infantile, juvenile, and adult) of neuronal ceroid-lipofuscinosis (NCL), observed in the last 10 years at the Neurological Institute of Milan. Late Infantile NCL (LINCL) (8 patients, 4m/4f). Age at onset: 2-4 1/2 years. Seizures (6 patients) or decline of mental capacities (2 patients) were the presenting symptoms, followed by myoclonus and ataxia; visual loss and optic atrophy occurred in 6 patients within 3 years. All but 2 children became bedridden within 3 1/2 years. CT and MRI demonstrated different degrees of cerebral and cerebellar atrophy within 3 years from onset of the disease. Ultrastructural studies showed fingerprint profiles (FP) and osmiophilic bodies (OB) in circulating lymphocytes; curvilinear bodies (CB) and FP were detected in eccrine secretory cells. Juvenile NCL (JNCL) (7 patients, 4m/3f). Age at onset: 6-9 years. Visual loss with retinal degeneration was the presenting symptoms, accompanied in all but 2 patients by slight mental impairment. Seizures occurred within 2-4 years. CT and MRI detected cerebral or cerebellar atrophy in those patients (5 patients) with a clinical follow-up longer than 4 years. Electron microscopy showed FP on circulating lymphocytes, and both FP and CB on skin biopsy specimens. Adult NCL (ANCL) (4 patients, 3 m/1f). Age at onset: 12-50 years. Progressive myoclonus epilepsy (1 patient) or dementia with motor disturbances (3 patients) were the clinical phenotypes of the disease. MRI demonstrated cerebral and cerebellar atrophy within 6 years from onset. Electron microscopy disclosed FP in cytoplasmic vacuoles inside eccrine secretory cells.

Intrathecal immune activation in three patients with progressive myoclonic ataxia.

Three patients displaying a clinical picture of progressively evolving multifocal action myoclonus and cerebellar ataxia showed a marked intrathecal immune activation, which was persistent over a 2- to 5-year time span in the two serially investigated patients. A thorough search for metabolic, toxic, infectious, or degenerative causes of myoclonus was unsuccessful. The presence of intrathecal immune activation in at least a subgroup of patients with the clinical features of progressive myoclonic ataxia suggests the possibility of immune-mediated damage within the central nervous system in this condition.

Primary antiphospholipid syndrome (PAPS) and isolated partial seizures in adolescence. A case report.

The case of a young male patient presenting isolated clustered partial seizures is reported. Despite the normality of the neurological features, as well as of ictal and interictal EEG, the MRI (performed three days after the symptoms) disclosed bilateral signal alterations in the parietal cortical region. These abnormalities disappeared at the MRI control examination performed one month later. The finding of positive anticardiolipine antibodies made possible the diagnosis of partial epileptic seizures symptomatic of a vascular disorder ascribed to a Primary antiphospholipid Syndrome (PAPS).

Burst suppression and impairment of neocortical ontogenesis: electroclinical and neuropathologic findings in two infants with early myoclonic encephalopathy.

We report the electroclinical and neuropathologic correlations in 2 children aged 2.5 months affected by early myoclonic encephalopathy characterized by epileptic seizures, erratic myoclonus, and an EEG pattern of burst suppression. Despite different etiologies, the neuropathologic findings showed similar abnormalities in both cases, with no substantial impairment of the myelination processes. Islands of matrix tissue scattered in the periventricular region and neurons aligned marginally in the bulbar olives were detected. The presence of numerous large spiny neurons dispersed in the white matter along the axons of the cortical gyri was the most striking finding. The neurons have been interpreted as abnormally persisting interstitial cells in 2.5-month-old children. These early generated neurons, normally present during neocortical histogenesis, are programmed to die near the end of gestation or soon after birth. The interstitial cells are regarded as a waiting compartment of afferent fibers during cortical development. Their persistence in our patients represents an anatomic condition for cortical disconnection providing a pathophysiologic basis to burst-suppression phenomena.

Adult onset myoclonic Huntington's disease.

A patient with adult onset Huntington's disease (HD) and prominent action myoclonus is described. Neither epileptiform activity nor electroencephalography (EEG) correlates of the movements was found. Unlike the case with most (nonmyoclonic) HD patients, centro-parietal components of somatosensory evoked potentials (SEPs) were well defined and a clear V2 response was found. Treatment with valproic acid greatly reduced myoclonus suggesting that the gamma-aminobutyric acid (GABA) system might be involved in the pathophysiology of myoclonus in HD.

Progressive myoclonus epilepsies: an electroclinical, biochemical, morphological and molecular genetic study of 17 cases.

Electroclinical, morphological, biochemical and molecular genetic data from 17 patients affected by progressive myoclonus epilepsies (PME) are reported. Twelve patients were characterized by prominent action myoclonus, sporadic seizures, mild ataxia, lack of dementia and persistence of normal EEG background activity; three patients showed a more rapid worsening of symptomatology, characterized by early mental impairment, massive and action myoclonus, cerebellar signs and tonic clonic seizures; in these patients EEG background activity was slow, even in early stages of the disease. In two patients, previously classified as cryptogenetic PME, a mitochondrial aetiology was recognized by the presence of ragged red fibers in muscle biopsy and by a reduction of the respiratory chains enzymes. Molecular genetical investigation of mtDNA demonstrated the reported heteroplasmic point mutation at nt 8344 of mtDNA in the two MERRF patients, while it was negative in all of the others.

Intrauterine growth in the offspring of epileptic mothers.

The present paper concerns the fetal growth of 315 newborns of epileptic mothers prospectively followed from the beginning of pregnancy. In comparison with Italian standards, neonatal weight, length and head circumference at birth were below the 10th percentile in respectively 15.7%, 1.1% and 19.2% of the newborns. Weight at birth was above the 90th percentile in 8 cases. Observed frequencies were significantly higher than expected frequencies for both weight and head circumference. The percentage of newborns with a small head circumference increased significantly according to the number of drugs taken by the mother during the first three months of pregnancy: 7.1% with no drug, 16.8% with one drug, 23.6% with two drugs and 50% with three drugs. A statistically significant correlation was found between gestational age-adjusted head circumference and drug-level scores during the first trimester. Head circumferences below the 10th percentile were fewer among newborns treated with CBZ than among newborns treated with either PB or VPA.

Malformations in offspring of 305 epileptic women: a prospective study.

This paper deals with malformations detected in 26 of 315 newborns of 305 epileptic mothers followed prospectively. In 3 more cases, malformations were detected in utero and therapeutic abortion was performed. Two hundred and seven women were on monotherapy, 102 on polytherapy and 9 were not treated. In total, malformations overall incidence was 9.1%. Minor anomalies were detected in 42 newborns (13.3%). A higher rate of malformations and minor anomalies was found among offspring of mothers treated with valproic acid (VPA). In the VPA group, mothers of malformed babies had higher plasma levels in the first trimester than mothers of babies without malformations. The need for accurate prenatal diagnostic studies in pregnant women with epilepsy is stressed.

Influence of surgery and antiepileptic drugs on seizures symptomatic of cerebral tumours.

One hundred and twenty-eight adult patients presenting with and operated on for supratentorial neoplasms were studied. Sixty-five had preoperative seizures and were treated with antiepileptic drugs (AEDs). Among the 63 patients without preoperative epileptic fits, 41 were given AEDs (either phenobarbital or phenytoin) as prophylactic treatment and 22 were not treated. The preoperative epilepsy course was considered with respect to tumour site and histological type. Early and late postoperative seizure occurrence was considered in the different groups of patients. The results suggest the usefulness of a short term preventive treatment with AEDs after surgery in patients without preoperative seizures. In patients with preoperative epilepsy, AEDs should be continued after surgery. However long-term AEDs treatment should not be recommended in patients without preoperative epilepsy. In fact, no significant difference in late seizure occurrence was found between preventively treated and untreated patients.

Cerebral MR findings in tuberous sclerosis.

Cerebral magnetic resonance (MR) and CT findings of two sisters affected by clinically defined tuberous sclerosis are reported. Magnetic resonance showed a greater number of lesions than did CT. In addition, MR depiction of the abnormalities better corresponded to the pathological findings usually described in this disease.

Plasma concentrations of carbamazepine and carbamazepine 10,11-epoxide during pregnancy and after delivery.

Plasma concentrations of carbamazepine were monitored in 9 pregnant epileptic patients treated with the drug alone at constant doses during pregnancy and for at least 3 months after delivery. In addition, plasma concentrations of the metabolite, carbamazepine 10,11-epoxide were measured in 6 of the 9 patients. Plasma carbamazepine concentrations were fairly stable during pregnancy, and carbamazepine relative plasma clearances were significantly higher in weeks 4 to 24 than in weeks 25 to 32. After the end of the second trimester, there were no variations in plasma carbamazepine 10,11-epoxide concentrations and carbamazepine 10,11-epoxide:carbamazepine ratios. Both parameters were significantly higher in weeks 4 to 24 than in weeks 25 to 32 of pregnancy.

Changes in primidone/phenobarbitone ratio during pregnancy and the puerperium.

Plasma concentrations of primidone and its metabolite phenobarbitone were monitored in 9 pregnant epileptic patients treated with primidone (and in 3 cases other antiepileptic drugs) given at constant doses throughout pregnancy and the puerperium. Phenobarbitone plasma concentrations were monitored in another 6 patients given phenobarbitone itself. A trend towards increasing primidone plasma concentrations during the second quarter of pregnancy was evident in all patients, with a concomitant significant decrease in primidone-derived phenobarbitone plasma concentrations. A trend towards a lowering of plasma concentrations of phenobarbitone administered as such was confirmed. These results suggest the usefulness of a careful monitoring of primidone and primadone-derived phenobarbitone during pregnancy and the puerperium. Discrepancies of findings with primidone and phenobarbitone are discussed in view of the possible mechanism involved.