E. Gardella

Encephalopathy with electrical status epilepticus during slow sleep or ESES syndrome including the acquired aphasia

Encephalopathy with electrical status epilepticus during sleep or ESES is an age-dependent and self-limited syndrome whose distinctive features include a characteristic age of onset (with a peak around 4-5 years), heterogeneous seizures types (mostly partial motor or unilateral seizures during sleep and absences or falls while awake), a typical EEG pattern (with continuous and diffuse paroxysms occupying at least 85% of slow wave sleep) and a variable neuropsychological regression consisting of IQ decrease, reduction of language (as in acquired aphasia or Landau-Kleffner syndrome), disturbance of behaviour (psychotic states) and motor impairment (in the form of ataxia, dyspraxia, dystonia or unilateral deficit). Despite the long-term favourable outcome of epilepsy and status epilepticus during sleep (SES), the prognosis is guarded because of the persistence of severe neuropsychological and/or motor deficits in approximately half of the patients. No specific treatment has been advocated for this syndrome, but valproate sodium, benzodiazepines and ACTH have been shown to control the seizures and the SES pattern in many cases, although often only temporarily. Subpial transection is proposed in some instances as in non-regressive acquired aphasia. Recent data support the concept that ESES syndrome may include a large subset of developmental or acquired regressive conditions of infancy.

Central pattern generators for a common semiology in fronto-limbic seizures and in parasomnias. A neuroethologic approach.

Central pattern generators (CPGs) are genetically determined neuronal aggregates in the mesencephalon, pons and spinal cord subserving innate motor behaviours essential for survival (feeding, locomotion, reproduction etc.). In higher primates CPGs are largely under neocortical control. We describe how certain motor events observed in parasomnias and epileptic seizures could have similar features and resemble motor behaviours, which can be the expression of the same CPG. Both epilepsy and sleep can lead to a temporary loss of control of neomammalian cortex that facilitates through a common platform (arousal) the emergences of stereotyped inborn fixed action patterns. Therefore we suggest that, independently from the nature of the trigger, be it a seizure or a parasomnia, the same CPGs can be involved, “caught up”, leading to a common motor semiology (the “Carillon theory”).

Transcranial magnetic stimulation in partial epilepsy: drug-induced changes of motor excitability

Single‐pulse transcranial magnetic stimulation (s‐TMS) with recording of motor evoked potentials (MEPs) from thenar muscles of both hands was performed on 84 patients with cryptogenic partial epilepsy and 50 healthy controls. We analyzed the cortical latency (CL), central conduction time (CCT), and threshold intensity (TI) required to elicit liminal MEPs at rest. In the patients, CL and CCT were normal, but TI was significantly higher than in the controls. Of the 84 patients, 65 were taking one or more antiepileptic drugs and 19 were untreated. The untreated patients had a significantly lower TI than the treated patients. In the treated patients, the TI increase paralleled the number of drugs taken. Additionally, in 2 subgroups of patients undergoing major modifications of antiepileptic treatment, TI dropped after partial withdrawl of medication and increased following the commencement of therapy. The results suggest that anticonvulsants depress the excitability of human motor pathways in epileptic subjects.

Electroclinical features of idiopathic generalised epilepsy with persisting absences in adult life.

OBJECTIVES: To describe the electroclinical features of typical absences persisting in adult life. METHODS: Twelve adult patients (aged 21 to 56 years) with idiopathic generalised epilepsy featuring typical absences as the prominent clinical feature were studied. All patients underwent a full clinical and neurophysiological investigation including ictal documentation of seizures. RESULTS: Neurological examination and neuroradiological investigations were normal in all cases. Clinical findings included a median age at onset of absences of 14 (range 4-32) years, almost constant tonic-clonic seizures (in 83% of patients), frequent episodes of absence status (in 33% of patients), and associated cognitive or psychiatric disturbances. Interictal EEG findings showed normal background activity, generalised paroxysms of spike waves or polyspike waves, and inconstant focal spikes (in five patients); runs of polyspikes were seen during non-REM sleep. Ictal EEG findings showed generalised spike waves at 3 Hz, sometimes preceded by multiple spikes, or more complex EEG patterns with sequences of polyspikes intermingled with spike waves or polyspike waves, showing discharge fragmentation or variation of intradischarge frequency. CONCLUSION: The results of the present study show that absences persisting in adult life may show particular clinical and EEG patterns, distinct from those in childhood or adolescence.

A wavelet-based energetic approach for the analysis of biomedical signals: Application to the electroencephalogram and electro-oculogram

Wavelet transform has emerged over recent years as a favoured tool for the investigation of biomedical signals, which are highly non-stationary by their nature. A relevant wavelet-based approach in the analysis of biomedical signals exploits the capability of wavelet transform to separate the signal energy among different frequency bands (i.e., different scales), realizing a good compromise between temporal and frequency resolution. The rationale of this paper is twofold: (i) to present a mathematical formalization of energy calculation from wavelet coefficients, in order to obtain uniformly time distributed atoms of energy across all the scales; (ii) to show two different applications of the wavelet-based energetic approach to biomedical signals. One application concerns the study of epileptic brain electrical activity, with the aim of identifying typical patterns of energy redistribution during the seizure. Results obtained from this method provide interesting indications on the complex spatio-temporal dynamics of the seizure. The other application concerns the electro-oculographic tracings, with the purpose of realizing an automatic detector of a particular type of eye movements (slow eye movements), important to identify sleep phases. The algorithm is able to identify this eye movement pattern efficiently, characterizing it in rigorous energetic terms. The energetic approach built within the framework of the multiresolution decomposition appears as a powerful and versatile tool for the investigation and characterization of transient events in biomedical signals.

A video-polygraphic analysis of the cataplectic attack.

OBJECTIVES AND METHODS To perform a video-polygraphic analysis of 11 cataplectic attacks in a 39-year-old narcoleptic patient, correlating clinical manifestations with polygraphic findings. Polygraphic recordings monitored EEG, EMG activity from several cranial, trunk, upper and lower limbs muscles, eye movements, EKG, thoracic respiration. RESULTS Eleven attacks were recorded, all of them lasting less than 1 min and ending with the fall of the patient to the ground. We identified, based on the video-polygraphic analysis of the episodes, 3 phases: initial phase, characterized essentially by arrest of eye movements and phasic, massive, inhibitory muscular events; falling phase, characterized by a rhythmic pattern of suppressions and enhancements of muscular activity, leading to the fall; atonic phase, characterized by complete muscle atonia. Six episodes out of 11 were associated with bradycardia, that was maximal during the atonic phase. CONCLUSIONS Analysis of the muscular phenomena that characterize cataplectic attacks in a standing patient suggests that the cataplectic fall occurs with a pattern that might result from the interaction between neuronal networks mediating muscular atonia of REM sleep and neural structures subserving postural control.

Age-related gender differences in reporting ictal fear: analysis of case histories and review of the literature.

To determine if there are age or gender‐related differences in reporting fear as a symptom of epileptic seizure, all clinical charts of patients evaluated at the “C. Munari – Epilepsy Surgery Center” of Milan from 1990 to June 2005 were analyzed, looking for patients with ictal fear. Among the 2,530 clinical charts examined (1,330 male and 1,200 female), 265 patients were found with ictal fear (100 men, 165 women). The gender difference in reporting ictal fear was not so marked in the pediatric age group (98 girls, 74 boys), whereas in adult patients the difference was significant (158 women, 83 men). Interestingly, more men than women (14:3) had ictal fear during childhood that disappeared during adulthood. The literature review confirmed that ictal fear is significantly more common in women, though there is no gender difference in the pediatric age group.

Photic reflex myoclonus: a neurophysiological study in progressive myoclonus epilepsies.

Purpose: To investigate the neurophysiological features of photic reflex myoclonus (PRM) in patients with progressive myoclonus epilepsies (PMEs) of different types (Unverricht‐Lundborg disease, Laforas disease, cryptogenic).

Ictal grasping: prevalence and characteristics in seizures with different semiology.

Summary:  Purpose: The aim of this study was to investigate ictal grasping (IG), defined as the act of gripping something firmly during focal epileptic seizures, and to evaluate whether it characterizes specific seizure types.

A wavelet based analysis of energy redistribution in scalp EEG during epileptic seizures

In this work, wavelet decomposition and multiresolution analysis are used to explore the changes in scalp EEG signals during epileptic seizures. EEG tracings, which include non-epileptic periods, the beginning of seizure and the peak of seizure, have been decomposed in five details using order 10 Daubechies orthonormal wavelets. Energy has then been computed, at each detail, from square wavelet coefficients, in order to unmask the presence of brief episodes of energy relocation among different scales. Results reveal the existence of significant changes in energy distribution at seizure onset; this redistribution, however, exhibits significant differences from one patient to another, and also among different channels in the same patient. Some channels exhibit a significant energy increase at low scales (high frequencies greater than 20 Hz) at seizure onset, whereas energy drops at higher scales. Other channels, however, exhibit energy increase at high scales (frequency less than 15 Hz) revealing a predominance of low-frequency activity. These two patterns may be simultaneously present at seizure onset and may change with different spatial evolution during the subsequent seizure progression. Wavelet analysis appears as a powerful tool for extracting features relative to seizure, and to study their propagation among different regions in the scalp.