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.

Pre-ictal increase in theta synchrony between the hippocampus and prefrontal cortex in a rat model of temporal lobe epilepsy.

The pathologically synchronized neuronal activity in temporal lobe epilepsy (TLE) can be triggered by network events that were once normal. Under normal conditions, hippocampus and medial prefrontal cortex (mPFC) work in synchrony during a variety of cognitive states. Abnormal changes in this circuit may aid to seizure onset and also help to explain the high association of TLE with mood disorders. We used a TLE rat model generated by perforant path (PP) stimulation to understand whether synchrony between dorsal hippocampal and mPFC networks is altered shortly before a seizure episode. We recorded hippocampal and mPFC local field potentials (LFPs) of animals with spontaneous recurrent seizures (SRSs) to verify the connectivity between these regions. We showed that SRSs decrease hippocampal theta oscillations whereas coherence in theta increases over time prior to seizure onset. This increase in synchrony is accompanied by a stronger coupling between hippocampal theta and mPFC gamma oscillation. Finally, using Granger causality we showed that hippocampus/mPFC synchrony increases in the pre-ictal phase and this increase is likely to be caused by hippocampal networks. The dorsal hippocampus is not directly connected to the mPFC; however, the functional coupling in theta between these two structures rises pre-ictally. Our data indicates that the increase in synchrony between dorsal hippocampus and mPFC may be predictive of seizures and may help to elucidate the network mechanisms that lead to seizure generation.

Refractory nonconvulsive status epilepticus in coma: analysis of the evolution of ictal patterns / Estado de mal epiléptico não convulsivo refratário no coma: análise da evolução dos padrões ictais

OBJECTIVE: Nonconvulsive status epilepticus (NCSE) is currently considered as one of the most frequent types of status epilepticus (SE). The objective of the present study was to identify the natural history of the electrographical evolution of refractory NCSE and to establish the relationship between ictal patterns and prognosis. METHODS: We analyzed, retrospectively, 14 patients with loss of consciousness and NCSE. The ictal patterns were classified as discrete seizures (DS), merging seizures (MS), continuous ictal discharges (CID), continuous ictal discharges with flat periods (CID-F), and periodic lateralized epileptiform discharges (PLEDs). RESULTS: The ictal patterns were DS (n=7; 50.0%), PLEDs (n=3; 1.4%), CID (n=2; 14.3%), MS (n=1; 7.1%), and CID-F (n=1; 7.1%). CONCLUSIONS: NCSE electrographic findings are heterogeneous and do not follow a stereotyped sequence. PLEDs were related to a higher probability of neurological morbidity and mortality.

OBJETIVO: Estado de mal epiléptico não convulsivo (EMENC) é atualmente considerado uma das formas mais frequentes de estado de mal epiléptico. O objetivo deste estudo foi identificar a história natural da evolução eletrográfica do EMENC refratário, bem como estabelecer relações entre padrões ictais e o prognóstico. MÉTODOS: Foram analizados, retrospectivamente, 14 pacientes com comprometimento da consciência e EMENC. Os padrões ictais foram classificados em crises isoladas (CI), crises subintrantes (CS), descarga ictal contínua (DIC), descarga ictal contínua com períodos de atenuação (DIC-A) e descargas epileptiformes periódicas lateralizadas (PLEDs). RESULTADOS: Os padrões ictais observados foram CI (n=7; 50,0%), PLEDs (n=3; 1,4%), DIC (n=2; 14,3%), CS (n=1; 7,1%) e DIC-A (n=1; 7,1%). CONCLUSÕES: Achados eletrográficos no EMENC refratário são heterogêneos e não obedecem a uma sequência estereotipada. As PLEDs estão associadas à maior probabilidade de morbidade e mortalidade neurológica.