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Query: UMLS:C0027066 (myoclonus)
 4,275 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Epilepsy with myoclonus is thought to be linked to the motor system. At birth, development of the central nervous system in humans is far from being achieved. Post-natal changes take place at different levels in this neuronal system. These modifications suggest that the motor cortex is a highly dynamic structure during post-natal development. They may account for the age-dependence of various epileptic syndromes. (1) The number of synapses increases during the early post-natal years and then decreases to reach the adult level around puberty. (2) Neurons differentiate and synthesize various neurotransmitters. (3) Dendrites grow actively and participate in the formation of local cortical circuits. (4) Electrophysiological properties of cortical neurons change during the first months of rodent development. This could reflect modifications of the ion channels present in the cell membrane. (5) The pyramidal tract myelinate and exuberant collaterals are selectively removed. These two processes are dependent on neuronal electrical activity. It has been demonstrated that selective collateral stabilization is promoted by glutamate release and stimulation of the N-methyl-D-aspartate (NMDA) receptor. So, seizures occurring during the neonatal period may interact with these normal developmental features. Furthermore, neuronal electrical activity and seizures stimulate the transcription of specific messenger RNAs coding for neurotrophic factors like nerve growth factor (NGF) or brain-derived neurotrophic factor (BDNF). The overproduction of neurotrophic factors leads to maldevelopment of the cortex.
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PMID:Epilepsy with myoclonus and post-natal development of the motor system in humans: a hypothesis. 941 55

In this study, we have investigated the expression of the nuclear transcription factor (c-Fos, NFkB), growth factors (nerve growth factor--NGF, brain-derived neurotrophic factor--BDNF), peptides (enkephalin, galanin) and glutamate transporter (AA 504-523 rat EAAC1) in 6 dogs sacrificed immediately after seizure attack during encephalomyelitis due to canine distemper virus (CDV) (as assessed by clinical examination, RT-PCR and viral RNA detection either in blood or brain tissue and CDV immunohistochemistry in brain slices). In all these CDV affected dogs, the observed neurological signs included untreatable seizures, leading to cluster seizure activity and status epilepticus. In the inter-ictal phase abnormal mentation, postural and gait deficits and sometimes involuntary movements such as myoclonus were recorded. The same investigation was carried out in 5 control dogs affected by different disorders, all characterized by the absence of seizures. Brains were dissected out immediately after euthanasia and fixed; sections collected from the dorsal hippocampus were processed for immunohistochemistry. By comparing hippocampus sections obtained from dog with and without seizure, the following regulations were observed. A strong up-regulation of glutamate transporter throughout the cell layers was found together with the onset of nuclear Fos and NFkB-IR in the pyramidal cell layer X. Among the investigated peptides, we observed a slight increase in enkephalinergic fibers and a strong up-regulation of mu-opioid receptors, whereas galanin-IR seemed to be weaker. Finally, both NGF and BDNF expression was strongly up-regulated. BDNF-IR was mainly localized in the apical dendrite in pyramidal neurons. To our knowledge, these data offer the first indication that molecular events described in experimental kindling also occur during spontaneous pathology in animal species sharing close similarities to human neuropathology.
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PMID:A molecular study of hippocampus in dogs with convulsion during canine distemper virus encephalitis. 1676 33