Electrophysiology muscle recording

Formal neurobehavioral evaluation of both children at age 3 years 10 months generated the results summarized in Table 7-1. Further testing of Elizabeth showed profound hypotonia (decreased muscle tone), electrophysiologi-cal evidence of peripheral neuropathy, normal somatosensory evoked potentials, and a normal electroencephalogram recorded during sleep. 

The low-affinity fast channel syndrome is a rare, recessive condition where patients generally present with moderately severe myasthenic symptoms from birth (Uchitel et al 1993, Ohno et al 1996). Electrophysiologic studies revealed decremental CMAP and very small MEPPs. Single channel recordings from biopsied muscle endplate showed infrequent, abnormally brief openings in response to ACh. Morphologic studies demonstrated normal end plate structure, with normal number of AChR and no evidence of myopathy. 

Figure 2. Schematic diagram the electrophysiological assay used to test for biological activity of spider venom components. Lx>ngitudinal ventrolateral muscles of Musca domestica were impaled with an intracellular microelectrode, which recorded excitatory junctional potentials (EJP) in response to nerve stimulation or ionophoretic junctional potentials (IP) in response to glutamate application by ionophoresis.

The electrophysiological procedure provided an evaluation of the reinnervation of plantar muscles after transection and grafting of the sciatic nerve. Electrical stimuli were applied to the nerve via percutaneous needle electrodes, both proximal and distal to the transection site, and the resulting compound muscle action potentials (CMAPs) elicited in the plantar muscles of the foot were recorded using a concentric needle. The time between the stimulation of the nerve and the onset of the elicited CMAPs, termed the distal motor latency, was measured. ... 

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