Action potential compound muscle

The causative oiganophosphate was identified in nine patients four fenthion, two dimethoate. two monocrotophos, and one mclhamidophos. Standard biochemistry and cerebrospinal fluid examination were normal. Cholinesterase (ChE) assays were not available. Electromyography (EMG) showed normal motor and sensory nerve conduction velocities and normal needle myography. Tetanic stimulafion of the abductor pollicis brevis muscle 24-48 hr after the onset of IMS showed a marked fade at 20 and 50 Hz. A train of four stimuli applied at 2 Hz produced no changes in the amplitude of the compound muscle action potential (CMAP). CMAPs are the motor responses recorded with surface electrodes over a muscle after stimulation of its motor nerve. 

Compound muscle action potential (amplitude)" Reduced Nramal to slightly reduced Normal NOTmal... 

Amplitude of compound muscle action potential with stimulation at 3 Hz Unchanged Unchanged Decreased Unchanged... 

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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