Lesion of nerves
Electrical response are useful in diagnosis of injury or lesion of nerves.
These changes will be the following.
1. A lesion of upper motor neuron
2.A lesion of lower motor neuron
3.Damage to the muscle itself
4.A functional disorder
Changes in electrical reaction
When there is a disease or injury of motor nerve or muscles then there will be a change in their response to electrical stimulation.
Upper Motor Neurone Lesion (UMNL)
When there is a lesion of upper motor neuron there is no change in lower motor neuron (in the accessible part of the motor pathway) which would lead to an altered electrical reaction.
We obtain a normal type of response to electrical stimulation. Sometimes the nerve and muscle are hyper-excitable and react to lower intensity of current than that normally required.
Lower Motor Neurone Lesion (LMNL)
Damage to the lower motor neuron may involve either anterior horn cell or fibers of the nerve roots or peripheral nerve.
A lesion involving nerve fiber is classified into three groups
Faradic IDC test
1.The partial reaction of denervation
2.Complete reaction of denervation
3.An absolute reaction of denervation
The partial reaction of denervation
More current is required to produce minimal contraction. This is owing to the fact that the denervated fibers will fail to respond and only innervated fibers will respond to the shorter duration of impulse (0.2 or 1ms) of faradic current.
Interrupted direct current will bring about contraction through the nerve in the innervated fibers and directly stimulate the denervated fibers. The response will be in the form of muscle twitch than in normal.
Complete reaction of denervation
The interrupted direct current there will be a slow muscle twitch response.
The absolute reaction of denervation
The progressive atrophy of a denervated muscle and ultimate fibrosis, no response, to even the interrupted direct current is obtained.
Quality term bend test
Quality term bend test is otherwise called force span bend or power-time test or abundancy time bend. Rule depends on the way that both the nerve and the muscle reaction relies on upon the force of the current and span of motivation. The force of current required to energize a nerve or a muscle has an association with the term of the drive. Quality span bend test cont… Shorter the span of the motivation more will be the power of current required to acquire a negligible compression. On the other hand longer the term of drive lesser will be the force of current expected to acquire negligible withdrawal. The quality and term of electrical jolt a chart can be plotted called SD bend.
SDC test demonstrates the relationship between the greatness of the change of jolt and the span of the boost, This is a plot of the beat abundancy versus beat span at the limit. As the beat is dynamically diminished, the beat adequacy increments. At to a great degree tight heartbeat lengths, the jolt will be insufficient regardless of how high the beat sufficiency. The beat adequacy required to viably empower the heart diminishes as the beat span increases. The voltage level at which a further increment in heartbeat length does not bring about continued fall in heartbeat abundancy is termed the RHEOBASE.