Electrical response are useful in diagnosis of injury or lesion of nerves.
These changes will be the following
1.A lesion of upper motor neurone
2.A lesion of lower motor neurone
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. These changes are known as electrical reaction changes.
Upper Motor Neurone Lesion (UMNL)
When there is a lesion of upper motor neurone there are no change in lower motor neurone (in the accessible part of the motor pathway) which would lead to altered electrical reaction.
Normal type of response is obtained with electrical stimulation, although sometime 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 neurone may involve either anterior horn cell or fibers of the nerve roots or peripheral nerve.
Lesion involving nerve fiber is classified into three groups
Faradic IDC test
1.Partial reaction of denervation
2.Complete reaction of denervation
3.Absolute reaction of denervation
Partial reaction of denervation
Faradic response is that more current will be 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
No response to faradic or faradic type current is obtained since the whole nerve will not be conducting.
The interrupted direct current there will be a slow muscle twitch response.
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. Force of current required to energize a nerve or a muscles has an association with the term of 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 demonstrate the relationship between the greatness of the change of jolt and the span of the boost. The capacity to catch the myocardium can be characterized by a quality term bend. This is a plot of the beat abundancy versus beat span at limit. As the beat term is dynamically diminished, the beat adequacy increments so as to look after catch. 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 acontinued fall in heartbeat abundancy is termed the RHEOBASE.