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Biomedical Signal and Image Processing
Using other muscles to drive prosthetic systems needs a significant period of training
for the person using the system.
Knowing the overall needs to EMG signals, next we focus on the diagnostic applications of EMG.
11.4 NEUROMUSCULAR DISEASES AND EMG
The majority of muscular diseases have a neurological basis. Several neuromuscular
diseases are diagnosed by processing of the EMG signal and detecting particular
deviations from the normal EMG. In diagnostics using EMG, the exact deviations
identify the source of the disorder. Many examples of EMG abnormalities root in
factors such as disorder in the cell body of the nerve cell, disturbance in the axon of
the nerve delivering the excitation, failing of the neuromuscular transmission within
the motor unit, defects in the muscle cell membrane, and finally general imperfections in the entire muscle.
The partial or complete loss of EMG signal is often due to the loss of nervous
excitation. The nerve cell attached to the motor unit may degrade at various locations
between the spinal cord and the motor unit, thus depriving the muscle of the action
potential. This in turn results in significant reduction in EMG strength or even the
complete loss of this signal.
Muscular disorders will require different types of clinical attention than nervous
disorders. The EMG will most likely not reveal the neurological cause of the visually
observed abnormalities in the muscle function. This importance of this statement
can be further realized knowing that the neurological degeneration can be as far
away as the spinal cord.
Several examples of diseases related to either the neural mediation or the
muscular dysfunctions are Parkinson’s disease, radiculopathy, plexopathy, polyneuropathy, myopathy, and anterior horn cell disease or amyotrophic lateral sclerosis
(ALS). A brief description of some of these diseases will be given when we focus on
the use of EMG in diagnostics of motor neurons and motor unit–related diseases. In all
aforementioned diseases, the EMG signal is frequently used to discover the different
types of nerve damage and other physiological disorders involved. Next, we explore the
EMG changes in such abnormalities.
11.4.1 ABNORMAL ENERVATION
When the nerve cell has effectively been destroyed, there will be no more action
potentials delivered to the motor unit that enervates the muscle fibrils. Damage
to the motor neuron can result from several illnesses, among which polio is an
example.
When the continuity of the axon of an enervating neuron has been compromised
by mechanical or physiological means, the motor unit will be denervated. The muscle is thus partially paralyzed, and, with increasing damage, more severe paralysis will occur. A denervated muscle fibril shows a particular pattern in the EMG
when it starts producing spontaneous depolarizations several days after the onset
Biomedical Signal and Image Processing
Using other muscles to drive prosthetic systems needs a significant period of training
for the person using the system.
Knowing the overall needs to EMG signals, next we focus on the diagnostic applications of EMG.
11.4 NEUROMUSCULAR DISEASES AND EMG
The majority of muscular diseases have a neurological basis. Several neuromuscular
diseases are diagnosed by processing of the EMG signal and detecting particular
deviations from the normal EMG. In diagnostics using EMG, the exact deviations
identify the source of the disorder. Many examples of EMG abnormalities root in
factors such as disorder in the cell body of the nerve cell, disturbance in the axon of
the nerve delivering the excitation, failing of the neuromuscular transmission within
the motor unit, defects in the muscle cell membrane, and finally general imperfections in the entire muscle.
The partial or complete loss of EMG signal is often due to the loss of nervous
excitation. The nerve cell attached to the motor unit may degrade at various locations
between the spinal cord and the motor unit, thus depriving the muscle of the action
potential. This in turn results in significant reduction in EMG strength or even the
complete loss of this signal.
Muscular disorders will require different types of clinical attention than nervous
disorders. The EMG will most likely not reveal the neurological cause of the visually
observed abnormalities in the muscle function. This importance of this statement
can be further realized knowing that the neurological degeneration can be as far
away as the spinal cord.
Several examples of diseases related to either the neural mediation or the
muscular dysfunctions are Parkinson’s disease, radiculopathy, plexopathy, polyneuropathy, myopathy, and anterior horn cell disease or amyotrophic lateral sclerosis
(ALS). A brief description of some of these diseases will be given when we focus on
the use of EMG in diagnostics of motor neurons and motor unit–related diseases. In all
aforementioned diseases, the EMG signal is frequently used to discover the different
types of nerve damage and other physiological disorders involved. Next, we explore the
EMG changes in such abnormalities.
11.4.1 ABNORMAL ENERVATION
When the nerve cell has effectively been destroyed, there will be no more action
potentials delivered to the motor unit that enervates the muscle fibrils. Damage
to the motor neuron can result from several illnesses, among which polio is an
example.
When the continuity of the axon of an enervating neuron has been compromised
by mechanical or physiological means, the motor unit will be denervated. The muscle is thus partially paralyzed, and, with increasing damage, more severe paralysis will occur. A denervated muscle fibril shows a particular pattern in the EMG
when it starts producing spontaneous depolarizations several days after the onset