228
Biomedical Signal and Image Processing
decreased movement capabilities and a diminished sensation. This type of neural
disease can be caused by inflammation or compression of the nerve. The EMG
signals are similar to those observed in radiculopathy, combined with a different
pattern in the central nervous system observed in EEG signals. This is the major
difference between radiculopathy in which central nervous system is unaffected
and plexopathy in which the brain waves too show some irregular patterns.
Polyneuropathy is a disorder of the peripheral nerves. The distal nerve axons are
more likely to be affected than the proximal fibers. The EMG of the patients suffering from polyneuropathy shows signs of denervation of the muscle. Myopathy is
a purely muscular disorder. The pathological symptoms are related to ion channel
dysfunction in the motor units. One chronic disorder that may be associated with
neuromuscular causes is cerebral palsy. Cerebral palsy is actually a brain disorder in
the motor areas of the cerebrum.
11.4.3 ABNORMAL NEUROMUSCULAR TRANSMISSION IN MOTOR UNITS
Certain diseases are known to cause abnormal transmission within motor units. The
most known case of such abnormality is myasthenia gravis.
The pathological condition of myasthenia gravis involves a blockage of the nicotinic ACh receptors on muscle fibers, leading to paralysis. This is a chronic illness classified by abnormal rapidly occurring fatigue in the skeletal muscles. The
first contraction will proceed normally, while the subsequent contractions become
increasingly weaker. The EMG in this situation is characterized by omission of depolarization spikes and decreasing amplitude over time, as shown in Figure 11.7.
In Alzheimer’s disease, the neurotransmitter ACh is selectively destroyed, and,
thus, muscle function is impaired. Another well-known muscle-related disease is
anterior poliomyelitis, which affected hundreds of thousands of children before a
vaccine was developed, specifically attacking and killing motoneurons in the anterior (ventral) spinal cord. Multiple sclerosis is another relatively common disease that
involves demyelination of the motor axons in the ventral roots and somatic nerves.
0.1 s
9
6
3
0
20
μV
kg
–20
FIGURE 11.7 EMG of myasthenic muscle.
Biomedical Signal and Image Processing
decreased movement capabilities and a diminished sensation. This type of neural
disease can be caused by inflammation or compression of the nerve. The EMG
signals are similar to those observed in radiculopathy, combined with a different
pattern in the central nervous system observed in EEG signals. This is the major
difference between radiculopathy in which central nervous system is unaffected
and plexopathy in which the brain waves too show some irregular patterns.
Polyneuropathy is a disorder of the peripheral nerves. The distal nerve axons are
more likely to be affected than the proximal fibers. The EMG of the patients suffering from polyneuropathy shows signs of denervation of the muscle. Myopathy is
a purely muscular disorder. The pathological symptoms are related to ion channel
dysfunction in the motor units. One chronic disorder that may be associated with
neuromuscular causes is cerebral palsy. Cerebral palsy is actually a brain disorder in
the motor areas of the cerebrum.
11.4.3 ABNORMAL NEUROMUSCULAR TRANSMISSION IN MOTOR UNITS
Certain diseases are known to cause abnormal transmission within motor units. The
most known case of such abnormality is myasthenia gravis.
The pathological condition of myasthenia gravis involves a blockage of the nicotinic ACh receptors on muscle fibers, leading to paralysis. This is a chronic illness classified by abnormal rapidly occurring fatigue in the skeletal muscles. The
first contraction will proceed normally, while the subsequent contractions become
increasingly weaker. The EMG in this situation is characterized by omission of depolarization spikes and decreasing amplitude over time, as shown in Figure 11.7.
In Alzheimer’s disease, the neurotransmitter ACh is selectively destroyed, and,
thus, muscle function is impaired. Another well-known muscle-related disease is
anterior poliomyelitis, which affected hundreds of thousands of children before a
vaccine was developed, specifically attacking and killing motoneurons in the anterior (ventral) spinal cord. Multiple sclerosis is another relatively common disease that
involves demyelination of the motor axons in the ventral roots and somatic nerves.
0.1 s
9
6
3
0
20
μV
kg
–20
FIGURE 11.7 EMG of myasthenic muscle.