Neurogenic vs. Myogenic Diseases Flashcards
1
Q
Normal Muscle- Biopsy
A
- Mosaic pattern of the 3 muscle fiber types
- Muscles may have proportionately more fast-glycolytic (FG) muscles fibers as compared to slow, oxidative (SO) secondary to its function
- Ex:
- -Gastrocnemius (FG): Better for ballistic/fast movements
- -Soleus (SO): Postural muscle, Better for walking, & More endurance
2
Q
Neurogenic Diseases
A
-Involves nerve cell bodies, axons and/or dendrites involved
-Needle EMG:
Denervated muscle is spontaneously active at rest (fibrillation potentials)
3
Q
Fibrillation potentials
A
- Only see on EMG-spikes present at rest
- Short duration (<3 ms)
- Low amplitude (<300 µv)
- Occur in semi-rhythmical runs (<30/second).
4
Q
Neurogenic Disease-Muscle Biopsy
A
- neuron atrophy causes muscle atrophy of the same muscle fiber type
- regeneration occurs through collateral sprouting
- since MN type determines muscle fiber type, re-innervated muscle fibers assume histochemical properties of neuron (change fiber type)
- Results in muscle fiber type grouping [due to re-innervation]
5
Q
Muscle Fiber Type Grouping
A
- As opposed to mosaic pattern of normal mm
- Convert FG -> SO (collateral sprouting)
- Compress nerve going to mm will affect FG before SO
6
Q
Myogenic Disease
A
- Involve muscle degeneration
- Needle EMG: little muscle activity at rest
- Muscle Biopsy:
- -Muscle fiber atrophy in a random fashion
- ALL muscle fiber types affected
- retains the mosaic pattern but fewer overall # and size of all types of muscle fibers
7
Q
Examples of Neurogenic Diseases
A
- Compression of nerve roots or peripheral nerves
- Bell’s Palsy*
- Diabetic polyneuropathy*
- Alcoholic polyneuropathy
- Polio and post-polio syndrome
- Amyotrophic lateral sclerosis (ALS)*
- Guillian-Barre syndrome (GB)*
8
Q
Examples of Myogenic Diseases
A
Muscular Dystrophy
9
Q
Demyelinating disease
A
Multiple Sclerosis
