Muscle morphology after SCI Flashcards
What are one of the most obvious muscular abnormalities associated with SCI?
profound muscular atrophy
Muscle fibre cross sectional area after SCI is approximately?
30-80% of that in the able bodied
When is atrophy more pronounced?
after LMN injury (cauda equina)
What fibre types is atrophy most profound in?
type IIa fibre types
When does atrophy approximately level off?
after 2 years
What is the decrease in fibre CSA accompanied by?
increases in interstitial fat
What muscle is the major player in the storage of glucose and the maintenance of normal glucose regulation/metabolism?
Skeletal muscle
What is type II diabetes?
(A.k.a. non insulin dependent diabetes mellitus)
-is a condition characterized by increased blood glucose levels (hyperglycemia) resulting from the bodys inability to store glucose
-the pancreas doesn’t produce enough insulin OR the body has an impaired response to insulin (insulin resistance)
What is type I diabetes?
the pancreas no longer produces insulin
The ingestion of CHO leads to
the secretion of insulin from pancreas which leads to the storage of CHO in muscle (and liver) and fat (in adipose tissue)
Bauman and Spungen, 1994:
100 individuals with SCI (50 paraplegia, 50 tetraplegia)
50 age matched able bodied controls
22% of those with SCI were classified as NIDDM compared to 6% of controls (worse glucose tolerance in those with tetraplegia)
Why is there an increased risk of diabetes in individuals with SCI:
- loss of muscle mass and ability to contract
- increased insulin resistance
The higher your injury the higher the increase for type 2 diabetes because:
There is more muscle to be affected
Is a bigger problem for those with tetraplegia
What is glucose intolerance?
an inability to properly store/metabolize glucose
62% of individuals with tetraplegia
50% of individuals with paraplegia
18% of able bodied
What is insulin resistance?
An inability to respond to, and use insulin
i.e. any given amount of insulin secreted from the pancreas results in a lesser transport of glucose into muscle and liver and fat into adipose tissue
-individuals with SCI have greater insulin resistance than the able bodied (approx 3-4 times) due to decreased muscle mass
SCI leads to:
decreased muscle mass and paralysis which leads to type II diabetes
Type II diabetes branches off into secondary problems due to increased blood glucose which leads to kidney failure and peripheral neuropathy. Peripheral leads to somatic which leads to weakness and decrease in sensation and neuropathy leads to autonomic which leads to UTI and ED
Type II diabetes also branches off into secondary problems due to increased fat in blood which leads to the conversion to LDL which leads to increased risk of CVD
Exercise training may partially reverse the atrophy that is associated with SCI:
25-50% is realistic:
-resistance training
-FES (functional electrical stimulation- involuntary)
-BWSTT (body weight support treadmill training)
Exercise training may also partially reverse the glucose intolerance that is associated with SCI due to:
- increased muscle mass
-decreased insulin resistance (increased insulin sensitivity)
-increased GLUT4 content in muscle (with exercise)
skeletal muscle in individuals with SCI is not only prone to atrophy and decreased strength but also to?
decreased fatigue resistance
Why the decreased fatigue resistance in SCI?
reduction of aerobic enzymes- maybe
reduction in muscle capillarization- maybe
reduction in the NA+, K+ ATPase enzyme- (Yes 50%)
muscle spasticity may?
preserve type I fibre representation in individuals with SCI
What is spasticity?
involuntary, random, increase in muscle tone (agonists and antagonists) common in individuals with UMN SCI
-is velocity dependent and position dependent
-is tested via ashworth scale
-is random
What is clonus?
-repetitive contraction of a muscle due to an uninhibited stretch reflex
-example: toe tap
-not random
-spinal cord injury is preventing this turn off (uninhibited)
What is a contracture?
-reduced range of motion in a joint due to chronic shortening of a muscle
-muscle contraction, not spasticity
-can happen to any muscle that chronically shortened over time
Ashworth test of spasticity:
- move the joints of the lower limb (hip, knee, ankle) and record the amount of resistance (spasticity) based on a 6 point scale
-need a metronome
- no increase in muscle tone
- slight increase, catch and release.OR min resistance at end of ROM
1+ slight increase, catch (no release) and min resistance for less than half of ROM - more marked increase, through most of ROM but still easily moved
3.considerable increase, passive movement difficult - rigid in flexion or extension
