neuromuscular disease pathology

Question 1

describe the scale for muscle weakness (0-5 - Oxford scale)

Answer 1

5- normal power
4- moderate movement against resistance
3- moves against gravity but not resistance
2- moves with gravity eliminated
1- flicker
0- no mvt

Question 2

Describe different ‘weakness patterns’

Answer 2

-proximal vs distal
-symmetric weakness or not
-exercise related weakness
-painful & weak

Question 3

what are muscle fasciculations?

Answer 3

-involuntary muscle movement

Question 4

compare proximal vs distal weakness

Answer 4

-proximal - weakness in the muscles closer to the torso- muscular dystrophies etc
-distal - muscles further from the torso- may suggest neuropathic conditions eg peripheral neuropathy

Question 5

what is an upper motor vs lower motor lesion?

Answer 5

1. upper motor lesion - lesion in the brain & spinal cord
2. lower motor lesion - located in anterior horn of spinal cord or peripheral nerves

Question 6

what are examples of causes of upper motor lesion?

Answer 6

Stroke (cerebrovascular accident).
Spinal cord injury.
Multiple sclerosis.
Brain tumor

Question 7

what are examples of causes of lower motor lesion?

Answer 7

-motor neuron disease
-Polio.
-Spinal muscular atrophy.
-Peripheral nerve injury or compression.

Question 8

what are the clinical features of an upper motor neurone lesion?

Answer 8

-increased muscle tone - leading to stiffness and resistance to mvt
-hyperreflexia eg knee jerk etc
babinski sign -upward extension of big toe and fanning of other toes upon stimulation of sole of foot

Question 9

what are the clinical features of a lower motor lesion?

Answer 9

-decreased muscle tone- limpness and decreased resistance to passive mvt
-hyporeflexia - diminished or absent reflexes
-fascilations - visible twitching of muscle fibres
-muscle atrophy - wasting due to denervation

Question 10

what are examples of MOIs that can cause nerve injury?

Answer 10

compression
laceration
ischemia

Question 11

what is neuropraxia?

Answer 11

-mildest form of nerve injury
-transient dysfunction without structural damage to nerves
-compression or stretching of nerves

Question 12

what is axonotmesis?

Answer 12

-characterized by disruption of the axon while the connective tissue framework remains intact.
-caused by more severe crush or compression injuries

Question 13

describe neurotmosis

Answer 13

-most severe type of nerve injury
-complete disruption of both the axons and surrounding framework

Question 14

compare grade III vs grade IV neurotmosis injury

Answer 14

-grade III- axon and myelin severed - eg severe blunt injury with damage to endoneurium
-grade IV - axon and myelin severed - severe blunt injury with damage to endoneuriumz and perineurium

Question 15

what is an example of a NMJ disease?

Answer 15

myasthenia Gravis

Question 16

what is myasthenia gravis?

Answer 16

• an autoimmune disease in which the body attacks the Ach receptors on the post synaptic membrane - therefore Act cannot bind and initiate a response

Question 17

what are examples of symptoms of myasthenia gravis?

Answer 17

-droopy eyelids
- difficulty making facial expressions
-weak arms , legs or neck

Question 18

how is muscle disease classified?

Answer 18

-congenital
-immune mediated
-metabolic
-channel related eg Ca2+, K+

Question 19

what is muscular dystrophy

Answer 19

-genetic disorder that is characterised by progressive muscle weakness and degeneration of muscles
-caused by genetic mutations which results in the absence of essential proteins and presence of abnormal proteins in muscle cells

Question 20

what is myositis?

Answer 20

-immune mediated muscle disease
-inflammation of muscle cells - leading to weakness, pain and sometimes muscle wasting

Question 21

compare dermatomyositis vs polymyositis

Answer 21

-dermatomyositis - muscle inflammation and skin rashes
-polymyositis - inflammation and weakness in several muscle groups

Question 22

what is myotonia?

Answer 22

-prolonged muscle contraction or delayed muscle relaxation after voluntary contraction or stimulation.
- abnormality in the electrical properties of muscle cell membranes, leading to difficulty in muscle relaxation

Question 23

what is metabolic myopathy?

Answer 23

weakness in muscles caused by defects in metabolic pathways which affect energy production (ATP) in muscle cells
eg mitocondrial myopathies