W10 Neuro: Muscle Weakness

Question 1

Define Strength

Answer 1

Ability to generate sufficient tension in a muscle for the purposes of posture and movement

Question 2

What are the two components of strength/tension generation?

Answer 2

• Central drive: primary cortical areas selecting the muscles that need to contract
• Peripheral: Hypertrophy (certain CSA is needed to produce adequate force)

Question 3

Muscle force is dependent on?

Answer 3

• Number/type of motor units recruited
• Characteristics of motor unit discharge (eg speed of muscle force generation)
• Size (cross-sectional area) of muscle

Question 4

Role of type 1 muscle fibres vs type 2?

Answer 4

Type 1 = endurance ie maintaining our posture
Type 2 = fast peak force generation

Question 5

In patients with neurological conditions they won’t activate all their ….. …..
This means it is…. (provide an example)

Answer 5

They won’t active all their motor units which makes it difficult to reach peak force

For example, they might be able to perform a sit to stand but struggle with a weighted squat as it requires > motor units

Question 6

True or False: An interruption along any point of the motor pathway can result in weakness

Answer 6

True

Question 7

Common effects of weakness

Answer 7

– Slowness of muscle activation: initiation and during the movement –> muscles forces are not built up quickly enough to carry out the movement at usual speed

– Loss of dexterity-coordination x muscle strength –> dexterity and strength: an ability to generate force in synergic muscles (agonist, antagonist and stabilisers). The loss of strength consequently reduces coordination.

Question 8

Paralysis vs paresis

Answer 8

• Paralysis: total or severe loss of muscle strength (muscle is completely paralysed)
• Paresis: partial loss of muscle strength (muscle isn’t complete paralysed ie not a 0 or a 1 in a MMT – more likely a 2,3 or 4)

Question 9

Define:
Hemiplegia/paresis
Paraplegia/paresis
Tetraplegia/paresis

Answer 9

• Hemiplegia: total or severe loss of muscle strength in half of the body (one side)
• Paraplegia: total or severe loss of muscle strength in the lower half (trunk and lower limbs)
• Tetraplegia: total or severe loss of muslce strength in four limbs and trunk (with or without head movement control)

Question 10

Strength training is the key to treating weakness. What principles are used for people with MMT >3 vs MMT <3

Answer 10

MMT > 3 = FITT & eccentrically trained patients have better symmetrical results than concentrically trained

MMT < 3 = train at mid range, shorten lever, use manual guidance, train in gravity elimintated positon

Question 11

Secondary impairments of strength

Answer 11

Swelling
Mechanical insufficiency
Atrophy