MS - reasoning

Question 1

spasticity/tone

Answer 1

• Hugos & Cameron 2020 found Spasticity occurs in 60–84% of people with MS
• Spasticity in MS results from demyelination and/or axonal degeneration in descending inhibitory CNS motor tracts (corticospinal, medial reticulospinal, lateral vestibular, and dorsal reticulospinal tracts) causing disinhibition of muscle contraction
  1. under-active agonist
  2. over active antagonist
  3. shortened antagonist

Question 2

length

Answer 2

• Contracture (loss of passive joint range of motion) is a common motor impairment in multiple sclerosis (MS)
  prevalence of contracture in people with MS is 57% (Hoang et al 2021) and the ankle is the most commonly affected joint (prevalence 44%, Hoang et al., 2014).

1. ↓ sarcomere number & ↓ muscle length → ↑ resistance to passive stretch
2. Range in which you can function reduces, mid range is the strongest muscle length, if a muscle is stiffened to inner range it limits function
3. when muscles are immobilised in the shortened position there is an increase in the proportion of collagen to contractile muscle

Question 3

strength

Answer 3

• people with MS can have 3-fold longer central motor conduction times and nearly half the motor neuron firing rates compared with controls. (Willingham et al 2023)
• Lesions or plaques in the CNS alter the neural activation of muscles by disrupting neuromotor transmission to spinal neurons
  1. number of motor units recruited
  2. frequency of motor unit recruitment
  3. efficiency of synergistic coordination

pre CNS pathology weakness
* ageing
* sedentary lifestyles
* other pathologies (OA, RA, diabetes)

Question 4

proprioception

Answer 4

performance of sensory tasks requiring an interhemispheric transfer of information and postural control rely on the integrity of the corpus callosum (CC) The CC is affected from the early stages of MS
Landolo et al 2020

Question 5

sensation

Answer 5

• Deep pressure (ascending pathway- medial/anterior spinothalamic contralateral)
  Anterolateral pathway tract projection crosses over at the spinal cord
• Light touch (ascending pathway- dorsal column-medial lemniscus pathway
  dorsal column- medial leminscus pathway tract projection crosses over at medulla oblongata

Sensory axons from peripheral proprioceptors enter the dorsal root ganglion of the spinal cord and then ascend
- The upper limb afferents synapse in the nucleus cuneatus at the medulla.
- fibres then cross midline, to ascend in the medial lemniscus to the ventral posterolateral (VPL) nucleus of the thalamus.
- Projections from this area travel through the posterior limb of the internal capsule to Brodmann’s areas 3a and 2 of the primary somatosensory area in the parietal cortex
Gardner and Johnson, 2013

• As primary somatosensory areas, these regions are involved in detection, localization, and discrimination of somatosensory information.
• Specifically, area 3a primarily receives muscle spindle input to process information about limb position
• area 2 combines this and cutaneous information to facilitate hand posture, grip force and tactile object recognition Amaral, 2013

Question 6

coordination

Answer 6

• the cerebellum integrates neural information (sensory, visual, proprioceptive, and even cognitive) necessary for conducting and coordinating movements in a smooth and timely fashion

ataxia - cerebellum Dysmetria – inaccurate (undershoot or overshoot) amplitude of movement of intended limb at end-position
Dyssynergia – decomposition of movement, loss of smooth performance of multi-joint movements and lack of coordination between agonist and antagonist
Dysdiadochokinesis - Inability to perform rapidly alternating movements of force or rhythm
Tremor – movement oscillations due to lack of coordination between agonist and antagonist
Intention tremor – exaggerated with movement
Resting tremor – seen at rest, reduces with movement

Question 7

normal movement is

Answer 7

skill
aquired through learning
goal/task specific
efficent/economic
individual

Question 8

normal movement looks like

Answer 8

goal orientated
graded
coordinated
efficent/economic
smooth

Question 9

normal muscle tone

Answer 9

constant state of mild muscle tension, readiness of a muscle to contract

Question 10

normal postural tone

Answer 10

maintain body upright against gravity, allows selective movement to attain functional skills (stabilise some parts and allow others to move)

Question 11

Muscle Strength

Answer 11

The highest amount of tension or force that a muscle
or muscle group can voluntary exert in one maximal
effort.