Sensori-motor impairments after a stroke Flashcards
What are positive impairments after a stroke?
additional features.
Spasticity
Increased tendon reflexes
What are negative impairments after a stroke?
Loss of pre-existing function
Loss of strength
Loss of co-ordination
Loss of sensation
What is spasticity?
Hyperexcitability of the stretch reflex
Velocity dependent
Often referred to as increased tone
What is tone?
Resistance to passive movement
What can increased tone be due to
Contracture, spasticity, excessive muscle activity
Why is spasticity not just increased tone?
Spasticity is velocity dependent
What are some secondary impairments following a stroke?
Loss of fitness Contracture Learned non-use Swelling Shoulder pain Shoulder subluxaion
Which impairments have the greatest impact on activity?
Historically, was thought positive features, particularly spasticity. However, it was later learnt that weak agonist muscles were more of a problem than excessive antagonist muscles.
Negative impairments - loss of strength has the strongest and most consistent relationships with activity limitation.
How is spasticity measured?
Ashford vs Tardieu
What is the ashford scale?
Measures “tone” - resistance to passive movement
grades 0-4 represent “no increase in tone” to “limb rigid in flexion or extension”
What is the Tardieu scale?
Measures velocity dependent - resistance to passive movement.
Limb moved at 3 speeds v1, v2, v3
Quality of muscle reaction is graded
Grades 0-4 represent “no resistance” to “unfatiguable clonus”
GPP for spasticity
Interventions to decrease spasticity other than an early comprehensive therapy program should NOT be routinely provided for people who have mild to moderate spasticity (i.e. spasticity that does not interfere with stroke survivor’s activity or personal care
Stroke guidelines for people with moderate to severe spasticity
B :botox with reha
C: e stim and/or emg biofeedback
What is the relationship between strength and activity
curvilinear
Weak populations: very strong relationship between strength and activity
In strong/normal population - no relationship between strength and activity
What are the assumptions about the distribution of loss of strength after a stroke? are they correct?
Assumption distal muscles affected more, UL extensors more affected than flexors, LL flexors more affected than extensors
These are NOT supported by evidence
Assess each patient and se what their problems are!!
What are the causes of loss of strength after a stroke?
neural and peripheral canges
What are the neural changes that cause loss of strength after a stroke?
- Loss of upper motor neurons as direct result of the stroke
- Loss of lower motor neurons due to trans-synaptic degeneration
- Decreased excitability of motor neurons
- Loss of orderly recruitment of motor units
These neural changes result in activation failure
Activation capacity =
proportion of muscle force that can be voluntarily activated
Activation failure =
proportion of muscle force not activated voluntarily
What peripheral changes cause loss of strength after a stroke?
-Loss of muscle mass
- Loss of motor units (some suggestion more Type 2 motor units lost)
Remodelling of motor units
- collateral sprouting
-Increased innervation ratio, less orderly recruitment
What is collateral sprouting
Motor neurons supplying muscle fibres that didn’t have input
What are the characteristics of loss of strength after a stroke?
Inner range of muscles is more severely affected
Difficulty sustaining muscle contractions
Difficulty producing force rapidly.
What are the options for increasing strength after stroke?
Devices:
E stim
EMG triggered ES
EMG biofeedback
Active exercise
- Isolated movements
Task specific
Mental practice
Robotics
Mirror therapy
How do the principles of strengthening differ in grade 0-2 ?
Unable to move against resistance.
Need low load/high reps
Use functional positions e.g. modified sit to stand, modified standing, modified walking - i.e treadmill and bodyweight
