What is tone?
The resistance of a normal, relaxed limb to passive stretch
What is tone determined by?
- Passive mechanical properties of soft tissues
- Inertia of the limb
What is hypertonus & what is it caused by?
Increased resistance (tone impairment), caused by
- Contracture
- Spasticity
What is contracture?
Increased stiffness due to changes in passive mechanical properties of the soft tissue
What is spasticity?
- Abnormal reflex muscle contraction
- Velocity dependent increase in tonic stretch reflexes
- Due to hyper-excitability of the stretch reflex
- One component of upper motor neuron syndrome
What is the role of the stretch reflex in normal movement?
- Small part in movement
- Don’t initiate or control movement
- Dynamic modulation of muscle reflexes occurs during motor tasks
What does recent evidence show regarding spasticity after stroke?
- Spasticity after stroke is often mild & does not always occur
- Spasticity doesn’t appear to be related to activity limitations
What evidence is there for spasticity in plantar flexors after stroke?
- Investigated spasticity in ankle PF’s & impact on walking after stroke
- Stroke patients exhibited action tonic stretch reflexes that were of similar magnitude to control subjects
What evidence is there for spasticity of the upper limb after stroke?
- Looked at stroke survivors to determine impact of spasticity on UL activity performance
- Spasticity was seen early but did not hinder recovery of activities
- Contracture was more likely to develop in patients with poor outcomes
- Not clear if contracture caused poor outcomes or if loss of range caused contracture
What is the evidence regarding modulation of stretch reflexes in adults with CP?
- Trained adults with CP to modulate their stretch reflex using EMG biofeedback
- Subjects could learn to regulate stretch reflex
- No impact on dexterity or activity performance
What is are the primary impairments of stroke?
- Loss of strength
- Loss of dexterity
- Increased stretch reflex/loss of inhibition causing spasticity
What is a common cause of contracture in patients after stroke?
They are often immobilised as a result of primary impairments (secondary impairment)
What does immobilisation cause?
- Atrophy
- Loss of sarcomeres
- Accumulation of connective tissue
- Increased fat content
- Degenerative changes at the MTJ
What evidence is there for the relationship between spasticity & contracture after stroke?
- Investigated development of weakness, spasticity, contracture & disability over 1 year period in stroke patients
- Patients with early spasticity were likely to develop contracture in the first 4-6 months
- Patients with weakness are likely to develop contracture after 6 months
What are the common measurement tools for tone?
- Ashworth Scale
- Tardieu Scale
What evidence is there for the Tardieu & Ashworth scales?
- Examined effectiveness of the Ashworth & Tardieu scales for differentiating between spasticity and contracture
- Tardieu scale predicted spasticity 100% of the time
- Ashworth scale predicted spasticity 63% of the time
- Tardieu scale predicted contracture 94% of the time (Ashworth couldn’t distinguish between the two)
Why is the Tardieu scale able to distinguish between spasticity & contracture (unlike Ashworth)?
- Gives muscle response at slow & fast speeds
- Highlights velocity-dependent changes in movement
What are some of the differences between spasticity & contracture?
- Spasticity is velocity-dependent, contracture is not
- Spasticity is a primary impairment, contracture is secondary
- Spasticity is due to increased excitability of stretch reflex
- Contracture is due to changes in the soft tissue
What are the key strategies for managing mild-moderate spasticity?
- Maintain muscle length & joint ROM
- Train muscle activity for specific actions
- Eliminate inappropriate muscle force during attempts at motor tasks
What are the key strategies for managing moderate-severe spasticity (e.g. MS)?
- Pharmacology
- Serial casting (casting in end of range)
What is the evidence for upper limb stretching in stroke patients?
- Stroke patients with UL paralysis
- No stretch vs ER stretch at end of comfortable range
- Stretch for 30min, 5 days per week for 4 weeks
- Statistically & clinically significant difference (12 degrees) between groups
What is the evidence for serial casting combined with stretching in TBI patients?
- TBI patients & ankle PF contracture
- 1/52 casting + stretching vs 1/52 usual physio
- Significant increase in ankle DF with casting & stretching compared usual physio
What is the evidence for stretching?
- Cochrane review of stretching for neurological conditions
- Little or no effect of stretch on pain, spasticity, activity limitation, participation restriction or QOL
- Mod-high quality evidence stretching doesn’t elicit clinically important effects
What are the clinical implications of the Cochrane review?
- Need to monitor patients closely when treating contracture (not all patients respond the same)
- If active training is not possible, stretching should still be used to prevent/reverse contracture
- Need to continue reading current literature
