Lecture and practical 1 - Spasticity Flashcards
What are the outdated and currently accepted definitions of spasticity?
Outdated = Velocity-dependent increase/overactivity of tonic stretch reflexes
Currently accepted = Disordered sensory-motor control due to upper-motor neuron lesion leading to intermittent or sustained involuntary activation of muscles
Describe the stretch reflex including the roles of the different types of motor neurons
Sensory 1a afferent neurones are activated due to stretch detected by golgi tendon organs and spindles
Synapse in ventral horn with alpha motor neurons which contract the extrafusal muscle fibres to contract the muscle
Gamma motor neurons control sensitivity of stretch reflex by controlling myofibrils to set normal muscle tone and length for the alpha neurons
What is reciprocal inhibition?
The 1a afferent neuron bifurcates in the ventral horn.
Synapses with alpha motor neurons to contract the muscle fibres of the agonist
Synapses with inhibitory interneurons which innervate the alpha motor neurons for the antagonist inhibiting this
What is normal tone
Sufficient tension to maintain stability and to enable movement
Give 5 standard things that impact tone
Posture
Temperature
Emotions i.e. stress
Visual/auditory stimuli
Medical factors i.e. skin ulcers, UTIs etc
Identify and categorise the neural components of upper motor neuron lesions
Positive:
- Spasticity
- Spasms
- Clonus
- Associated Reactions
Negative:
- Weakness
- Impaired motor control
- Decreased range of movement
What are the non-neural impacts of an upper motor neuron lesion
Secondary adaptive changes:
- Contractures
- Muscle stiffness
What are associated reactions?
An increase in spasticity/tone due to voluntary activation of unaffected muscles or involuntary movements such as coughing and sneezing
What are contractures?
Shortening of muscles, tendons, skin and nearby soft tissues impacting range of movement at a joint
Give 2 clinical scales for assessing tone, identify the more accepted one and explain why
Tardieu Scale - measures at 3 different velocities
Modified Ashworth Scale
The Tardieu scale is more accepted because the MAS overdiagnoses spasticity in cases of contracture
What is the common pattern of spasticity in the upper limb
Flexor synergy:
Elbow = flexed
Forearm = supinated
Wrist = flexed
Fingers and thumb = flexed and adducted
What is the common pattern of spasticity in the lower limb
Extensor synergy:
Hip = flexed, adducted and internally rotated
Knee = extended
Foot = plantar flexed and inverted
What is neuroplasticity and how does it relate to spasticity rehabilitiation
Neuroplasticity is the ability of the brain to form synaptic connections after injury (or in response to learning)
Repetition required to build synaptic connections, movements must be performed and repeated even if imperfectly, the MDT must be on board to ensure a 24 hour approach to rehabilitation to enable repetition/frequency required for effective neuroplasticity use
Describe the method of administration and mechanism of botulinum toxin
Administration = focal, directly into the muscles affected (guided by ultrasound)
Mechanism = binds to receptors on the pre-synaptic neuron, the toxin-receptor complex is taken into the neuron by endocytosis, the toxin is then released and binds to SNARE proteins and prevents the vesicles containing acetylcholine (an excitatory neurotransmitter) from binding to the membrane and releasing the contents into the synapse
Describe the method of administration and mechanism of baclofen
Administration = systemically and intrathecally
Mechanism = Binds to gaba receptors to increase inhibitory effects reducing muscle spindle sensitivity to acetylcholine from alpha motor neurons
Describe the method of administration and mechanism of tinzanadine
Administration = systemically
Mechanism = Pre-synaptic inhibition increases and prevents release of excitatory neurotransmitters
What were considerations inspired by the practical session regarding medication for managing spasticity
Medication for managing spasticity can have side effects that heighten some other already disabling effects of the patient’s neurological impairments. For example the stroke patient we met at the session was greatly impacted by neurofatigue and medication for his spasticity worsened this. They can also increase cognitive issues.
How can positioning be used across lying, sitting and standing for spasticity management?
Lying = modified supine and side-lying positions and use of supportive aids
Sitting = alignment focused to improve stability of pelvis and hips
Standing = gravity can facilitate extensor activity - this is enabled by therapists and equipment such as standing frames
Why is splinting debated within spasticity management?
Greater than 6 hours of stretching a day can be required to see meaningful change
2023 Stroke guidelines indicate focus needs to be on treatment of activity and functional movement and not passive features
In what situations is splinting required regarding spasticity management
Risks to skin-integrity i.e. fingernails digging into palm of hand and creating cuts
Personal hygiene risks i.e. fists clenched meaning unable to wash hands
What is the main aim of therapy/exercise treatment for spasticity management and give 3 sub aims this can entail
To maximise function and activity:
- Prevent secondary complications
- Strengthen muscles
- Promote normal movement patterns
Give two types of surgical intervention for spasticity
Tendon lengthening/replacement
Selective dorsal rhizotomy - Cutting of afferent sensory neurons at certain spinal cord levels
What is learnt disuse and how does it apply to spasticity rehab
Patients need to be massively encouraged to carry out movement (even if imperfect) in affected limb and not just adapt to using a single limb (learnt disuse).
What is the Ashford Goal Classification?
A goal classification based on patients receiving botox for spasticity.
Helps give more structure to the goal-setting process.
Divides goals into 2 categories, symptoms/impairments and activities/functions with 3 subcategories in each
What is goal attainment scaling
Goal attainment scaling is a way of statistically/more objectively measuring progress across varied patient-decided goals
What are the 3 domains of the ICF problem list
Body functions
Activities
Participation
Why do contractures occur?
Sarcomeres (muscular units) partake in the sliding filament theory (myosin binds to actin and slides, dettaches then reattaches further down)
Continuous shortening of muscles causes a reduction in the number of sarcomeres
This impacts the length of the muscle impacting ability to generate force and achieve range of movement
What does electrical stimulation do and not do for shortened muscles
It doesn’t prevent loss of sarcomeres in muscle tissue but it does prevent connective tissue change
What spinal tracts are involved in spasticity and how?
Lesions to corticospinal tracts lead to weakness
Lesions in non-pyramidal tracts such as the rubrospinal tract lead to mixed effects and imbalance between inhibitory and excitatory influence on alpha motor neurones leading to uncontrolled overactivity of certain muscle groups
