Spasticity Flashcards
What happens soon after a spasticity-causing event?
Key characteristics of spasticity emerge after the neurogenic shock stage, including hyperreflexia, reflex cascade, and reversion to early motor system patterns.
What is hyperreflexia in spasticity?
Hyperreflexia is the primacy of basic excitatory protective reflexes (e.g., stretch reflex, withdrawal reflex, joint protective reflexes) operating with poor or absent HMC modulation.
How does hyperreflexia affect reflex responses?
It causes exaggerated responses to both normal and noxious stimuli, such as a larger-than-normal reaction to touching something hot.
What is Reflex Cascade (Domino Reflex/Reflex Spillover/Spastic Reaction)?
It is when one stimulus activates a sequence of reflex responses that spreads in either or both directions from the original activation, often including clonus at affected joints.
What happens during reversion to early motor system patterns in spasticity?
The motor system reverts to primitive patterns, often showing flexion dominance or abnormal reflexes like Babinski’s Sign.
What is Flexion Dominance in spasticity?
It is when the lesion causes the motor system to revert to a flexed, “fetal position,” where flexion becomes the normal and comfortable resting position for affected joints.
What is Babinski’s Sign?
Babinski’s Sign occurs when the primitive Babinski reflex re-emerges abnormally in adults, causing reflex toe extension and ankle dorsiflexion in response to plantar stimulation.
Why is Babinski’s Sign abnormal in adults?
In normal CNS maturation, the infantile Babinski reflex is replaced by a functional toe flexion and ankle plantarflexion response for standing and walking.
What is clonus?
Clonus is the alternating activation of agonist and antagonist stretch reflex responses acting on a joint, causing a “reverberating” back-and-forth action.
What are spastic co-contractions?
Abnormal antagonist contractions occur during voluntary agonist effort, creating a rigidity-like appearance during clinical observation.
What is spastic dystonia?
It is a muscle contraction present at rest, leading to a holding position that is very sensitive to stretch.
What are the key muscle tone abnormalities seen in spasticity?
- Resting tone can be too high, too low, or fluctuate.
- Abnormal tone setting occurs with posture changes, walking, etc.
- Tone can change dramatically with emotion, pain, etc.
What motor control abnormalities are associated with spasticity?
- Diminished fine motor control.
- Synergistic stabilization patterns become stereotyped.
What are the effects of contractures in spasticity?
- Reduced range of motion (ROM) and specificity of movements.
- Early activation of protective reflexes.
- Ischemia and pain add to muscle irritability.
- Develop within 6 months after the spasticity-causing event.
What is 1a neuronal sprouting?
It is when 1a neurons add telodendria (axon terminal branches), increasing their number of synapses on their partner alpha motor neuron in the stretch reflex arc.
