Spasticity¶
Doug Bryant and Jake Dovgan
Background¶
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Spasticity is a velocity-dependent increase in resistance to passive stretch.
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It differs from hypertonia in that hypertonia is resistance to passive stretch that is not velocity-dependent.
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Spasticity is believed to result from disruption of descending inhibitory modulation of the alpha motor neurons by an upper motor lesion, producing hyperexcitability.
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Grading (by the Modified Ashworth Scale)
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0=no increase in tone
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1=slight increase in muscle tone, manifested by a catch and release or by minimal resistance at the end of ROM when affected part is moved in flexion or extension
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1+=slight increase in muscle tone, manifested by a catch followed by minimal resistance through the remainder of ROM (less than half)
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2=more marked increase in muscle tone through most of ROM, but affected part is easily moved.
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3=considerable increases in muscle tone; passive movement difficult
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4=affected part is rigid in flexion or extension
Management¶
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Spasticity can have functional benefits, including improving standing and transfers. However, it can also cause weakness, poor dexterity, pain, and contractures.
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If spasticity is having undesirable effects, first line of treatment is PT/OT and physical modalities such as stretching.
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Oral Medications
| Medication | Mechanism of Action | Side Effects/Important Considerations |
|---|---|---|
| Baclofen | GABA-B agonist | sedation, fatigue, nausea, centrally acting – risk of withdrawal |
| Tizanidine | Alpha-2 agonist | sedation, dizziness, xerostomia, weakness, centrally acting – risk of withdrawal |
| Diazepam/ Benzodiazepines | GABA-A agonist | sedation, confusion, hypotension, centrally acting – risk of withdrawal |
| Dantrolene | inhibits Ca release from sarcoplasmic reticulum | weakness, sedation, nausea, hepatotoxicity, acts directly on skeletal muscle |
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Intrathecal baclofen: Reserved for patients who have significant side effects with oral anti-spasticity medications or who have severe, persistent, and diffuse spasticity despite maximal doses.
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Injections
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Botulinum toxin: Blocks the presynaptic release of acetylcholine from motor endplates of the lower motor neuron at the myoneural junction. Effect usually lasts 3-8months
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Alcohol block: Phenol and ethanol are neurolytic agents that can be used to block nerves with motor function.
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Surgeries
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Selective dorsal rhizotomy, osteotomy, muscle tendon lengthening, release, or transfer
***If a patient experiences worsening of spasticity, it is important to consider other underlying conditions such as infections, pressure ulcers, constipation, or bladder distention***