Which statement about extensor tone in MS and wheelchair adjustments is accurate?

Which statement about extensor tone in MS and wheelchair adjustments is accurate?

• A. Reclining back increases extensor tone
• B. Tilt-in-space reduces extensor tone
• C. Elevating leg rests decrease extensor tone
• D. Toe loops control proximal tone

Answer: (A)

Posture directly influences spasticity in MS because muscle tone is affected by how much a muscle is stretched and by the neural input from muscle spindles. Reclining the back positions the trunk and legs in a way that holds the extensor muscle groups—like the hip and knee extensors—under a greater passive stretch against gravity. In MS, the stretch reflex of these muscles becomes more excitable, so this increased passive stretch elevates extensor tone. In contrast, tilt-in-space, leg-rest adjustments, or toe loops mainly change how weight is distributed or how the limbs are aligned without markedly increasing the passive stretch on proximal extensor muscles, so they’re less likely to raise proximal extensor tone.

Posture directly influences spasticity in MS because muscle tone is affected by how much a muscle is stretched and by the neural input from muscle spindles. Reclining the back positions the trunk and legs in a way that holds the extensor muscle groups—like the hip and knee extensors—under a greater passive stretch against gravity. In MS, the stretch reflex of these muscles becomes more excitable, so this increased passive stretch elevates extensor tone. In contrast, tilt-in-space, leg-rest adjustments, or toe loops mainly change how weight is distributed or how the limbs are aligned without markedly increasing the passive stretch on proximal extensor muscles, so they’re less likely to raise proximal extensor tone.