- Velocity dependence- increased tone of spasticity is velocity dependent, that is, the faster the stretch, the greater the muscle resistance.
- ‘Clasp-knife’ phenomenon– spastic limb initially resists movement and then suddenly gives way, like the resistance of a folding knife blade.
- Distribution- differential distribution with antigravity muscles are more affected
Spasticity is associated with:
- Clonus– involuntary rhythmic contractions, response to sudden sustained stretch, alternate loading and off-loading of muscle spindles.
- Spasms- sudden involuntary movements involving multiple muscle groups and joints, repetitive and sustained, represent an exaggerated reflex withdrawal response to nociceptive stimuli.
- Exaggerated tendon reflexes- The deep tendon reflexes are exaggerated.
- Babinski sign is positive.
- Spastic co-contraction- inappropriate activation of antagonistic muscles during voluntary activity. It is due to loss of reciprocal inhibition during voluntary contraction.
- Motor weakness
- Slowed movements
- Loss of dexterity
Spasticity results in