Spasticity In Hand


Spasticity is a motor disorder characterized by a velocity-dependent increase in tonic stretch reflexes (muscle tone) with exaggerated tendon jerks, resulting from hyper excitability of the stretch reflex.

Characteristic Features

  • 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:

  • Clonusinvoluntary 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

  • Stiffness
  • Contracture
  • Fibrosis
  • Atrophy