Spasticity

Spasticity is characterized by Muscular Hypertonia / Muscle-stiffness
It might interfere with Movement / Speech or Discomfort / Pain
Along with Hyper reflexia and Clonus, it is a part of UMN entity.
It is often used interchangeably with hypertonia.
It is dependent on the Muscle speed and range of motion and manifests itself when the muscle contracts at high speed. This means that when the speed and amplitude of contraction exceeds the threshold, Spasticity occurs

Asymmetric: Because it involves the antagonist muscles
Velocity-dependent: It increases tonic stretch reflexes and tendon jerks, resulting from hyper-excitability of the stretch reflex

Strength dependent: Increasing the strength of muscle stretch reflex causes the muscle to contract with greater intensity and power in response to stretching, and this contraction has a direct relationship with the strength of stretching. In this condition, spasticity is occurred.

Spasticity has two analogues:

Rigidity: Spasticity is Velocity-dependent but rigidity is not
Spasm: It is necessarily painful opposite to Spasticity. Also Spasticity has them of paralysis opposite to Spasm

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