Velocity-dependent increase in tonic stretch reflexes (i.e muscle tone) with exagerrated tendon jerks, resulting in hyperexitability of the stretch reflex as one compnent of the UMN syndrome

Positive signs

  • Exagerrated DTR’s
  • Resistance to passive stretch

Negative signs

  • Weakness
  • Loss of dexterity

Assessment of spasticity

Modified Ashworth Scale for Grading hypertonia Grade Description

  • 0 -No increase in muscle tone
  • 1 -Slight increase in muscle tone, manifested by a catch and release or by minimal resistance at the end of the range of motion when the affected part(s) is moved in flexion or extension
  • 1+ -Slight increase in muscle tone, manifested by a catch, followed by minimal resistance throughout the remainder (less than half) of the ROM
  • 2 -More marked increase in muscle tone through most of the ROM, but affected part(s) easily moved
  • 3 -Considerable increase in muscle tone, passive movement difficult
  • 4 -Affected part(s) rigid in flexion or extension
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