Upper vs Lower Motor Neuron Lesions

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Muscle Tone[edit]

  • flexion/extension, pronation/supination of joint through its ROM

Hypotonia[edit]

    • LMN lesions, spinal shock, cerebellar lesions-flaccidity

Hypertonia[edit]

  • Spasticity - UMN lesion. Pyramidal tract involved
  • limb moves, then catches, and then goes past catch (clasp-knife)
    • test by rapidly supinating forearm
  • Rigidity
    • UMN lesions, extrapyrimidal tract lesion
    • increased tone throughout ROM (cog-wheeling, lead-pipe)
    • circumducting the wrist

Power[edit]

  • UMN
    • flexors > extensors in upper limbs
    • extensors > flexors in lower limbs
  • LMN
    • reduced power in specific motor neuron distribution
      • deltoids - arm abduction - C5 C6 (axillary)
      • biceps - elbow flexion - C5 C6 (musculocutaneous)
      • triceps - elbow extension - C6 C7 C8 (radial)
      • thumb flexion - C6 C7 (median)
      • wrist extensors - C7 C8 (radial)
      • interossei of hand - finger abduction/adduction - C8 T1 (ulnar)
      • hip flexion - L1 L2 L3 (femoral)
      • hip adduction - L2 L3 L4 (obturator)
      • hip abduction - L4 L5 S1 (superior gluteal)
      • knee extension - L2 L3 L4 (femoral)
      • knee flexion - L5 S1 S2 (sciatic)
      • ankle dorsiflexion - L4 L5 (deep peroneal)
      • ankle plantar flexion - S1 S2 (tibial)
      • foot inversion - L4 L5 (posterior tibial)
      • foot eversion - L5 S1 (superficial peroneal)
  • compare between L and R
  • GRADE
    • 0 nil
    • 1 flicker of movement
    • 2 movement cannot overcome gravity
    • 3 movement cannot overcome any resistance
    • 4 movement is weaker than normal
    • 5 normal

Special Tests[edit]

Pronator Drift[edit]

  • have the patient stand with eyes closed and arms held straight out and hands supinated
  • + → patient cannot maintain this position
    • muscle weakness (pronation and outward drift)
    • UMN lesion (pronation and downward drift)
      • standing problems

Fine Finger Movements[edit]

  • ask patient to touch each finger to crease of thumb (show patient how) and speed it up
  • look for right and left differences, slow if UMN lesion

Clonus[edit]

  • Ankle or Patellar clonus in UMN Lesion

Other OSCE Modules[edit]