Human Nervous system - Upper-vs-Lower-Motor-Neuron-Lesions

Inspection

Mostly seen in Spinal cord Injury

Muscle Bulk

  1. loss of muscle bulk in LMN and late in UMN

  2. symmetry

 Muscle grith

Fasciculations present in LMN, none in UMN

Muscle Tone

  1. flexion/extension, pronation/supination of joint through its ROM

Hypotonia

  1. flaccidity

  2. LMN lesions, spinal shock, cerebellar lesions

Hypertonia Spasticity UMN lesion. Pyramidal tract involved

limb moves, then catches, and then goes past catch (clasp-knife)

  1. Test by rapidly supinating forearm

  2. Rigidity

    1. UMN lesions, extrapyrimidal tract lesion
    2. increased tone throughout ROM (cog-wheeling, lead-pipe)
    3. circumducting the wrist

Power UMN

  1. flexors > extensors in upper limbs
  2. extensors > flexors in lower limbs
  3. LMN
  4. reduced power in specific motor neuron distribution
    1. deltoids  arm abduction  C5 C6 (axillary)
    2. biceps  elbow flexion C5 C6 (musculocutaneous)
    3. triceps  elbow extension C6 C7 C8 (radial)
    4. thumb flexion  C6 C7 (median)
    5. wrist extensors C7 C8 (radial)
    6. interossei of hand  finger abduction/adduction  C8 T1 (ulnar)
    7. hip flexion  L1 L2 L3 (femoral)
    8. hip adduction  L2 L3 L4 (obturator)
    9. hip abduction L4 L5 S1 (superior gluteal)
    10. knee extension L2 L3 L4 (femoral)
    11. knee flexion  L5 S1 S2 (sciatic)
    12. ankle dorsiflexion  L4 L5 (deep peroneal)
    13. ankle plantar flexion S1 S2 (tibial)
    14. foot inversion L4 L5 (posterior tibial)
    15. foot eversion  L5 S1 (superficial peroneal)

  5. compare between L and R

  6. GRADE

    1.  nil
    2.  flicker of movement
    3. movement cannot overcome gravity
    4. movement cannot overcome any resistance
    5. movement is weaker than normal
    6. normal

Special Tests

Pronator Drift have the patient stand with eyes closed and arms held straight out and hands supinated

  1. patient cannot maintain this position
  2. muscle weakness (pronation and outward drift)
  3. UMN lesion (pronation and downward drift)

Fine Finger Movements 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 Ankle or Patellaer clonus in UMN Lesion

Reflexes

Deep Tendon Reflexes biceps tendon (C5-6)

  1. brachioradialis tendon (C5-6)

  2. triceps tendon (C6-8)

  3. knee jerk (L2-4)

  4. Achilles tendon (S1-2)

  5. hyperactive ankle jerk ? examine for clonus at knee and ankle

  6. absent ? use reinforcements (teeth clenching for UL, Jendrassiks maneuver for LL)

  7. UMN ? hyperreflexia, but may be flaccid

  8. LMN ? diminished reflexes

Grading

  1.  low normal

  2. normal

  3. high normal

  4. clonus (sustained > 3 beats)

  5. note if reinforcements used (teeth clenching, hand grips)

Babinskis reflex (L5-S1) dorsiflexion of the big toe with/without fanning of the other toes (UMN lesion)