Upper vs. lower motor neuron lesions

Inspection

Muscle Bulk

• loss of muscle bulk in LMN and late in UMN
• symmetry

Fasciculations

• present in LMN, none in UMN

Muscle Tone

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

Hypotonia

• • flaccidity
  • LMN lesions, spinal shock, cerebellar lesions

Hypertonia

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

Power

• 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

Pronator Drift

• 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)

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

Reflexes

Dorsal Tendon Reflexes

• biceps tendon (C5-6)
• brachioradialis tendon (C5-6)
• triceps tendon (C6-8)
• knee jerk (L2-4)
• Achilles tendon (S1-2)

• hyperactive ankle jerk → examine for clonus at knee and ankle
• absent → use reinforcements (teeth clenching for UL, Jendrassik’s maneuver for LL)

• UMN → hyperreflexia, but may be flaccid
• LMN → diminished reflexes

Grading

• 0 nil
• 1 low normal
• 2 normal
• 3 high normal
• 4 clonus (sustained > 3 beats)

• note if reinforcements used (teeth clenching, hand grips)

===Babinski’s reflex (L5-S1)

• + → dorsiflexion of the big toe with fanning of the other toes (UMN lesion)

Other OSCE Modules

Observed structured clinical examination

Acute Confusion - Acute Coronary Syndrome Orders - Anemia - Arterial Blood Gasses - Asthma - Blood Pressure - Chest pain - Chest XRay - CHF - Coma - COPD - Cranial Nerves - Diabetic History - Diabetic Foot - Dysphagia - EKGs - Gallbladder and Liver - Liver Disease - Gait and Balance - Headache - Hematemesis - Hypertension - Jugular Venous Pulses - Knee Exam - Lymph Nodes - Community Acquired Pneumonia - Parkinson Disease - Peripheral Arterial Insufficiency - Pneumonia Examination - Precordial Exam - STD's - Spleen - Swollen Leg Exam - Thyroid Exam - Upper vs Lower Motor Neuron Lesions - Urinary Incontinence