- Reflexes
- Tone
- Power
- Fasciculation
- Muscle bulk
Inspection
- Muscle bulk: loss of muscle bulk in LMN and late in UMN
- Symmetry
- Fasciculation: 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
- Rigidity – LMN lesions, extrapyrimidal tract lesion
- Increased tone throughout ROM (cog-wheeling, lead-pipe)
- Circumducting the wrist
- Spasticity – UMN lesion
Power (compare between L and R)
- 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)
* 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
- 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)
- Stand with eyes closed and arms held straight out and hands supinated
- Fine finger movements
- Touch each finger to crease of thumb (show patient how) and speed it up
- Look for right and left differences, slow if UMN lesion
Reflex
- Deep tendon reflex (DTR)
- 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
Grade* 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)