Lower limb neuro exam

Question 1

How do you begin a lower limb neuro exam?

Answer 1

Ask the patient if they are in any pain
Assess gait (normal and heel-to-toe)
Perform Romberg’s test

Question 2

How do you perform Romberg’s test?

Answer 2

• Ask the patient to stand with their feet together, arms stretched in front of them with hands supinated
• Stand within arms reach to support them if they fall
  
  • if a patient loses balance with their eyes open, this suggests cerebellar dysfunction
  • if a patient can maintain the position with their eyes open but lose balance with them closed, this suggests a loss of proprioception (positive Romberg’s sign)

Question 3

What is assed when observing a patients gait?

Answer 3

Stance: broad base = ataxic gait
Stability: staggering/slow/unsteady gait = cerebellar disease
Arm swing: absent/reduced = Parkinsonian gait
Steps: high = foot drop, small/shuffling = Parkinsonian gait, one leg in stiff and swings round = hemiplegic gait
Turning: difficulty turning = cerebellar disease

Question 4

What are you looking for on inspection in a lower limb neuro exam?

Answer 4

SWIFT
Scars
Wasting of muscles (suggests LMN lesion, or disuse atrophy)
Involuntary movements (e.g. chorea, myoclonus)
Fasciculations (suggests LMN lesion)
Tremor
+ walking aids

Question 5

How do you asses tone in a lower limb neuro exam?

Answer 5

• Ask the patient to lie on the bed and fully relax their legs
• Check the tone of the hip muscles by rolling each leg checking for increased tone (UMN lesion) = foot remains in line with knee, or decreased tone (LMN) = very floppy
• Check the tone of other muscle groups by briskly lifting the knee of the bed, checking for increased tone (UMN lesion) = foot also lifts off, or decreased tone (LMN lesion) = very floppy
• Check for ankle clonus by slightly flexing the knee and ankle, rapidly dorsiflexing the ankle, and then keeping the foot in that position to feel for clonus (rhythmic beats of involuntary muscle contraction>5 = UMN lesion)

Question 6

How do you asses power in a lower limb neuro exam?

Answer 6

• Hip flexion (L2) = raise leg, push down
• Hip extension (L5) = raise leg, pull up
• Hip abduction (L4/L5) = bend knee try to move outwards, push in
• Hip adduction (L2/3/4) = bend knee try to move inwards, push out
• Knee flexion (S1) = bend knee try to keep down, pull towards you
• Knee extension (L3/4) = bend knee try to kick, push down
• Ankle dorsiflexion (L4/5) = point foot up, push down
• Ankle plantar-flexion (S1/2) = point foot down like car pedal, pull up
• Big toe flexion = curl toes, try to stop
• Big toe extension (L5) = point toe up, push down

Question 7

How is power described in a lower limb neuro exam?

Answer 7

MRC power scale:
0 = no contraction
1 = flicker or trace of contraction
2 = active movement when gravity is eliminated
3 = active movement against gravity
4 = active movement against gravity and resistance
5 = normal power

UMN lesion = pyramidal (mostly affects lower limb flexors)
LMN lesion = focal pattern

Question 8

How do you asses reflexes in a lower limb neuro exam?

Answer 8

• Knee (L3/4): with leg relaxed (either take the weight or over the side of the bed), tap the patellar tendon
• Ankle (S1): either have patient on bed with hip abducted, knee flexed, and ankle dorsiflexed, or kneeling on chair, tap Achilles tendon and observe contraction of gastrocnemius and plantar flexion
  
  • hyperreflexia = UMN lesion
  • hyporeflexia = LMN lesion
• Plantar reflex (L5/S1): run blunt object along lateral edge of the sole of the foot then medially under the toes, observe flexion (normal) or extension (UMN lesion) of the big toe

Question 8

How do you asses sensation in a lower limb neuro exam?

Answer 8

Light touch (cotton wool, dermatomes)
Vibration (128Hz tuning fork, big toe/ankle/knee)
Proprioception (toe/ankle/knee)
Pain (only describe in OSCE, sensory level)
Temperature (only describe in OSCE)

Question 9

Where are the dermatomes in the lower limb?

Answer 9

L1 = inguinal region at very top of thigh
L2 = lateral and middle aspect of anterior thigh
L3 = medial aspect of the knee
L4 = medial aspect of the lower leg
L5 = dorsum of foot
S1 = lateral aspect of little toe

Question 10

How do you asses coordination in a lower limb neuro exam?

Answer 10

Heel-to-shin test:
- ask patient to place heel on opposite knee and run down shin in a straight line
- then return to knee and repeat in a smooth motion
*incoordination suggests cerebellar pathology

Question 11

How do you complete a lower limb neuro exam?

Answer 11

Cranial nerve exam
Upper limb neuro exam
Cerebellar assessment