Lower limb PNS exam

Question 1

After WIPE, what is the first step in the lower limb PNS exam?

Answer 1

Assess gait

• ask patient to walk from one side of the room to another
• ask them to walk on their tiptoes for a rough assessment of distal power
• Romberg’s test:
  1. ask the patient to stand their their feet together, stand behind them in case they fall
  2. ask the patient to close their eyes and see if they can maintain their balance
  3. if they lose balance = Romberg positive = problem with their proprioception peripherally and/or centrally

Question 2

What do you look for upon general inspection of the patient?

Answer 2

1. tremors
2. muscle wasting and fasciculations (LMN signs)
3. resting posture
4. bony deformity and skin changes
   anything else of notes, such as scars, walking aids etc

Question 3

How do you assess tone in a lower limb PNS?

Answer 3

• *ask about pain/tenderness
  1. with the patient at 45° on the bed. ask them to relax their legs
  2. gently roll each leg from side to side
• spasticity in the ankle = UMN lesion
• completely floppy = LMN lesion
  3. briskly pick up the leg underneath each knee
• kicking out of the ankle = UMN lesion
  4. gently roll each ankle then briskly dorsiflex the foot
• beats pf clonus (repetitive muscle contraction) = UMN lesion

Question 4

How do you test power in a lower limb PNS? State the myotome for each movement.

Answer 4

1. test each spinal root individually, comparing each side
2. ask patient to perform each movement and ask them to resist you pushing/pulling against them (hold the joint you are testing to isolate the movement):
   - hip flexion (L2/3)
   - hip extension (L4/5)
   - knee flexion (L5/S1)
   - knee extension (L3/4)
   - ankle dorsiflexion (L4/5)
   - ankle plantar flexion (S1/2)
   - big toe extension (L5 only)
3. any weakness can be UMN or LMN damage

Question 5

How do you assess co-ordination in a lower limb PNS?

Answer 5

1. perform on each leg, one at a time:
   - ask the patient to touch the back of their heel to their contralateral knee
   - slide their heel down the leg until its straight
   - kick up with their straight leg to hit your hand with their big toe
   - return to the starting position with their heel against the other knee
   - repeat 3 times
2. foot stamping:
   - stamp each foot alternately on the floor, increasing speed
   - this is easier for patients who cannot perform the heel-to-shin test

Question 6

What do co-ordination problems indicate?

Answer 6

• cerebellar lesion (or may actually reflect weakness in the legs)

Question 7

Generally, how should you assess reflexes in a lower limb PNS? What reflexes do you examine

Answer 7

1. test each leg individually, comparing each side
2. for all reflexes, patient should be lying comfortably on the couch
3. examine the following reflexes:
   - patellar tendon
   - achilles tendon
   - plantar response (Babinski reflex)

Question 8

How do you test the patellar reflex and what is the myotome?

Answer 8

1. hold weight if patient’s leg beneath their knee and ask them to relax
2. tap tendon below patella
3. look for knee extension

Myotome: L3/L4

Question 9

How do you test the Achilles reflex and what is the myotome?

Answer 9

1. lie patient’s lower leg across their contralateral shin
2. holding the sole of their foot, gently dorsiflex their ankle
3. tap the thickest part of the tendon
4. look/feel for the plantar flexion against your hand

Myotome: S1/S2

Question 10

How do you test the plantar response/Babinski reflex and

Answer 10

1. warn the patient that tis might feel uncomfortable
2. using a blunt instrument, scrap up the lateral side of their sole and across to their big toe
3. or start with a finger, move to using thumb nail
4. big toe should plantar flex

Question 11

If a patient dorsiflexes when eliciting the Babinski reflex, what does this indicate?

Answer 11

UMN lesion

normal in babies