Peripheral Nerve : Lower Limb (exam)

Question 1

For a lower limb PNS what are you looking for on general observation?

Answer 1

SWIFT

• symmetry
• muscle wasting
• Involuntary movements
• fasiculations
• tremors

Bedside:
mobility aids

Question 2

What is the general layout of a lower limb PNS exam?

Answer 2

• WIPE (wash hands, intro, pt details, explain/consent)
• ask if in pain
• Gen inspection
• tone
• power
• coordination
• reflexes
• sensation
• end pieces

Question 3

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

Answer 3

1) roll each leg (observe foot movement to see if increases or reduction in tone)
2) Passively flex and extend knee and ankle

Question 4

what is clasp knife spasticity?

Answer 4

Clasp knife spacticity is increased tone caused by upper motor neurone disorders.

• it is initial resistance, followed by sudden reduction in resistance to movement

Question 5

What is “initial resistance followed by sudden reduction in resistance to movement”

Answer 5

Clasp knife spasticity .

This is increased tone caused by upper motor neurone disorders

Question 6

What is “lead pipe” rigidity/

Answer 6

In disorders of the basal ganglia “lead pipe” rigidity is detected due to sustained resistance throughout range of movement

Question 7

What is sustained resistance throught range of movement known as? and what causes it?

Answer 7

“lead pipe” rigidity caused by basal ganglia disorders

Question 8

What is “cog wheel” rigidity

Answer 8

“cog wheele” rigidity occurs in parkinson’s disease because tremor is superimposed in the underlying lead pipe rigidity

Question 9

What is tremor superimposed on underlying lead pipe rigidity also known as? what causes it?

Answer 9

“cog wheel” rigidity caused by parkinsons

Question 10

what is decreased tone caused by?

Answer 10

• lower motor neurone
  Or
• cerebellar lesion

Question 11

How is power tested in the lower limb PNS>

Answer 11

• Test each muscle group, 1st patient does movement, then against resistance*
  1) Hip flexion, extension, abduction, adduction
  2) Knee flexion/extension
  3) Ankle dorsiflexion and plantarflexion
  4) Big toe flexion/extension

Question 12

What is involved when testing co-ordination in the lower limb PNS?

Answer 12

1) Heel -shin test

2) Toe tapping

Question 13

What reflexes are tested in the lower limb PNS exam and what are the nerve roots associated with each?

Answer 13

1) Patella (L3/4)
2) Ankle jerk (S1/S2)
3) Plantar /

4) Babinski reflex ( support ankle, scratch sole from lateral side of heel up and across base of toes.)
- normal big toe will flex
- abnormal big to extend - UMNL

5) Clonus (suddenly dorsiflex ankle, hold in position. Clonus is when foot flaps rhythimically - in upper motor neurone lesion)

Question 14

What is an abnormal babinski reflex and what does this signify?

Answer 14

normal - big toe flex

abnormal - big toe extend. this is a sign of an upper motor neuron lesion.

Question 15

What is a clonus ?

Answer 15

• suddenly dorsiflex ankle, hold in position. on release foot will move back and forth.

It is a sign of upper motor neurone lesion.

Question 16

How is sensation tested in lower limb PNS?

Answer 16

1) test for light touch and sharp touch - compare dermatomes on both sides

Question 17

How is proprioception tested in lower limb PNS?

Answer 17

1) pt close eyes
2) move big toe up and down, explain movement
3) move toe, pt identifies direction 3X
4) if they can’t identify movement , then do the same with proximal joint.

Question 18

How is vibration sensation tested in lower limb PNS?

Answer 18

Use 128hz tuning fork on sternum.

then pt close eyes

use fork on big toe joint.

say when vibration starts and stops.

*If cant identify then move to proximal joint

Question 19

What end pieces are relevant for lower limb PNS?

Answer 19

1) Romberg test

(pt stand with eyes closed, and feet together)

If they become unsteady then they have positive rombergs test.

• if unsteady with eyes open - then cerebellar lesion
• if unsteady with eyes closed then sensory ataxia

2) Gait
- parkinsons shuffle
- broad base gait (cerebellar lesion)
- high step gait (foot drop)

Question 20

How would you explain and gain consent for a lower limb peripheral exam?

Answer 20

WIPE
Wash hands

Introduce Self - “hello, my name is ….., I’m a 3rd year medical student”

Patient details - “Can I start by checking your name, age and date of birth”

Explain - “Today I’ve been asked to do an examination of the nerves in your legs.

It will involve testing the co-ordination, reflexes and sensation in your legs.

You’ll have to be exposed from the waist down,

and the examiner will act as a chaperone today

• Is this ok with you?