Guidance on Sensory Testing of the Lower Limb
1) What you do depends on the context
For example, if a patient is well with no sensory symptoms, a quick check of sensation on
outer thigh, calf and feet may be sufficient.
However, if the patient had a history of back pain and there was concern about nerve root
compression, check by dermatomes- one touch for L2, L3, L4, L5 and S1
If the patient has diabetes and complains of tingling feet, pain in the feet or a sensation as
though walking on cotton wool, a sensory neuropathy would be suspected and a stocking
distribution of sensory loss would be expected. In this case, test from normal to area of
reduced sensation and then back again to demonstrate the line of demarcation
2) Books vary in their dermatome descriptions- but a guide is as follows:
L2- outer upper thigh (just below greater trochanter)
L3 medial lower thigh
L4 medial calf
L5 lateral calf, dorsum of foot
S1 lower lateral border of foot or small toe
 Dr R Clarke
www.askdoctorclarke.com
1
3) Sensory modalities
Ideally, you'd check light touch (LT), pin prick (PP), temperature, vibration and joint position
sense (JPS).
However, PP and temp are mainly carried by same pathways, so ethyl chloride spray (which
is cold) is not really needed as well as PP, though it is often used by anaesthetists to assess
whether an epidural has been effective (eg prior to caesarean section).
Sharp end of neurotips- test pin prick (though a paper clip can be equally effective)
Vibration sense and JPS have a major overlap- so in life often just one is done.
For example, assessing a patient in the diabetic clinic will usually involve testing LT and
vibration sense plus checking the ankle jerks (usually absent in diabetic neuropathy).
4) In an exam, best to do four modalities: LT, PP, Vibration, JPS
Test LT and PP in each dermatome (see above). Remember to start by testing sensation in
an area of normal skin so that you demonstrate that the patient can tell difference between
the two ends of the neurotip.
Then check JPS at big toe and vibration sense at tip of big toe and on medial malleolus.
5) Light touch can be done in a number of ways
• light finger touch
• cotton wool
• 10g monofilament
• blunt end of neurotips
 Dr R Clarke
www.askdoctorclarke.com
2
6) Monofilament testing
This is increasingly used as a semi-objective screening test for sensory peripheral
neuropathy in diabetic patients.
A fibre of synthetic plastic (monofilament, as used in fishing lines etc) is designed so that
when it is applied to the skin with just enough force to make it bend, the force is equivalent
to a load of 10g and the stimulus is therefore reproducible and standardised.
Apply at 90 degrees to the skin and with enough force to make the filament bend:
There are different regimes for using it, some involving 5 or 8 applications to the foot. The
simplest approach involves using it in 3 areas:
L4- medial longitudinal arch (plantar aspect foot).
L5- plantar aspect of big toe
S1- lateral aspect of foot on dorsum
If one is not felt, this implies reduced sensation and if all are not felt, absent sensation.
 Dr R Clarke
www.askdoctorclarke.com
3