Neurological Testing (Dermatomes)

Question 1

What is a dermatome?

Answer 1

This is an area of skin supplied by a single spinal nerve.

Question 2

Technique

Answer 2

• baseline of the sensation by touching cotton wool on arms, with their eyes closed and ask patient to say when they feel the cotton wool.
• supine lying with legs to about 30 degrees
• dab the cotton wool on the dermatome and ask the patient to say when they feel it to say ‘yes’. Then test in the same place on the other side and ask the patient to say ‘same’ or ‘different’.
• test the full extent of the dermatome.

Question 3

Negative Test

Answer 3

This would be if the sensation felt was the same on each side -> the nerve roots would be clear down to that dermatome, so information can travel to brain.

Question 4

Positive Test

Answer 4

A different sensation or no sensation will be felt down one leg to the other -> blocked nerve roots present, making it difficult for nerve impulses to get information to the brain

Question 5

L2

Answer 5

Anterior and Lateral aspect of the thigh.

Question 6

L3

Answer 6

Further down thigh, Anterior and Medial aspect.

Question 7

L4

Answer 7

Medial aspect of leg below knee, down the the great toe.

Question 8

L5

Answer 8

Lateral aspect of leg below knee, also covers toes 2-4.

Question 9

S1

Answer 9

Very lateral aspect on foot and short way up posterior part of leg.

Question 10

S2

Answer 10

Posterior aspect of leg and thigh.