Dr Adriaan Liebenberg My Spine Explained | Page 16

My Spine Explained
Figures 2.2
These two illustrations demonstrate
the dermatomes of the body.
A dermatome is the area of the skin
that is being supplied with sensation
by a specific spinal nerve.
Your specialist will use this map to get
an idea of which nerve is being com-
pressed in nerve root mediated pain
(radiculopathy). Note for instance that
compression of the fourth lumbar
nerve (L4) will cause pain over the
shin and compression of the fifth nerve
root (L5) will cause pain over the outer
part of the shin and on top of the foot.
The whole body is divided into der-
matomes and the dermatome map is an
invaluable aid for your specialist.
These areas are, however, not com-
pletely fixed and there is some overlap
and certainly differences between the
exact locations of dermatomes from
patient to patient.
It is important to confirm the nature of nerve compression with an MRI scan
or CT myelogram (see the chapter Tests and Scans). Radicular or nerve root
pain is experienced in a specific dermatome and should not be confused with
referred pain, which is pain that spreads from inflamed tissue such as the disc
and the facet joints to non-specific areas on the skin. Referred pain is fre-
quently said to be non-dermatomal, as it does not comply with dermatomal
patterns, and is therefore an indication that it is unlikely to be nerve root-
related.
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