Introduction: In people with lumbosacral nerve root compression, the perceived leg pain is expected to be in a dermatomal distribution. In practice, this is not the case, the most common hypothesis being inter-individual variability in the dermatomal supply by nerve roots. Our alternative hypothesis is that pain can be perceived anywhere in the sclerotome innervated by the compressed root. We tested this hypothesis.

Methods: We included patients with MRI-supported single nerve root compression (uni- or bilateral) who underwent decompression by one surgeon (TG) between 2002 and 2005 and who reported improved or resolved pain at follow-up.

Everyone drew the distribution of their pain on a standard template and graded their pain using a visual analogue scale (VAS) before and after surgery (3–6 months). Successive pain drawings for each nerve root were superimposed.

Results: 54 nerve roots were decompressed (S1=17, L5=31, L4=6).

S1 nerve root compression was associated with pain in the lower back, buttock and thigh.

Conclusion: This small preliminary study implies that pain in lumbosacral nerve root compression is more sclerotomal than dermatomal in its distribution.