Aim: To determine the distribution of pain which can be most reliably attributed to individual lumbo-sacral nerve root compression.

Introduction: Patients are selected for nerve root decompression based on a correlation between symptoms, signs and imaging findings. However, the belief that a given pain may be attributable to a specific nerve root varies widely between surgeons. Some will only consider decompressing a nerve root in the presence of pain radiating in a classical dermatomal distribution whilst others consider nerve root compression to be a cause of back, buttock or thigh pain.

We sought to determine the distribution of pain which significantly improves following decompression of lumbo-sacral nerve roots.

Methods: Data from consecutive patients undergoing lumbo-sacral nerve root decompression between 2002 and 2005 was prospectively analysed. Inclusion criteria were:

uni- or bilateral single level nerve root decompression

For individual nerve roots the distribution of pain described on post-operative pain drawings was sub-tracted from that described on pre-operative pain drawings. This produced a composite pain drawing demonstrating the distribution of pain most reliably improved by decompressing a particular nerve root.

Results: 52 cases fulfilled the inclusion criteria. There were 6 L4, 36 L5 and 17 S1 nerve root decompressions. The distribution of dramatically improved pain following nerve root decompression did not follow the classic dermatomal patterns described in standard text books.

Conclusions:

Pain as a consequence of lumbo-sacral nerve root compression does not appear to be restricted to classical dermatomal distributions.

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.