Dermatomes, Interesting read from Spine

Spine:
POST ACCEPTANCE, 15 January 2013
doi: 10.1097/BRS.0b013e318286b7dd
Clinical Case Series: PDF Only
Do L5 and S1 nerve root compressions produce radicular pain in a dermatomal pattern?Taylor, CS BSc, MBBS; Coxon, A PhD, MBCS, MICR; Watson, P BSc; Greenough, CG MD, MChir, FRCSPublished Ahead-of-Print


Abstract
Structured Abstract: Study Design. Observational case series.

Objective. To compare the pattern of distribution of radicular pain with published dermatome charts.

Summary of Background Data. Dermatomal charts vary, and previous studies have demonstrated significant individual subject variation.

Methods. Patients with radiologically and surgically proven nerve root compression caused by prolapsed intervertebral disc completed computerised diagrams of the distribution of pain and pins and needles. 98 patients had L5 compressions and 83 had S1 compressions.

Results. The distribution of pain and pins and needles did not correspond well with dermatomal patterns. Of those patients with L5 NRC, only 22 (22.4%) recorded any hits on the L5 dermatome on the front, and only 60 (61.2%) on the back with only 13 (13.3%) on both. Only 1 (1.0%) patient placed >50% of their hits within the L5 dermatome. Of those patients with S1 NRC, only 3 (3.6%) recorded any hits on the S1 dermatome on the front, and only 64 (77.1%) on the back with only 15 (18.1%) on both. No patients placed >50% of their hits within the S1 dermatome. Regarding pins and needles, 27 (29.7%) of L5 patients recorded hits on the front alone, 27 (29.7%) on the back alone and 14 (15.4%) on both. 19 (20.9%) recorded >50% of hits within the L5 dermatome. 3 (3.6%) S1 patients recorded hits on the front alone, 44 (53.0%) on the back alone and 18 (21.7%) on both. 12 (14.5%) recorded >50% of hits within the S1 dermatome.

Conclusion. Patient report is an unreliable method of identifying the anatomical source of pain or paraesthesia caused by nerve root compression.