ASSESSMENT OF SPINAL MUSCULATURE USING SURFACE ELECTROMYOGRAPHIC SPECTRAL COLOR MAPPING

Study Design. A technique is described for analyzing electromyogram da ta from lumbar spinal muscles, with special reference to discriminatio n of People with back pain. The ability to discriminate was evaluated in 99 people (61 healthy and 38 with chronic or acute back pain), and the influence of load was assessed. Objectives. To evaluate methods of analysis of complex electromyogram data and to assess correlation of information with clinical condition in people with and without back pa in. Summary of Background Information. In previous analyses of electro myogram data, only a small part of the data have been used. Spinal mus cular decompensation has been postulated in chronic low back pain, but there has been no direct demonstration of this phenomenon. Objective measures are still elusive. Methods. Lumbar spinal surface electromyog rams were recorded during an isometric lifting task. The data were rep resented graphically as color-coded plots of electromyogram frequency, time, and electromyogram amplitude. Spectral width at half-peak ampli tude (spectral half width) was calculated from the digitized, summed d ata. Ninety-nine people were tested: 48 men (29 with no recent [in the past past 2 years] history of back pain, 16 with chronic back pain, 3 with acute back pain) and 51 women (32 with no recent back pain and 1 9 with chronic back pain). Results. Spectral color maps in people with chronic back pain were markedly different from those in healthy le. S pectral half width was greater in people with chronic back pain than i n healthy people (P < 0.01). Blinded analysis of spectral color maps a llowed discrimination of people with back pain from healthy people wit h a sensitivity of 76% and a specificity of 81%. People With a history Of back pain had markedly variable half widths. Conclusions. A new me thod of analysis of electromyogram data from lumbar spinal muscles has allowed discrimination between people with back pain and healthy peop le. This provides direct evidence of a correlation between muscular el ectrical function, measured by electromyogram, and low back pain. This technique may have potential as an objective measurement tool.