The pain on cervical or lumbar areas with radiation to extremity was well known symptoms of radiculopathy involving cervical or lumbosacral roots. The root lesion can be diagnosed by clinical findings, myelography, computed tomography (C.T.) or magnetic resonance imaging (M.R.I.), and electromyography. The electromyography has been regarded as a sensitive and specific method for the evaluation of radiculopathy, but its distribution was poorly studied yet.

The purpose of this study is to disclose the distribution of electromyographic abnormalities of the radiculopathy. Since January 1988 to December 1992, 172 cases of cervical and 334 cases of lumbosacral radiculopathy were analysed by retrospective study.

The results were as follows;

1) Subjects were divided into 4 groups: unilateral involvement of a single segment (40.1%), unilateral involvement of multiple segments (22.0%), bilateral involvements of a single segment (20.9%), bilateral involvements of multiple segments (16.9%) in cervical radiculopathy and unilateral involvements of a single segment (38.4%), unilateral involvements of multiple segments (10.5%), bilateral involvements of a single segment (30.3%), bilateral involvements of multiple segments (20.7%) in lumbosacral radiculopathy. The most common single radiculopathy was C7 in cervical and L5 in lumbosacral radiculopahty.

2) The mean duration of symptoms was significantly longer in the group with changes of motor unit potential and firing rate only than the groups with abnormal spontaneous activities of extremities and paravertebral muscles.

3) In cervical radiculopathy, the mean age of the subjects with involvement of multiple segments was 48.5±12.4 years and that of the subjects with single segment was 50.1±15.2 years (p>0.05), and the mean age of the subjects with bilateral involvement was 52.4±13.0 years, while that of the subjects with unilateral involvement was 47.1±13.6 years (p<0.05). In lumbosacral radiculopathy, the mean age of the subjects with involvement of multiple segments was 49.3±14.4 years, while that of the subjects with single segment was 43.3±15.6 years (p<0.05), and the mean age of the subjects with bilateral involvement was 47.5±14.7 years, while that of the subjects with unilateral involvement was 42.6±15.7 years (p<0.05). These findings suggest the degenerative process with age.

4) C.T. or M.R.I. findings were well correlated with the electromyographic findings in the evaluation of the side of involvements but not the segment.

5) The side of radiculopathy was not directly related to the side of symptoms. The subjectis who had bilateral radiculopathy with unilateral symptom were 27%, 40% in cervical and lumbosacral radiculopathy, respectively.

Electromyographers should be aware of the high frequency of multiple segments and bilateral involvements so that complete examinations can be planned and performed.