Electrophysiologic examinations including electromyography (EMG), late responses and somatosensory evoked potentials (SSEP) were performed on the L4, L5 and S1 roots distributed regione on the 34 cases of low back pain with had already studies of myelography and computerized tomography (CT) scan. The SSEP findings were compared to the EMG, myelography and CT scan findings with the sensitivity and speciticity between them.

The results were as follows.

1) Among the thirty four cases who had done either a myelogram, CT scan, or both, twenty two cases (64.7%) showed evidence of nerve root compression sign on EMG study and 23 cases (67.6%) showed to be positive in SEP findings.

2) The sensitivity was 59.1% and the specificity was 41.7% when the EMG findings were compared to myelgram and CT scan findings, and the sensitivity was 83.6% and the specificity was 25.0% when the SSEP findings were compared to myelogram and CT scan findings. There was no statistical significance between the EMG and SSEP.

3) Ten cases out of eleven who showed on EMG positive findings revealed that positive findings in SSEP studies and 5 cases free from EMG, myelogram and CT scan findings showed positive findings in SSEP studies.