Electrodiagnostic tests
Electromyography and Nerve Conduction Studies Three studies investigated the diagnostic
accuracy of electromyography to detect LSS [21, 28, 29, 32-34, 54].
The first article by Haig et al. [33] evaluated the diagnostic accuracy of electromyography and nerve
conduction studies using a clinical reference standard. The sensitivity of EMG was 63%; the
specificity was 54%. The sensitivity of NCS was 54%; the specificity was 75%. The combined
accuracy of EMG and NCS had a sensitivity of 79% and a specificity of 50%. In addition to the
conventional EMG evaluation the article reported the diagnostic accuracy of paraspinal mapping; the
sensitivity was 29%, the specificity was 100%.
The following articles by Haig et al. [32, 34] used clinical confirmation of LSS only as the reference
standard without consideration of imaging and/or surgery findings. The overall evaluation of MRI had
a sensitivity of 59% and a specificity of 44%. A minimum canal diameter of ≤ 11.95 mm had a
sensitivity of 27% and a specificity of 77%. The sensitivity and specificity of EMG (including
paraspinal mapping) and NCS combined were 73% and 48%, respectively. The findings on MRI were
able to differentiate persons with LSS from asymptomatic subjects but not from persons with
mechanical low-back pain, whereas electrodiagnosis was able to marginally discriminate all groups.
The article of Chiodo et al. assessed the asymptomatic subjects among the previously described study
population [21]. The specificity for EMG was 59%; the specificity for MRI was 44%. There was no
statistically significant relationship between the false positive rate of electrodiagnosis and MRI.
The study of Yagci et al. evaluated the diagnostic accuracy of paraspinal mapping using a clinical
reference standard [54]. The sensitivity ranged from 72% to 97%, and the specificity ranged from 63%
to 100% .
The study of Fisher et al. compared the diagnostic accuracy of conventional electrodiagnosis and
computerized recording and analysis of EMG and NCS (NC-stat) [28, 29]. MRI or post-myelographic
CT was used as a reference standard . The sensitivity for EMG was 60%, and the specificity was 82%.
The sensitivity for EMG combined with NCS was 90%, and the specificity was 45%. The sensitivity
for NC-stat ranged from 60% to 90%, and the specificity ranged from 27% to 82%.
DSEP Two studies investigated the diagnostic accuracy of dermatomal somatosensory-evoked
potentials (DSEP). One study had CT or MRI as a reference standard [52]; this study showed a
sensitivity of 96%, the specificity was not reported. The other study had surgery as a reference
standard [51]; the sensitivity ranged from 78% to 94%, but the specificity was not reported.
Magnetic stimulation MCT One study investigated the diagnostic accuracy of the caudal motor
conduction time (caudal MCT) after magnetic stimulation. This study showed a sensitivity of 56%
[35], the specificity was not reported.
Selective lumbar root sheath infiltration One study investigated the diagnostic accuracy of selective
lumbar root sheath infiltration with successful outcome of surgery as a reference standard. This study
did not report a sensitivity or specificity but showed a positive predictive value of 95% [19].