In a recent retrospective study of 2,450 consecutive lumbar pedicle screw placements in 418 patients, tEMG was found to have a specificity of 99.9% and sensitivity of 43.4% when a stimulation threshold of 5.0 mA was used.
The surgeons operated at two hospitals and had access to all four modalities: SSEP, TcMEP, sEMG, and tEMG performed by an experienced neurophysiologist.
For cervical surgeries, 47% of surgeons additionally used sEMG, while for thoracic 71% of surgeons additionally used sEMG and tEMG. Most surgeons (44%) used all four modalities for lumbar deformity surgery (Table 1).
Thirty-five percent surgeons used SSEP and tEMG when doing posterior spinal fusions with instrumentation.
(9-82-83) However, many surgeons still feel that IOM is essential, especially during high risk cases, such as cervical procedures, revision cases, and instrumentation and fusion surgeries, which may benefit from sEMG or tEMG monitoring of nerve root function.