Table 1.
D-wave | Muscle MEPs | Corrective measures | Predicted outcome |
---|---|---|---|
Unchanged | Present | None | Unchanged |
Unchanged or above 50% | Present with minor changes (decreased amplitude or increased threshold) | Transiently move surgical manipulation to a different area; warm irrigation; correct hypotension | Unchanged |
Unchanged or above 50% | Lost uni- or bilaterally | All the above, then transiently stop surgery and/or improve spinal cord blood flow (local irrigation with papaverine). If mMEPs do not re-appear, abandon surgery in selective cases; as a rule surgery can proceed | Transient motor deficit (affecting the involved extremity) |
Decreased >50% | Lost bilaterally | Stop surgery immediately. If D-wave does not recover, abandon surgery | Permanent motor deficit |
Unmonitorable | Lost bilaterally | All the above. If mMEPs do not recover, abandon surgery | Cannot differentiate between transient and permanent motor deficit |
mMEPs muscle motor evoked potentials