Abstract
Aim:
To present the results of multi-modal IOM in 298 patients who underwent spinal deformity correction.
Method:
We reviewed the notes, surgical and IOM charts of all patients who underwent spinal surgery with the use of cortical and cervical SSEPs, as well as upper/lower limb transcranial electrical MEPs under the senior author. We recorded IOM events which we categorised as true, transient true and false (+) or (−). We correlated the IOM events with surgical or anaesthetic incidents.
Results:
Diagnosis included idiopathic scoliosis in 224, congenital in 12, syndromic in 14, scoliosis with intraspinal anomaly in 5, scoliosis with congenital cardiac disease in 4, spondylolisthesis in 2, spinal tumour in one, and Scheuermann's kyphosis in 36 patients.
We identified 3 true (+) monitoring events occurring in 2 patients (1%), 6 transient true (+) (2%), and 11 transient false (+) events (3.7%). True (+) events occurred during deformity correction in one patient with severe AIS and during osteotomies in another with severe Scheuermann's. Transient true (+) events occurred during posterior osteotomies in 2 patients with Scheuermann's, during scoliosis correction (apical correction with sublaminar wires) in one and placement of concave apical pedicle screw in another patient, and 2 IOM changes during positioning (one during reduction of spondylolisthesis-one during positioning on the surgical table). Transient false (+) events were mainly related to low blood pressure (10 patients). There were no false (−) IOM events and none of our patients had postoperative neurological complications.
Sensitivity of our IOM technique was 100% [all patients with impending spinal cord injury will have a (+) event] and specificity 96% (patients with normal IOM had 96% chance that the cord was safe). Positive predictive value was 65.3% (65.3% chance that an IOM event reflected a surgical-related cause of cord injury); negative predictive value 100% (100% chance that normal IOM corresponded to no cord injury). We found no difference between patients with AIS and Scheuermann's in terms of risk of true or transient true (+) IOM events (Fisher's exact test, p=0.12).
Discussion:
Multimodal IOM is highly sensitive and specific for spinal cord injury. This technique is reliable to assess the condition of the spinal cord during high-risk major spinal deformity surgery.
Conflict of interest statement: None
