The effect of positive changes during intraoperative monitoring of the functional improvement in patients with cervical compressive myelopathy

Abstract

BackgroundCervical compressive myelopathy (CCM) is a progressive, degenerative spine disease and the most common cause of spinal cord dysfunction in older individuals. Current clinical guidelines for spinal surgery recommend multimodal intraoperative monitoring (IOM) during spinal surgery as a reliable and valid diagnostic adjunct to assess spinal cord integrity. The aim of this study was to evaluate the effect of positive changes during IOM on the functional status in patients with CCM.MethodsPatients who underwent spinal surgery with IOM due to CCM were enrolled. During the surgery, patients underwent IOM using motor evoked potential (MEP) and somatosensory evoked potential (SEP). MEP and SEP were checked before and immediately after decompression. A decrease in latency >10% or an increase in amplitude >50% was regarded as a “positive changes”. Subjects were divided according to the presence of positive changes. Motor scores of American Spinal Injury Association (ASIA) impairment scale and Korean version of Modified Barthel Index (K-MBI) were evaluated before and after operation.ResultsTwenty-nine patients underwent spinal surgery due to CCM. Eleven patients showed positive changes in MEP during IOM. When the two groups were compared, improvement rate in the ASIA motor score and K-MBI were significantly higher in patients with positive changes than in patients without positive changes at 1 month after surgery. However, 6 months after surgery, there were no significance differences between the groups. Regardless of positive change, nearly all patients suffered from neuropathic pain after operation.ConclusionPositive changes in MEP during IOM may affect functional improvement 1 month after operation and early discharge without significant complications in CCM patients. However, they do not affect the neuropathic pain and long-term functional outcome. Thus, tailored proper management is needed to achieve maximal functional recovery in each patient after cervical spinal decompression surgery.

Intraoperative Motor Evoked Potential Improvement in Cervical Spondylotic Myelopathy: Comparison of Cortical Stimulation Parameters

“…MEPI was evident in more than 50% of the patients undergoing surgery, in contrast to previous studies 11,12 finding much smaller proportions. However, direct comparisons with those studies might not be possible since the cortical stimulation parameters were not reported.…”

“…21 However, these findings are not based on IOM data. Two previous studies 11,12 produced different results, correlating MEP improvement with better outcomes at 6 months and 1 month. However, the stimulation protocols were not stated explicitly and are actually unlikely to be comparable between the two studies, and their outcome measures were also dissimilar.…”

“…In two studies that have addressed IOM in CSM surgery, the intraoperative improvement of MEPs was referred to as a 'positive change' and 'MEP signal improvement' . 11,12 The first of these studies involved 59 patients, of which 21 (36%) showed improvement in MEPs, which correlated with a better prognosis at up to 6 months. In the second study involving 29 patients, 11 (38%) had a better outcome only at 1 month postoperatively.…”

Successful Motor Evoked Potential Monitoring in Cervical Myelopathy : Related Factors and the Effect of Increased Stimulation Intensity

“…Some controversy remains about the overall efficacy of surgery for cervical myelopathy [ 7 , 14 ] although recent data have associated IONM with postoperative clinical outcome benefits [ 1 , 16 , 29 ]. Further research that utilizes larger samples, comparable and efficient stimulation protocols, and standardized outcome measures for longer follow-up periods may shed some light on this matter.…”

Cervical Spondylotic Myelopathy: Natural Course and the Value of Diagnostic Techniques –WFNS Spine Committee Recommendations

“…Positive changes in MEP during monitoring may reflect a functional improvement 1 month after surgery in CSM patients [61]. However, the neuropathic pain and long-term functional outcomes are not affected.…”