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

Abstract

Cervical 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 strongly 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. Patients 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 shortened in latency greater than 10% or an increase in amplitude greater than 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. Twenty-nine patients underwent spinal surgery due to CCM. Among these patients, 11 showed positive changes in MEP during IOM. When the two groups were compared, improvement rate in the AISA motor score and K-MBI were significantly higher in patients with positive changes than in patients without positive changes at 1 month after surgery. The duration of hospital stay was significantly shortened in the ‘positive change’ group. Regardless of positive change, nearly all patients suffered from neuropathic pain after operation. Positive changes in MEP during IOM may affect better functional improvement 1 month after operation and early discharge without significant complications in CCM patients. However they do not affect the neuropathic pain. Thus, tailored, proper management is needed to achieve maximal functional recovery in each patient after cervical spinal decompression surgery.