The systemic immune-inflammation index and cervical cord compression are associated with intramedullary spinal cord signal intensity in health-screening individuals and neurological recovery in degenerative cervical myelopathy.

Abstract

Intramedullary spinal cord signal intensity (ISI) on MRI is commonly observed in degenerative cervical myelopathy (DCM) and is generally regarded as a marker of spinal cord injury. However, ISI is also increasingly detected in individuals undergoing health screening without documented clinical myelopathy, and the biological and structural factors underlying ISI across the clinical spectrum remain poorly understood. To investigate the prevalence and determinants of MRI-defined ISI in health-screening individuals without documented clinical myelopathy and to examine whether systemic inflammation and cervical cord compression are associated with ISI and postoperative neurological recovery in patients with DCM. Retrospective observational prognostic cohort study. Two independent cohorts were analyzed: (1) 300 health-screening individuals without documented clinical myelopathy who underwent routine cervical MRI, and (2) 328 patients who underwent cervical decompression surgery for DCM. Presence of MRI-defined ISI. Neurological function and clinical outcomes were assessed using the visual analog scale (VAS), neck disability index (NDI), modified Japanese Orthopaedic Association (mJOA) score, and mJOA recovery rate at 2 years. We conducted a retrospective observational study comprising two independent cohorts. The health-screening cohort included 300 individuals without documented clinical myelopathy who underwent cervical MRI and routine blood testing. MRI-defined ISI was assessed, and clinical, biochemical, and radiographic variables-including the systemic immune-inflammation index (SII) and cervical cord compression index (CCI)-were compared between individuals with and without ISI. Multivariable logistic regression was used to identify independent factors associated with ISI. The DCM surgical cohort consisted of 328 patients who underwent cervical decompression surgery. Patients were stratified according to (1) the presence of ISI on MRI and (2) neurological outcome based on the mJOA recovery rate. Multivariable logistic regression models were used to determine independent factors associated with ISI and neurological recovery. In the health-screening cohort, ISI was identified in 44 of 300 individuals (14.7%). Multivariable analysis demonstrated that higher SII and greater CCI were independently associated with the presence of ISI. In the DCM cohort, ISI was present in 149 of 328 patients (45.4%). Male, higher SII, and reduced spinal cord transverse area (TA) were independently associated with ISI. When neurological recovery was assessed, poorer mJOA recovery was independently associated with elevated SII and reduced TA. In a health-screening cohort without documented clinical myelopathy, systemic inflammatory burden and cervical cord compression were independently associated with MRI-defined ISI. Importantly, ISI was not observed in a completely non-compressive setting. In patients with DCM, inflammatory burden and spinal cord morphology were associated with ISI and postoperative neurological recovery. These findings suggest that inflammatory status may provide clinically accessible risk stratification information for MRI-defined ISI and postoperative neurological recovery in degenerative cervical disease.