The role of spared spinal cord in post-surgery recovery depends on age in cervical spondylotic myelopathy–a case series study

Abstract

Object: New evidence shows that the degree of microscopic alterations in spinal cord (SC) regions appearing normal on conventional MRI has some predictive value of neurological impairment and recovery in patients with cervical spondylotic myelopathy (CSM). Although SC physiological reserves and plastic potential are likely to decrease as a function of age, the effects of age on such relationships remain unknown. We hypothesized that the preoperative level of spared SC microscopic alterations projects the postoperative functional outcome and this prediction is age-dependent Methods: Nine CSM patients exhibiting neurological symptoms less than one year underwent decompressive surgery. Preoperative neuronal (N-acetylaspartate, NAA) and cellular turnover (choline, Cho) biomarkers were quantified by means of MR spectroscopy (MRS) in spared SC regions in the closed proximity to the compression level (C2 level). Pre-and postoperative (at six months after surgery) clinical status were assessed using modified Japanese Orthopaedic Association (mJOA) and 9-Hole Peg test (9HPT). Relationships between MRS biomarkers and clinical changes were determined and controlled for patient's age.Results: Consistent with prior findings, significant clinical improvement was detected at six months after surgery (mJOA, p=0.002; 9HPT, p=0.001). As predicted, NAA and NAA/Cho significantly related to changes in mJOA (p=0.02) and 9HPT (p=0.005) scores respectively. Notably, these relationships did not survive age correction (p=0.1 and p=0.06 respectively). Conclusions:Our preliminary results are consistent with MRS potential to assay the degree of microscopic injury and viability of the spared SC to prognosticate functional recovery after decompressive surgery in this population. Likewise, our findings provide initial evidence that the contribution of the spared SC in postoperative recovery depends on the patient's age at the diagnosis.