Cervical stenosis (CS), or tightening of the spinal canal, that causes long-term neurological impairment including neck pain and motor weakness, is termed cervical spondylotic myelopathy (CSM). However, substantial compression of the spinal cord does not necessarily entail more severe symptomatology and evaluations of clinical magnetic resonance imaging (MRI) scans are only weakly associated with patient symptom severity and have shown limited value in predicting patient disease progression or response to treatment. Thus, non-invasive imaging biomarkers that better reflect patient symptoms are in great need. While the spinal cord is the primary site of injury in CSM, the brain can also present with degenerative or compensatory changes in relation to patient symptoms. The purpose of this dissertation was to evaluate, via advanced MRI scans, the associations between structure, function, and microstructure, of the spinal cord and brain, with neurological symptoms and pain severity in patients with CS.
High-resolution structural, resting-state functional, and diffusion MRI scans of the brain and spinal cord were acquired in 26 CS patients and 17 healthy control subjects. Measures of brain and spinal cord structure, functional connectivity, and microstrucutre, were compared to the modified Japanese Orthopedic (mJOA) and the Neck Disability Index (NDI) scores. Similar to previous findings, structural measures of the spinal cord were not associated with symptom severity. However, patients with CS presented decreased brain structure with worsening neurological symptoms in subregions of the primary sensorimotor cortex, the superior frontal gyrus, and precuneus, and in the anterior cingulate and putamen in relation to both neurological and pain symptoms. These regions also demonstrated altered functional connectivity, presenting mostly with increasing connectivity with worsening symptoms. Diffusion MRI revealed altered microstructure consistent with degenerative changes in the spinal cord, both at the site of injury and at uncompressed sites, and further rostrally in the corticospinal tracts in the brain.
This cross-sectional study brings the brain and spinal cord together using advanced MRI to paint a more holistic picture of patients with CSM, and provides a groundwork for future studies to evaluate the brain and spinal cord longitudinally and after surgery to help determine optimal treatment strategies.