Brain MRI to detect cervical spinal cord critical demyelinating lesions in progressive MS

Critical demyelinating lesions anatomically associated with progressive motor impairment in multiple sclerosis (MS) are mostly found in the cervical spinal cord. In clinical practice and research studies, imaging of spinal cord is usually restricted to brain magnetic resonance imaging (MRI), which can show its most superior region.

To evaluate the ability of brain MRI to detect spinal cord critical lesions in progressive MS.

Individuals with one or two tandem spinal cord critical lesions were selected from a cohort of people with progressive MS, evaluated at Mayo Clinic between July 1, 2021-June 30, 2022. Lesions were cross-checked on spinal cord MRI to ensure visibility. Brain MRI performed at Mayo Clinic or an outside institution during clinical evaluation were assessed; if none were available, the most recent prior MRI was evaluated. Brain MRIs were defined "informative" if critical lesions were identified on axial and sagittal sequences and "incompletely informative" if not.

Sixty-five participants were identified, brain MRIs were "informative" in 3 cases (4.6%) and "incompletely informative" in 62 (95.4%). Among those "incompletely informative", 53 (81.5%) had no critical lesion visible on any sequence, 8 (12.3%) had a critical lesion visible only on sagittal sequences, and 1 (1.5%) had two tandem critical lesions with only the upper lesion detected. Detection of spinal cord critical lesions on brain scans was mainly successful by using MPRAGE and FLAIR sequences.

Brain MRI is inadequate for detecting spinal cord critical demyelinating lesions in progressive MS and dedicated spinal cord imaging is required.