Distinguishing DCM from MS and ALS: Clinical and Diagnostic Insights

Degenerative cervical myelopathy (DCM) is a leading cause of progressive spinal cord dysfunction and can closely mimic multiple sclerosis (MS) or amyotrophic lateral sclerosis (ALS) when early motor signs overlap; a recent review clarifies the clinical, imaging, and testing distinctions that reduce misdiagnosis and guide timely management.

Which historical and examination features point toward DCM rather than MS or ALS? Neck and shoulder pain and mechanical symptoms favor DCM: roughly half of patients report neck/shoulder pain and about 80% experience hand numbness. Early hand clumsiness, gait disturbance, and mixed sensory changes are common to all three disorders, so context and pattern matter.

MRI remains central to evaluation. The characteristic DCM signature is structural cord compression with anterior–posterior canal narrowing and focal T2-weighted intramedullary hyperintensity that correlates with myelopathic change. By contrast, MS typically shows discrete intramedullary white-matter plaques and brain lesions, and ALS usually lacks focal compressive cord lesions. When MRI shows cord compression concordant with clinical myelopathy, prompt surgical referral is indicated; disseminated intramedullary plaques or supportive CSF findings should redirect the workup toward a neuroimmunologic evaluation.

Advanced spine imaging (diffusion tensor imaging, spinal cord volumetry, susceptibility-weighted imaging) can add pathophysiologic detail but remains supportive rather than diagnostic. Crucially, imaging–clinic concordance determines next steps: incidental cord compression without clinical myelopathy warrants alternate diagnostic pathways rather than reflex surgery. These modalities have limited but growing value in refining the differential.

Electrophysiology and CSF studies further refine equivocal presentations. EMG/NCS in ALS typically show widespread active denervation with chronic reinnervation across multiple regions; DCM produces more segmental motor-unit changes, with distal sensory nerve action potentials relatively preserved unless radiculopathy is present. Somatosensory and motor evoked potentials may show central conduction delay in both DCM and MS. Combined brain MRI and CSF oligoclonal bands favour MS. Overall, CSF and serum biomarkers and electrophysiology are supportive adjuncts; a tiered testing strategy using EMG/NCS and selective CSF analysis helps avoid inappropriate immunotherapy or delayed surgical care.