Cervical canal dimensions vary according to neck posture, and conventional magnetic resonance imaging (MRI) performed in a neutral position may underestimate the degree of cervical spinal cord compression. We report a patient with progressive cervical myelopathy in whom clinical deterioration was discordant with findings on static MRI. Dynamic MRI performed during cervical extension demonstrated significant multilevel spinal canal stenosis, which prompted timely surgical intervention. This case highlights the diagnostic value of dynamic MRI in situations of clinical-radiological mismatch and underscores its role in informing an appropriate surgical strategy.