Careful evaluation of symptom progression and radiographic findings are essential tools when approaching cases of suspected chronic myelopathies. In this case, a 26-year-old woman presented with progressive ambulatory and bladder dysfunction for 4 years. Her examination was marked by bilateral lower-extremity upper motor neuron signs and distal large-fiber sensory loss. Neurologic workup for acquired causes of this presentation was unrevealing. MRI of the brain revealed a characteristic radiologic finding. Guided genetic testing ultimately yielded the final diagnosis. In this clinical vignette, we review the approach to chronic myelopathy including consideration of genetic etiologies and pursuit of targeted gene testing. We further discuss the typical clinical and radiographic findings of a rare diagnosis.