Proposed diagnostic criteria and nosology of acute transverse myelitis

To the Editor: The Transverse Myelitis Consortium Working Group should be congratulated for the proposed diagnostic criteria and nosology of acute transverse myelitis (ATM).1 However, in the differential diagnosis only scarce attention was given to fibrocartilaginous embolization from nucleus pulposus embolism (NPE), a condition that is often undiagnosed and frequently confused—clinically and pathologically—with ATM.2 For instance, Bots et al.3 reexamined a teaching specimen of so-called ATM and found an acute transverse myelopathy due to NPE. Although the exclusion criterion of <4 hours from onset to nadir would effectively exclude most vascular cases, in our review of the natural history of NPE,2 we found that at least 42% of the cases had progressed for periods of ≥4 hours; furthermore, a prodromal history of intermittent back pain is not uncommon, lasting for periods of weeks to up to 4 months.4 …