NMOSD-like and longitudinal extensive HTLV1-associated myelitis are extremes that flank an overlooked continuum

• Published in: Multiple sclerosis journal - experimental, translational and clinical Vol. 7; no. 3; p. 20552173211037361
• Main Authors: Bonnan, Mickael, Olindo, Stéphane, Signate, Aissatou, Lobjois, Quentin, Stephant, Maeva, Boulos, Dalia Dimitri, Cabre, Philippe
• Format: Journal Article
• Language: English
• Published: London, England SAGE Publications 01-07-2021; Sage Publications Ltd
• Subjects: Neuromuscular diseases; Original; Viral infections; HTLV-1-associated myelopathy; human t-lymphotropic virus 1 infection; Neuromyelitis optica spectrum disorder; myelitis; optic neuritis
• ISSN: 2055-2173; 2055-2173
• DOI: 10.1177/20552173211037361

Background
HTLV1-associated myelitis (HAM) is a slowly progressive myelopathy in which spinal cord MRI demonstrates no lesion or atrophy.
Objective
We examined the overlap between NMOSD features and HTLV1 infection.
Methods
We included all HTLV1-infected patients recruited in French West Indies (FWI) or referred from different centers, and suffering from at least one NMOSD feature. Literature connecting HTLV1-infection and NMOSD was reviewed.
Results
We included six NMOSD-like HAM with acute onset, seronegative against AQP4 and MOG-Abs. All displayed extensive longitudinal myelitis, and the optic nerve was involved in three. We gathered 39 cases of NMOSD-like HAM patients from the literature. Atypical signs of HAM were relapses (15.4%), sensory level (50%), upper limb symptoms (35.9%), optic neuritis (10.2%). Typical lesions involved lateral funiculi and featured a double rope sign (56.3%).
Conclusion
We propose that acute onset of NMOSD-like HAM could be more frequent than expected and should be evoked in high-risk patients. Extensive but often transient cord lesions could be the hallmark of an excessive inflammation of the funiculi targeted by HTLV1 infection. Although usually minor, a few HAM cases demonstrate specific MRI lesions, and the most severe cases may mimic NMOSD attacks.