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NMOSD-like and longitudinal extensive HTLV1-associated myelitis are extremes that flank an overlooked continuum
Mickael Bonnan1, Stéphane Olindo2, Aissatou Signate3
1Service de Neurologie, Centre Hospitalier, Pau, France.
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.
Insights
Acute onset of Neuromyelitis Optica Spectrum Disorder (NMOSD)-like symptoms in Human T-lymphotropic virus type 1 (HTLV1) infection may be common. These cases often show extensive spinal cord lesions and can mimic NMOSD attacks.
Area of Science:
- Neuroimmunology
- Infectious Diseases
- Neurology
Background:
- Human T-lymphotropic virus type 1 (HTLV1)-associated myelitis (HAM) typically presents as a slowly progressive myelopathy with no visible spinal cord lesions on MRI.
- Distinguishing HAM from other myelopathies, such as NMOSD, can be challenging.
Purpose of the Study:
- To investigate the overlap between features of Neuromyelitis Optica Spectrum Disorder (NMOSD) and HTLV1 infection.
- To identify NMOSD-like presentations in patients with HTLV1 infection.
Main Methods:
- Inclusion of HTLV1-infected patients with at least one NMOSD feature from the French West Indies and other centers.
- Review of existing literature on the connection between HTLV1 infection and NMOSD.
Main Results:
- Six patients with NMOSD-like HAM, seronegative for AQP4 and MOG antibodies, presented with acute onset, extensive longitudinal myelitis, and optic nerve involvement in three.
- Literature review identified 39 additional cases of NMOSD-like HAM with atypical signs including relapses, sensory levels, upper limb symptoms, and optic neuritis.
- Typical HAM lesions involved lateral funiculi, with a "double rope sign" observed in over half of the cases.
Conclusions:
- Acute onset of NMOSD-like HAM may occur more frequently than previously thought and should be considered in at-risk individuals.
- Extensive, potentially transient, spinal cord lesions could indicate heightened inflammation in HAM, particularly affecting the funiculi targeted by HTLV1.
- Severe HAM cases can present with specific MRI findings that mimic NMOSD attacks.
