Neuromyelitis optica shorter lesion can cause important pyramidal deficits

• Short transverse myelitis (STM) in NMO has been recently reported.
• Prognostic markers for NMO, besides NMO-IgG, are not consensually defined.
• T1 hypointensity was not associated to pyramidal symptom severity.
• A STM might yield similar pyramidal compromise than LETM.

ObjectiveEvaluate the correlation between spinal cord lesion length and pyramidal function system score in a cohort of patients with NMO.MethodologyRetrospective retrieval of all exams performed in our center from January 2004 to December 2012 for patients with NMO. The exams were evaluated for lesion length, contrast enhancement and T1 hypointensity; these variables were correlated with the functional system score from the EDSS, performed no more than three months from the scan.Results41 patients were included. Although patients with lesion extension ≥ 2 vertebral segments did not present worse pyramidal scores in a direct comparison, the influence of lesion length was not so strong when patients were separated in 3 groups (≥ 2, ≥ 3 or ≥ 4 vertebral segments) and evaluated with a receiving operating characteristics (ROC) curves. Gadolinium enhancement also contributed to more severe pyramidal system scores, but T1 hypointensity did not.ConclusionAlthough patients with spinal cord lesion extending ≥ 3 vertebral segments had more pyramidal disability, its difference was not so strong when compared to patients with ≥ 2 or ≥ 4 vertebral segments. This suggests that lesion extension might not be the most important factor in favoring a worse prognosis in spinal cord lesions in NMO.