To examine the relationship between Platelet to Lymphocyte Ratio (PLR) at onset and risk of severe disability from an attack of monophasic Idiopathic Transverse Myelitis (ITM) and the relationship of PLR to relapse and disability among double seronegative Neuromyelitis Optica Spectrum Disorder (DSN-NMOSD) patients.

ITM is a monophasic neurological inflammatory attack of the spinal cord that is not associated with any infections, metabolic or vascular anomalies, or spinal cord compression.

This is a retrospective study on monophasic ITM and DSN-NMOSD cases at MassGeneralBrigham Hospitals. Spearman correlation analysis and linear regression analyses were conducted to evaluate the relationships between log-transformed PLR and Expanded Disability Status Scale (EDSS). Logistic regression analyses were also conducted to assess whether log-transformed PLR is associated with severe disability defined by an EDSS ≥ 4. Finally, logistic regression analyses were performed to assess whether log-transformed PLR is associated with relapse risk and EDSS ≥ 4 or ≥ 6 between monophasic ITM and DSN-NMOSD.

A total of 46 monophasic ITM patients was divided into low (<137) and high (≥137) PLR based on the calculated median PLR. Correlation analysis showed a positive association between EDSS and log-transformed PLR (Spearman’s ρ=0.299,p=0.043). Linear regression analyses between log PLR and EDSS showed no significant association (β = 0.35, 95% CI -0.72.-1.42,p=0.512). In both logistic regression analyses, log-transformed PLR did not show significant association with severe disability (univariate OR= 2.59, 95% CI 0.65-12.25,p=0.196; multivariate OR=1.44, 95%CI 0.24-9.06,p=0.690). Furthermore, logistic regression analyses of relapsing DSN-NMOSD cases showed that log-transformed PLR was not associated with risk of relapse and EDSS level of ≥ 4 or  ≥ 6.

In monophasic ITM, while PLR at onset and EDSS are correlated, PLR did not associate with risk of severe disability, contrary to previous studies. Among DSN-NMOSD cases, PLR was not associated with either relapse risk or disability.