Primary progressive multiple sclerosis diagnostic criteria: a reappraisal

Area of Science:

• Neurology
• Medical Diagnostics
• Clinical Research

Background:

• Diagnostic criteria for multiple sclerosis (MS) differ significantly between primary progressive (PPMS) and relapsing-remitting (RRMS) forms.
• This heterogeneity complicates MS diagnosis and highlights the need for unified criteria, particularly regarding dissemination in space (DIS).

Purpose of the Study:

• To evaluate the feasibility of a single diagnostic algorithm for demonstrating DIS in all forms of MS.
• To assess the performance of existing RRMS and PPMS DIS criteria when applied across different MS subtypes.

Main Methods:

• Applied five sets of RRMS DIS criteria (Barkhof-Tintoré, Swanton et al., oligoclonal bands plus lesions, and two-step approaches) to 145 established PPMS patients (PPMS-1).
• Applied two sets of PPMS DIS criteria (Thompson et al., 2005 McDonald criteria) to the same PPMS-1 cohort.
• Analyzed a second cohort of 55 early-stage PPMS patients (PPMS-2) using identical criteria.
• Compared fulfillment rates of various DIS criteria across both PPMS cohorts.

Main Results:

• Fulfillment rates for DIS criteria varied across the applied sets, with higher rates observed when incorporating cerebrospinal fluid (CSF) findings.
• For PPMS-1, fulfillment rates ranged from 73.8% (C1) to 96% (C4, C5); for PPMS-2, rates ranged from 66.7% (C1) to 92.3% (C4).
• The study suggests that a unified set of DIS criteria for both RRMS and PPMS might be achievable and beneficial.

Conclusions:

• The findings support the potential for a single algorithm to demonstrate DIS across all MS forms.
• Integrating CSF analysis, specifically oligoclonal bands, significantly enhances DIS fulfillment in PPMS.
• Unifying DIS criteria in future MS diagnostic criteria revisions should be considered to streamline diagnosis.