Objective:

Differentiating autoimmune from idiopathic inflammatory myelopathies (IM) remains challenging in resource-limited settings, where diagnostic tools may be limited or delayed.

Background:

To identify clinical and radiological features associated with autoimmune versus idiopathic IM in a tertiary center in Peru.

Design/Methods:

We conducted an observational study including adults with IM (August 2024–March 2026). Patients were classified as autoimmune (multiple sclerosis [MS], neuromyelitis optica spectrum disorder [NMOSD], MOG antibody-associated disease [MOGAD]) or idiopathic (exclusion of other diagnosis). Clinical, laboratory, MRI, and outcome data were collected. Between-group comparisons were performed, and negative binomial regression identified factors associated with autoimmune etiology.

Results:

Seventy patients were included (58.7% autoimmune). Autoimmune IM were more frequent in women (70.8% vs. 37.0%, p=0.004), more commonly presented as a relapsing case (85.7% vs. 14.3%, p<0.001), and more often associated with cranial nerve involvement (52.3% vs. 25.8%, p=0.022). Autoimmune cases less frequently showed longitudinally extensive lesions (≥3 segments: 63.6% vs. 87.1%, p=0.024), while cervical predominance was more frequent (75.0% vs. 51.9%, p=0.074). No significant differences were observed in serum, CSF, or brain MRI findings. In multivariable analysis, female sex (PR 1.78, 95% CI 1.05–3.03), relapsing course (PR 1.86, 95% CI 1.14–3.02), and longitudinally extensive lesions (PR 0.68, 95% CI 0.47–0.98) were independently associated with autoimmune etiology. At six months of wollow-up, disability remained high in both groups (EDSS ≥4.0: 70.0% vs. 60.0%, p=0.584).

Conclusions:

Autoimmune and idiopathic IM show distinct clinical profiles. Readily identifiable features such as relapsing course and cranial nerve involvement may help guide etiological suspicion in resource-limited settings, whereas routine MRI and laboratory findings provide limited discrimination.