Conus medullaris involvement in demyelinating disorders of the CNS: A comparative study

Background: Differentiation of the demyelinating disorders of the CNS seems challenging in practice. Conus medullaris, the cone-shaped end of the spinal cord, is more involved in anti-MOG patients based on preliminary studies, a possibly helpful detail in its differentiation. Nevertheless, the evidence is still limited and the underlying cause is unclear and undiscussed in previous studies. Objective: To contribute to preliminary studies by comparing conus involvement among patients with MS, antiAQP4, and anti-MOG diseases using larger sample size. Methods: More than a thousand MS, anti-AQP4, and anti-MOG patients were followed up for a maximum of five years, scanned for conus medullaris involvement. Data regarding each cohort were then analyzed and compared using statistical methods. Results: The rate of conus medullaris involvement was significantly higher in anti-MOG patietns (OR = 27.109, P < 0.001), followed by anti-AQP4 (OR = 4.944, P = 0.004), and MS patients (OR = reference). Survival analysis showed higher pace and cumulative incidence of conus attacks in anti-MOG patients. Conus-involved patients, showed no significant difference regarding age, sex, concurrent brain lesions, and their partial recovery. Predictive values show that the probability of being diagnosed with anti-MOG is roughly 13 times higher in conusinvolved patients (25.93% vs. 1.97%), although this probability was still higher for MS, as it has a much higher incidence. Conclusion: Despite minor differences, the results were in line with previous studies, confirming the higher rate of conus medullaris involvement among anti-MOG patients. Potential underlying causes are proposed and remain to be investigated in future studies.