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

•Lesions of conus medullaris are more frequent in anti-MOG patients, followed by anti-AQP4 and MS patients.•Conus involvement, magnifies the probability of being diagnosed with anti-MOG disease, by more than 13 times (1.97 vs. 25.93%), among the patients with demyelinating diseases of the CNS.•Conus medullaris contains the least amount of white matter, and therefore MOG molecules, in the spinal cord, however, it has a higher surface to volume ratio, which may be the cause of higher rate of conus involvement in anti-MOG patients. 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. To contribute to preliminary studies by comparing conus involvement among patients with MS, anti-AQP4, and anti-MOG diseases using larger sample size. 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. 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 conus-involved patients (25.93% vs. 1.97%), although this probability was still higher for MS, as it has a much higher incidence. 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.