To assess the frequency of spinal cord central canal dilation on magnetic resonance imaging (MRI) in patients with myelin-oligodendrocyte glycoprotein antibody-associated disease (MOGAD) myelitis compared to myelitis patients with aquaporin-4-positive-neuromyelitis optic spectrum disorder (AQP4+NMOSD) and multiple sclerosis (MS).

The spinal cord MRIs of myelitis patients with MOGAD (n=63), AQP4+NMOSD (n=37), and MS (n=26) were evaluated for central canal dilation, defined as T2-hyperintensity with similar consistency to cerebrospinal fluid within a myelitis T2-lesion. Clinical data were collected from the medical record for MOGAD patients. The expanded disability status scale (EDSS) was used to quantify disability at nadir.

The median EDSS score at nadir for the MOGAD myelitis patients was 6 (range: 0-8). MOGAD patients experienced weakness (55/63[87%]), urinary retention/incontinence (50/63[79%]), numbness/paresthesias (48/63[76%]), and stool incontinence/constipation (36/63[57%]). Central canal dilation was more frequent in patients with MOGAD (23/63[37%]) than MS (0/26[0%]); p<0.001) but did not differ from AQP4+NMOSD (14/37[38%]; p=0.89). Spinal canal dilation resolved on follow-up axial MRI for most MOGAD (29/34[85%]) and AQP4+NMOSD (13/14[93%]) patients.

Central canal dilation is a common radiologic accompaniment of acute MOGAD and AQP4+NMOSD myelitis, but not MS myelitis. The resolution of central canal dilation on follow-up MRI in most patients suggests it is transient and related to the acute inflammatory edema. Central canal dilation may differentiate MOGAD and AQP4+NMOSD from MS. Its recognition could facilitate earlier testing for MOG-IgG and AQP4-IgG, accurate diagnosis, and treatment.