Comparison of Ocular Motor Findings Between Neuromyelitis Optica Spectrum Disorder and Multiple Sclerosis Involving the Brainstem and Cerebellum

This study aimed to define the clinical features and involved structures that aid in differentiation of neuromyelitis optica spectrum disorder (NMOSD) from multiple sclerosis (MS) involving the brainstem and cerebellum. We analyzed the clinical and ocular motor findings, and lesion distribution on brain MRIs in 42 patients with MS (17 men, mean age ± SD = 37 ± 12) and 26 with NMOSD (3 men, mean age ± SD = 43 ± 15) that were recruited from two university hospitals in South Korea (whole study population). An additional subgroup analysis was also conducted in 41 patients presenting acute brainstem or vestibular syndrome (brainstem syndrome population). Logistic regression analysis showed that bilaterality of the lesions (p = 0.012) and presence of horizontal gaze-evoked nystagmus (hGEN, p = 0.041) were more frequently associated with NMOSD than with MS in the whole study population. In the brainstem syndrome population, only hGEN (p = 0.017) was more frequent in NMOSD than in MS. The lesions specific for NMOSD were overlapped in the medial vestibular nucleus (MVN) and nucleus prepositus hypoglossi (NPH) at the pontomedullary junction. In conclusion, presence of hGEN and bilateral lesions involving the MVN and NPH favor the diagnosis of NMOSD rather than MS.