The risk factors of neuropathic pain in neuromyelitis optica spectrum disorder: a retrospective case-cohort study

Background: Neuropathic pain is a common complication in neuromyelitis optica spectrum disorder (NMOSD), which seriously affects the quality of life of NMOSD patients, with no satisfactory treatment. And risk factors of neuropathic pain are still uncertain. Objective: To investigate the risk factors of neuropathic pain in a NMOSD cohort. Materials: and Methods Our study was a retrospective case-cohort study, the patients diagnosed with NMOSD in the Department of Neurology from the Second Affiliated Hospital of Guangzhou University of Chinese Medicine from January 2011 to October 2021 were screened. Inclusion criteria were (1) patients diagnosed as NMOSD according to the International Panel for NMO Diagnosis (IPND) criteria. (2) the aquaporin-4 immunoglobulin G antibodies (AQP4-IgG) test was performed. Patients without AQP4-IgG antibody were excluded. Clinical data, including sex, age of the first onset, symptoms of the first episode including neuropathic pain and attack types, localization of lesions of the first episode on Magnetic Resonance Imaging (MRI) and APQ4-IgG status were collected from the hospital system database. Neuropathic pain was defined according to the International Association for the Study of Pain criteria and was described as “pain arising as a direct consequence of a lesion or disease affecting the somatosensory system”. Results: 119 patients were screened and finally 86 patients fulfilling the inclusion and exclusion criteria were enrolled in our study. The prevalence of neuropathic pain in patients with NMOSD was 43.0%. Univariate analysis showed that the factors associated with neuropathic pain were the age at the onset, the attack type of optic neuritis, the attack type of myelitis, length of spinal cord involvement, localization of thoracic lesion, optic lesion, upper thoracic lesions, lower thoracic lesions, extended spinal cord lesions and extended thoracic lesions. Multivariate regression analysis showed that extended thoracic lesions (OR 23.24 [1.97-274.59], P =0.013) and gender (OR 13.97 [1.3-150.59], P =0.03) were independently associated with neuropathic pain among NMOSD patients. Conclusion: Extended thoracic lesions and gender were independent risk factors of neuropathic pain among patients with NMOSD.