Spinal Movement Disorders Prevalent in Non-MS Demyelinating Disorders of Spinal Cord

Hesham Abboud, MD, PhD

Recently published data from a prospective observational study revealed that spinal-generated movement disorders are highly prevalent in non-multiple sclerosis (MS) demyelinating disorders of the spinal cord and their prevalence rates were much higher than the rates reported in MS. Overall, the prevalence was highest in aquaporin-4-positive neuromyelitis optica spectrum disorder (AQP4+ NMOSD) and lowest in myelin oligodendrocyte glycoprotein antibody disorder (MOGAD).

Published in the Journal of Neurology, the study featured patients with idiopathic transverse myelitis (ITM; n = 31; 49%), NMOSD without AQP4-IgG (n = 13; 21%), NMOSD with AQP4 (n = 12; 19%), and MOGAD (n = 7; 11%). Led by Hesham Abboud, MD, PhD, an associate professor of neurology at Case Western Reserve University, all patients answered a movement disorders survey and underwent a movement disorder-focused exam based on a modification of the Unified Parkinson Disease Rating Scale (UPDRS).

Of the included patients, 73% (n = 46) showed presence of spinal movement disorder, with the highest rates observed in AQP4+ NMOSD (92%; n = 11), followed by NMOSD without AQP4 (77%; n = 10), ITM (68%; n = 21), and MOGAD (57%; n = 4). For a small portion of patients (11%; n = 7), spinal movement disorders were the first symptoms of the disease heralding the initial relapse. The most frequent spinal movement disorders were tonic spasms (57%; n = 36), focal dystonia (25%; n = 16), spinal tremor (16%; n – 10), spontaneous clonus (9.5%; n = 6), secondary restless legs syndrome (9.5%; n = 6), and spinal myoclonus (8%; n = 5).

"Spinal movement disorders can happen independent of and in absence of spasticity," Abboud et al wrote. "In addition to pain, spinal movement disorders have several other negative impacts on quality of life, including interference with ambulation and balance. Amongst these four diseases, LETM and AQP4-IgG are independent risk factors for spinal movement disorders, while MOG-IgG and African American race are associated with a lower risk."

Apart from fixed dystonia, all other spinal movement disorders were paroxysmal or intermittent (80%). Less commonly, 25% of patients reported spinal movement disorders were painful and pain was exclusive to tonic spasms and paroxysmal dystonia. All other spinal movement disorders were considered painless. Despite this, patients who experienced spinal movement disorders had several other impacts, including interference with ambulation (15% of patients), negative impact on sleep (4%), impairment of skin hygiene (4%), triggering falls (2%), and negative impact on driving (2%).

READ MORE: Apheresis Therapy Outperforms Intravenous Methylprednisolone in Long-Term Treatment of NMOSD Attacks

Patients who developed spinal movement disorders, compared with those who did not, were more likely to have longitudinally extensive transverse myelitis (LETM; RR, 1.538; 95% CI, 1.061-2.229; P = .009), longer disease duration (mean difference, 60.492; 95% CI, 27.660-93.325; P = .000) longer follow-up duration (mean difference, 6.980; 95% CI, 0.763-13.196; P = .029), and more likely to be treated with long-term disease-modifying therapy (RR, 1.365; 95% CI, 0.977-1.906; P = .049).

Using a multivariate logistic regression model, LETM and AQP4-IgG seropositivity were independent predictors for the development of spinal movement disorders (RR, 6.416 [95% CI, 1.308-31.474] P = .022; RR, 43.670 [95% CI, 1.723-1107]; P = .022) while MOG-IgG and African American race were associated with a lower risk of developing these movement disorders (RR, 0.023 [95% CI, 0.001-0.580]; P = .022; RR, 0.151 [95% CI, 0.024-0.961]; P = .045). Of note, lesion location on axial MRI was not predictive of the development of spinal movement disorders.

Regarding African American race as an independent protective factor, investigators wrote, "The same finding was present in our previous retrospective study of spinal movement disorders in NMOSD suggesting that racial differences may play a role in spinal movement disorder susceptibility. Therefore, this may also be contributing to the difference in prevalence rates between our predominantly white cohort and the Asian studies."

Regardless of AQP4 status, those with NMOSD were more likely to have LETM (RR, 1.541; 95% CI, 1.030-2.308; P = .041), anterior spinal lesions (RR, 2.473; 95% CI, 1.220-5.011; P = .009), lateral spinal lesions (RR, 5.580; 95% CI, 1.744-17.855; P = .000), or central spinal lesions (RR, 3.297; 95% CI, 1.464-7.425; P = .002). From the spinal movement disorder stand point, patients with NMOSD were more likely to have tonic spasms (RR, 1.699; 95% CI, 1.120-2.576; P = .014), especially isometric tonic spasms (RR, 1.754; 95% CI, 1.017-3.024; P = .044), and spinal myoclonus (RR, 6.167; 95% CI, 0.732-51.906; P = .022).

REFERENCE
1. Abboud H, Sun R, Modak N, et al. Spinal movement disorders in NMOSD, MOGAD, and idiopathic transverse myelitis: a prospective observational study. Journal of Neurol. Published online June 15, 2024. doi:10.1007/s00415-024-12527-6