Oral corticosteroid dosage and taper duration at onset in myelin oligodendrocyte glycoprotein antibody-associated disease influences time to first relapse.

BACKGROUND: We sought to identify an optimal oral corticosteroid regimen at the onset of myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD), which would delay time to first relapse while minimising cumulative corticosteroid exposure. METHODS: In a retrospective multicentre cohort study, Cox proportional hazards models examined the relationship between corticosteroid course as a time-varying covariate and time to first relapse. Simon-Makuch and Kaplan-Meier plots identified an optimal dosing strategy. RESULTS: We evaluated 109 patients (62 female, 57%; 41 paediatric, 38%; median age at onset 26 years, (IQR 8-38); median follow-up 6.2 years (IQR 2.6-9.6)). 76/109 (70%) experienced a relapse (median time to first relapse 13.7 months; 95% CI 8.2 to 37.9). In a multivariable model, higher doses of oral prednisone delayed time to first relapse with an effect estimate of 3.7% (95% CI 0.8% to 6.6%; p=0.014) reduced hazard of relapse for every 1 mg/day dose increment. There was evidence of reduced hazard of relapse for patients dosed ≥12.5 mg/day (HR 0.21, 95% CI 0.07 to 0.6; p=0.0036), corresponding to a 79% reduction in relapse risk. There was evidence of reduced hazard of relapse for those dosed ≥12.5 mg/day for at least 3 months (HR 0.12, 95% CI 0.03 to 0.44; p=0.0012), corresponding to an 88% reduction in relapse risk compared with those never treated in this range. No patient with this recommended dosing at onset experienced a Common Terminology Criteria for Adverse Events grade >3 adverse effect. CONCLUSIONS: The optimal dose of 12.5 mg of prednisone daily in adults (0.16 mg/kg/day for children) for a minimum of 3 months at the onset of MOGAD delays time to first relapse.

MOG antibody-associated optic neuritis.

Myelin oligodendrocyte glycoprotein (MOG) antibody-associated disease (MOGAD) is a demyelinating disorder, distinct from multiple sclerosis (MS) and neuromyelitis optica spectrum disorder (NMOSD). MOGAD most frequently presents with optic neuritis (MOG-ON), often with characteristic clinical and radiological features. Bilateral involvement, disc swelling clinically and radiologically, and longitudinally extensive optic nerve hyperintensity with associated optic perineuritis on MRI are key characteristics that can help distinguish MOG-ON from optic neuritis due to other aetiologies. The detection of serum MOG immunoglobulin G utilising a live cell-based assay in a patient with a compatible clinical phenotype is highly specific for the diagnosis of MOGAD. This review will highlight the key clinical and radiological features which expedite diagnosis, as well as ancillary investigations such as visual fields, visual evoked potentials and cerebrospinal fluid analysis, which may be less discriminatory. Optical coherence tomography can identify optic nerve swelling acutely, and atrophy chronically, and may transpire to have utility as a diagnostic and prognostic biomarker. MOG-ON appears to be largely responsive to corticosteroids, which are often the mainstay of acute management. However, relapses are common in patients in whom follow-up is prolonged, often in the context of early or rapid corticosteroid tapering. Establishing optimal acute therapy, the role of maintenance steroid-sparing immunotherapy for long-term relapse prevention, and identifying predictors of relapsing disease remain key research priorities in MOG-ON.

Frailty and Associated Environmental Factors Only Have Small Effects on Age of Onset in Huntington's Disease.

BACKGROUND: Over one third of age of onset variation in Huntington's disease is unexplained by CAG repeat length. In Alzheimer's disease, frailty partly modulates the relationship between neuropathology and dementia. OBJECTIVE: We investigated whether a multi-domain frailty index, reflecting non-genetic factors in Huntington's disease, similarly modulates the relationship between CAG repeat length and age of onset. METHODS: We created a frailty index assessing comorbidities, substance abuse, polypharmacy, and education. We applied multiple linear regression models to 2,741 subjects with manifest Huntington's disease from the Enroll-HD cohort study, including 729 subjects with late-onset (post-60 years) disease, using frailty index or constituent item scores and CAG repeat length as independent variables. We used actual and "residual" ages of onset (difference between actual and CAG-based predicted onset) as dependent variables, the latter offsetting the increased time available to accumulate comorbidities in older subjects. RESULTS: Higher frailty index scores were associated with significantly lower residual ages of onset in the late-onset subgroup (p = 0.03), though the effect was small (R2 = 0.27 with frailty as a predictor vs. 0.26 without). Number of comorbidities was also associated with significantly lower residual ages of onset in the late-onset subgroup (p = 0.04). Drug abuse and smoking were associated with significantly earlier ages of onset in the whole cohort (p < 0.01, p = 0.02) and late-onset subgroup (p < 0.01, p = 0.03). CONCLUSIONS: The impact of non-genetic factors on age of onset, assessed using a frailty index or separately, in Huntington's disease is limited.

Properties of short-latency responses in the upper limbs evoked by axial impulses during leaning: evidence for reticulospinal projections.

We studied the short-latency (SL) effects of postural perturbations produced by impulses applied over the spine of the C7 vertebra or the sternum ("axial impulses") in 12 healthy subjects. EMG recordings were made bilaterally from the triceps brachii, biceps brachii, soleus, and tibialis anterior muscles, and unilaterally from the deltoid, forearm flexors, forearm extensors, and first dorsal interosseous (FDI) muscles. Sternal impulses evoked short-latency responses in the biceps when subjects leaned posteriorly to support approximately 12% of their body weight with the arms, but these responses were only modestly larger than for isometric contraction of the arms (26.3 vs. 14.7%). In contrast, clear excitatory responses could be evoked in the deltoid, triceps, forearm muscles, and FDI when leaning anteriorly to support similar amounts of body weight. These responses were significantly larger than during isometric contraction. The deltoid (42.5%) and triceps (44.7%) had the largest responses in supported anterior lean and onset latencies increased distally in this condition (mean 31.8 ms in deltoid to 53.7 ms in FDI). There was a disproportionate delay between the forearm muscles and FDI. For both directions of lean, postural reflex responses normally present in the legs were severely attenuated. SL upper limb excitatory responses were bigger in proximal muscles as well as larger and more widespread for anterior axial perturbations compared to posterior axial perturbations when using the arms to support body weight. Our findings also provide further evidence of a role for reticulospinal pathways in mediating these rapid postural responses to accelerations of the trunk.