Pittock, S J

ABSTRACTIntroduction: Voltage‐gated Kv1 potassium channel complex (VGKC) autoantibodies subtyped for leucine‐rich glioma‐inactivated 1 (LGI1), contactin‐associated‐proteinlike 2 (CASPR2), and Kv IgGs have a spectrum of neurological presentations. Painful polyneuropathy is seen in some patients, but nerve pathology descriptions are lacking. Methods: Clinicopathologic features were studied in subtyped VGKC‐autoantibody‐seropositive patients who had undergone nerve biopsies. Results: Five patients were identified, 1 LGI1 IgG positive and 1 CASPR2 IgG positive, but all negative for Kv1.1‐, 1.2‐, 1.6‐subtyped IgG autoantibodies. Median symptom duration was 17 months. Pain was the predominant symptom; 3 had mild sensory loss and/or weakness. Histopathological abnormalities were limited to axonal loss in 3. None had mononuclear cellular infiltrates. Electron micrographs revealed no interstitial abnormalities. Three patients reported marked improvement in pain with immunotherapy. Conclusions: The nerve biopsy histopathology of patients subtyped for LGI1 and CASPR2 IgGs within the VGKC‐complex spectrum disorders shows either normal density or axonal fiber loss without inflammatory infiltrates. A reversible neural hyperexcitable mechanism is considered to be the cause of this painful polyneuropathy. Muscle Nerve 55: 520–525, 2017

ObjectiveNeuromyelitis optica (NMO) and its spectrum disorders (NMOSD) are inflammatory demyelinating diseases (IDDs) with a specific biomarker, aquaporin‐4–immunoglobulin G (AQP4‐IgG). Prior NMO/NMOSD epidemiological studies have been limited by lack of AQP4‐IgG seroprevalence assessment, absence of population‐based USA studies, and under‐representation of blacks. To overcome these limitations, we sought to compare NMO/NMOSD seroepidemiology across 2 ethnically divergent populations.MethodsWe performed a population‐based comparative study of the incidence (2003–2011) and prevalence (on December 31, 2011) of NMO/NMOSD and AQP4‐IgG seroincidence and seroprevalence (sera collected in 80–84% of IDD cases) among patients with IDD diagnosis in Olmsted County, Minnesota (82% white [Caucasian]) and Martinique (90% black [Afro‐Caribbean]). AQP4‐IgG was measured by M1 isoform fluorescence‐activated cell‐sorting assays.ResultsThe age‐ and sex‐adjusted incidence (7.3 vs 0.7/1,000,000 person‐years [p < 0.01]) and prevalence (10 vs 3.9/100,000 [p = 0.01]) in Martinique exceeded that in Olmsted County. The AQP4‐IgG age‐ and sex‐adjusted seroincidence (6.5 vs 0.7/1,000,000 person‐years [p < 0.01]) and seroprevalence (7.9 vs 3.3/100,000 [p = 0.04]) were also higher in Martinique than Olmsted County. The ethnicity‐specific prevalence was similar in Martinique and Olmsted County: 11.5 and 13/100,000 in blacks, and 6.1 and 4.0/100,000 in whites, respectively. NMO/NMOSD represented a higher proportion of IDD cases in Martinique than Olmsted County (16% vs 1.4%; p < 0.01). The onset age (median = 35–37 years) and female:male distribution (5–9:1) were similar across both populations; 60% of prevalent cases were either blind in 1 eye, dependent on a gait aid, or both.InterpretationThis study reports the highest prevalence of NMO/NMOSD in any population (10/100,000 in Martinique), estimates it affects 16,000 to 17,000 in the USA (higher than previous predictions), and demonstrates it disproportionately affects blacks. Ann Neurol 2016;79:775–783

ObjectiveTo compare longitudinally extensive myelitis in neuromyelitis optica spectrum disorders (NMOSD) and spinal cord sarcoidosis (SCS).MethodsWe identified adult patients evaluated between 1996 and 2015 with SCS or NMOSD whose first myelitis episode was accompanied by a spinal cord lesion spanning ≥3 vertebral segments. All NMOSD patients were positive for aquaporin‐4–immunoglobulin G, and all sarcoidosis cases were pathologically confirmed. Clinical characteristics were evaluated. Spine magnetic resonance imaging was reviewed by 2 neuroradiologists.ResultsWe studied 71 patients (NMOSD, 37; SCS, 34). Sixteen (47%) SCS cases were initially diagnosed as NMOSD or idiopathic transverse myelitis. Median delay to diagnosis was longer for SCS than NMOSD (5 vs 1.5 months, p < 0.01). NMOSD myelitis patients were more commonly women, had concurrent or prior optic neuritis or intractable vomiting episodes more frequently, had shorter time to maximum deficit, and had systemic autoimmunity more often than SCS (p < 0.05). SCS patients had constitutional symptoms, cerebrospinal fluid (CSF) pleocytosis, and hilar adenopathy more frequently than NMOSD (p < 0.05); CSF hypoglycorrhachia (11%, p = 0.25) and elevated angiotensin‐converting enzyme (18%, p = 0.30) were exclusive to SCS. Dorsal cord subpial gadolinium enhancement extending ≥2 vertebral segments and persistent enhancement >2 months favored SCS, and ringlike enhancement favored NMOSD (p < 0.05). Maximum disability was similar in both disorders.InterpretationSCS is an under‐recognized cause of longitudinally extensive myelitis that commonly mimics NMOSD. We identified clinical, laboratory, systemic, and radiologic features that, taken together, help discriminate SCS from NMOSD. ANN NEUROL 2016;79:437–447

Background: To date, no treatment for neuromyelitis optica (NMO) has been granted regulatory approval, and no controlled clinical studies have been reported. Objective: To design a placebo-controlled study in NMO that appropriately balances patient safety and clinical–scientific integrity. Methods: We assessed the “standard of care” for NMO to establish the ethical framework for a placebo-controlled trial. We implemented measures that balance the need for scientific robustness while mitigating the risks associated with a placebo-controlled study. The medical or scientific community, patient organizations, and regulatory authorities were engaged early in discussions on this placebo-controlled study, and their input contributed to the final study design. Results: The N-MOmentum study (NCT02200770) is a clinical trial that randomizes NMO patients to receive MEDI-551, a monoclonal antibody that depletes CD19+ B-cells, or placebo. The study design has received regulatory, ethical, clinical, and patient approval in over 100 clinical sites in more than 20 countries worldwide. Conclusion: The approach we took in the design of the N-MOmentum trial might serve as a roadmap for other rare severe diseases when there is no proven therapy and no established clinical development path.