Comparison of rituximab efficacy in treatment-naive and refractory inflammatory myopathies: experiences from a tertiary care centre.

OBJECTIVES: To find out if Rituximab (RTX) is effective in "treatment naive" idiopathic inflammatory myopathies (IIM), and whether there could be differential treatment responses between the "treatment naive" and treatment "refractory" IIM. METHODS: Data obtained from a prospectively maintained database comprising patients with IIM treated with rituximab. Patient details were obtained at baseline, 3-months, 6-months intervals, and subsequent follow up visits. Treatment response was categorised as improved, worsening, or stable based on manual muscle testing (MMT8) scores, patient global and physician global improvement (PtGA and PGA) for skin and joint symptoms improvement and spirometry at 6 months. The time to clinical improvement and remission were noted and survival analysis curves were constructed. RESULTS: 60 patients with IIM (including 18 with anti-SRP myopathy) were included, out of which 33 who received RTX were treatment naïve. The remaining 27 were started on rituximab for refractory myopathy. Mean age was 39 years (SD12.58) in "treatment-naive" group and 43 years (SD 12.12) in "refractory" group. At 6 months of follow up, 48/55 (87%) patients showed response, 31/31 (100%) in "treatment-naive" and 17/24 (70%) in "refractory" cases, p 0.006*. In refractory group, 7 (29%) had stable disease. The mean changes in MMT8 were significantly more in the "treatment-naive" treatment group (13.41(SD 7.31) compared with "refractory" IIM 8.33 (SD 7.92) (p= 0.017*). Majority of patients were able to reduce dose below 5 mg/day before 6 months. No major adverse events were reported over the median follow-up of 24 (IQR 36) months. CONCLUSIONS: Rituximab is effective and safe across the spectrum of IIM. Early use in disease is associated with better outcomes.

Sensitivity and specificity of phrenic nerve electrophysiology to predict mechanical ventilation in the Guillain-Barré syndrome.

INTRODUCTION/AIMS: In Guillain-Barré syndrome (GBS), the sensitivity and specificity of phrenic compound muscle action potential (CMAP) measurements to predict endotracheal mechanical ventilation are unknown. Hence, we sought to estimate sensitivity and specificity. METHODS: We performed a 10-year retrospective analysis of adult GBS patients from our single-center laboratory database (2009 to 2019). The phrenic nerve amplitudes and latencies before ventilation were recorded along with other clinical and demographic features. Receiver operating curve (ROC) analysis with area under the curve (AUC) was used to determine the sensitivity and specificity with 95% confidence interval (CI) for phrenic amplitudes and latencies in predicting the need for mechanical ventilation. RESULTS: Two hundred five phrenic nerves were analyzed in 105 patients. The mean age was 46.1 ± 16.2 years, with 60% of them being male. Fourteen patients (13.3%) required mechanical ventilation. The average phrenic amplitudes were lower in the ventilated group (P = .003), but average latencies did not differ (P = .133). ROC analysis confirmed that phrenic amplitudes could predict respiratory failure (AUC = 0.76; 95% CI, 0.61 to 0.91; P < .002), but phrenic latencies could not (AUC = 0.60; 95% CI, 0.46 to 0.73; P = .256). The best threshold for amplitude was ≥0.6 mV, with sensitivity, specificity, and positive and negative predictive values of 85.7%, 58.2%, 24.0%, and 96.4%, respectively. DISCUSSION: Our study suggests that phrenic CMAP amplitudes can predict the need for mechanical ventilation in GBS. In contrast, phrenic CMAP latencies are not reliable. The high negative predictive value of phrenic CMAP amplitudes ≥0.6 mV can preclude mechanical ventilation, making these a useful adjunct to clinical decision-making.

Epstein-Barr virus infection in a woman with aquaporin-4 seropositive neuromyelitis optica.

Neuromyelitis optica spectrum disorders (NMOSD) are characterised by pathological antibodies to aquaporin-4 water channels of astrocytes, resulting in severe brain and spinal cord injury. Serological evidence suggests that Epstein-Barr virus (EBV) reactivation may contribute to their pathogenesis. We describe an unusual case of a woman with fever, rash and headache preceding an Aquaporin-4 antibody positive longitudinally extensive transverse myelitis. EBV was detected in her cerebrospinal fluid by polymerase chain reaction assay. This case highlights the potential role of EBV in the pathogenesis of NMOSD.