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This document is a reply to a letter in response to a previously published article titled "Clinical Characteristics and Treatment Outcomes in Patients with Double-Seronegative Myasthenia Gravis." The authors of the reply express gratitude for the comments and acknowledge the importance of further discussion on the topic of patients without detectable antibodies to nicotinic acetylcholine receptor (AChR) and muscle-specific kinase. They agree with the suggestion that electrophysiological findings and complementary diagnostic tests should be considered in the diagnosis of myasthenia gravis (MG). The authors also highlight the need for further characterization of serological markers in seronegative MG patients and the potential role of novel antibodies in the disease. They conclude that dSNMG patients show significant clinical improvement after treatment, supporting an immune-mediated pathophysiology, and emphasize the importance of developing new biomarkers for personalized clinical characterization and individualized therapeutic approaches. [Extracted from the article]

Introduction: Assessing myasthenia gravis (MG) can be challenging, and multiple scales are available to evaluate disease severity. We evaluated the utility of a single, simple question, as part of the MG evaluation: "What percentage of normal do you feel regarding your MG, 0%-100% normal?"Methods: A retrospective chart review of patients attending the neuromuscular clinic from January 2014 to December 2015 was performed. Responses were correlated with symptoms and signs, the Quantitative Myasthenia Gravis Score (QMGS), the Myasthenia Gravis Impairment Index (MGII), and the 15-item Myasthenia Gravis Quality of Life scale (MG-QOL15).Results: The total cohort included 169 patients. The percentage of normal correlated strongly with limb muscle weakness and MG scales, moderately with bulbar and respiratory symptoms, and weakly with ocular manifestations.Discussion: The question, "What percentage of normal do you feel regarding your MG?" is feasible and valid, and can be incorporated easily into routine clinical evaluation. Muscle Nerve 57: 240-244, 2018. [ABSTRACT FROM AUTHOR]

Objectives To explore the correlations between different muscle cramp characteristics including cramp frequency and severity and clinical and large and small nerve fiber measures in patients with diabetes type 1 (DM 1) and 2 (DM 2). Methods Prospective cross sectional study of healthy controls and patients with DM 1 and DM 2 recruited between April 2009 and November 2012. Participants underwent clinical evaluation and large and small nerve fiber studies, and the frequency and correlations of muscle cramps were explored. Results 37 controls, 51 patients with DM 1, and 69 patients with DM 2 were studied. Muscle cramps were the most frequent symptom captured by the Toronto Clinical Neuropathy Score (TCNS) in all groups, up to 78% in patients with DM 2. In patients with DM 1, but not DM 2, muscle cramp frequency and severity were correlated with clinical (TCNS) and both large (electrophysiology and vibration perception thresholds) and small nerve fiber measures. Conclusions Muscle cramps are frequent in diabetes and are correlated with clinical and both small and large nerve fiber measures in DM 1, suggesting that their origin and propagation might extend beyond the motor nerve. Significance Muscle cramps correlate with nerve fiber measures in DM 1. [ABSTRACT FROM AUTHOR]

Introduction: Electrophysiological studies play an important role in the diagnosis of myasthenia gravis (MG). The objectives of this study was to explore the correlation of jitter and decrement with various clinical symptoms and signs and disease severity.Methods: We performed a retrospective chart review of 75 MG patients who attended the neuromuscular clinic from April 2013 to May 2014. We compared clinical characteristics between patients with high jitter (>100 µs) and decrement (>10%), and patients with lower values to explore the correlations and optimal thresholds of jitter and decrement for different clinical features.Results: High jitter and decrement values were associated with more severe disease, manifested by more frequent symptomatic bulbar and limb muscle weakness, more frequent ocular and limb muscle weakness on examination, higher quantitative MG score, and generalized disease.Conclusions: The yield of the electrophysiological assessment in MG extends beyond disease diagnosis and correlates with disease severity and the presence of generalized disease. Muscle Nerve 56: 445-448, 2017. [ABSTRACT FROM AUTHOR]

Introduction: Repetitive nerve stimulation (RNS) showing ≥ 10% decrement is considered the cutoff for myasthenia gravis (MG), but this has never been validated. The objective of this study was to find an optimal validated cutoff value for decrement on RNS.Methods: We performed retrospective chart review of patients who had electrophysiological assessment for possible MG from 2013 to 2015.Results: A total of 122 patients with MG and 182 controls were identified. RNS sensitivities for generalized and ocular MG using the traditional ≥10% cutoff value were 46% and 15%, respectively, for frontalis recordings, and 35% and 19%, respectively, for nasalis recordings. Using a decrement cutoff value of 7% for frontalis and 8% for nasalis increased the sensitivities by 6-11%, with specificities of 95-96%.Conclusions: For RNS in facial muscles, we suggest a cutoff value of 7-8%, which increases test sensitivity by 6-11%, while preserving high specificity for the diagnosis of MG. Muscle Nerve, 2016 Muscle Nerve 55: 166-170, 2017. [ABSTRACT FROM AUTHOR]

Introduction: The MG-QOL15 is a validated, health-related quality of life (HRQOL) measure for myasthenia gravis (MG). Widespread use of the scale gave us the opportunity to further analyze its clinimetric properties.Methods: We first performed Rasch analysis on >1,300 15-item Myasthenia Gravis Quality of Life scale (MG-QOL15) completed surveys. Results were discussed during a conference call with specialists and biostatisticians. We decided to revise 3 items and prospectively evaluate the revised scale (MG-QOL15r) using either 3, 4, or 5 responses. Rasch analysis was then performed on >1,300 MG-QOL15r scales.Results: The MGQOL15r performed slightly better than the MG-QOL15. The 3-response option MG-QOL15r demonstrated better clinimetric properties than the 4- or 5-option scales. Relative distributions of item and person location estimates showed good coverage of disease severity.Conclusions: The MG-QOL15r is now the preferred HRQOL instrument for MG because of improved clinimetrics and ease of use. This revision does not negate previous studies or interpretations of results using the MG-QOL15. Muscle Nerve 54: 1015-1022, 2016. [ABSTRACT FROM AUTHOR]

Highlights • A sonographic median-ulnar cross-sectional area ratio (MUR) is described in carpal tunnel syndrome (CTS). • The MUR is simple to acquire, and a cut-point of >2.09 yields 86% sensitivity and 84% specificity. • MUR performs with high diagnostic accuracy and correlates with electrical severity of CTS. Abstract Objective To investigate the use of a sonographic median-to-ulnar cross-sectional area ratio (MUR) in diagnosis of carpal tunnel syndrome (CTS); and to compare the MUR with currently used sonographic parameters, and electrophysiology. Methods Subjects with CTS and healthy volunteers underwent ultrasound studies of the median and ulnar nerves in the wrist and forearm. Various sonographic parameters and ratios were calculated, and compared between CTS patients and controls. The sensitivity and specificity of the different parameters were compared by plotting receiver operator characteristic curves. Correlations of sonographic results with electrophysiologic studies were calculated. Results The MUR was increased in patients with CTS, in comparison with controls. A cut-point of >2.09 yielded a sensitivity of 86% and specificity of 84%. This was comparable to the currently used ultrasound metrics for CTS. The MUR also correlated with electrophysiologic severity. Conclusions The MUR is an effective means of diagnosing CTS and correlates with electrophysiologic severity. Significance This report provides support for the use of the MUR in the sonographic diagnosis of CTS. [ABSTRACT FROM AUTHOR]

Objectives To explore the increased diagnostic yield of repetitive nerve stimulation (RNS) following activation for myasthenia gravis (MG) diagnosis, and compare with testing an additional muscle at rest only. Methods We performed a retrospective chart review of patients diagnosed with MG attending the neuromuscular clinic from 2013 to 2015 and extracted data on electrophysiological studies, including frequency of decrement of 10% or above, with facial RNS at rest, and following activation. Results The total cohort included 102 patients with MG, 65 with generalized, and 37 with ocular MG. Facial RNS sensitivities for diagnosing MG were 32–46% and 14–19% respectively. The increase in RNS sensitivity following muscle activation was 6–8% for frontalis muscle recordings, and 0–2% for nasalis muscle recordings. Recording from both muscles at rest only, increased the sensitivity by 9–15%. Conclusion RNS is a valid method for confirming a clinical diagnosis of MG. The increased diagnostic yield of RNS following activation is controversial. Our study shows that the increased diagnostic yield of facial RNS following activation is modest, and is less than performing facial RNS in a second muscle. Significance Performing facial RNS in an additional muscle at rest appears to be more sensitive than facial RNS in a single muscle after activation. [ABSTRACT FROM AUTHOR]

Incidence and prevalence estimates in myasthenia gravis have varied widely. Recent studies based on administrative health data have large sample sizes but lack rigorous validation of MG cases, and have not examined the North American population. Our aim was to explore trends in MG incidence and prevalence for the years 1996–2013 in the province of Ontario, Canada (population 13.5 million). We employed a previously validated algorithm to identify MG cases. Linking with census data allowed for the calculation of crude- and age/sex-standardized incidence and prevalence rates for the years 1996–2013. The regional distribution of MG cases throughout the province was examined. Mean age at the first myasthenia gravis encounter was 60.2 ± 17.1 years. In 2013, there were 3611 prevalent cases in Ontario, and the crude prevalence rate was 32.0/100,000 population. Age- and sex-standardized prevalence rates rose consistently over time from 16.3/100,000 (15.4–17.1) in 1996 to 26.3/100,000 (25.4–27.3) in 2013. Standardized incidence rates remained stable between 1996 (2.7/100,000; 95% CL 2.3–3.0) and 2013 (2.3/100,000; 2.1–2.6). Incidence was highest in younger women and older men, and geographic variation was evident throughout the province. In conclusion, this large epidemiological study shows rising myasthenia gravis prevalence with stable incidence over time, which is likely reflective of patients living longer, possibly due to improved disease treatment. Our findings provide accurate information on the Canadian epidemiology of myasthenia gravis and burden for health care resources planning for the province, respectively. [ABSTRACT FROM AUTHOR]