Citations

AbstractIntroduction/AimsRecently, our group found an association between diabetes mellitus (DM) and lumbosacral radiculoplexus neuropathy (LRPN) in Olmsted County, Minnesota; we found a higher risk (odds ratio [OR], 7.91) for developing LRPN in diabetic compared with nondiabetic patients. However, the influence of other comorbidities and anthropomorphic variables was not studied.MethodsDemographic and clinical data from 59 LRPN patients and 177 age/sex‐matched controls were extracted using the Rochester LRPN epidemiological study. Differences between groups were compared by chi‐square/Fisher exact test or Wilcoxon rank‐sum test. Uni‐ and multivariate logistic regression analysis were performed.ResultsFactors predictive of LRPN on univariate analysis were DM (OR, 7.91; 95% confidence interval [CI], 4.11‐15.21), dementia (OR, 6.36; 95% CI, 1.13‐35.67), stroke (OR, 3.81; 95% CI, 1.32‐11.01), dyslipidemia (OR, 2.844; 95% CI, 1.53‐5.27), comorbid autoimmune disorders (OR, 2.72; 95% CI, 1.07‐6.93), hypertension (OR, 2.25; 95% CI, 1.2‐4.13), obesity (OR, 2.05; 95% CI, 1.11–3.8), body mass index (BMI) (OR, 1.1; 95% CI, 1.04‐1.15), and weight (OR, 1.02; 95% CI, 1.009‐1.037). On multivariate logistic regression analysis only DM (OR, 8.03; 95% CI, 3.86‐16.7), comorbid autoimmune disorders (OR, 4.58; 95% CI, 1.45‐14.7), stroke (OR, 4.13; 95% CI, 1.2‐14.25), and BMI (OR, 1.07; 95% CI, 1.01‐1.13) were risk factors for LRPN.DiscussionDM is the strongest risk factor for the development of LRPN, followed by comorbid autoimmune disorders, stroke, and higher BMI. Altered metabolism and immune dysfunction seem to be the most influential factors in the development of LRPN.

Abstract Objective To determine whether histopathological, electromyographic and laboratory markers correlate with clinical measures in inclusion body myositis (IBM). Methods We reviewed our electronic medical records to identify patients with IBM according to European Neuromuscular Center (ENMC) 2011 criteria, seen between 2015 and 2020. We only included patients who had a muscle biopsy and needle electromyography (EMG) performed on the same muscle (opposite or same side). We used a detailed grading system [0 (normal) to 4 (severe)] to score histopathological and EMG findings. Clinical severity was assessed by the modified Rankin scale (mRS), muscle strength sum score (SSS), quadriceps strength and severity of dysphagia on swallow evaluation. Serum markers of interest were creatine kinase level and cN-1A antibodies. Results We included 50 IBM patients, with a median age of 69 years; 64% were males. Median disease duration at diagnosis was 51 months. On muscle biopsy, endomysial inflammation mainly correlated with dysphagia, and inversely correlated with mRS. Vacuoles and congophilic inclusions did not correlate with any of the clinical measures. On EMG, the shortness of motor un it potential (MUP) duration correlated with all clinical measures. Myotonic discharges, and not fibrillation potentials, correlated with the severity of inflammation. Serum markers did not have a statistically significant correlation with any of the clinical measures. Conclusions Dysphagia was the main clinical feature of IBM correlating with endomysial inflammation. Otherwise, inclusion body myositis clinical measures had limited correlation with histopathological features in this study. The shortness of MUP duration correlated with all clinical measures.

Abstract Amyloidosis refers to an etiologically heterogeneous group of protein misfolding diseases, pathologically characterized by extracellular amyloid fibrils producing congophillic amorphous deposits in organs and tissues, which may lead to severe organ dysfunction and mortality. Clinical presentations vary and are often nonspecific, depending on what organs or tissues are affected. In systemic amyloidosis, the peripheral nervous system is commonly affected, whereas the skeletal muscles are only rarely involved. Immunoglobulin light chain (AL) amyloidosis and hereditary transthyretin (ATTRv) amyloidosis are the most frequent types of systemic amyloidosis involving the neuromuscular system. Localized amyloidosis can occur in skeletal muscle, so‐called isolated amyloid myopathy. Amyloid neuropathy typically involves small myelinated and unmyelinated sensory and autonomic nerve fibers early in the course of the disease, followed by large myelinated fiber sensory and motor deficits. The relentlessly progressive nature with motor, painful sensory and severe autonomic dysfunction, profound weight loss, and systemic features are distinct characteristics of amyloid neuropathy. Amyloid myopathy presentation differs between systemic amyloidosis and isolated amyloid myopathy. Long‐standing symptoms, distal predominant myopathy, markedly elevated creatine kinase level, and lack of peripheral neuropathy or systemic features are highly suggestive of isolated amyloid myopathy. In ATTR and AL amyloidosis, early treatment correlates with favorable outcomes. Therefore, awareness of these disorders and active screening for amyloidosis in patients with neuropathy or myopathy are crucial in detecting these patients in the everyday practice of neuromuscular medicine. Herein, we review the clinical manifestations of neuromuscular amyloidosis and provide a diagnostic approach to this disorder.

Abstract Immune checkpoint inhibitors have revolutionized the landscape of cancer treatment. Alongside their many advantages, they elicit immune-related adverse events, including myopathy, which potentially result in substantial morbidity if not recognized and treated promptly. Current knowledge of immune checkpoint inhibitor-associated myopathy is limited. We conducted a 5-year retrospective study of patients with immune checkpoint inhibitor-associated myopathy. Clinical features, survival and ancillary test findings were analysed and compared with those of immune-mediated necrotizing myopathy patients without immune checkpoint inhibitor exposure seen during the same time period. We identified 24 patients with immune checkpoint inhibitor-associated myopathy (median age 69 years; range 28–86) and 38 patients with immune-mediated necrotizing myopathy. Ocular involvement occurred in 9/24 patients with immune checkpoint inhibitor exposure, without electrodiagnostic evidence of neuromuscular transmission defect, and in none of the immune-mediated necrotizing myopathy patients (P < 0.001). Myocarditis occurred in eight immune checkpoint inhibitor-associated myopathy patients and in none of the immune-mediated necrotizing myopathy patients (P < 0.001). Median creatine kinase was 686 IU/l in the immune checkpoint inhibitor cohort (seven with normal creatine kinase) compared to 6456 IU/l in immune-mediated necrotizing myopathy cohort (P < 0.001). Lymphopenia was observed in 18 and 7 patients with and without immune checkpoint inhibitor exposure, respectively (P < 0.001). Myopathological findings were similar between patients with and without immune checkpoint inhibitor exposure, consisting of necrotic fibres with no or subtle inflammation. Necrotic fibres however arranged in clusters in 10/11 immune checkpoint inhibitor-associated myopathy patients but in none of the immune checkpoint inhibitor-naïve patients (P < 0.001). Despite the lower creatine kinase levels in immune checkpoint inhibitor-exposed patients, the number of necrotic fibres was similar in both groups. Immune checkpoint inhibitor-associated myopathy patients had a higher frequency of mitochondrial abnormalities and less number of regenerating fibres than immune-mediated necrotizing myopathy patients (P < 0.001). Anti-hydroxy-3-methylglutaryl-CoA reductase or signal recognition particle antibodies were absent in patients with immune checkpoint inhibitor exposure but positive in two-thirds of immune checkpoint inhibitor-naïve patients. Most patients with immune checkpoint inhibitor-associated myopathy responded favourably to immunomodulatory treatments, but four died from myopathy-related complications and one from myocarditis. Intubated patients had significantly shorter survival compared to non-intubated patients (median survival of 22 days; P = 0.004). In summary, immune checkpoint inhibitor-associated myopathy is a distinct, treatable immune-mediated myopathy with common ocular involvement, frequent lymphopenia and necrotizing histopathology, which contrary to immune-mediated necrotizing myopathy, is featured by clusters of necrotic fibres and not accompanied by anti-hydroxy-3-methylglutaryl-CoA reductase or signal recognition particle antibodies. Normal or mildly elevated creatine kinase level does not exclude the diagnosis.

AbstractBackgroundLimited data exist regarding myopathies with early or prominent dysphagia.MethodsA retrospective study was performed (January 2003 to August 2019) to identify myopathy patients in whom dysphagia was the initial symptom or was disproportionately severe compared with limb weakness.ResultsThirty‐two patients were identified. The median age at diagnosis was 65 y (range, 36–80 y). Inclusion body myositis (IBM) (n = 15), immune‐mediated necrotizing myopathy (IMNM) (n = 5), and oculopharyngeal muscular dystrophy (n = 4), were the most common diagnoses. In 4 patients (3 IMNM and 1 nonspecific myositis) dysphagia evolved rapidly. At evaluation, 21 patients required diet alterations, 5 required feeding tubes, and 8 had aspiration pneumonia. Follow‐up data were available for 20 patients (median, 24 mo). Eight patients received immunosuppressive therapies with improvement in 7, including 3 of 4 with rapidly progressive dysphagia.ConclusionsIBM and IMNM accounted for approximately two‐thirds of patients with early or prominent dysphagia at our institution. Rapidly progressive dysphagia may predict immunotherapy responsiveness.

Background and purposeHereditary transthyretin (hATTR) amyloidosis causes progressive polyneuropathy resulting from transthyretin (TTR) amyloid deposition throughout the body, including the peripheral nerves. The efficacy and safety of inotersen, an antisense oligonucleotide inhibitor of TTR protein production, were demonstrated in the pivotal NEURO‐TTR study in patients with hATTR polyneuropathy. Here, the long‐term efficacy and safety of inotersen are assessed in an ongoing open‐label extension (OLE) study.MethodsPatients who completed NEURO‐TTR were eligible to enroll in the OLE (NCT02175004). Efficacy assessments included the modified Neuropathy Impairment Score plus seven neurophysiological tests composite score (mNIS + 7), the Norfolk Quality of Life – Diabetic Neuropathy (Norfolk QOL‐DN) questionnaire total score and the Short‐Form 36 Health Survey (SF‐36) Physical Component Summary (PCS) score. Safety and tolerability were also assessed.ResultsOverall, 97% (135/139) of patients who completed NEURO‐TTR enrolled in the OLE. Patients who received inotersen for 39 cumulative months in NEURO‐TTR and the OLE continued to show benefit; patients who switched from placebo to inotersen in the OLE demonstrated improvement or stabilization of neurological disease progression by mNIS + 7, Norfolk QOL‐DN and SF‐36 PCS. No new safety concerns were identified. There was no evidence of increased risk for grade 4 thrombocytopenia or severe renal events with increased duration of inotersen exposure.ConclusionInotersen slowed disease progression and reduced deterioration of quality of life in patients with hATTR polyneuropathy. Early treatment with inotersen resulted in greater long‐term disease stabilization than delayed initiation. Routine platelet and renal safety monitoring were effective; no new safety signals were observed.

Abstract Introduction Although peripheral neuropathy and cardiomyopathy are well‐recognized manifestations of transthyretin (ATTR) amyloidosis, myopathy has been rarely reported. Methods In this study we reviewed our muscle biopsy database (January 1998 to June 2018) to identify patients with ATTR amyloid myopathy confirmed by molecular or proteomic analysis. Clinical and laboratory findings were reviewed. Results We identified eight ATTR amyloid myopathy patients (5 hereditary ATTR [ATTRv] and 3 wild‐type ATTR [ATTRwt]). Myopathy was the initial manifestation in all ATTRwt patients and followed peripheral neuropathy (4 patients) or cardiomyopathy (1 patient) in ATTRv patients. One ATTRv patient developed myopathy after liver transplant. Peripheral neuropathy and cardiac amyloidosis occurred in seven and six patients, respectively. Muscle biopsy showed interstitial amyloid deposition in all patients, rare necrotic/regenerating fibers in six, and vacuoles in four. Discussion Myopathy can be the initial manifestation of ATTRwt amyloidosis and can precede the peripheral neuropathy or occur after liver transplant in ATTRv amyloidosis.