Muscle & Nerve最新文献

Introduction/aims: The standard procedure to establish reference values in a neuromuscular laboratory involves examining healthy controls, as nerve size varies with the population and muscle echo intensity (EI) is device-specific. We aimed to derive these reference values by extrapolation from a studied sample (the e-norms method), compare them with published reference values, and determine their diagnostic accuracy.

Methods: We retrospectively analyzed data from consecutive patients who underwent nerve and/or muscle ultrasound in our ultrasound laboratory, which is a tertiary referral center for neuromuscular diseases in Southern Poland in the years 2018-2023. We plotted the cross-sectional area (CSA) of the nerve segments and EI of the individual muscles and derived descriptive statistics from the plateau of the e-norms curve. We compared the mean difference of the nerve size to other studies and determined the ability of the muscle EI to discriminate myopathic versus healthy subjects using receiver operator characteristics curves.

Results: We analyzed 1124 nerves and 1154 muscles from 109 and 99 subjects, respectively. The derived reference values for nerve CSA were mostly concordant with other studies, including all nerve segments in the legs and with the exception of compression sites and the most proximal nerve segments in the arms. Using the reference values for muscle EI established with the e-norms method, we were able to discriminate myopathic from healthy subjects with 85% sensitivity and 92% specificity.

Discussion: The e-norms is a feasible method to establish reference values in the neuromuscular ultrasound laboratory.

Introduction/aims: Neurolymphomatosis is a hematological condition defined by the direct infiltration of malignant lymphomatous cells into the peripheral nervous system. Since nerve conduction studies may disclose demyelinating features, clinicians may misdiagnose neurolymphomatosis as chronic inflammatory demyelinating polyneuropathy (CIDP). This study aimed to determine whether patients with neurolymphomatosis met the 2021 revised criteria for CIDP.

Methods: We retrospectively analyzed 23 patients with primary or secondary neurolymphomatosis from nine French hospitals. We analyzed whether patients with a diagnosis of neurolymphomatosis met the 2010 and 2021 CIDP criteria.

Results: 152 motor nerves were analyzed, and conduction blocks were found in 13.8% of them. Eight patients (34.7%) demonstrated at least one conduction block. Other demyelinating parameters fulfilling the 2021 CIDP criteria were rare, including reduced conduction velocities (1.7%), prolonged distal motor latencies (3%), absent F-waves (12.4%), and prolonged F-wave latencies (7.7%). Five patients met the 2010 CIDP criteria, whereas only one met the 2021 CIDP criteria.

Discussion: Demyelinating features are rare in neurolymphomatosis, and a conduction block is the most frequent abnormality. Consequently, only one patient met the 2021 criteria for CIDP diagnosis. This is likely attributable to the inclusion of sensory criteria. Furthermore, the new criteria emphasize the importance of identifying red flags, such as pain or monoclonal gammopathy, which could suggest an alternative diagnosis to CIDP. Clinicians should consider neurolymphomatosis in patients who present with red flags or atypical CIDP.

Lumbosacral radiculopathy is a common disorder evaluated by the electrodiagnostic medicine (EDX) consultant. Making this task difficult is the abundance of radiculopathy mimics. Peripheral neurologic mimics are common, but musculoskeletal mimics are not rare and may be less familiar to many EDX consultants. Awareness of the most common musculoskeletal mimickers-particularly key historical and physical examination features that can distinguish them from radiculopathies-can lead to an accurate diagnosis for the patient and referring provider. Part 1 of this monograph covered theoretical issues surrounding why radiculopathy mimics occur. This second part reviews the most common musculoskeletal mimics, including facet arthropathy, myofascial pain syndrome, hip pathology, greater trochanteric pain syndrome, piriformis syndrome, sacroiliac joint dysfunction, hamstring pathology, iliotibial band syndrome, and plantar fasciitis. Diagnosis of these musculoskeletal mimickers is complicated by nonspecific physical examination and imaging findings, and diagnostic injections are frequently necessary to confirm the diagnosis. Treatment for most mimickers includes physical therapy, anti-inflammatory medications, guided injections, and other conservative measures, only rarely followed by surgical intervention. EDX consultants can efficiently incorporate a few high-yield maneuvers into their physical examination based on the location of the pain to provide answers to patients presenting with a musculoskeletal mimic of a lumbosacral radiculopathy.

Introduction: Medial femoral cutaneous (MFC) sensory nerve action potentials (SNAPs) can be easily recorded using distal stimulation. This study aimed to identify a new parameter using MFC SNAPs for the early electrophysiological diagnosis of length-dependent axonal polyneuropathy (LDAP) associated with uremic neuropathy.

Methods: Patients with chronic renal failure who were referred to the electrodiagnostic laboratory due to symptoms suggesting polyneuropathy were included. Assessments encompassed neurological examination, Michigan Neuropathy Screening Instrument (MNSI), and Semmes-Weinstein monofilament test. Antidromic radial, median, ulnar, MFC, sural, and superficial peroneal sensory; median, ulnar, tibial, and peroneal motor nerve conduction studies were performed. Sural-to-radial amplitude ratio (SRAR) and sural-to-medial femoral cutaneous amplitude ratio (SMFCAR) were calculated, and their diagnostic sensitivities were compared with the age and sex matched healthy controls.

Results: Thirty-two chronic renal failure patients (mean age 60.0 ± 9.6 years) and 37 controls (60.6 ± 9 years) were included. MNSI indicated clinical polyneuropathy in 59.4% of patients, while sural SNAP amplitude was diagnostic in 78%. Median SRAR and SMFCAR values were significantly lower in patients than controls (p < .001 for both). The cut-off values for SMFCAR and SRAR were <1.82 and <0.30, respectively, both with a sensitivity of 59% and a specificity of 94%.

Discussion: Sural SNAP is the most sensitive parameter in the diagnosis of LDAP. SMFCAR is not superior to SRAR. If the sural SNAP amplitude is normal, SMFCAR can serve as an alternative to SRAR in dialysis patients with bilateral arteriovenous fistulae or in those unable to undergo radial NCS.

Rippling muscle disease (RMD) is a rare disorder of muscle hyperexcitability. It is characterized by rippling wave-like muscle contractions induced by mechanical stretch or voluntary contraction followed by sudden stretch, painful muscle stiffness, percussion-induced rapid muscle contraction (PIRC), and percussion-induced muscle mounding (PIMM). RMD can be hereditary (hRMD) or immune-mediated (iRMD). hRMD is caused by pathogenic variants in caveolin-3 (CAV3) or caveolae-associated protein 1/ polymerase I and transcript release factor (CAVIN1/PTRF). CAV3 pathogenic variants are autosomal dominant or less frequently recessive while CAVIN1/PTRF pathogenic variants are autosomal recessive. CAV3-RMD manifests with a wide spectrum of clinical phenotypes, ranging from asymptomatic creatine kinase elevation to severe muscle weakness. Overlapping phenotypes are common. Muscle caveolin-3 immunoreactivity is often absent or diffusely reduced in CAV3-RMD. CAVIN1/PTRF-RMD is characterized by congenital generalized lipodystrophy (CGL, type 4) and often accompanied by several extra-skeletal muscle manifestations. Muscle cavin-1/PTRF immunoreactivity is absent or reduced while caveolin-3 immunoreactivity is reduced, often in a patchy way, in CAVIN1/PTRF-RMD. iRMD is often accompanied by other autoimmune disorders, including myasthenia gravis. Anti-cavin-4 antibodies are the serological marker while the mosaic expression of caveolin-3 and cavin-4 is the pathological feature of iRMD. Most patients with iRMD respond to immunotherapy. Rippling, PIRC, and PIMM are usually electrically silent. Different pathogenic mechanisms have been postulated to explain the disease mechanisms. In this article, we review the spectrum of hRMD and iRMD, including clinical phenotypes, electrophysiological characteristics, myopathological findings, and pathogenesis.

Introduction/aims: The degree of change in neuropathic impairment and quality of life (QoL) that is clinically meaningful to patients with hereditary transthyretin amyloidosis with polyneuropathy (ATTRv-PN) is not established. This study aimed to estimate the magnitude of treatment differences that are meaningful to patients in measures of neuropathy and QoL and to determine whether eplontersen achieved a meaningful improvement versus placebo.

Methods: Data from the NEURO-TTRansform trial on patients with ATTRv-PN treated with eplontersen (n = 141) or historical placebo (n = 59) were used. Anchor-based approaches were used to estimate thresholds for meaningful differences in the modified Neuropathy Impairment Score +7 (mNIS+7) composite score, Norfolk QoL-Diabetic Neuropathy (Norfolk QoL-DN) total score, Neuropathy Symptoms and Change (NSC) total score, and modified body mass index (mBMI). Differences between the least squares means of the treatment groups were analyzed.

Results: Meaningful improvement in mNIS+7 was estimated as -4.0 points and deterioration as 1.8 points. The estimated ranges of meaningful improvement and deterioration in Norfolk QoL-DN were -12.8 to -4.0 points, and 5.9 to 14.7 points, respectively. For NSC, ranges were -2.4 to -1.3 points for meaningful improvement, and 0.6 to 5.8 points for deterioration. The estimated meaningful improvement in mBMI was 9.8 kg/m² × g/L and deterioration was -40.9 kg/m² × g/L. Improvements in each measure with eplontersen versus placebo were greater than the estimates of meaningful differences.

Discussion: Eplontersen demonstrated a clinically meaningful effect on neuropathic impairment, QoL, and nutritional status. Such estimates have implications for clinical practice and trials.

Introduction/aims: Assessing upper limb muscle strength is important for understanding health outcomes, such as daily function and mortality. Ultrasound (US) is increasingly used to evaluate muscle health, but the relationship between its measures of morphology and isometric strength has not been thoroughly explored in upper limb muscles. The aim of this study was to evaluate the associations between US morphological measures and isometric strength in functionally relevant upper limb muscles in healthy adults.

Methods: Twenty-four healthy volunteers (30.0 ± 10.8 years) underwent B-mode, axial US scans of the first dorsal interosseus (FDI), flexor pollicis longus (FPL), biceps brachii (BB), brachialis (BR), and triceps brachii lateral head (TB). Participants performed corresponding maximal voluntary contractions (MVC), including first digit distal phalanx flexion, second digit abduction, and elbow flexion and extension. US images were segmented to obtain maximal muscle thickness (MT) and cross-sectional area (CSA).

Results: Strong positive correlations were found between muscle strength and BB MT (r = .83; p < .001), BR CSA (r = .84; p < .001), and TB MT (r = .70; p < .001). Moderate positive correlations were found for strength and FDI CSA (r = .67; p < .001), FDI MT (r = .47; p < .05), FPL CSA (r = .54; p < .01), and FPL MT (r = .42; p < .05). No significant correlation was found between strength and BR MT (r = .16; p > .05).

Discussion: Our data showed moderate-to-strong associations between US muscle morphology and strength, suggesting that US is likely a good biomarker for strength. However, its use is not "one size fits all." Future investigations should continue to assess this relationship in different muscles and expand the generalizability to clinical populations.

Introduction/aims: The number of clinical trials in facioscapulohumeral muscular dystrophy (FSHD) is expected to increase in the near future. There is a need for clinical outcome assessments (COAs) that can capture disease progression over the relatively short time span of a clinical trial. In this study, we report the natural progression of FSHD and determine the feasibility of COAs for clinical trials.

Methods: Genetically confirmed FSHD patients underwent various COAs at baseline and after 5 years. COAs consisted of the Motor Function Measure (MFM), manual muscle testing using the Medical Research Council score, six-minute walk test, quantitative muscle strength assessment of the quadriceps muscle, clinical severity score, and FSHD evaluation score (FES). Statistical significance and the minimal clinically important difference (MCID) were calculated and power calculations were performed.

Results: One hundred fifty-four symptomatic FSHD patients were included, with a mean (SD) age of 51.4 (14.6) years old. All COAs showed a minimal, yet statistically significant progression after 5 years. MCID was reached for the MFM Domain 1, MFM total score, and FES. These three COAs showed the lowest sample size requirements for clinical trials (185, 156, and 201 participants per group, respectively, for a trial duration of 2 years).

Discussion: The captured FSHD disease progression rate in 5 years was generally minimal. The COAs in this study are not feasible for clinical trials with a duration of 2 years. Extended trial durations or novel outcome assessments might be necessary to improve trial feasibility in FSHD.

Introduction/aims: Fluctuating symptoms and fatigue are common issues in myasthenia gravis (MG), but it is unclear if these symptoms are related to physical activity or sleep patterns. This study sought to determine the day-to-day relationship between patient-reported symptoms and physical activity and sleep over 12 weeks.

Methods: Sixteen participants with generalized MG wore a wrist-mounted accelerometer continuously for the study duration and reported their symptoms and fatigue each evening. Cumulative link mixed models were used to analyze whether clinical and demographic characteristics, physical activity, and sleep were related to symptom severity and fatigue over the study period. Three types of models were constructed: a cohort model, a model in which data was scaled to each participant, and individual models.

Results: The cohort model indicated that higher disease severity, female sex, more comorbidities, less physical activity, more inactive time, and lower quantity of sleep were significantly associated with increased symptom severity and fatigue (p < .05). However, in the within-participant scaled model, there were almost no significant associations with physical activity or sleep. In the individual models, some participants showed similar results to the cohort model, but others showed no associations or the opposite response in some variables.

Discussion: While physical activity and sleep were associated with self-reported symptoms and fatigue within this population, this was not necessarily applicable to individuals. This demonstrates the importance of an individualized analysis for determining how physical activity and sleep may impact outcomes in MG, with implications for clinical and self-management.