Muscle & Nerve最新文献

Background: Primary lateral sclerosis (PLS) is an ultrarare upper motor neuron syndrome with a prognosis unique from classical ALS. The study of PLS is complicated by its rarity and the difficulty distinguishing PLS from ALS. We present data from a 1-year prospective follow-up study on PLS and efforts to distinguish it from ALS.

Methods: Seventy-six PLS participants enrolled in this prospective natural history study. EMG studies, blood neurofilament light chain levels (NfLs), and demographic characteristics were obtained at baseline. At 1-year follow-up, repeat EMG studies were conducted to determine which participants fulfilled criteria for ALS. Baseline characteristics were then compared to determine features that predict reclassification.

Results: Seventy participants completed 1-year follow-up. Five of the 70 were reclassified to ALS (7.1%). Those reclassified had higher trends in baseline blood NfL levels (91.4 vs. 34.0 pg/mL, p = 0.13) and shorter symptom duration (39 vs. 69 months in the PLS group, p = 0.15). Reclassification was noted in both probable and definite PLS participants. All cases with a symptomatic duration of less than 2 years retained the PLS phenotype (5 of 5). NfL levels over 90 pg/mL predicted reclassification with 94% specificity and 60% sensitivity. No other features predicted reclassification to ALS.

Conclusions: In our population, reclassification of PLS to ALS occurred at a low frequency at 1 year follow-up (7.1%). Baseline NfL was the strongest predictor in differentiating UMN dominant ALS from PLS at 1-year follow-up. Based on our data, we propose EMG and NfL criteria for enrollment in future PLS trials.

Small fiber neuropathy (SFN) is a common neurological diagnosis with a multitude of symptoms, including dysautonomia symptoms (e.g., orthostatic dizziness) as well as sensory disturbances, such as a tingling sensation or burning pain. The disease can be due to metabolic, autoimmune, or hereditary factors, and treatment plans stem from SFN etiology. Diabetes, autoimmune disease, infection, vitamin deficiencies, post-vaccination syndromes can all cause SFN. Needle electromyography and nerve conduction studies can be performed to exclude other neuromuscular conditions by ruling out large fiber neuropathies. The gold standard of diagnosis for SFN remains an abnormal skin biopsy. For non-idiopathic cases, treatment of underlying causes, including metabolic, nutritional, infectious, autoimmune, or toxin-related, is critical for symptom improvement. Most treatment options for idiopathic SFN are geared toward symptom management for neuropathic pain and paresthesia and include antiepileptics, antidepressants, and topical ointments. First-line medications include amitriptyline, nortriptyline, gabapentin, and pregabalin. Second-line treatments can include serotonin-norepinephrine reuptake inhibitors and selective serotonin reuptake inhibitors such as duloxetine and venlafaxine, as well as lidocaine patches and capsaicin.

Dysmyelinating forms of hereditary motor and sensory neuropathy (HMSN) typically exhibit uniform conduction slowing on electrophysiological studies. However, this has been challenged in the past few decades with the discovery of novel gene mutations that induce nonuniform conduction slowing resembling acquired demyelinating neuropathies. Conduction block (CB) and/or excessive temporal dispersion (TD) are characteristic of segmental changes. Nevertheless, there is no consistent definition for CB and TD in inherited neuropathies. Pathological changes at paranodal regions or segmental demyelination might be explanatory in some patients.

Introduction/aims: Pain-related evoked potentials with concentric electrodes (PrEP-CE) provide a method for screening for small fiber neuropathy, which is usually the first manifestation of hereditary transthyretin amyloid polyneuropathy (ATTR v-PN). Despite that, this technique has not yet been fully explored in this condition. The current study aimed to compare PrEP-CE responses among patients with ATTRv-PN, presymptomatic carriers of TTR mutations, and healthy controls.

Methods: We recruited 17 patients with ATTRv-PN, 12 presymptomatic TTR mutation carriers (pre-ATTRv-PN), and 13 healthy controls. PrEP-CE were obtained by separately stimulating the hands and feet. We analyzed the latencies of negative (N1) and positive (P1) peaks and peak-to-peak amplitudes between groups using nonparametric tests.

Results: Median ages were 45 years for both ATTRv-PN and pre-ATTRv-PN groups, and 32 years for controls. In the arms, N1 and P1 latencies were significantly longer in the ATTRv-PN group compared to controls (p < 0.05). In the legs, P1 latency was significantly longer in the ATTRv-PN (p = 0.005) and the pre-ATTRv-PN (p = 0.001) groups vs. controls. PrEP-CE amplitudes were reduced in both the ATTRv-PN (p = 0.015) and the pre-ATTRv-PN (p = 0.021) compared to the control group.

Discussion: PrEP-CE facilitates recognition of ATTRv-PN, with lower limb P1 latency and amplitude indicating small fiber involvement. It is a rapid, well-tolerated technique that may support the assessment of small-fiber impairment in ATTRv-PN.

Introduction/aims: Traditional methods for assessing the neurophysiological function of the hypoglossal nerve involve placing electrodes directly on the tongue, but these are limited by technical challenges. We propose an alternative method for hypoglossal nerve conduction studies.

Methods: This study included 34 healthy adults, in whom compound muscle action potentials (CMAP) were recorded using an alternative electrode placement method, with the superficial active electrode positioned on the submental region and the reference electrode placed contralaterally. Repetitive nerve stimulation (RNS) was performed to assess decremental responses. Statistical analyses included descriptive measures, normality testing, and estimation of normative values. Univariate comparisons tested whether the amplitude and area decrement values differed significantly from a hypothetical mean of 10%. A linear mixed-effects model was used to assess side-related differences in hypoglossal nerve parameters.

Results: Data from 34 healthy adults (median age 34.5 years, 61.8% female) yielded reproducible CMAP and RNS recordings. CMAP onset latency averaged 1.27 ms (upper limit 1.58 ms), with amplitudes > 0.88 mV and areas > 3.22 μV·ms, showing low inter-individual variability. Mean amplitude decrement was -0.53% (SD 2.91) and mean area decrement -1.62% (SD 3.62), both below the 10% threshold (p < 0.001).

Discussion: Our alternative method addresses the limitations of traditional techniques by eliminating the need for specialized electrodes and minimizing issues related to saliva interference. Despite potential challenges in patients with obesity or facial hair, this approach offers a practical solution for the assessment of hypoglossal nerve function.

Aim: Polyneuropathy, organomegaly, endocrinopathy, monoclonal protein, and skin changes (POEMS) syndrome is a rare paraneoplastic syndrome associated with significant neurologic morbidity. Better understanding of the manifestations of this disease is crucial to early diagnosis and improvement of prognosis.

Methods: We retrospectively reviewed medical record data of adult patients diagnosed with POEMS syndrome between 2007 and December 2023 fulfilling the 2014 International Myeloma Working Group criteria for POEMS syndrome in a single tertiary care Hospital in Brazil. Clinical, laboratory and electrophysiological data were analyzed.

Results: Thirty-three patients were included, with median time from symptom onset to diagnosis of 13 (11-35) months, and 30% of patients were nonambulatory at the diagnosis. Neuropathy was present in 100% of patients, and early proximal muscle weakness was present in 57%. Nerve conductions studies (NCS) disclosed demyelinating polyneuropathy with axonal damage in 96% and conduction block in 33%. Serum monoclonal paraprotein heavy chain was IgG subtype in 73% and lambda light chain in 91%. Castleman disease was diagnosed in 6% of patients. Organomegaly, bone lesions and endocrinological profiles were similar to previously reported cohorts.

Discussion: Patients in our cohort had similar clinical profiles to previously reported data. However, unlike other large cohorts, our study showed a high proportion of IgG class paraprotein, non-length-dependent findings and conduction block on electrophysiology, and a lower number of cases associated with Castleman's disease. Our findings highlight the importance of pursuing a POEMS syndrome diagnosis even in the presence of atypical electrophysiological features.

Introduction/aims: Dissociation of echogenicity of the flexor digitorum profundus (FDP) and flexor carpi ulnaris (FCU) on neuromuscular ultrasound has been reported to be a useful sign to differentiate inclusion body myositis (IBM) from more common disease mimics, but it is not clear that this finding is pathognomonic of IBM. Our study aimed to evaluate whether this sign may be present in certain muscular dystrophies.

Methods: This case series included 6 genetically confirmed muscular dystrophy patients (2 Becker muscular dystrophy [BMD], 2 myotonic dystrophy type 2 [DM2], 1 myotonic dystrophy type 1 [DM1], and 1 facioscapulohumeral muscular dystrophy type 1 [FSHD1]), whose clinical picture was notable for selective deep finger flexor weakness. Neuromuscular ultrasound had been used to image the proximal medial forearm, where echointensity (EI) of the FDP and FCU was visually graded according to the Heckmatt scale and an FDP/FCU EI ratio was generated from quantitative grayscale analysis.

Results: The FDP had a higher EI-by Heckmatt grade and quantitative grayscale-than the FCU in all 6 patients, indicating preferential ultrasonographic involvement of the FDP in these muscular dystrophy cases.

Discussion: Ultrasonographic FDP-FCU dissociation of echogenicity confirms selective deep finger flexor involvement. The differential diagnosis of this imaging sign includes IBM but also certain muscular dystrophies (BMD, DM1, DM2, and FSHD), which should be considered in uncommon presentations of suspected IBM or when additional supportive diagnostic findings thereof are lacking.

Introduction/aims: Nerve enlargement has been reported in patients with Friedreich ataxia (FRDA). The underlying cause remains unclear, and both inflammatory processes and dysmyelination have been suggested as potential mechanisms. This study was aimed at assessing nerve morphology with high-resolution ultrasound, to identify and describe patterns of nerve pathology.

Methods: Patients with genetically confirmed FRDA were included, clinically examined, and assessed with high-resolution ultrasound. Cross-sectional area measurements were compared with previously published normal values.

Results: Among 20 included patients, ultrasound abnormalities were found in 17 (85%). Nerve enlargement of the median and/or ulnar nerve in the proximal nerve segments was observed in 45% of patients and was statistically significant compared to published normal values. Lower extremity nerve enlargement was observed in 20% of patients. Eight patients did not show any nerve enlargement. Diminished cross-sectional area, indicative of nerve atrophy, was present, particularly in the distal segments of the ulnar nerve (in 25% of patients, p < 0.05) and the tibial nerve (popliteal fossa in 30% of patients, medial malleolus in 30% of patients, both p < 0.05). Nerve enlargement showed no significant correlations with disease severity or age of disease onset.

Discussion: Peripheral nerve morphology in FRDA is variable and includes not only nerve enlargement but also nerve atrophy, thus reflecting complex segmental pathology beyond axonal degeneration.