Accuracy of muscle ultrasonography in detecting fasciculations for the diagnosis of amyotrophic lateral sclerosis: a systematic review and meta-analysis.

purposeThis systematic review and meta-analysis aims to evaluate the diagnostic accuracy of muscle ultrasonography in detecting fasciculations for the diagnosis of amyotrophic lateral sclerosis (ALS).

methodsFollowing PRISMA-DTA guidelines, we systematically searched PubMed, Embase, Cochrane Library, Ovid Medline, Sinomed, Web of Science, CNKI and VIP for studies published up to July 8, 2025 that evaluated muscle ultrasonography to detect fasciculations for ALS diagnosis. The study protocol was registered in PROSPERO (CRD420251057866). Studies were screened using predefined inclusion and exclusion criteria and data were extracted. Risk of bias was assessed with QUADAS-2. Statistical analyses (Stata 16.0 and R 4.5.1 with the "midas," "metandi," and "mada" packages) were used to calculate pooled sensitivity (Sen), specificity (Spe), positive likelihood ratio (LR+), negative likelihood ratio (LR-), and diagnostic odds ratio (DOR). We constructed forest plots, hierarchical summary receiver operating characteristic (HSROC) curves, summary ROC (SROC) curves and calculated the area under the SROC curve (AUC). Univariate meta-regression and subgroup analyses explored sources of heterogeneity. Publication bias was assessed using Deeks' funnel plot asymmetry test. Fagan nomograms were also used to illustrate the changes from pre-test to post-test probability and to enhance clinical interpretability.

resultsThirteen studies involving 1176 participants met the inclusion criteria. Muscle ultrasonography for fasciculation detection in ALS yielded a pooled sensitivity of 0.87 (95% CI 0.83-0.91) and specificity of 0.91 (95% CI 0.86-0.94). The pooled LR+ was 9.81 (95% CI 6.25-15.40) and LR- was 0.14 (95% CI 0.10-0.19), with a DOR of 70.03 (95% CI 41.72-117.56). The area under the SROC curve was 0.94 (95% CI 0.91-0.95). Meta-regression identified scan duration as a primary factor influencing diagnostic accuracy, with scan durations ≥ 30 s associated with higher sensitivity but relatively lower specificity. Deeks' funnel plot showed no significant asymmetry (p = 0.61), indicating no notable publication bias. Fagan nomograms showed that, at a pre-test probability of 30%, the post-test probability increased to 81% after a positive MUS result and decreased to 6% after a negative result.

conclusionMuscle ultrasonography demonstrates good pooled diagnostic accuracy for detecting fasciculations in ALS and may serve as a useful adjunct to electrodiagnostic evaluation. Scan duration appears to significantly affect the diagnostic performance, with longer scanning improving sensitivity at the cost of reduced specificity. We speculate that prolonged scanning may be more useful in clinical scenarios where fasciculations are subtle or atypical, whereas shorter scanning may be sufficient when fasciculations are already readily apparent. Nevertheless, further large-scale prospective studies are needed to validate standardized scanning protocols and to better define the clinical role of MUS in ALS diagnostic pathways.