Clinically visible but often unperceived: Low awareness of fasciculations in amyotrophic lateral sclerosis.

BACKGROUND: Fasciculations are a key clinical sign of amyotrophic lateral sclerosis (ALS) but also occur in other conditions such as benign fasciculation syndrome. Patients often present with perceived twitching fearing ALS; however, the extent to which ALS patients themselves perceive fasciculations has not been systematically examined. We therefore aimed to clarify how often ALS patients are aware of fasciculations that are clinically visible.

METHODS: We prospectively studied 34 ALS patients. First, a structured questionnaire assessed initial symptoms, chief complaints, and awareness of twitching. Then, the frequency and concordance between objective fasciculations and subjective awareness of fasciculations (twitching) were analyzed across five body regions (bilateral upper and lower limbs and trunk) based on simultaneous visual observation and patient reports.

RESULTS: In the questionnaire, only one of the 34 patients (3 %) reported twitching as the initial symptom, and none presented with twitching as the chief complaint. More than half (19, 56 %) had never noticed twitching. In the fasciculation analysis, patients showing objective fasciculations without subjective awareness were most common (21/34, 62 %), whereas those with objective fasciculations accompanied by subjective awareness were fewer (10/34, 29 %), indicating relatively low concordance between visible fasciculations and patient awareness. No patient exhibited subjective awareness without objective fasciculations. These findings suggest that the majority of visible fasciculations in ALS are not perceived by patients.

CONCLUSION: Fasciculations in ALS are rarely the initial or presenting symptom and are often unperceived by patients despite being clinically visible.