ECG-related fasciculation potential.

We report the observation of an unusual fasciculation potential (FP). This FP was time-locked to the electrocardiogram (ECG) in 87% of the discharges. The motor unit action potential (MUAP) of the FP was also elicited as H-reflex. As mechanism we propose spindle afferent discharges mechanically triggered by the arterial pulse, i.e. a reflex fasciculation. We suggest that such a heartbeat-related mechanism could explain synchronous fasciculations described by Norris (Arch. Neurol., 1965, 13: 495-500).