Endplate Noise
Spontaneous, low-amplitude electrical activity recorded from the muscle endplate region during electromyography. Represents normal miniature endplate potentials and should be distinguished from pathological spontaneous activity.
Full Definition
Endplate noise consists of low-amplitude (10-50 microvolts), brief-duration electrical potentials recorded from the neuromuscular junction region during needle EMG examination. These potentials represent normal spontaneous release of acetylcholine from nerve terminals, producing miniature endplate potentials. Endplate noise has a characteristic sound described as 'seashell' murmur or static-like activity. It is a normal finding when the needle electrode is positioned near the endplate zone and should not be confused with pathological spontaneous activity such as fibrillation potentials or positive sharp waves.
Usage
Usage note: Write as one word 'endplate' not 'end plate' or 'end-plate' when referring to this EMG finding.
In Context
- "Endplate noise was noted in the midportion of the muscle, consistent with needle placement near the motor point." — EMG report
- "The low-amplitude activity was determined to be endplate noise rather than pathological spontaneous potentials." — Electrodiagnostic study