EMG vagus nerve stimulator artifact.

Area of Science:

• Neurology
• Biomedical Engineering

Background:

• Electromyography (EMG) is a diagnostic technique used to assess the health of muscles and nerves.
• Vagus nerve stimulator (VNS) devices are implanted to treat conditions like epilepsy and depression.
• Artifacts in EMG can complicate diagnosis by mimicking pathological findings.

Observation:

• A patient with a VNS implant undergoing an EMG study for suspected Amyotrophic Lateral Sclerosis (ALS) exhibited unusual EMG signals.
• These artifacts resembled positive sharp waves and fibrillations, which are indicative of denervation or muscle damage.
• The observed artifacts correlated with the VNS generator's programmed settings.

Findings:

• VNS devices can generate electromagnetic interference that manifests as EMG artifacts.
• These artifacts can be mistaken for genuine EMG abnormalities, potentially leading to a false-positive diagnosis of neuromuscular disorders.
• The characteristics of the VNS-EMG artifacts align with the VNS device's operational parameters.

Implications:

• EMG interpretation requires heightened caution in patients with VNS implants to avoid misdiagnosis.
• EMG may serve as a potential tool for monitoring the activity and function of VNS devices.
• Further research is warranted to understand and mitigate VNS-induced EMG artifacts and explore their diagnostic potential.