Hypoglossal Artifact

EEG Sample Credit: The Learning EEG (learningeeg.com)

Artifacts can disrupt an EEG and cause significant disturbance to the background activity and the overall ability to interpret the study. Glossokinetic potentials or Hypoglossal artifacts are caused by movement of the tongue. The artifact appears as slower, diffuse delta frequency activity, that is mostly synchronized and symmetrical with a frontal dominance. Chin, nose, or cheek references may also enhance artifacts from eye movement or glossokinetic potentials associated with tongue movement or talking. 

When possible any observed artifact by the technologist should be eliminated and/or replicated to prove its source. The hypoglossal artifact can be reproduced by asking the patient to move their tongue, or to say "la la la" or “lilt” (a lingual phoneme) for verification. ‍‍This is the best way to differentiate it from frontal delta activity. 

When the tongue moves, the change in the electrical field spreads to the scalp and is recorded by the scalp electrodes. The produced waveform seen can be single or rhythmic diffuse delta waves. The delta appearing waves are prominent in the frontal region and may look a lot like vertical eye movement artifact. The appearance of the Glossokinetic artifact varies by person; the same tongue movement brings out large artifacts in some but not in others. The use of eye electrodes can help in the differentiation of hypoglossal artifact or infraorbital artifact.