Investigation of the use of three electroencephalographic electrodes for long-term electroencephalographic recording in awake and sedated dogs.

OBJECTIVE: To compare electroencephalography (EEG) artifact associated with use of the subdermal wire electrode (SWE), gold cup electrode (GCE), and subdermal needle electrode (SNE) over an 8-hour period in sedated and awake dogs. ANIMALS: 6 healthy dogs. PROCEDURES: 8 EEG channels were recorded during 20-minute video-EEG recording sessions (intermittently at 0.5, 2, 4, 6, and 8 hours) with and without chlorpromazine sedation. Nonphysiologic artifacts were identified. Duration of artifact was summed for each channel. Number of unaffected channels (NUC) was determined.
RESULTS: NUC was significantly affected by electrode type and sedation over time; median for SWE (2.80 channels; 95% confidence interval [CI], 0.84 to 5.70 channels) was significantly different from medians for GCE (7.87 channels; 95% CI, 7.44 to 7.94 channels) and SNE (7.60 channels; 95% CI, 6.61 to 7.89 channels). After 4 hours, NUC decreased in awake dogs, regardless of electrode type. In awake dogs, duration of artifact differed significantly between SWE and GCE or SNE; medians at 8 hours were 61.55 seconds (95% CI, 21.81 to 173.65 seconds), 1.33 seconds (95% CI, 0.47 to 3.75 seconds), and 21.01 seconds (95% CI, 6.85 to 64.42 seconds), respectively. CONCLUSIONS AND CLINICAL RELEVANCE: The SWE had a significant duration of artifact during recording periods > 2 hours, compared with results for the GCE and SNE, in awake dogs. The GCE, SNE, and sedation resulted in significantly more channels unaffected by artifact. For longer recordings, caution should be exercised in selecting EEG electrodes and sedation state, although differences among electrodes may not be clinically relevant.