Prolonged Electrode Implantation in Experimental Studies: Critical Evaluation of a Technique

Abstract

Stainless steel electrodes were chronically implanted through the right facial canal of 30 guinea pigs, close to the potential generator (VIII nerve). Compound action potential (CAP) thresholds, N₁ latencies and input-output curves were recorded on day of implantation and 2, 4 and 8–12 weeks later. In the same sitting, auditory evoked brain stem response (ABR) thresholds, latencies and inter-peak-latencies were measured on both sides as a control. N₁ thresholds and latencies at low and high intensities were stable. N₁ amplitudes, however, showed some variation. Rate of infection was low and reimplantation was successful. Preserving the facial nerve as a land mark was found advantageous, particularly on reimplantation, and did not affect the CAP recording. The technique, originally described by Hildesheimer et al., proved to be reproducible. A few technical difficulties are pointed out and the implication of some interesting findings are discussed.

Key Words:

• long-term electrode
• facial canal
• compound action potential