Experimental Facial Nerve Paralysis: Influence of Decompression

Abstract

An experimental model was employed to establish an endotemporal bone facial nerve paralysis in cats. Twelve facial nerves were initially surgically decompressed— Both bony decompression and sheath decompression—to determine if any harm was done to the nerves by these procedures. Transient harm was found in 3 of the 12 nerves. After the course of the facial paralysis without any decompression was determined, 39 cats underwent either bony or sheath nerve decompression, both immediately after injury and after a delay. The cats were followed clinically and electrophysiologically; the nerve excitability test and the amplitude and latency of muscle response evoked by nerve stimulation were used to evaluate nerve function. While immediate postinjury bony decompression resulted in slightly earlier recovery times, immediate sheath splitting significantly lengthened recovery times and worsened the electrophysiologic test results. Histologic studies confirmed the clinical and electrophysiologic results anatomically. Delayed nerve decompression, either bony or sheath, was not associated with faster recovery rates.