Artikel
Optical stimulation of the facial and sciatic nerve in the gerbil
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Veröffentlicht: | 8. August 2007 |
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Introduction: Within the last years, the use of electrical nerve monitoring during parotid, thyroid, and certain skull base surgeries, became more frequent in the field of otolaryngology. Besides electrical stimulation, action potentials (AP) can also be triggered via optical stimulation. Recently Wells et al. [Ref. 1] and Izzo et al. [Ref. 2] reported successful optical stimulation of the rat sciatic nerve (SN) and the gerbil auditory system, respectively. Both groups used pulsed, low-energy, infrared light. Continuing with this approach, we have expanded these observations made by Wells et al. onto the sciatic nerve of the gerbil, as well as investigated the effects of optical stimulation on the gerbil facial nerve (FN).
Methods: FN and SN of gerbils were individually prepared. Stimulation of nerves were performed using a Holmium:YAG laser, Λ2.1 with 250µs pulse width. AP were recorded at the nerve (CnAP) and within the response muscles (CmAP). Following radiation, the nerves were stained with OsO4.
Results: Seven FN and twelve SN were optically stimulated using energies ranging from 0.11 to 3.5 J/cm2. For the SN, CmAP of up to 1800µV and CnAP up to 150µV could be measured. The FN produced CmAP up to 710µV and CnAP up to 180µV. Light microscopy revealed obvious nerve damage with energies around 3 J/cm2 and no such tissue damage with energies below 1.7 J/cm2.
Discussion: Peripheral nerves like the FN and the SN can be stimulated with pulsed laser light. The high selectivity and no-contact characteristics of this novel stimulation procedure figures to be of value for nerve monitoring in the field of otolaryngology. Further research must be done to compare different laser stimuli and to unveil the currently unknown excitation mechanism.
Supported by NIH HHS-N-260-2006-00006C.