Optical stimulation of the facial nerve: a new monitoring technique?

TY - JOUR

T1 - Optical stimulation of the facial nerve: a new monitoring technique?

AU - Teudt, Ingo

AU - Nevel, Adam E

AU - Izzo, Agnella D

AU - Walsh, Joseph T

AU - Richter, Claus-Peter

PY - 2007

Y1 - 2007

N2 - OBJECTIVES/ HYPOTHESIS: One sequela of skull base surgery is iatrogenic damage to cranial nerves, which can be prevented if the nerve is identified. Devices that stimulate nerves with electric current assist in nerve identification. Contemporary devices have two main limitations: 1) the physical contact of the stimulating electrode and (2) the spread of the current through the tissue. In contrast to electrical stimulation, pulsed infrared optical radiation can be used to safely and selectively stimulate neural tissue and might be valuable for screening. METHODS: The gerbil facial nerve was exposed to 250 microsecond pulses of 2.12 microm radiation delivered via a 600-microm-diameter optical fiber at a repetition rate of 2 Hz. With use of 27 GA, 12-mm intradermal electrodes, muscle action potentials were recorded. Nerve samples were examined for possible tissue damage. RESULTS: Eight facial nerves were stimulated with radiant exposures between 0.71 and 1.77 J/cm, resulting in compound muscle action potentials (CmAPs) that were simultaneously measured at the m. orbicularis oculi, m. levator nasolabialis, and m. orbicularis oris. Resulting CmAP amplitudes were 0.3 to 0.4 mV, 0.15 to 1.4 mV, and 0.3 to 2.3 mV, respectively, depending on the radial location of the optical fiber and the radiant exposure. Individual nerve branches were also stimulated, resulting in CmAP amplitudes between 0.2 and 1.6 mV. Histology revealed tissue damage at radiant exposures of 2.2 J/cm but no apparent damage at radiant exposures of 2.0 J/cm. CONCLUSIONS: The experiments showed that selective muscle action potentials can be evoked optically in the gerbil facial nerve without direct physical contact.

AB - OBJECTIVES/ HYPOTHESIS: One sequela of skull base surgery is iatrogenic damage to cranial nerves, which can be prevented if the nerve is identified. Devices that stimulate nerves with electric current assist in nerve identification. Contemporary devices have two main limitations: 1) the physical contact of the stimulating electrode and (2) the spread of the current through the tissue. In contrast to electrical stimulation, pulsed infrared optical radiation can be used to safely and selectively stimulate neural tissue and might be valuable for screening. METHODS: The gerbil facial nerve was exposed to 250 microsecond pulses of 2.12 microm radiation delivered via a 600-microm-diameter optical fiber at a repetition rate of 2 Hz. With use of 27 GA, 12-mm intradermal electrodes, muscle action potentials were recorded. Nerve samples were examined for possible tissue damage. RESULTS: Eight facial nerves were stimulated with radiant exposures between 0.71 and 1.77 J/cm, resulting in compound muscle action potentials (CmAPs) that were simultaneously measured at the m. orbicularis oculi, m. levator nasolabialis, and m. orbicularis oris. Resulting CmAP amplitudes were 0.3 to 0.4 mV, 0.15 to 1.4 mV, and 0.3 to 2.3 mV, respectively, depending on the radial location of the optical fiber and the radiant exposure. Individual nerve branches were also stimulated, resulting in CmAP amplitudes between 0.2 and 1.6 mV. Histology revealed tissue damage at radiant exposures of 2.2 J/cm but no apparent damage at radiant exposures of 2.0 J/cm. CONCLUSIONS: The experiments showed that selective muscle action potentials can be evoked optically in the gerbil facial nerve without direct physical contact.

M3 - SCORING: Zeitschriftenaufsatz

VL - 117

SP - 1641

EP - 1647

JO - LARYNGOSCOPE

JF - LARYNGOSCOPE

SN - 0023-852X

IS - 9

M1 - 9

ER -