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Department of Anesthesiology; Polyclinic Jean Villar; Bruges-Bordeaux, France; jmbmdphd{at}club-internet.fr (Bernard) Laboratoire d'Explorations Fonctionnelles; Hôtel-Dieu, University Hospital; Nantes, France (Péréon)
In Response:
We appreciate the questions raised by Dr. de Lacroix de Lavalette (1). Prospective studies that compare regional anesthesia and local infiltration anesthesia for facial soft-tissue surgery are still missing, probably because personal experience inextricably confounds the performance of each technique, preventing any possibility of an unbiased design. Our aim was to show that observation of a blink reflex can help identify and anesthetize trigeminal nerve branches with a high success rate. In expert hands, blind infiltration around the emergence of the infraorbital nerve is associated with 22% of failure (2). It appears thus that our technique improves the quality of facial regional anesthesia, while avoiding the use of sedative and narcotic drugs. This technique minimizes the risk of confusion and respiratory depression in elderly and fragile patients.
To provide physiologic support of our finding, we performed laboratory recordings from the orbicularis oculi muscles in an adult volunteer. We stimulated the infraorbital nerve as we described in our report (3). We also stimulated the superior maxillary nerve, a deep branch of the trigeminal nerve, after inserting a needle into the fossa infratemporalis. We recorded typical homolateral biphasic R1 and bilateral polyphasic R2 responses from both nerves, similar to those used by clinical neurophysiology laboratories as a diagnostic tool (Fig. 1). Clinically, the blink was more visible on the side of the stimulation, probably because the intensity of the stimulation (0.5 mA) was close to the R2 reflex threshold (1 mA) and was too low to transmit across multiple synapses. Habituation may also have affected the polysynaptic response (4).
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Other applications of our technique may be found in addition to regional anesthesia for facial soft-tissue surgery. For example, the technique may prove useful for anesthesia and analgesia by deep infiltration for major face surgeries or for therapy of trigeminal neuralgia and cancer pain. This area deserves further research.
REFERENCES
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