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Letter to the Editor

Which Method for Intraoral Glossopharyngeal Nerve Block Is Better?

Henthorn, Randall W. MD; Amayem, Ahmed MD; Ganta, Raghuvender MD

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To the Editor:

We use a bilateral glossopharyngeal nerve (GPN) block for fiberoptic oral endotracheal intubation in awake patients. It reduces the gag reflex for easier placement of an intubator guide. Each GPN's lingual branch goes from the lower border of the superior constrictor muscle and enters submucosa near the base of the posterior tonsillar pillar (PTP). It passes medial to the base of the anterior tonsillar pillar (ATP) and enters the root of the tongue [1]. Local anesthetic injected near the base of either of these pillars should spread to anesthetize the lingual branch.

Two methods are described. Benumof [2] advocates a relatively new anterior tonsillar pillar method. The tongue is swept to the opposite side. A 25-gauge spinal needle is inserted 0.5 cm deep, just lateral to the base of the ATP Figure 1, and 2 mL of lidocaine is injected on each side. Woods and Lander [3] demonstrated blunting of cardiovascular stimulation and gagging with laryngoscopy in 30 patients. More studies documenting efficacy and complications are needed.

Figure 1
Figure 1:
Technique for blocking the lingual branch of the glossopharyngeal nerve. The tongue is swept to the opposite side. Local anesthetic is injected 0.5 cm deep, immediately lateral t alpha the base of each anterior tonsillar pillar, with a 25-gauge spinal needle.

By an older method, local anesthetic was injected near the base of the PTP. These GPN blocks were effective, with few complications [4,5]. Often substantial topical anesthetic and sedation are used, making evaluation of the nerve block itself difficult. Brown [6] uses a similar technique using a 22-gauge spinal needle bent 1 cm from the distal end. The mouth is widely opened, and the tongue is pressed down with a Macintosh blade. The needle tip is directed laterally and inserted in submucosa along the caudal portion of the PTP. Five mL is injected bilaterally.

The PTP method requires more exposure for needle guidance and placement. Thus, it will be more difficult to correctly place the needle in those patients with large tongues and/or impaired mouth opening. In addition, greater downward tongue retraction will be required, and gagging is likely. On the other hand, the ATP is easily exposed and tongue movement does not elicit the gag reflex. Patient tolerance is good after anesthetizing the pillar area with topical anesthetic. Since the ATP method is easier to teach and perform, we believe it is better.

Randall W. Henthorn, MD

Ahmed Amayem, MD

Raghuvender Ganta, MD

Department of Anesthesiology, The University of Oklahoma Health Sciences Center, Veterans Medical Center, Oklahoma City, OK 73152

REFERENCES

1. Netter F. Atlas of human anatomy. West Caldwell, NJ: CIBA-Giegy Corp., 1989.
2. Benumof JL. Management of the difficult adult airway. Anesthesiology 1991;75:1094-6.
3. Woods AM, Lander CJ. Abolition of gagging and the hemodynamic response to awake laryngoscopy [abstract]. Anesthesiology 1987;67:A220.
4. Demeester TR, Skinner DB, Evans RH, Benson DW. Local nerve block for peroral endoscopy. Ann Thorac Surg 1977;24:278-83.
5. Barton S, Williams JD. Glossopharyngeal nerve block. Arch Otolaryngol 1971;93:186-7.
6. Brown DL. Atlas of regional anesthesia. Philadelphia: WB Saunders, 1992:190-2.
© 1995 International Anesthesia Research Society