A wake intubation is often performed in patients anticipated to have a difficult airway.1,2 During awake intubation, patients may experience discomfort, and multiple reflexes (cough, glottic closure, and/or gag) may be triggered by manipulations inside the oral cavity and pharynx.3

Analgesic techniques for awake intubation include regional anesthesia, which is divided into topical anesthesia and nerve blocks. In topical anesthesia, lidocaine spray, viscous lidocaine, and nebulized lidocaine have been used.4 Nerve blocks include superior laryngeal, recurrent laryngeal, and glossopharyngeal nerve blocks,4,5 which are usually used in combination.3,6 A study using a combination of superior laryngeal, recurrent laryngeal, and glossopharyngeal nerve blocks was reported in which a glossopharyngeal neve block was performed using the anatomic landmark technique for a peristyloid approach.7

We performed ultrasound-guided superior laryngeal, recurrent laryngeal, and glossopharyngeal nerve blocks to facilitate awake intubation in a patient predicted to have a difficult airway. In particular, we performed a glossopharyngeal nerve block via the parapharyngeal space approach.8

Written informed consent was obtained from the patient for publication of this report. This article adheres to the CAse REports (CARE) guidelines.

CASE DESCRIPTION

An 87-year-old man (height, 161 cm; weight, 51 kg) was diagnosed with an exacerbation of arm muscle weakness due to cervical spondylolisthesis and osteonecrosis of the right mandible. Simultaneous cervical laminectomy and mandibulectomy were planned. The patient could only open his mouth to less than 1 finger’s breadth (Mallampati class IV).

Based on the physical findings, an awake intubation was planned. The patient was placed in a semisitting position, and the cervical collar was removed. Initially, 50 μg fentanyl was administered intravenously. Glossopharyngeal, superior laryngeal, and recurrent laryngeal nerve blocks were planned.

The parapharyngeal space approach was used to perform a glossopharyngeal nerve block with 1.5 mL 1% lidocaine (Figures 1–2). An ultrasound probe was placed on the lateral neck inferior to the mandible. The landmark for the block was the hyoid bone, which has a specific structure because of its greater horn. The probe was tilted slightly cephalad to locate the pharyngeal wall. The pharyngeal wall near the tonsil was targeted (Figure 1).

Figure 1.:

Parapharyngeal space approach with an in-plane technique. A, In-plane technique. B, The yellow dashed arrow indicates the needle entry path. A local anesthetic (✳) is injected in the submucosal PW. C and D, Anatomy for the parapharyngeal space approach. FA indicates facial artery; PW, pharyngeal wall; SMG, submandibular gland.

Figure 2.:

Parapharyngeal space approach with an out-of-plane technique. A, The ultrasound probe is placed under the patient’s right mandible, and a 25-G needle (25 mm) is used to puncture the parapharyngeal space using an out-of-plane technique. B, The yellow dashed arrow indicates the needle entry path. A local anesthetic (✳) is administered to the submucosal PW. C and D, Anatomy of the parapharyngeal space approach. PW indicates pharyngeal wall; SA, sublingual artery; SMG, submandibular gland.

On the right side, the initial plan was to insert the needle from the right lateral edge of the ultrasound probe using an in-plane technique. However, the intended puncture site was near the proximal facial artery. To avoid an arterial injury, the puncture site was changed to the superior side of the ultrasound probe, using an out-of-plane technique (Figure 2).

Bilateral superior laryngeal nerve blocks were performed using an out-of-plane approach. The probe was placed near the lateral edge of the thyroid cartilage and oriented slightly medially in a sagittal direction, providing an image to guide insertion of the needle. The lesser horn of the hyoid bone was easily visualized, as it appeared like 2 protrusions. One mL 1% lidocaine was injected into the thyrohyoid membrane between the hyoid bone and the thyroid cartilage on each side using a 25-G needle (25 mm).

Bilateral recurrent laryngeal nerve blocks were performed using a translaryngeal out-of-plane approach. First, the thyroid cartilage was visually differentiated from the laryngeal prominence (“Adam’s apple”) as a surface landmark. The ultrasound probe was placed transverse to the thyroid cartilage, which appeared as a triangular roof. The probe was moved caudally until the triangular thyroid cartilage disappeared, and a bright white line appeared in the midline,5 which was the cricothyroid membrane. After the cricothyroid membrane was identified, a 25-G 25-mm needle was inserted approximately 1.5 cm toward the cricothyroid membrane. After confirming air backflow, a translaryngeal block of the recurrent laryngeal nerve at the level of the cricothyroid membrane was performed with 2 mL 4% lidocaine.

An additional 50 μg fentanyl was administered intravenously, and 1 puff 8% lidocaine was sprayed intranasally toward the deep right upper nasal meatus to block the anterior ethmoid nerve. The pterygopalatine ganglion block was performed with 2 puffs 8% lidocaine sprayed deep into the right middle nasal meatus. A right nasal fiberoptic intubation was performed smoothly. At the postoperative visit, the patient reported no memory of any discomfort during the awake intubation.

DISCUSSION

An awake intubation was successfully performed for a patient predicted to have a difficult airway. An ultrasound-guided glossopharyngeal nerve block was performed using a parapharyngeal space approach,8 a superior laryngeal nerve block, and a recurrent laryngeal nerve block. The cricothyroid muscle of the larynx is innervated by the superior laryngeal nerve, and the other muscles of the larynx are innervated by the recurrent laryngeal nerves. Therefore, blocking both the superior laryngeal nerves and the recurrent laryngeal nerves should be sufficient to prevent reflexive contractions as the endotracheal tube passes through the glottis and enters the trachea. The glossopharyngeal nerve block suppresses airway reflexes, particularly the gag and cough reflexes, and provides analgesia.4,5,7 Performing a glossopharyngeal nerve block is not mandatory for awake intubation, but it facilitates the procedure.4,5,7

A glossopharyngeal nerve block can be performed using an intraoral4,5 or an extraoral approach.5 The extraoral approach, also known as the peristyloid approach, is performed from the lateral neck, targeting the styloid process using an anatomic landmark technique5,7 or ultrasound-guided techniques.9–11 The peristyloid approach is considered less desirable because of the risk of bleeding.5

In the present patient, an extraoral approach for the glossopharyngeal nerve block8 was used due to limited intraoral accessibility. The anatomical details of this approach have been reported previously. However, there are few clinical reports of its use.12–14 To our knowledge, this is the first report of using the parapharyngeal approach to perform a glossopharyngeal nerve block for an awake intubation in a patient predicted to have a difficult airway. The recurrent laryngeal nerve block was performed with a translaryngeal block at the level of the cricothyroid membrane.3,5

One drawback of nerve block techniques in the neck is that they usually require the administration of analgesics and sedatives to reduce the patient’s pain and anxiety. In the present patient, intravenous fentanyl was administered for analgesia during the block. An alternative would be a titrated infusion of remifentanil.

In the present patient, the parapharyngeal space approach to the glossopharyngeal nerve block was performed using a nonechogenic needle. An echogenic needle is an alternative to improve visibility and decrease the chance of an accidental arterial puncture.

The administration of local anesthetic agents into the parapharyngeal space is technically straightforward and has a low risk of inducing hemorrhage. The utility of the parapharyngeal space approach to a glossopharyngeal nerve block for awake intubation should be further investigated in larger multicenter studies.

DISCLOSURES

Name: Nozomi Wada, MD.

Contribution: This author helped in writing the original draft.

Name: Akiko Furutani, MD.

Contribution: This author helped with chart review and manuscript preparation.

Name: Joho Tokumine, MD, PhD.

Contribution: This author helped with editing the manuscript.

Name: Harumasa Nakazawa, MD, PhD.

Contribution: This author helped with the conceptualization of the case report.

Name: Keisuke Shimazu, MD.

Contribution: This author helped with chart review and manuscript preparation.

Name: Tomoko Yorozu, MD, PhD.

Contribution: This author helped with the validation of results and supervision.

This manuscript was handled by: BobbieJean Sweitzer, MD, FACP.

ACKNOWLEDGMENTS

The authors thank Dr Takashi Yoshimatsu, MD, PhD (Director, Department of Anesthesiology, Ogikubo Hospital, Tokyo, Japan) and Dr Alan Kawarai Lefor, MD, MPH, PhD, FACS (Professor, Department of Surgery, Jichi Medical University, Tochigi, Japan).

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