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Complications of Percutaneous Block and Lesioning of the Glossopharyngeal Nerve

Serdar Erdine MD, FIPP

Medical Faculty of Istanbul University, Istanbul Pain Center, Istanbul, Turkey

Introduction

Glossopharyngeal neuralgia is a severe transient stabbing pain experienced in the ear, base of the tongue, tonsillar fossa or beneath the angle of the jaw. It is commonly provoked by swallowing, talking or coughing, and may remit and relapse in the fashion of trigeminal neuralgia. It is unilateral, sharp stabbing, and severe and there is no clinically evident neurologic disorder if it is not related with a tumor or other secondary causes [1].

Although it looks like trigeminal neuralgia, the incidence of glossopharyngeal neuralgia is very low at 0.2–0.5 per 100 000 persons per year.

If pharmacologic treatment does not relieve pain or causes serious side effects, percutaneous block and lesioning of the glossopharyngeal nerve may be considered.

Anatomy of the Glossopharyngeal Nerve

The glossopharyngeal nerve containing sensory, motor, and autonomic fibers originates from the medulla oblongata, leaves the skull through the central part of the jugular foramen, in a separate sheath of the dura mater, lateral to and in front of the vagus and accessory nerves. In its passage through the jugular foramen, it grooves the lower border of the petrous part of the temporal bone, and, at its exit from the skull, passes forward between the internal jugular vein and internal carotid artery; it descends in front of the internal carotid, and beneath the styloid process and the muscles connected with it, to the lower border of the stylopharyngeus. It then curves forward, forming an arch on the side of the neck and lying upon the stylopharyngeus and constrictor pharyngis medius. From there, it passes under cover of the hyoglossus and is finally distributed to the palatine tonsil, the mucous membrane of the fauces and the base of the tongue and the mucous glands of the mouth.

The motor fibers innervate the stylopharyngeus muscle. The sensory fibers innervate the posterior third of the tongue, the palatine tonsils and the mucous membranes of the mouth and pharynx. Parasympathetic nerves travel along with the glossopharyngeal nerve to innervate the parotid gland (Figure 17.1a,b).

**Figure 17.1** (a) 3D-computed tomography T scan showing the course of the glossopharyngeal nerve exiting the jugular foramen. Note the close relationship to the vagus nerve, internal carotid artery, and internal jugular vein. (b) 3D-computed tomography scan showing the course of the glossopharyngeal nerve and its relationship to the vagus nerve, internal carotid vessel and internal jugular vein as it exits from the jugular foramen and courses toward the angle of the mandible and mastoid process.(*Source*: Courtesy of S. Erdine.)

Indications

Diagnostic nerve block for pain in the glossopharyngeal nerve distribution
Prognostic nerve block prior to neurodestructive procedures
Glossopharyngeal neuralgia
Vascular compression of the glossopharyngeal nerve
Cancer pain (palliation)
Inflammation.

Contraindications

Local infection
Coagulopathy
Vital function instability
Psychopathologies
Anatomic anomaly.

Technique

There are multiple approaches for glossopharyngeal block or lesioning:

Intraoral approach
Extraoral approach under flouroscopy
Ultrasonographic approach.

Intraoral Approach

With the patient’s mouth open wide, the tongue is retracted. 23-G 60 mm disposable needle, l ml syringe, with 1–2% lidocaine is inserted into the mucosa at the lower lateral portion of the posterior tonsillar pillar. After aspiration, 7 to 10 ml of local anesthetic, with or without steroid, are injected in small increments. For the block in the ramus lingualis, the needle is advanced about 1.5 cm toward the tongue base from the contact point between the palatine arch and the lateral margin of the tongue on the affected side. After aspiration, 0.5 ml of a local anesthetic is injected [3].

This method carries risk of infection and iatrogenic injury to several neurovascular structures, including the internal carotid artery, vagus nerve, brainstem, vertebral artery, and upper cervical spinal nerves. An intraoral approach is used for regional anesthesia of the tonsilla. It does not have a place in chronic pain treatment.

Extraoral Approach

Because the glossopharyngeal nerve is composed of both sensory and motor fibers, RF thermocoagulation is unwise, not recommended, and will not be discussed. The same is valid for the use of neurolytic agents. The use of neurolytic agents such as phenol should only be confined for cancer pain. PRF should be considered.

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