Glossopharyngeal nerve block may be used for patients with pain due to cancer involving the base of the tongue, the epiglottis, or the palatine tonsils. It can also be used to distinguish glossopharyngeal neuralgia from trigeminal and geniculate neuralgia.
The nerve exits from the cranium via the jugular foramen medial to the styloid process and courses anteromedially to supply the posterior third of the tongue, pharyngeal muscles, and mucosa. The vagus and spinal accessory nerves also exit the cranium via the jugular foramen and descend alongside the glos-sopharyngeal nerve in close proximity to the inter-nal jugular vein.
The block is performed using a 5-cm 22-gauge nee-dle inserted just posterior to the angle of the man-dible (Figure 47–9). The nerve is approximately 3–4 cm deep; therefore, use of a nerve stimulator facilitates correct placement of the needle. An alter-native approach is from a point over the styloid process, midway between the mastoid process and the angle of the mandible; the nerve is located just anteriorly.
Complications include dysphagia and vagal block-ade resulting in ipsilateral vocal cord paralysis and tachycardia. Block of the accessory nerve and hypoglossal nerves causes ipsilateral paralysis of the trapezius muscle and the tongue, respectively. Care-ful aspiration is necessary to prevent intravascular injection.