Introduction
The glossopharyngeal nerve is both a sensory and motor nerve.
The sensory component supplies the posterior third of the tongue, tonsils, pharynx, middle ear, and carotid sinus.
The motor component supplies stylopharyngeus (elevates larynx and pharynx facilitating swallowing).
Parasympathetic fibres supply the parotid and salivary glands.
A patient with a glossopharyngeal nerve palsy will have an absent gag reflex and difficulty swallowing.
The glossopharyngeal nerve originates from the medulla, close to the vagus. It leaves the skull through the jugular foramen then passes between the internal jugular vein and internal carotid artery.
- Nerves IX and X are tested together
- Test the gag reflex
- Ask the patient to say “aah” and look for deviation of uvula (testing CN X)
CN IX, X, XI and XII are closely situated anatomically so investigations are similar for all.
In trauma, CT is required to exclude basal skull fractures. Consideration should be given to the possibility of upper cervical spine fractures and either plain X rays or CT scan arranged.
For non-traumatic causes, CT head may identify a brainstem stroke (lateral medullary syndrome).
Consideration of carotid artery dissection may be needed, depending on the clinical features.
Jugular foramen syndrome is a palsy of CN IX, X, XI and XII. Causes are:
- Tumours (metastases, neurofibromata, cerebellopontine angle lesions)
- Meningitis
- Infection from the middle ear spreading into the posterior fossa
Carotid artery dissection presents with cranial nerve palsy in up to 12% of patients with CN IX to XII being most commonly affected. This is thought to be the result of nerve compression by an expanding internal carotid artery.
More information on cervical artery dissection can be found in the session on Cervical Artery Dissection.
Isolated glossophayngeal nerve palsy is rare. It is usually damaged with X and XI, close to the jugular foramen. XII is also involved if the lesion is outside the skull. Cranial nerve palsies of IX to XII are a classic sign of occipital condyle fractures.
Upper cervical spine injury complicated by injury to nerves IX and X has been described. The mechanism is thought to be ischaemia secondary to vertebral artery damage.
The image below is a CT scan demonstrating a fracture of the atlas (C1). Such an injury may be associated with occipital condyle fractures and palsies of CN IX to XII. Click on the image to enlarge.
