How do you examine the 9th (glossopharyngeal) and 10th (vagus) cranial nerves?

Examination of Cranial Nerves IX (Glossopharyngeal) and X (Vagus)

Test CN IX and CN X together by assessing the gag reflex, observing palatal elevation with phonation ("say ah"), evaluating swallowing function, and checking for uvular deviation, with the uvula deviating away from the side of the lesion. 1

Motor Function Testing

Palatal Elevation Test

• Have the patient open their mouth and say "ah" while you observe the soft palate with a tongue depressor and light 1
• The soft palate should elevate symmetrically, and the uvula should remain midline 1
• On the affected side, the palate appears lower and moves less than the normal side 1
• With unilateral vagal palsy, the uvula deviates toward the intact (healthy) side due to unopposed muscle contraction 1

Gag Reflex Assessment

• Touch the posterior pharyngeal wall bilaterally with a tongue depressor to elicit the gag reflex 1
• However, the absence or presence of the gag reflex does not confirm or exclude oropharyngeal dysfunction, as it is an unreliable sign 2
• A 2024 study demonstrated that the gag reflex showed poor diagnostic value for neurogenic oropharyngeal dysphagia, and clinicians should not rely solely on this reflex 2

Swallowing Evaluation

• Observe the patient swallowing water or their own saliva 1
• Note any coughing, choking, or difficulty with the swallow 1

Sensory Function Testing

Taste Assessment (CN IX)

• Test taste on the posterior one-third of the tongue using sweet, salty, sour, or bitter substances 1
• CN IX provides both general sensation and taste to the posterior third of the tongue 1
• Loss of sensation accompanied by impaired taste signals CN IX dysfunction 1

General Sensation

• Test general sensation of the posterior pharynx and posterior tongue 1
• CN IX provides general sensation to these areas, while CN X provides visceral sensation to the pharynx and larynx 3

Vocal Cord Function (CN X)

Voice Quality Assessment

• Listen for hoarseness, breathy voice quality, or nasal speech 3
• These findings suggest vocal cord paralysis from vagal dysfunction 3
• Isolated vocal cord paralysis without other deficits suggests recurrent laryngeal nerve pathology, requiring imaging from skull base to mid-chest 1

Cough Strength

• Ask the patient to cough forcefully 3
• A weak, ineffective cough suggests vocal cord weakness from CN X dysfunction 3

Anatomical Localization Principles

Brainstem vs. Peripheral Lesions

• Brainstem lesions affecting the nucleus ambiguus cause ipsilateral palatal weakness with associated brainstem signs (such as ataxia, crossed sensory findings, or other cranial nerve involvement) 1
• Peripheral lesions at the jugular foramen typically involve CN IX, X, and XI together, causing palatal weakness, vocal cord paralysis, and trapezius/SCM weakness 1
• The nerves travel in close anatomical proximity through the jugular foramen, making them vulnerable to combined injury from single lesions 1

Clinical Pitfalls and Special Considerations

Referred Otalgia

• Otalgia (ear pain) with a normal ear examination suggests referred pain from pharyngeal or laryngeal pathology via the vagus nerve 4
• The vagus nerve provides general sensory innervation to the ear, creating the anatomic pathway for referred otalgia from laryngeal or pharyngeal lesions 4

Glossopharyngeal Neuralgia

• Glossopharyngeal neuralgia presents as severe oropharyngeal and otic pain triggered by swallowing, typically from neurovascular compression but requiring imaging to exclude tumor 1

Diagnostic Imaging Recommendations

• The American College of Radiology recommends imaging for any confirmed CN IX or X deficit, using contrast-enhanced MRI of the orbits, face, and neck, with thin-cut high-resolution sequences through the posterior fossa, jugular foramen, and neck 1
• For vocal cord paralysis, imaging must visualize the full extent of the vagus nerve from the skull base to the mid-chest, as the vagus has the longest course of any cranial nerve 3, 4
• Pre- and postcontrast imaging provides the best opportunity to identify and characterize lesions along the nerve course 1