The Clinical Syndrome
Glossopharyngeal neuralgia is a rare condition characterized by paroxysms of pain in the sensory division of the cranial nerve IX. Although the pain of glossopharyngeal neuralgia is similar to that of trigeminal neuralgia, it occurs 100 times less frequently. Glossopharyngeal neuralgia occurs more commonly in patients older than 50 years. The pain is located in the tonsil, laryngeal region, and posterior tongue. The pain is unilateral in most patients, but can occur bilaterally 2% of the time. Rarely, the pain of glossopharyngeal neuralgia is associated with bradyarrhythmias; in some patients, it is associated with syncope. These cardiac symptoms are thought to be due to overflow of neural impulses from the glossopharyngeal nerve to the vagus nerve. Although rare, this unusual combination of pain and cardiac arrhythmia can be lethal.
Signs and Symptoms
The pain of glossopharyngeal neuralgia is in the distribution of cranial nerve IX ( Fig. 20.1 ). In some patients, overflow pain may occur in areas innervated by the trigeminal nerve, upper cervical segments, or both. The pain is neuritic and is unilateral in 98% of patients. It is often described as shooting or stabbing, with a severe intensity level. The pain of glossopharyngeal neuralgia is often triggered by swallowing, chewing, coughing, or talking. With the exception of trigger areas in the distribution of cranial nerve IX, the patient’s neurological examination should be normal. Because tumors at the cerebellopontine angle may produce symptoms identical to those of glossopharyngeal neuralgia, an abnormal neurological examination is cause for serious concern ( Fig. 20.2 ). Dull, aching pain that persists between the paroxysms of pain normally associated with glossopharyngeal neuralgia is highly suggestive of a space-occupying lesion and requires thorough evaluation.
Magnetic resonance imaging (MRI) of the brain and brainstem should be performed in all patients thought to have glossopharyngeal neuralgia. MRI of the brain provides the best information regarding the cranial vault and its contents. MRI is highly accurate and helps identify abnormalities that may put the patient at risk for neurological disasters secondary to intracranial and brainstem pathology, including tumors and demyelinating disease (see Fig. 20.2 ). MRI can also aid in the identification of blood vessels that may be compressing the glossopharyngeal nerve ( Fig. 20.3 ). Magnetic resonance angiography (MRA) may be helpful in identifying aneurysms responsible for neurological symptoms. In patients who cannot undergo MRI, such as patients with pacemakers, computed tomography (CT) is a reasonable second choice.
Clinical laboratory tests consisting of complete blood cell count, automated chemistry profile, and erythrocyte sedimentation rate are indicated to rule out infection, temporal arteritis, and malignancy that may mimic glossopharyngeal neuralgia. Endoscopy of the hypopharynx with special attention to the piriform sinuses also is indicated to rule out occult malignancy. Differential neural blockade of the glossopharyngeal nerve may help strengthen the diagnosis of glossopharyngeal neuralgia.
Glossopharyngeal neuralgia is generally a straightforward clinical diagnosis that can be made on the basis of a targeted history and physical examination. Diseases of the eye, ears, nose, throat, and teeth may mimic trigeminal neuralgia or may coexist and confuse the diagnosis. Tumors of the hypopharynx, including the tonsillar fossa and piriform sinuses, may mimic the pain of glossopharyngeal neuralgia, as may tumors at the cerebellopontine angle. Occasionally, demyelinating disease may produce a clinical syndrome identical to glossopharyngeal neuralgia. The jaw claudication associated with temporal arteritis also sometimes confuses the clinical picture, as does trigeminal neuralgia.