Physical examination serves to eliminate alternative diagnoses.
Signs of cranial nerve dysfunction or other abnormality of neurologic examination excludes the diagnosis of idiopathic TN and suggests that pain may be secondary to a structural lesion. Mechanism of pain production remains controversial. Pain is perceived when nociceptive neurons in a trigeminal nucleus involve thalamic relay neurons. Abnormal vessels, aneurysms, tumors, chronic meningeal inflammation, or other lesions may irritate trigeminal nerve roots along the pons. Uncommonly, an area of demyelination, such as may occur with multiple sclerosis, may be the precipitant.