Objective:To observe whether there is abnormal expression of tetrodotoxin-resistant (TTX-R)hNa v1.8 channel protein in demyelinated fibers of the affected nerves in patients with trigeminal neuralgia(TN), and to explore the relationship between ectopic discharges and TN.Methods: Six affected inferior alveolar nerves obtained from patients with idiopathic TN were studied. One great auricular nerve and one normal inferior alveolar nerve were used,which were obtained from patients undergoing combined radical neck dissection with glossectomy (negative control) and mandibulectomy (normal controls) . One rat spinal nerve was used as positive control. Immunohistochemical method and electron microscope were used to observe the expression of TTX-R hNa v1.8 channel protein in all groups. Results: Strong expression of hNa v1.8 channel protein was found in the demyelinated fibers of the affected nerves in patients with TN, weak expression in the neuraxon of rat spinal nerve,and none in the normal inferior alveolar nerve and the great auricular nerve. Conclusion: Abnormal expression of hNa v1.8 channel protein in the demyelinated fibers in patients with TN may play an important role in the pathogenesis of TN.