[Opioid effectiveness for neuropathic pain in a patient with glossopharyngeal neuralgia]

A 55-year-old man complained of intermittent piercing pain on the right side of his throat. In a visit to our hospital, he was diagnosed with glossopharyngeal neuralgia and was treated with carbamazepine. But he obtained no pain relief and had drug-induced hypersensitivity syndrome due to carbamazepine on admission. We discontinued the carbamazepine, so the severity of the throat pain increased. We then administered codeine, which alleviated the pain; an increase in the dosage led to complete pain remission. After his general condition improved, he underwent an operation for microvascular decompression. In general, opioids are not efficacious against neuropathic pain, including glossopharyngeal neuralgia. However, recent studies do show their effectiveness against such pain via various mechanisms. They may control neuropathic pain through their effects on cortical brain regions and the thalamus, they may affect the descending antinociceptive pathway via actions on the periaqueductal gray, and they may modulate pain transmission in the spinal dorsal horn. We believe this to be the first case report to mention the effectiveness of opioids for glossopharyngeal neuralgia. If the control of pain is difficult in cases of glossopharyngeal neuralgia, opioids may be a useful therapeutic option.