What happened, in summary

A 53-year-old man presented with double vision and was diagnosed with Stage IV non-small cell lung cancer with a solitary pontine metastasis. Because the pontine lesion enlarged and another brain metastasis was present in the right parietal lobe, he received CyberKnife stereotactic radiosurgery before systemic chemotherapy: 20 Gy to the pontine lesion and 23 Gy to the right parietal lesion. Six months later, he developed neuralgia in the right arm and leg. Imaging initially raised concern for progression of the pontine lesion, but 11C-methionine PET showed no recurrence and instead supported radiation necrosis from prior treatment. The pain was diagnosed as central neuropathic pain from radiation necrosis in the pons. It was severe: constant dull aching pain rated 6/10, intermittent shooting and squeezing pain rated 10/10, hyperalgesia and allodynia in the right forearm, and increasing paralysis of the right limbs. Oxycodone 40 mg/day plus nonsteroidal anti-inflammatory drugs, acetaminophen, eperisone, pregabalin, and dexamethasone did not control the pain. Duloxetine was added and oxycodone was switched to hydromorphone 12 mg/day, but relief was temporary and he still needed immediate-release hydromorphone about 5 times daily. Adding methadone 5 mg/day reduced pain within 1 week and lowered rescue use to 0-1 times daily; the dose was later increased to 15 mg/day. His lung cancer reached complete remission after 2 years of chemotherapy with an anti-VEGF drug, and the pontine lesion remained stable. During a later pain crisis with insomnia, appetite loss, and suicidal thoughts, methadone was escalated to 25 mg/day with hydromorphone 8 mg/day, bringing effective control and allowing other adjunctive drugs to be reduced or stopped.