Postherpetic Neuralgia

A 73-year-old woman presents with persistent pain and itching in the right T10 dermatome from just above the thoracolumbar junction to the umbilicus since a documented episode of herpes zoster in the same region 1 year earlier. She describes a severe, continuous burning pain, unpredictable paroxysms of lancinating pain lasting a few seconds, and intense hypersensitivity to light tactile stimulation, such as clothing brushing against the skin. On physical examination, there are signs of cutaneous scarring throughout the right T10 dermatome, with areas of excoriation caused by scratching. She has patchy loss of tactile perception in this distribution as well as areas of pain provoked by a light brush. Acetaminophen did not help her pain. How would you manage this patient's condition?