DEAR DR. ROACH: In April 2014 I had an outbreak of shingles — right hip, leg and foot. I got the shingles vaccine in 2010, but apparently it did not work. My doctor prescribed Neurontin. The following month, I was diagnosed with follicular lymphoma, and for the next year, I received six rounds of chemotherapy (cyclophosphamide, doxorubicin, vincristine and rituximab) followed by 20 radiation treatments. The treatments were successful, and the cancer is in remission. While that is a true blessing, I am now suffering from constant pain in my right foot and have been for over two years. I have done everything I can think of to get relief. I have had X-rays, an ultrasound and a nerve conduction study; I have been examined by a neurologist, a podiatrist, a spine specialist, a chiropractor and an acupuncturist; I have taken Lyrica, used topical creams, received laser therapy and spinal injections, and used a TENS unit. Nothing has helped. I take 10 mg of Percocet three times a day, which does give me some measure of relief but the pain never goes away completely. There are days, even with the Percocet, where the pain can be debilitating. The neurologist told me that in his opinion, I do not have ”typical” neuropathy; he believes I suffer from chemotherapy-induced nerve damage and that most likely the condition is irreversible. I hate to think I have to live with this condition for the rest of my life. Do you have any suggestions or an opinion that might lead me to finding a solution to this condition? — I.P.

ANSWER: The constant pain in the foot could very well be a neuropathy: I think it is the most likely explanation based on what you’ve told me. I also think your neurologist is correct that it is likely to be related to the chemotherapy, especially the vincristine, which is well-known for causing permanent neuropathy in a proportion of those who use it. I suspect that without the chemotherapy, your post-herpetic neuralgia (the term for neuropathic pain following shingles) would likely have gone away. However, the damage caused by the Zoster virus increased the likelihood of damage due to the chemotherapy. At least, that’s my opinion about how you may have acquired this pain syndrome.

Your neurologist has tried many of the common therapies for neuropathy, but there are some people in whom nothing works. I don’t have an answer for your continued pain. My experience is that the doses of gabapentin (Neurontin) needed sometimes are much higher than most doctors are comfortable giving. In the study that got gabapentin approved for post-herpetic neuralgia, the most effective dose was 1,200 mg three times daily. Unfortunately, this dose has significant side effects, and it may take months of slowly increasing the dose to get there.

DEAR DR. ROACH: I read your recent column on central sleep apnea. That article could have been describing me. I kept being told that my CSA was idiopathic. Well, I finally had a brain MRI, and it turns out I have an Arnold-Chiari malformation. CSA is a hallmark of Chiari, but two neurologists and sleep-disorder specialists didn’t catch it. After I was diagnosed, decompression surgery gave me my life back. September is Chiari awareness month. From all I have read, 1 in 1,000 people have it. It often is misdiagnosed as migraine. CSA in a healthy person should always be followed with a brain MRI to check for Chiari, I believe. It was my only symptom for the many years my brain stem was pushed upon. — E.M.

ANSWER: I appreciate your writing, and am happy to pass on the information.

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Dr. Roach regrets that he is unable to answer individual letters, but will incorporate them in the column whenever possible. Readers may email questions to [email protected] or request an order form of available health newsletters at 628 Virginia Dr., Orlando, FL 32803. Health newsletters may be ordered from

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