DEAR DR. ROACH: For two weeks, I have had double vision when I look down to the lower side. Each eye is individually normal, but I have double vision when using both eyes. An MRI was done by my doctor and was normal. Now my doctor suspects myasthenia gravis.

Please let me know whether it is curable or for life. Is treatment available? — P.K.S.

ANSWER: My textbook lists over 70 causes of double vision on downward gaze. Many of these would cause an MRI result to be abnormal, but not all. Myasthenia gravis, a disease of the specific spot where the nerves interact with muscles (called the acetylcholine receptor), is a common cause of double vision in this situation. Your doctor will likely test you for antibodies to the acetylcholine receptor (or other closely related structures). The diagnosis may be confirmed by an electrodiagnostic study, which evaluates the function of the nerve/muscle junction.

If you do have myasthenia gravis, there are three kinds of treatments: symptomatic medical treatments, immunosuppression and surgery.

Pyridostigmine is a commonly used initial treatment for the symptoms of mild to moderate myasthenia. It stops the breakdown of the neurotransmitter — the chemical that the nerve uses to tell the muscle to fire — allowing for more effective muscle function. Some people do very well with this treatment, but it is minimally effective for others. Immune globulin and plasma exchange can be done in people with exacerbations of the disease.

Because MG is an autoimmune disease, suppressing the immune system can help control the course of the disease. This may be necessary for people who do not have a good response to pyridostigmine. Steroids are the usual first treatment. Other agents, such as azathioprine and mycophenolate, are used to improve effectiveness and reduce the many side effects of steroids. These take weeks to months to become effective.

Surgery on the thymus gland is indicated in people with a tumor of the gland, but may also can be recommended for people younger than 60 with antibodies to the acetylcholine receptor. The benefit of surgery takes effect slowly and improves over years.

DEAR DR. ROACH: I have chronic back pain and am on Eliquis. I have heard that the NSAID Celebrex can be taken without a bleeding problem because it is a Cox-2 NSAID. Is this true? Does it work for chronic pain? — O.C.H.

ANSWER: Aspirin and the nonsteroidal anti-inflammatory drugs (ibuprofen, naproxen and many others) work by inhibiting the enzymes cyclooxygenase-1 and cyclooxygenase-2. This reduces inflammation and provides pain relief, but it also inhibits the action of the specialized blood-clotting cells called platelets. Although aspirin has a strong effect, NSAIDs also increase bleeding risk, especially when taken in combination with other agents that decrease blood clotting, such as warfarin or apixaban (Eliquis).

Celecoxib (Celebrex) works by blocking only the enzyme cyclooxygenase-2 (hence, COX-2 inhibitor). This decreases but does not eliminate bleeding risk. People are still at an increased risk of bleeding on Celebrex and the other COX-2 inhibitors, just not to the same degree as with the traditional NSAIDs.

Using Eliquis and Celebrex together increases risk, especially of bleeding from the stomach and intestines. You and your doctor need to decide how bad the back pain is to see if it’s worth the risk. I certainly encourage use of other treatments, especially exercise, physical therapy and Tylenol before using an NSAID. Topical medications may also help.

One other medication I seldom see used but which might be reasonable is salsalate: It has minimal if any effects on the platelets yet still provides some anti-inflammatory and pain relief effect.

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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 ToYourGoodHealth@med.cornell.edu or send mail to 628 Virginia Dr., Orlando, FL 32803.

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