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Q: I have been experiencing numbness in the right side of my right thigh. At night when I go to bed, that numbness turns into a hot burning sensation.  I recently had an operation on my left shoulder, but I wouldn't think this would have anything to do with the numbness. Do you have any suggestions as to what might cause this kind of numbness? Do you think it will eventually go away?

A: Numbness is usually a symptom of a nerve problem. Compression, inflammation, trauma, or diseases associated with nerve damage (especially diabetes) are the most common causes of nerve disease (doctors call this neuropathy). Neuropathy can also occur for no identifiable reason.

A common example of a temporary nerve problem is when your "foot falls asleep." This usually follows a prolonged period of sitting or lying in one position, when a nerve that brings sensation to the foot is compressed.

There are a number of reasons you may have numbness in the thigh. And it is possible that the recent surgery you had could be playing a role—more on that in a moment.

The most common cause of thigh numbness without other symptoms is compression or irritation of the nerve that supplies the skin of the upper, outside part of the thigh, called the lateral femoral cutaneous nerve. This condition is called meralgia paresthetica. Common triggers include:

  • Obesity

  • Trauma, including surgical injury

  • Constrictive clothing, such as a heavy equipment belt

  • Diabetes

During your recent surgery, it's possible you were placed in a position that put pressure on the lateral femoral cutaneous nerve (such as the fetal position); if that's the cause, symptoms should resolve over time.

Other possible causes of thigh numbness include problems with nerves that connect to the lateral femoral cutaneous nerve. For example, nerves in the lower back connect to the nerves of the thigh, so disc disease that compresses nerves in the lower back may cause numbness in the thigh.

It's likely that your doctor can find out the cause of your numbness just by reviewing your symptoms and performing a physical examination. No special tests are necessary to diagnose meralgia paresthetica. However, an MRI of the lower back or nerve conduction testing may be helpful if the cause is not clear after your doctor performs a physical exam.

Treatment includes removing or avoiding compression of the lateral femoral cutaneous nerve. Symptoms will usually go away over time after a person loses excess weight and wears loose clothing. For painful or particularly bothersome symptoms, a nerve block—an injection of a corticosteroid mixed with a Novocain-like numbing medication intended to interrupt nerve signals—may be recommended. Medications that may lessen symptoms of nerve irritation include gabapentin (Neurontin), carbamazepine (Tegretol), and amitriptyline (Elavil). For the most severe cases, surgery to decompress the nerve is a treatment of last resort.