Q. Over the past three months my friend's left leg seems to have lost weight. It is approximately 2" smaller in diameter than the left leg and it is almost continually numb. Any ideas what may cause this?

A. The condition you describe in which the muscle loses size is called atrophy. This can occur rapidly if a muscle group is not used for a time. The most common example would be the atrophy that occurs after an injury. For example, a person with an ankle sprain who requires crutches, a brace, or a cast for a few weeks will find that the calf muscles look shriveled up when the cast comes off, due to lack of use.

If there has been no injury to account for this, I would have concern that the nerve which stimulates the muscle is not working properly, thereby causing the muscle to contract less. The numbness is also frequently a sign of nerve dysfunction. This should be investigated by your doctor right away to determine the cause so a treatment plan can be made.

http://www.ninds.nih.gov/health_and_medical/disorders/paresthesia.htm

http://www.neurologychannel.com/neuropathy/

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