Hello, There are many causes of muscle spasms or cramps, including electrolyte abnormalities, dehydration, and nerve problems, but statins such as Simvastatin are well known for rarely causing damage to muscles, and I would want to make sure this is not the case for you. I would suggest stop taking the Simvastatin and letting your doctor know about your symptoms so that you can get your blood checked and make sure there is not damage to the muscle. You can also try making sure you are well hydrated to see if that helps. As for the numbness in your hands, I m not sure how that would be related to the muscle cramps in your leg, and I would suspect it has another cause, possibly neurologic. Hope I have answered your query. Let me know if I can assist you further. Take care Regards, Dr Aaron Branch, General & Family Physician