What is a back spasm? A back spasm is a sudden and involuntary contraction, or uncontrollable tightening, of a muscle in response to strain, overuse, weakness, or muscle pain related to injury or a disorder. Back spasms often occur near the spinal cord or near the nerve roots that lead in and out of the spinal cord. This can put pressure on one of these sensitive nerves, causing quite severe pain. It is common for muscle spasms to occur when you are exerting a lot of energy or are straining, such as while performing heavy lifting, working out, or engaging in a strenuous sports activity. You are especially prone to muscle spasms if you are doing any of these activities when you have not hydrated yourself sufficiently first or if your stores of potassium or calcium are low. Some spasms may be due to other disorders or the outside irritation of a nerve connected to that particular muscle. For example, a herniated disc often presses on spinal nerves and causes pain and spasm, while with spinal stenosis, the spinal cord is compressed because of a narrowing of either the spinal canal or the openings through which nerves extend away from the spinal column. When these hollow spaces narrow (a process called stenosis), pressure can be put on nearby nerves. If your back spasm is due to spinal stenosis or herniated disc, spinalcord compression can lead to serious injury to various nerves in the body and this damage can become permanent, even after relieving that pressure. Seek immediate medical care (call 911) for serious symptoms of nerve compression, such as loss of sensation in the limbs or shoulders; a complete loss of balance; or loss of bladder or bowel control, especially in combination with weakness in your legs. Also seek immediate care for serious symptoms, such as abnormal sensations or sudden weakness or numbness on one side of your body, paralysis, and changes in level of consciousness. Seek prompt medical care if you are being treated for spinal stenosis or a herniated disc but symptoms recur or are persistent.If your back spasm is persistent or causes you concern, seek prompt medical care.