What to Know About Leg Weakness

There are a number of different causes of leg weakness, and while they can be serious, many of them can be medically or surgically treated. If you have sudden leg weakness, this means that you could be experiencing a medical emergency. You should get a prompt medical evaluation so that you can get the right diagnosis and get started on the best treatment plan for maximal recovery as soon as possible.

Most of the causes of leg weakness require urgent medical attention. It may take anywhere from a few hours to a few days for your healthcare team to determine the reason for your leg weakness, depending on your preliminary test results and the cause of your medical problem.

Stroke/Cerebrovascular Accident

A stroke, often referred to as a cerebrovascular accident (CVA), is brain damage caused by interruption of blood flow to a region of the brain. There are several areas in the brain that work together to provide us with the ability to move our legs.

Sudden leg weakness, particularly on one side, can be one of the signs of a stroke or a transient ischemic attack (a temporary, reversible stroke). If you have a stroke, your best chance of recovery is dependent on getting treatment as soon as possible.

Guillain-Barre Syndrome

Guillain-Barre syndrome (GBS) is a life-threatening nerve disease that affects between one and two in 100,000 people in the U.S per year.

GBS begins with tingling or numbness in the feet and quickly progresses, producing weakness of the feet, followed by weakness that spreads to the legs, and eventually, weakness progressing up through the rest of the body.

The most dangerous aspect of GBS is that weakened chest muscles are unable to power adequate breathing, which can result in death. If you have GBS, your healthcare providers closely monitor your oxygen levels and breathing ability. You may need respiratory assistance through a breathing machine to ensure that your body receives enough oxygen.

GBS can be treated with powerful medications to reduce the symptoms and hasten recovery. Most people who have GBS survive, but may continue to experience unusual leg sensations or moderate leg weakness for months or years after the GBS has largely resolved.

Multiple Sclerosis

Multiple sclerosis (MS) is a fairly common neurological illness characterized by episodes of weakness, vision loss, and sensation disturbances, as well as a variety of other neurological symptoms. MS can cause leg weakness, affecting one or both legs at a time.

Typically, symptoms of multiple sclerosis come and go, with episodes that last for a few weeks or months at a time. Episodes are called MS exacerbations and generally improve partially or completely over time, but you may have a long-term decline of strength, vision, or sensation after each exacerbation.

It takes time and a number of different diagnostic tests to diagnose multiple sclerosis. Currently, there are several effective treatments for multiple sclerosis.

Pinched Nerve

A pinched nerve in the spine produces either leg weakness, leg numbness, or both. A pinched nerve can cause leg weakness on one side or both sides of the body.

Generally, a pinched nerve starts with mild or moderate symptoms of discomfort or tingling, and gradually worsens, causing severe pain and progressively worsening weakness. A pinched nerve is usually the result of arthritis or inflammation of the backbone, and sometimes it is the result of more serious backbone disease.

Sometimes, a pinched nerve can cause sudden leg weakness without a warning, particularly if it is caused by trauma to the backbone.

As with several of the other causes of leg weakness, it can take some time and a careful and thorough medical evaluation before a pinched nerve is definitively diagnosed.

There are several treatments available for a pinched nerve, including physical therapy, oral (by mouth) pain medications or anti-inflammatory medications, and medications that can be injected in the back, near the region of the pinched nerve.

Spinal Cord Disease or Injury

The spinal cord powers the body and controls sensation. The spinal cord is safely protected by the backbone (spine). If the spinal cord is damaged in any way, leg weakness can result.

Conditions and illnesses that can damage the spinal cord include a fracture of the backbone, a herniated disc, cancer spreading to the spine or to the spinal cord, infection of the spine or the spinal cord and multiple sclerosis.

A fairly uncommon type of stroke, a spinal cord infarct, affects the spine rather than the brain. A spinal cord infarct is caused by bleeding near the spine or a blood clot of the spinal arteries (the blood vessels that supply the spine).

These conditions that affect the spine are all emergencies that require prompt medical care to prevent permanent spine damage and leg weakness. The treatment for spinal cord disease or injury varies tremendously, depending on the cause.

Leg Trauma

A traumatic injury to the leg or to the pelvic region can damage muscles, nerves or joints, resulting in leg weakness.

Most of the time, if you experience a leg or pelvic injury that is severe enough to cause weakness, you should also expect to experience pain. However, if your spine or a spinal nerve is severely damaged, it is possible that you might not be able to adequately sense pain.

Management of leg weakness after leg trauma is geared towards repairing any repairable injury. Sometimes, physical rehabilitation is necessary to strengthen the leg after the injury is healed.

Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS), also known as Lou Gehrig's disease, is a relatively uncommon disease that causes body weakness and does not interfere with thinking or vision.

ALS typically begins with slight muscle twitches before weakness develops. Later, the twitches, accompanied by tingling and weakness, become difficult to ignore. ALS is an incurable disease that worsens within a few years.

People living with ALS may develop such severe weakness of the whole body, including the muscles of the mouth, that they can become unable to speak. New technology is making it easier for people living with ALS to communicate through eye movements. 

Neuropathy

Neuropathy refers to any issue that affects the distal nerves of the body, and can be due to a number of different reasons. Neuropathy causes numbness, tingling, loss of sensation and often, weakness. Typically, symptoms of neuropathy begin gradually.

Neuropathy can interfere with life in many ways, by causing severe and intolerable pain and by making it difficult for you to move your muscles as well as you would like to. There are a number of different causes of neuropathy, including diabetes, alcohol, and nutritional deficiency.

If you occasionally experience unusual sensations of your feet or legs, it is important to get medical attention. Neuropathy can be managed, but most of the time the nerve damage cannot be completely reversed, so it is important to get a diagnosis before the damage progresses.

Myopathy

Diseases of the muscles are called myopathy and they usually manifest with weakness. Myopathy can cause weakness of the arms, legs, hands, or feet.

Myopathy is often caused by hereditary and genetic problems, and it can be diagnosed with electromyography (EMG) and nerve conduction studies (NCV). Treatments include supportive braces, physical therapy, and sometimes, medications.

Toxins

A number of toxins, including lead poisoning and medications such as chemotherapy, can cause leg weakness. If you suddenly begin to experience weakness after you start a new medication, tell your healthcare provider right away because you may be experiencing toxicity.

Cancer

While cancer is one of the least likely causes of leg weakness, leg weakness can be the first sign of a tumor of the brain or spine. Also, a tumor in another part of the body, such as the breast, lungs, or kidneys, can metastasize (travel to) the brain or spine, causing leg weakness.

Your healthcare provider will check to see whether this is the case. Most of the time, tumors can be treated effectively with surgery, radiation, or chemotherapy.

A Word From Verywell

Leg weakness is a frightening thing to experience. Most of the time, leg weakness is the sign of a real medical problem that requires prompt attention. The causes of leg weakness can be managed so that the weakness does not continue to worsen. Sometimes, strength may be regained.

Because there are so many varied causes of leg weakness, the medical evaluation may take some time, often requiring a number of different diagnostic tests. It is vital that if you or a loved one experiences leg weakness, that you do not postpone or ignore your symptoms so that you can have the best chance at recovery.