Leg Weakness Can Be a Sign of a Serious Medical Issue (2024)

Weakness in the legs can be due to a spine or leg injury, but other potential causes can include diabetic neuropathy, cancer, stroke, myasthenia gravis, and more. It is a common symptom of many different health conditions and injuries. Not all reasons for this common symptom are serious, but some require immediate medical care.

Treatment can include conservative measures, such as improved exercise or avoiding vitamin D deficiency to help muscles work better. Many people benefit from treatment of an underlying condition, like multiple sclerosis, while others may require surgery to repair a spinal condition.

Stroke

A stroke is also called a cerebrovascular accident (CVA). A stroke occurs when blood flow to a region of the brain is interrupted or when there is sudden bleeding in the brain. Several areas of the brain work together to move your legs.

When leg weakness occurs as a result of a stroke, it comes on suddenly. Usually just one leg is affected.

The acronym FAST can help you determine whether you or someone else is having a stroke:

• Facial drooping: One-sided symptoms of eyelid drooping and downward curving mouth. If the person smiles, does one side droop?
• Arm or leg weakness: One-sided weakness can make you drop things, lean while walking, or fall. If they raise both arms, does one drift downward?
• Speech difficulties: The tongue may be affected by a stroke. Is the speech slurred?
• Time to call 911: Yes to any of these signs warrants emergency help. Time is a major factor in preventing brain damage. Never "wait and see" about stroke symptoms.

Also, watch for:

• Confusion
• Dizziness
• Double vision
• Drowsiness
• Nausea or vomiting
• Severe headache

If you have a stroke, getting quick treatment significantly boosts your chance of recovery. Physical, occupational, and speech therapy can help some people regain function.

Transient Ischemic Attack (TIA)

A transient ischemic attack (TIA), sometimes called a mini-stroke, occurs when blood flow to the brain is interrupted, but only briefly (as opposed to a stroke, in which blood flow is interrupted for long enough that it can cause irreparable damage to the affected area of the brain).

Symptoms of a TIA come on suddenly and are similar to stroke symptoms, but they usually go away within an hour. Still, since there is no way to tell if someone is having a TIA or a stroke, both should be considered an emergency.

In addition to weakness in the leg(s), TIA symptoms include:

• Numbness or weakness in the face or arms, especially on one side of the body
• Vision impairment
• Difficulty walking
• Dizziness
• Confusion
• Difficulty talking or understanding speech
• Loss of balance and coordination

A TIA is often a warning sign that someone is at risk for a more serious stroke. Approximately one-third of people who have a TIA will have a stroke in the future.

Aspirin and antiplatelet medications are typically prescribed for people at high risk of a stroke.

Autoimmune Diseases

An autoimmune disease is one in which the body's immune system, which usually attacks intruders like viruses and bacteria, attacks itself. There are more than 100 different autoimmune diseases. Here are some common ones that can cause leg weakness.

Guillain-Barre Syndrome

Guillain-Barré syndrome (GBS) is a nerve disease. It affects between 3,000 and 6,000 Americans per year.

GBS is different from stroke because it affects the nerves, not the brain, and it affects both sides of the body. GBS typically starts with tingling or numbness in both feet. From there, symptoms progress to:

• Foot weakness
• Weakness spreading to the legs
• Eventually, upward-spreading weakness throughout your body

The most dangerous possible complication of GBS is impaired breathing. This can be fatal.

Healthcare providers closely monitor the oxygen levels of people with GBS. You may need to be put on a machine to help you breathe and get enough oxygen until you recover.

Medications for GBS can reduce the symptoms and hasten recovery. Most people with GBS survive, but some have persistent leg sensations or moderate weakness for months or years.

Multiple Sclerosis

Multiple sclerosis (MS) is an autoimmune disease in which the immune system attacks and destroys the protective covering of nerve cells (myelin) of the brain, spinal cord, and/or eyes.

MS often causes weakness in one leg, but it can also affect both legs. Other symptoms of an MS flare include:

• Weakness
• Vision loss
• Sensation disturbances
• Other neurological symptoms

Multiple sclerosis symptoms typically come and go. Episodes may last for a few weeks or months. They generally improve but may have some lasting effects.

If your symptoms are vague and intermittent, get an appointment with your regular healthcare provider. MS is a serious, chronic condition but not usually a medical emergency.

An MS diagnosis takes time and a lot of tests. Several effective treatments are available.

Myasthenia Gravis

Myasthenia gravis (MG) is a condition that causes profound muscle weakness as a result of the immune system attacking receptors on muscle tissue. Weakness in the legs is among the common symptoms.

Other symptoms include:

• Weakness in the eyelid muscles
• Weakness in the jaw
• Arm weakness
• Weakness in muscles used for breathing

While there is no cure yet for myasthenia gravis, symptoms can be managed with treatments that include immunosuppressant drugs, acetylcholinesterase inhibitors, and plasma exchange (plasmapheresis).

Parkinson's Disease

Parkinson's disease is a condition that affects the brain and nervous system. People with Parkinson's disease gradually lose their ability to control their movements. One of the symptoms of Parkinson's disease is weakness in the legs.

Other symptoms of Parkinson's disease include:

• Spontaneous movements
• Tremors
• Stiffness
• Difficulty walking

There is no cure for Parkinson's disease, but the symptoms can be controlled with medication and lifestyle modifications.

Spinal Conditions

Conditions that affect the spine and spinal cord that often cause weak legs include:

Pinched Nerve

A pinched nerve in the spine can cause leg weakness and/or numbness. It may affect one or both sides.

Generally, a pinched nerve starts with mild or moderate tingling or discomfort and slowly gets worse. Sometimes, pain and weakness can become severe.

Pinched nerves are often caused by arthritis or spinal inflammation.

Other symptoms of a pinched nerve symptoms include:

• Sharp pain or a dull ache
• Tingling and pins-and-needles sensations
• Pain that shoots from your back down to your foot
• Numbness in the skin

Treatments for a pinched nerve include physical therapy, pain relievers and anti-inflammatory drugs, and cortisone injections.

Sciatica

Sciatica is caused by inflammation or compression of the sciatic nerve in the lower spine. In addition to one-sided leg weakness, sciatica symptoms include:

• Pain that radiates down one side of the leg
• Lower back pain
• Pain in the buttock
• Reduced range of motion

In most cases, sciatica resolves with conservative treatment including exercises, application of ice packs and/or heat, and pain medications.

Herniated Disc

A herniated, or "slipped" disc occurs when the soft, rubbery round discs that cushion and absorb shock in the vertebrae rupture and protrude, compressing spinal nerves and causing inflammation. This can cause weakness in one leg, in addition to:

• Numbness
• A tingling or burning sensation in the affected area
• Pain that worsens with standing or sitting

Symptoms of herniated discs often resolve with rest and conservative treatment, including medication. Physical therapy may be necessary, and some people require surgery.

Spinal Stenosis

Spinal stenosis refers to a narrowing of the spinal canal that causes compression of the spinal cord and/or nerve roots. Spinal stenosis most commonly affects the lower back (lumbar stenosis), often in older people. Osteoarthritis is a common cause.

Other symptoms aside from weakness in the legs include:

• Lower back pain
• Pain, or tingling in one or both legs
• Symptoms that worsen after walking or standing up
• Symptoms that subside after sitting down or leaning over

Treatments for spinal stenosis includephysical therapy to strengthen your leg muscles, nonsteroidal anti-inflammatory drugs (NSAIDs),muscle relaxants, andcortisone injections. In some cases, surgery may be necessary.

Spinal and Leg Trauma

A traumatic injury to the spine, leg, or pelvic region can result in weakness in the legs due to damaged muscles, nerves, or joints. Spinal injury, especially, can be quite serious.

Usually, an injury as severe as this causes a lot of pain, and symptoms will come on suddenly. But if you have severe damage to your spine or a spinal nerve, you might not feel it. Treatments depend on the specific type and extent of the injury.

Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS or Lou Gehrig's disease) is a relatively uncommon, incurable disease. It generally gets worse within a few years of diagnosis.

ALS causes body weakness but doesn't interfere with thinking or vision. It typically begins with tingling and weakness, which can be in the legs. Muscle twitches usually occur later as the disease progresses.

This disease affects both sides of the body. Even so, early symptoms may be more noticeable on one side.

ALS weakness can become severe throughout the body. Muscles of the mouth may become too weak for speech.

Currently, there is no cure for ALS, but symptoms can be managed with medications to help reduce fatigue, easemuscle cramps, and lessen pain. New technologies are making it easier for people with ALS to communicate through eye movements.

Neuropathy

Neuropathy is pain that results from damaged nerves. Common causes include uncontrolled diabetes, excessive alcohol use, and nutritional deficiencies. It can result in leg weakness if motor nerves are involved, and can sometimes interfere with mobility.

Symptoms of neuropathy tend to come on gradually and affect both sides. They include:

• Pain
• Weakness
• Numbness
• Tingling
• Loss of sensation

See your healthcare provider if you experience odd sensations in your feet or legs. It is important to get a diagnosis before the damage progresses.

Neuropathy can be managed but usually not reversed. Treatment may include pain relievers, prescription medications, and/or lidocaine patches and injections. In some cases, neuropathy can be treated with surgery.

Myopathy

Diseases of the muscles are called myopathies. They usually manifest with weakness of the arms, legs, hands, or feet.

Examples of myopathies include:

• Polymyositis (an inflammatory myopathy)
• Lyme disease (an infectious myopathy)
• Thyroid or parathyroid disease (muscle damage is secondary to thyroid disorder)
• Lupus and rheumatoid arthritis (inflammatory causes)
• Amyloidosis (rare muscle damage can occur)
• Muscular dystrophy (genetic disorder of the muscles)

Some of these are genetic. Others are not and may develop during adulthood. They can impact one or both legs.

Myopathy symptoms generally start gradually and progress over time. Some types of myopathy may become severe within a few days or weeks of starting.

Myopathies can be diagnosed with electromyography (EMG) and nerve conduction studies. Treatments can include supportive braces, physical therapy, and medications.

Drug Toxicity

Certain medications can cause leg weakness. Sometimes this is because the dosage is too high or due to an individual reaction to a certain drug.

Drugs that can cause weakness in the legs include:

• Chemotherapy medications
• Fluoroquinolone antibiotics
• Statins (cholesterol-lowering drugs)
• Steroid drugs
• Antivirals

Lead, arsenic, mercury, and other toxins also cause weakness in the legs, as can consuming too much alcohol (though this is temporary).

Other symptoms and side effects due to medications or exposure to toxins include:

• Muscle aches and pains
• Weight gain
• High blood sugar
• An allergic reaction

If you develop weakness after starting a new medication, tell your healthcare provider right away. You may be experiencing toxicity and will need to stop the medication or have your dosage adjusted.

Cancer

Cancer is one of the least likely causes of leg weakness. However, leg weakness can occasionally be the first sign of a brain or spinal tumor.

Cancer can also metastasize (spread) to the brain or spine, causing weakness in the legs. Symptoms can be sudden and may affect one side or both.

Let your healthcare provider know about your symptoms right away. Many tumors can be effectively treated with surgery, radiation, and/or chemotherapy. A spinal cord compression from a metastatic tumor may require urgent treatment with high-dose steroids.