Numbness in the arm has many possible causes that range from mild to severe. Simply sitting or sleeping in the wrong position can restrict the blood flow or put excess pressure on a nerve, making the arm go numb.
However, unexplained arm numbness may indicate an underlying health condition, such as nerve damage, a herniated disc, or cardiovascular disease. Severe causes of arm numbness include heart attacks and strokes.
In this article, we discuss eight possible causes of arm numbness and their treatments.
Blocked or compressed blood vessels can interfere with blood circulation to and from the heart. Poor circulation can cause numbness and tingling in the arms, hands, legs, and feet.
Reduced blood flow can cause other symptoms, such as:
- cold hands and feet
- extremely pale or blue-tinted skin
- swelling in the legs, ankles, and feet
- joint or muscle pain
Poor circulation is not a medical condition in itself, but it can happen if a person does not move enough during the day. It can also be a symptom of other conditions, including those below:
- Atherosclerosis occurs when cholesterol deposits, called plaque, accumulate in the blood vessels. Plaque buildups can cause the arteries to harden and narrow, restricting blood flow.
- Blood clots form when coagulated blood clumps together inside a blood vessel. Blood clots can create partial or complete blockages inside a blood vessel.
- Peripheral artery disease is a type of atherosclerosis in which plaque accumulates in the arteries in the arms and legs.
- Diabetes can affect the circulatory system because high levels of blood sugar lead to plaque formation and blood vessel damage.
Treatment for poor circulation depends on the underlying cause. Wearing compression wraps can help reduce swelling in the limbs. Exercising can also help improve circulation.
People who have large blood clots or several blocked arteries may require surgery. Doctors can prescribe medications to treat underlying health conditions that may contribute to poor circulation.
Peripheral neuropathy includes multiple conditions that damage the peripheral nervous system (PNS). The PNS carries information between the central nervous system — the brain and spinal cord — and the rest of the body.
Peripheral neuropathy causes a range of symptoms, depending on which nerves it affects. In general, people who have peripheral neuropathy may experience:
- numbness or tingling in the arms, hands, legs, or feet
- heightened sensitivity to touch and temperature changes
- muscle weakness
- uncontrollable muscle twitching
- muscle wasting, or loss of muscle
- excessive sweating
- feeling hot or cold
Several conditions can contribute to peripheral neuropathy, including:
Thoracic outlet syndrome (TOS) refers to a group of conditions that compress the nerves and blood vessels that pass between the collarbone and the first rib.
People who have TOS may experience numbness or tingling in a hand, as well as weakness in the neck or arm.
Physical therapy exercises that strengthen the chest and back muscles can help improve a person’s posture and reduce pressure on the nerves and blood vessels that pass through the thoracic outlet.
Doctors can prescribe medication to prevent blood clots and reduce pain. They may also recommend surgery if a person’s symptoms do not improve with physical therapy or medication.
Cervical spinal stenosis occurs when the hollow space of the spinal canal narrows, compressing the spinal cord. This compression can cause numbness or weakness in the arms or feet. It can also cause neck and back pain.
People can develop this condition if they have cervical spondylosis, which is arthritis that affects the part of the spine in the neck. Neck or back injuries and tumors in the spine can also contribute to cervical spinal stenosis.
Doctors treat this condition with medication, back braces, physical therapy, and surgery.
A herniated disk occurs when the soft nucleus of the disk slips through a crack in its outer portion.
A herniated disk can press against surrounding nerves, which may cause numbness or pain in the arm.
Treatment options for herniated disks include pain medication, physical therapy, and surgery.
People who have hemiplegic migraine experience temporary weakness or paralysis on one side of the body. This symptom can appear before or alongside a headache. People may feel numbness or tingling in the leg, arm, or side of the face.
Migraine also causes intense, throbbing headaches that can affect one or both sides of the head.
The symptoms of hemiplegic migraine vary from mild to severe. A severe hemiplegic migraine episode can cause additional symptoms, such as:
- memory loss
- personality changes
Doctors may prescribe pain relievers and nonsteroidal anti-inflammatory drugs to treat migraine.
According to the National Organization for Rare Disorders, doctors have not established standard treatment protocols for hemiplegic migraine because the condition is rare.
A heart attack occurs when the heart does not receive enough oxygen-rich blood. A blood clot or plaque buildup can create a partial or complete blockage in one or more of the blood vessels that supply the heart, causing a heart attack.
In rare cases, a heart attack can also happen when the coronary artery spasms, which tightens the vessel and restricts blood flow to the heart. The heart muscle may become damaged or stop functioning altogether if it does not receive enough oxygen.
The most common symptoms of a heart attack, according to the National Heart, Lung, and Blood Institute, include:
- pain or discomfort in one or both arms
- intense pressure in the chest
- pain in the upper stomach, which may feel like indigestion or heartburn
- shortness of breath
Other symptoms to look for include:
- pain or numbness in the back, shoulders, neck, or jaw
- feeling lightheaded or faint
- nausea and vomiting
A heart attack is a serious medical emergency. People should call 911 immediately if they think that they or someone else is having a heart attack.
Doctors will attempt to open the blocked artery and restore blood flow to the heart. The exact type of treatment will depend on the location of the blockage, the person’s overall health status, and the amount of time that has elapsed since the heart attack began.
A stroke occurs when something restricts or completely blocks blood flow to part of the brain.
Strokes often cause numbness in one arm, leg, or side of the face. Other symptoms of a stroke include:
- a sudden, severe headache
- vision changes
- difficulty speaking
- loss of coordination
There are two main types of stroke:
- Ischemic strokes occur when blood clots or fatty deposits develop inside a blood vessel and restrict blood flow to the brain.
- Hemorrhagic strokes occur when a blood vessel in the brain ruptures and bleeds into the surrounding tissue.
A stroke is a serious condition that requires emergency medical treatment.
A doctor can treat an ischemic stroke with thrombolytic medications that dissolve blood clots. If a person has a hemorrhagic stroke, a doctor will need to repair the damaged blood vessel, which may require surgery.
Arm numbness is a common symptom of many minor issues, such as temporarily cutting off the circulation, but it is also a sign of a heart attack or stroke.
People who have a high risk or history of cardiovascular disease should seek immediate medical attention if they experience unexplained numbness or tingling in their arm.
Persistent numbness in the arm without an apparent cause suggests an underlying medical problem that may require physical therapy or surgery.
Many people experience occasional numbness in an arm. Arm numbness can occur for several reasons that range from mild causes, such as sleeping in the wrong position, to a severe medical condition, such as a heart attack.
Sudden numbness in one or both arms may be a sign of a heart attack, stroke, or nerve damage, especially if a person has other symptoms.
People who experience arm numbness and weakness on one side of the body that precedes a severe headache may have a rare type of migraine called hemiplegic migraine.
Anyone who has arm numbness without an obvious cause should contact their doctor, especially if they have a history or increased risk of cardiovascular disease or diabetes.