Left arm numbness can be caused by numerous conditions, and fortunately not all are a cause for concern. Causes of numbness range from trauma to infections or inflammation. In most cases, the numbness arises from a lack of blood supply to an area or from nerve damage. The numbness can begin suddenly or be a gradual process, but if it’s constant, then it could be a warning sign of an impending heart attack. Whatever the cause, it’s important to get medical attention, if only to rule out the more serious causes.
Some Causes of Numbness in Your Left Arm
- Injury – you may have injured the muscles in your arm while playing sport or carrying something heavy. Numbness is common in cases of sprains or strains.
- Trauma – a fracture can bring about a lack of sensation in the fingers, elbow, lower or upper arm, or area near the collarbone. Sharp pain usually accompanies the fracture.
- Carpel tunnel syndrome – the median nerve serves your thumb, index finger, and middle finger. When irritated or compressed, it can result in numbness and/or tingling. If these occur closer to the wrists and joint in the arm, you may be suffering from carpel tunnel syndrome.
- Cubital tunnel syndrome – this is also known as ulnar nerve entrapment. The ulnar nerve passes through the elbow, and when increased pressure (usually from bone or connective tissue) is put on the nerve, it can lead to a lack of sensation, pain, and tingling in your elbow, hand, wrist, or fingers. Other symptoms can include a decrease in hand grip and a deformity of the hand that resembles a claw.
- Nerve damage and compression – sometimes a reduced sensibility to touch can be induced by blood circulation being interrupted by a compressed nerve. Numbness can result if the nerve that goes from your central nervous system to your left arm becomes compressed. Temporary lack of sensation can also occur after prolonged pressure on a nerve or nerves, for example, after sleeping on your arm for too long. Nerve damage can be caused by diabetic neuropathy, peripheral neuropathy, and injury.
- Brachial plexus injury – the brachial plexus is a network of nerves that send signals from your arm and shoulders to your spine. Damage to the nerves causes numbness and tingling in the arm or an inability to use your hand and fingers. The nerves are generally overstretched or torn and, depending on the seriousness of the injury, either can heal on their own or may require surgery.
- Ganglion cysts – usually not painful, these noncancerous cysts can develop on joints and may affect the movement of the joint or cause reduced sensibility to touch. They can be surgically removed if necessary.
- Stroke, angina, and arteriosclerosis – during a stroke, the blood supply to your brain is reduced and can cause numbness and/or tingling. There are usually other symptoms as well, such as headache, problems with your vision, and difficulty in walking and/or slurred speech. Angina also hampers the blood supply to the brain and can result in numbness in the left arm. Arteriosclerosis can also cause numbness due to the narrowing or hardening of the arteries and therefore reduced blood flow to some areas in the body.
- Heart attack – if you are experiencing pain in your jaw or shoulder, shortness of breath, palpitation, confusion, and/or tightness in your chest, you could be having a heart attack. Get medical help immediately!
- Crutch palsy – this is a type of nerve dysfunction, usually occurring in people using crutches. In time, the crutch compresses the nerve under the arm, causing numbness in the arms or other extremities of the upper body.
- Raynaud’s syndrome – this condition affects the blood supply to some areas of the body and causes the fingers, toes, tip of the nose, and ears to feel numb and cool in cold temperatures or when you’re under stress. It affects women more than men and is more common in regions with colder climates. Most sufferers frequently experience numbness in the arms.
- Multiple sclerosis – numbness may be caused by this autoimmune disease. It affects the brain and spinal cord, which can cause a loss of sensation.
- Hereditary amyloidosis – one of the symptoms of this illness is numbness in both arms. It is caused by an amyloid buildup in the tissues of the body.
- Thoracic outlet syndrome – this is a musculoskeletal condition that can cause pain, numbness, and tingling in the left arm. It is caused by the compression of nerves or blood vessels in the area between the lower neck and the axilla (armpit), and its symptoms can include pain in the neck, shoulder, arm, and hand, decreased grip strength, as well as changes to skin color and possible swelling.
- Cervical disc herniation – The bones in the spine are separated by discs, which act as shock absorbers. If a disc is damaged, it may bulge or rupture, and this is called a herniated or slipped disc. Herniated discs in the cervical spine can cause weakness, numbness, and pain around the neck, chest, shoulders, arms, and hands. Other common symptoms include muscle spasms, arm muscle weakness, and decreased grip strength.
- Indigestion– this usually causes burping and a burning sensation in the heart but can also cause left arm numbness.
- Vitamin B12 deficiency – the lack of this vitamin can cause a loss of sensation and tingling in the arms.
- Alcohol – if taken in excess, alcohol can cause a loss of sensation in the arms.
How Is Numbness Evaluated?
If your doctor thinks the problem is caused by peripheral nerve damage, common in diabetics, he may order an EMG (electromyogram) or nerve conduction study. This test will check the electrical properties of nerves in your arms. If he thinks it is brain- or spinal cord-related, you may be asked to undergo an MRI or CT scan. Blood tests may show signs of toxins or infections. For a fracture, an X-ray will be ordered. And in cases where arm numbness is accompanied by chest pain and other symptoms associated with a heart attack, you will need to undergo an ECG so that your heart function can be assessed.
- For fractures or swelling and pain, a warm compress is suggested.
- If you’re suffering from a nutritional deficiency, you can start taking supplements of calcium and vitamin B12.
- If the circulation has been interrupted for a while, moving your arms and hands may improve the blood circulation and relieve pain from pinched or compressed nerves.
- Medications and/or treatments are available for circulatory problems, diabetic neuropathy, or a ganglion cyst.
Depending on the cause of the numbness in your arm, it can appear and then disappear quickly such as when moving from areas of extremely cold temperatures to a warmer environment. If your numbness is chronic, then there is probably some nerve damage.
It’s important to talk with your doctor about any arm numbness that lasts more than a few minutes. As numbness can be a symptom of many different diseases, disorders, or conditions, it could be serious and should be diagnosed as soon as possible.