Any sensation of numbness in the left arm, or any extremity for that matter, is an indication of a neural issue. Numbness in the arm also may be accompanied by tingling, loss of sensation or lack of mobility, any of which should be assessed and treated by your family physician to reduce chances of complications or permanent damage. Dozens of conditions may cause numbness in the left arm, and understanding a few of them may prompt individuals to quickly seek medical attention and advice.
A pinched nerve in the neck, back or shoulder may cause a tingling sensation in the left arm. Numbness is often caused by pressure against nerves, which may interrupt blood flow, nerve pathway messages and nerve damage that affects feeling.
Brachial Plexus Injury
The brachial plexus is a bundle of nerves that runs from the neck through the shoulder. A pinched, damaged or injured or diseased nerve in this bundle may affect any part of the arm and hand, causing numbness or tingling that may be constant and throbbing and feel like pins and needles.
A fracture may also cause numbness in the left arm as a result of damaging nerve tissues or blood vessels. Fracture may occur in the clavicle (collarbone), scapula (shoulder blade), the humerus (upper arm bone), or the radius or ulna (lower arm bones).
Peripheral Vascular Issues
Narrowed blood vessels in the arm may also create tingling or numbness in any part of the arm or hand. A major cause of narrowed blood vessels is the result of clogged arteries caused by high cholesterol, which creates a buildup of plaque on artery walls.
Peripheral Neural Issues
A person diagnosed with diabetes, palsy or other conditions that affect nerve growth and development may suffer from peripheral nerve damage to the extremities.