Humans are indeed a complex organism. The human body itself consists of several body functions and mechanisms which took hundreds of years to be fully understood by scientists and even up till now is still being studied and researched on. One of the body parts functions that enable humans to do daily tasks are the arms. When a person experiences arm numbness specifically to the left arm, a person may be worried and ask a doctor for further explanation and possible treatment.

A numbness is a term used by most people to describe various symptoms including loss of sensation either partially (hypesthesia) or completely (anaesthesia), abnormal sensations such as tingling pain for no apparent reasons (pins-and-needles) and muscle weakness. There are many reasons that could lead the left arm to become numb. Even a simple mild cause by sleeping in the wrong positions for a long time can cause this symptom. At times, nerve injury and severe medical conditions ranging from gradual or sudden numbness is possible.

Hence, it is difficult to pinpoint to one exact disease or health conditions underlying the numbness of the left arm symptoms may be similar to one disease and another. Getting medical advice is the best way to understand the underlying reasons precipitating this numb sensation. Urgent medical attention is needed if the left arm numb occurs suddenly and is not caused by trauma or wrong body posture. Such unexplainable arm numbness such as stroke and heart attack may lead to a life-threatening condition.

Sine there are numerous reasons leading to symptom of left arm numbness, here are examples of causes or diseases that is commonly reported:

1-   Stroke– Also known as brain attack is characterised by something blocking the blood supply to part of the brain or when the brain’s blood vessels burst. Main symptoms of stroke can be remembered by the word FAST: Face-The face dropped to 1 side, inability to smile or drooped mouth/eyes, Arms-Inability to lift arms due to weakness or numbness, Speech-Slurred speech, inability to talk, Time-Time to call 999 as these sign and symptoms need fast medical intervention.

2-   Heart attack– Typically involves sudden blockage of the blood supply to the heart, commonly caused by blood clot. It can be life-threatening as it damages the heart muscles. Symptoms apart of the left arm numbness are chest discomfort such as pain, heavy sensation, feeling pressured or chest tightness, sweating and shortness of breath. Heart health

3-   Spinal stenosis– It is an abnormal narrowing of the spinal canal (containing the spinal cord and nerve) and the foramen where the nerve exits. A stenosis led to nerve compression which precipitated to pain, weakness, numbness and anormal nerve sensation like tingling. If the left arm numbness gets worse and progressive weakness, do seek prompt medical advice.

4-   Cervical radiculopathy– A condition characterised by nerve impingement or “pinched nerve” of the nerve in the neck due to compression or irritation of the nerve.  In younger people it could be caused by sudden injury like a herniated disk and in older people due to the ageing process.

5-   Thoracic Outlet Syndrome– It is a group of disorders involving irritation and compression of the nerve, arteries and veins located in the lower neck and chest. This syndrome can be caused by neck trauma, strenuous use of the arm and shoulder and formation of blood clot in the artery of the arm. People with this syndrome often complain with pain, numbness, tingling sensation and weakness involving the lower neck, collar bone and hand. Left arm numbness can also be presented.