There are a number of different sensations that indicate some abnormality is a certain area. Pain is considered to be the most serious and unbearable. However, not every medical problem presents with pain. Sometimes there are other sensations like tingling or prickling. On the other extreme from pain is numbness where there is reduced of no sensation. It can occur on any part of the body and the reasons for tingling and numbness may vary based on location.
Upper Limb Paresthesia
Paresthesia is a medical term to describe any abnormal sensation such as prickling, tingling and numbness. It must be differentiated from pain. While pain is known to be cause by unflammation which in turn is triggered by tissue injury, a paresthesia is not necessarily due to injury or tissue damage. A paresthesia is almost always due to a nerve problem where pain can be due to either a nerve problem or damage to tissue of an organ in the region where the pain is being experienced.
Nerves carry electrical signals to ad from the central nervous system (brain and spinal cord). When receptors at different sites in the body are stimulated, it generates signals that are relayed through the nerves. For example if the temperature receptor (thermoreceptor) is stimulated in by heat or cold then signals are relayed to the brain which perceives the sensation at the specific part of the body. Paresthesias may arise with abnormal stimulation, compression, irritation or damage of nerves and receptors.
External Causes of Numbness, Tingling and Prickling
There are a number of external factors that can cause tingling, prickling and numbness in a person who is healthy and has no underlying medical problem. In people with pre-existing diseases the tingling prickling and numbness is likely to arise sooner and be more intense with these external stimuli. External factors should always be considered in acute paresthesias of the upper limbs.
Pressure from the outside can compress nerves and blood vessels which may then lead to numbness or tingling of the arms, hands or fingers. This may be caused by:
- Any strap tied very tightly around the hand. Bag straps can have a similar effect especially the bag is heavy.
- Sleeping on the hand or arm like tucking it under the head.
- Tourniquet or blood pressure cuff that is inflated.
- Very tight wrist bands or even clothing.
Raising the arms above the head for a prolonged period can impair oxygen supply to the distal parts (hands and fingers) due to reduced blood flow. It is a problem if standing and raising the hand above the heart. Gravity impedes adequate blood distribution to the hands and fingers.
Cold can cause the blood vessels to constrict as the body attempts to reduce heat loss into the environment in order to maintain the core body temperature. While cold itself causes tingling, prickling or numbness the reduced blood flow to the arms due to the cold may also have the same effect. With the fingers, this is intense in a person who has Raynaud’s phenomenon.
Internal Causes of Arm Numbness, Tingling Prickling
Various diseases can affect the nerves in a number of different ways but it is easier to discuss the possible causes of arm, hand finger numbness or tingling according to the location of the problem.
The nerves that are responsible for carrying sensory impulses from the upper arm to the brain leave the spinal cord at different levels of C3 (third cervical vertebrae) to T2 (third thoracic vertebrae).
Spinal nerve compression
Spinal nerve compression is where the nerves leaving the spine at levels C3 to T2 are compressed. This is also known as a pinched nerve. It can occur for various reasons like bony spine outgrowths that press on the nerve but the most common is when the nerve is pressed by vertebrae by weakened intervertebral (IV) discs. A bulging IV disc or herniated disc is one type of disc problem.
Cervical spondylosis is a condition where chronic wear and tear on the spine leads to compression of the spinal nerves. The degeneration affects all the structural parts of the spine including the bones, cartilages and discs. It is usually due to lifelong wear and tear and is therefore mainly seen in older people.
SHOULDER and ARMPIT
Broken Shoulder Blade
The shoulder blade (scapula) can fracture like any bone in the body. It usually occurs as a result of falls, blows and injuries sustained with motor vehicle accidents. As with most fractures, there is severe pain in the area but there may also be other symptoms like arm numbness and tingling running all the way down to the hands and fingers.
Brachial Plexus Injury
The brachial plexus is a network of nerves that run from the lower neck to the shoulder. These nerves are responsible for sensation and movement of the shoulder, arm, hand an fingers. Injury may arise with stretching, compression and sometimes even severing of the nerves. Most brachial plexus injuries arise when the arm is forced upwards above the head.
UPPER ARM and ELBOW
This is a broad term for any ulnar nerve disease or damage. The symptoms can vary depending on the nature of the nerve disease, location of the damage and severity of the condition. It can lead to varying degrees of numbness, tingling or pain. There may also be some degree of muscle weakness of the forearm and hand.
Cubital Tunnel Syndrome
Cubital tunnel syndrome is one type of ulnar neuropathy that occurs when the ulnar nerve is compressed at the level of the elbow. Symptoms are most prominent in the hands and fingers that are supplied by the ulnar nerve. Numbness and tingling may felt at the little finger and half of the ring finger that lies next to it.
FOREARM and WRIST
Carpal Tunnel Syndrome
Carpal tunnel syndrome (CTS) is a condition where the median nerve is compressed as it travels through the carpal tunnel in the wrist. It is often associated with repetitive movements of the hands and fingers. The tendons that control movement of the hands and fingers become inflamed and the media nerve that travels through the carpal tunnel is then pressed against bones.
HANDS and FINGERS
Many different types of conditions can affect the nerves and blood vessels of the hands and fingers. Most of the nerve conditions arise higher up in the arm, the shoulder or at the spine.
Raynaud disease is a condition where the tiny arteries in the fingers abnormally narrow (constrict) thereby reducing blood flow to the fingers. The muscles in the artery walls suddenly contract thereby causing the arteries to constrict. Stress, cold and other factors can trigger this abnormal muscle contraction and vasoconstriction. Tingling and numbness are common symptoms during these episodes.