Author: Bryan Lang, PT, DPT, MHA, CSCS, Cert.DN: Doctor of Physical Therapy, Business Owner, Associate Professor, and Blog Contributor. Explores common client questions, helps find solutions for every day functional health concerns, and interprets difficult theories in healthcare rehabilitation. Committed to life-long learning and education. Learn more about Bryan on Google+.
Most Common Causes of Hand Numbness
Hand numbness usually occurs when a sensory nerve that carries signals from the hand to the brain becomes compressed, irritated, or damaged. When this happens, the nerve cannot transmit normal signals, which can cause tingling, reduced sensation, or a feeling that the hand has “fallen asleep.” In other cases, numbness may develop when blood flow to the hand is reduced, or when an underlying medical condition affects nerve function.
Below are some of the most common causes of numbness or tingling in the hands.
Carpal Tunnel Syndrome
Carpal tunnel syndrome is one of the most common causes of hand numbness. It occurs when the median nerve becomes compressed as it travels through the carpal tunnel in the wrist. This condition often causes numbness, tingling, or weakness in the thumb, index finger, middle finger, and part of the ring finger.
Symptoms often worsen at night or during repetitive hand activities such as typing, gripping tools, or using vibrating equipment.
Pinched Nerves in the Neck (Cervical Radiculopathy)
Nerves that control sensation in the hands originate in the cervical spine (neck). If a disc bulges, herniates, or degenerates, it can compress a nerve root and cause numbness or tingling that travels down the arm and into the hand.
Conditions that can cause cervical nerve compression include:
Herniated discs
Cervical spinal stenosis
Bone spurs in the neck
Peripheral Neuropathy
Peripheral neuropathy occurs when nerves outside the brain and spinal cord become damaged. This damage can interfere with how nerves send signals to the hands and feet.
One of the most common causes of peripheral neuropathy is diabetes, which can damage nerves over time due to prolonged high blood sugar levels.
Other possible causes of neuropathy include infections, autoimmune diseases, and exposure to toxins.
Vitamin Deficiencies
Certain nutrients are essential for maintaining healthy nerve function. A deficiency in vitamin B12 is particularly known to cause numbness or tingling in the hands and feet because the vitamin is needed to maintain the protective covering around nerves.
Other nutrient deficiencies that may contribute to nerve symptoms include low levels of:
Vitamin B1 (thiamine)
Vitamin B6
Vitamin E
Reduced Blood Circulation
Hand numbness can also occur when blood flow to the hand is temporarily reduced. Conditions such as Raynaud’s phenomenon can cause blood vessels in the fingers to constrict in response to cold temperatures or stress, leading to numbness, color changes, and tingling sensations.
Repetitive Strain or Overuse
Repeated motions of the wrist and hand can irritate surrounding tissues and place pressure on nearby nerves. Activities that involve frequent gripping, vibration, or prolonged typing may increase the risk of nerve compression and numbness.
Sleeping Position
Many people experience temporary hand numbness during sleep. This usually happens when a person rests on their arm or bends the wrist for a prolonged period, which can compress nerves or restrict blood flow. In most cases, the sensation resolves quickly once pressure is relieved.
Important But Less Common Causes of Hand Numbness
While the conditions above account for many cases of hand numbness, the problem can also originate from specific points where nerves are compressed along their pathway from the neck to the hand.
These include:
Thoracic Outlet Syndrome
Cervical nerve root disorders
Peripheral nerve entrapments in the forearm, elbow, or wrist
Hand numbness is a common sensation that most people experience at some point. It can happen suddenly and may feel like tingling, “pins and needles,” or a loss of sensation in the fingers. In many cases, numbness occurs when pressure is placed on a nerve for too long. However, persistent or recurring numbness in the arms or hands can also be a sign that a nerve is being compressed somewhere along its pathway from the neck to the hand.
Why Do My Arms and Hands Go Numb When I Sleep?
Many people notice their arms or hands going numb when they wake up after sleeping in a certain position. This usually happens because pressure on a nerve temporarily disrupts the nerve signals that carry sensation from the arm and hand to the brain. When a nerve is compressed while lying on an arm or resting the neck or shoulder in an awkward position, normal nerve signaling becomes interrupted, which can lead to the familiar tingling or numb sensation.
In most cases, this type of numbness resolves quickly once the pressure is removed and normal nerve signaling returns. However, if numbness happens frequently, lasts for long periods of time, or occurs even when you are not putting pressure on your arm, it may indicate that a nerve is being compressed elsewhere in the body. Nerves can become irritated or trapped in several areas, including the shoulder, neck, and forearm.
Below are three common locations where nerve compression can occur and lead to numbness in the hands.
Thoracic Outlet Syndrome (TOS) - Numbness in the Arms and Hands
When we move our arms, not only do muscles move, but many other structures move as well, including nerves and blood vessels. Thoracic Outlet Syndrome (TOS) occurs when nerves or blood vessels passing through the thoracic outlet become compressed by surrounding muscles, bones, or connective tissue. When these structures are compressed, the brachial plexus—the nerve network that carries signals to the arms and hands—cannot transmit normal nerve signals, which may lead to numbness, tingling, or weakness in the upper extremity.
One condition that can cause this type of compression is Thoracic Outlet Syndrome (TOS). TOS occurs when the brachial plexus (a network of nerves) or the subclavian artery or vein becomes compressed by structures in the neck or upper extremity. In about 95% of TOS cases, the brachial plexus is involved, while approximately 5% involve arterial compression and 2% involve venous compression.
Image courtesy of http://www.mdguidelines.com/images/Illustrations/to_o_syn.jpg
Most commonly, individuals who experience TOS are middle-aged women with respiratory dysfunction and forward posture, but not all of them present these traits. Studies have found that even environmental or traumatic stress and congenital abnormalities can contribute to TOS. The incidence and prevalence of TOS varies widely due to the conflicting definitions of the diagnosis [2]. Thus, the official prevalence and incidence is unknown, but studies have ranged the incidence between 1 and 80,000 per million people [3].
Symptoms of Thoracic Outlet Syndrome
Symptoms vary depending on whether nerves or blood vessels are being compressed.
If nerves are compressed, patients may experience:
Pain radiating down the arm
Increased or decreased sensitivity in the arms or hands
Numbness or tingling
Weakness in grip strength
If blood vessels are compressed, patients may report ischemic pain or numbness moving into the hand.
There are four anatomical spaces where compression may occur:
Sternocostovertebral space
Scalene triangle
Costoclavicular space
Pectoralis minor space
Compression often occurs due to tight musculature or decreased joint space, but healthcare professionals must also rule out other causes such as thyroid tumors, lymph node tumors, or a Pancoast tumor of the lung.
Image courtesy of http://mybwdoc.com/wp-content/uploads/2011/11/thoracic-outlet-syndrome.jpg
Nerve Root Disorders
Another potential cause of hand numbness originates in the cervical spine (neck).
Nerves that supply sensation and muscle control to the arms and hands begin at the spinal cord. The first portion of each nerve after it leaves the spinal cord is called the nerve root. If a nerve root becomes pinched, compressed, or damaged, the signals traveling to the arm and hand may be disrupted.
Each nerve root supplies sensation to specific areas of the arm, forearm, and hand. Researchers have mapped these regions to help medical professionals determine which nerve root may be affected based on the pattern of symptoms.
Herniated Discs in the Neck
Many people are familiar with disc bulges or herniated discs in the lower back, but the same issue can occur in the neck.
When a disc bulges or herniates, the outer structures containing the disc’s inner material can tear. The inner material may push outward and compress nearby structures, including nerve roots.
If the disc presses on a nerve root on one side of the spine, symptoms may occur only on that side of the body. In other cases, the disc may affect nerve roots on both sides, causing numbness or pain in both arms or hands.
Image placeholder – cervical disc bulge
Cervical Spinal Stenosis
Another common cause of nerve root compression is cervical spinal stenosis.
As we age, natural degeneration can occur in the spine. Discs between vertebrae may lose height, allowing excess movement. Over time, the body may respond by forming bone spurs.
As these bone spurs enlarge, they can narrow the spinal canal or the foramen, which is the opening where the nerve exits the spine. If the space becomes too narrow, the nerve root may be compressed, resulting in symptoms such as:
Numbness
Tingling
Pain
Decreased muscle strength in the arms or hands
Peripheral Nerve Entrapment
Nerves act like highways transporting signals throughout the body. These signals—called action potentials—allow us to feel sensation and control movement. If there is a blockage anywhere along the nerve’s path, those signals may not reach their destination.
Peripheral nerve entrapment occurs when a nerve becomes compressed further down the arm, forearm, or wrist. Several nerves can be affected.
Median Nerve Compression
The median nerve is most commonly associated with Carpal Tunnel Syndrome, which occurs where the wrist and forearm meet beneath a tunnel of tissue called the flexor retinaculum.
Other less common median nerve entrapment syndromes include:
Anterior Interosseous Nerve Syndrome (AINS)
Pronator Teres Syndrome
Pronator teres syndrome can sometimes mimic carpal tunnel syndrome. One key difference is numbness in the forearm, which typically does not occur with carpal tunnel syndrome.
Anterior interosseous nerve syndrome is rare and affects motor function rather than sensation. Patients with this condition are often unable to form the “OK” sign with their thumb and index finger.
The median nerve may become compressed at multiple points along its pathway, including:
Cervical nerve root level
Against a cervical rib
Between the anterior and middle scalene muscles
Between the clavicle and first rib
Under the pectoralis minor muscle
Beneath the ligament of Struthers
Near the bicipital aponeurosis
Between the two heads of the pronator teres
In the carpal tunnel
Ulnar Nerve Compression
The ulnar nerve is most commonly compressed at the elbow or wrist.
The two primary compression sites include:
Cubital tunnel (near the elbow)
Guyon’s canal (in the wrist)
Compression of the ulnar nerve may cause numbness or tingling in the fourth and fifth fingers, along with weakness in the hand.
This condition is sometimes referred to as cyclist’s palsy, because prolonged pressure on bicycle handlebars can compress the nerve.
Radial Nerve Compression
The radial nerve is most commonly compressed at the elbow within a region called the arcade of Frohse, located between the tendons of the supinator muscle.
Radial nerve entrapment may lead to conditions such as:
Radial tunnel syndrome
Posterior interosseous syndrome
Radial tunnel syndrome is often misdiagnosed as tennis elbow because the symptoms are very similar.
Radial nerve compression may cause:
Numbness on the back of the hand around digits 3–5
Weakness in wrist and finger extension
Radial nerve injuries are sometimes referred to as handcuff neuropathy, because the nerve can be injured by tightly bound handcuffs.
Common compression sites include:
Fibrous bands near the radial head
Radial recurrent vessels
Extensor carpi radialis brevis tendon
Arcade of Frohse (most common site)
Distal edge of the supinator muscle
When to Seek Help for Hand Numbness
There are many ways a nerve can become compressed or irritated without a major injury. In this article we explored compression sites:
Near the shoulder (Thoracic Outlet Syndrome)
In the neck (nerve root disorders)
In the forearm, wrist, and hand (peripheral nerve entrapment)
Occasional numbness that resolves quickly—such as when your hand “falls asleep”—is usually harmless. However, persistent numbness, tingling, or weakness should be evaluated by a healthcare professional.
Many nerve compression conditions can be treated conservatively with physical therapy. A physical therapist can evaluate nerve function, identify the source of compression, and develop a treatment plan to restore movement and reduce symptoms.
If you believe you may have a pinched nerve or ongoing numbness in your hands or arms, consider scheduling an evaluation with a physical therapist to discuss your symptoms and treatment options.
References
1] Andrews, J., Harrelson, G., & Wilk, K. (2012). Physical rehabilitation of the injured athlete (4th ed., pp. 317-318). Expert Consult.
[2]Hooper, T., Denton, J., McGalliard, M., Brismée, J., & Sizer, P. (2010, June 18). Thoracic outlet syndrome: A controversial clinical condition. Part 1: Anatomy, and clinical examination/diagnosis. Retrieved August 6, 2015.
[3] Silva, R., & Selmonosky, C. (n.d.). The Thoracic Outlet Syndrome (TOS) and its apparent relation to multiple sclerosis. A preliminary report. Retrieved August 7, 2015.