People with diabetes mellitus are at higher risk for any kind of peripheral neuropathy, including ulnar nerve entrapments.

Cubital tunnel syndrome is more common in people who spend long periods of time with their elbows bent, such as when holding a telephone to the head. Flexing the elbow while the arm is pressed against a hard surface, such as leaning against the edge of a table, is a significant risk factor. The use of vibrating tools at work or other causes of repetitive activities increase the risk, including throwing a baseball.

Damage to or deformity of the elbow joint increases the risk of cubital tunnel syndrome. Additionally, people who have other nerve entrapments elsewhere in the arm and shoulder are at higher risk for ulnar nerve entrapment. There is some evidence that soft tissue compression of the nerve pathway in the shoulder by a bra strap over many years can cause symptoms of ulnar neuropathy, especially in very large-breasted women.

The international debate regarding the relationship between CTS and repetitive motion in work is ongoing. The Occupational Safety and Health Administration (OSHA) has adopted rules and regulations regarding cumulative trauma disorders. Occupational risk factors of repetitive tasks, force, posture, and vibration have been cited.

The relationship between work and CTS is controversial; in many locations, workers diagnosed with carpal tunnel syndrome are entitled to time off and compensation.

Some speculate that carpal tunnel syndrome is provoked by repetitive movement and manipulating activities and that the exposure can be cumulative. It has also been stated that symptoms are commonly exacerbated by forceful and repetitive use of the hand and wrists in industrial occupations, but it is unclear as to whether this refers to pain (which may not be due to carpal tunnel syndrome) or the more typical numbness symptoms.

A review of available scientific data by the National Institute for Occupational Safety and Health (NIOSH) indicated that job tasks that involve highly repetitive manual acts or specific wrist postures were associated with incidents of CTS, but causation was not established, and the distinction from work-related arm pains that are not carpal tunnel syndrome was not clear. It has been proposed that repetitive use of the arm can affect the biomechanics of the upper limb or cause damage to tissues. It has also been proposed that postural and spinal assessment along with ergonomic assessments should be included in the overall determination of the condition. Addressing these factors has been found to improve comfort in some studies. A 2010 survey by NIOSH showed that 2/3 of the 5 million carpal tunnel cases in the US that year were related to work. Women have more work-related carpal tunnel syndrome than men.

Speculation that CTS is work-related is based on claims such as CTS being found mostly in the working adult population, though evidence is lacking for this. For instance, in one recent representative series of a consecutive experience, most patients were older and not working. Based on the claimed increased incidence in the workplace, arm use is implicated, but the weight of evidence suggests that this is an inherent, genetic, slowly but inevitably progressive idiopathic peripheral mononeuropathy.

The site and type of brachial plexus injury determine the prognosis. Avulsion and rupture injuries require timely surgical intervention for any chance of recovery. For milder injuries involving buildup of scar tissue and for neurapraxia, the potential for improvement varies, but there is a fair prognosis for spontaneous recovery, with a 90–100% return of function.

Most people relieved of their carpal tunnel symptoms with conservative or surgical management find minimal residual or "nerve damage". Long-term chronic carpal tunnel syndrome (typically seen in the elderly) can result in permanent "nerve damage", i.e. irreversible numbness, muscle wasting, and weakness. Those that undergo a carpal tunnel release are nearly twice as likely as those not having surgery to develop trigger thumb in the months following the procedure.

While outcomes are generally good, certain factors can contribute to poorer results that have little to do with nerves, anatomy, or surgery type. One study showed that mental status parameters or alcohol use yields much poorer overall results of treatment.

Recurrence of carpal tunnel syndrome after successful surgery is rare.

One way to prevent this injury from occurring is to be informed and educated about the risks involved in hurting your wrist and hand. If patients do suffer from median nerve palsy, occupational therapy or wearing a splint can help reduce the pain and further damage. Wearing a dynamic splint, which pulls the thumb into opposition, will help prevent an excess in deformity. This splint can also assist in function and help the fingers flex towards the thumb. Stretching and the use of C-splints can also assist in prevention of further damage and deformity. These two methods can help in the degree of movement the thumb can have. While it is impossible to prevent trauma to your arms and wrist, patients can reduce the amount of compression by maintaining proper form during repetitive activities. Furthermore, strengthening and increasing flexibility reduces the risk of nerve compression.

Ulnar nerve entrapment is classified by location of entrapment. The ulnar nerve passes through several small spaces as it courses through the medial side of the upper extremity, and at these points the nerve is vulnerable to compression or entrapment—a so-called "pinched nerve". The nerve is particularly vulnerable to injury when there has been a disruption in the normal anatomy. The most common site of ulnar nerve entrapment is at the elbow, followed by the wrist.

Causes or structures which have been reported to cause ulnar nerve entrapment include:

- Problems originating at the neck: thoracic outlet syndrome, cervical spine pathology, compression by anterior scalene muscles

- Problems originating in the chest: compression by pectoralis minor muscles

- Brachial plexus abnormalities

- Elbow: fractures, growth plate injuries, cubital tunnel syndrome, flexorpronator aponeurosis, arcade of Struthers

- Forearm: tight flexor carpi ulnaris muscles

- Wrist: fractures, ulnar tunnel syndrome, hypothenar hammer syndrome

- Artery aneurysms or thrombosis

- "Other": Infections, tumors, diabetes, hypothyroidism, rheumatism, and alcoholism

Injuries to the arm, forearm or wrist area can lead to various nerve disorders. One such disorder is median nerve palsy. The median nerve controls the majority of the muscles in the forearm. It controls abduction of the thumb, flexion of hand at wrist, flexion of digital phalanx of the fingers, is the sensory nerve for the first three fingers, etc. Because of this major role of the median nerve, it is also called the eye of the hand. If the median nerve is damaged, the ability to abduct and oppose the thumb may be lost due to paralysis of the thenar muscles. Various other symptoms can occur which may be repaired through surgery and tendon transfers. Tendon transfers have been very successful in restoring motor function and improving functional outcomes in patients with median nerve palsy.

Brachial plexus injury is found in both children and adults, but there is a difference between children and adults with BPI.

Injury of axillary nerve (axillary neuropathy) is a condition that can be associated with a surgical neck of the humerus fracture.

It can also be associated with a dislocated shoulder or with traction injury to the nerve, which may be caused by over-aggressive stretching or blunt trauma that does not result in fracture or dislocation. One form of this injury is referred to as axillary nerve palsy.

Injury most commonly occurs proximal to the quadrilateral space.

Injury in this nerve causes paralysis (as always) to the muscles innervated by it, most importantly deltoid muscle. This muscle is the main abductor of the shoulder joint from 18 to 90 degrees (from 0 to 18 by supraspinatus). Injury can result in a reduction in shoulder abduction. So a test can be applied to a patient with injury of axillary nerve by trying to abduct the injured shoulder against resistance.

The pain from axillary neuropathy is usually dull and aching rather than sharp, and increases with increasing range of motion. Many people notice only mild pain but considerable weakness when they try to use the affected shoulder.

Anatomically, damage to the axillary nerve or suppression of it causes the palsy. This suppression, referred to as entrapment, causes the nerve pathway to become smaller and impulses cannot move through the nerve as easily. Furthermore, if trauma causes damage to the myelin sheath, or injures the nerve another way, this will also reduce the ability of nerve impulse flow.

Usually, an outside force is acting to suppress the nerve, or cause nerve damage. Most commonly, shoulder dislocation or fractions in the shoulder can cause the palsy. Contact sports such as football and hockey can cause the injury Other cases have been caused by repeated crutch pressure or injuries accidentally caused by health professionals (iatrogenesis). Furthermore, following an anterior shoulder operation; damage to the axillary nerve is possible and has been documented by various surgeons, thus causing axillary nerve palsy. Other possible causes include: deep infection, pressure from a cast or splint, fracture of the humerus, or nerve disorders in which the nerves become inflamed.

There are rare causes of axillary nerve palsy that do occur. For instance, axillary nerve palsy can occur after there is blunt trauma in the shoulder area without any sort of dislocation or fracture. Examples of this blunt trauma may include: being hit by heavy an object, falling on shoulder, a strong blow while participating in boxing, or motor vehicle accidents. Another rare cause of axillary nerve palsy can occur after utilizing a side birthing position. When the patient lies on their side for a strenuous amount of time, they can develop axillary nerve palsy. This rare complication of labor can occur due to the prolonged pressure on the axillary nerve while in a side-birth position. Some patients who are diagnosed with nodular fasciitis may develop axillary nerve palsy if the location of the rapid growth is near the axilla. In the case of Nodular Fasciitis, a fibrous band or the growth of a schwannoma can both press against the nerve, causing axillary nerve palsy.

An injury to the axillary nerve normally occurs from a direct impact of some sort to the outer arm, though it can result from injuring a shoulder via dislocation or compression of the nerve. The axillary nerve comes from the posterior cord of the brachial plexus at the coracoid process and provides the motor function to the deltoid and teres minor muscles. An EMG can be useful in determining if there is an injury to the axillary nerve. The largest numbers of axillary nerve palsies arise due to stretch injuries which are caused by blunt trauma or iatrogenesis. Axillary nerve palsy is characterized by the lack of shoulder abduction greater than 30 degrees with or without the loss of sense in the low two thirds of the shoulder. Normally the patients that have axillary nerve palsy are involved in blunt trauma and have a number of shoulder injuries. Surgery is not always required to solve the problem (information from: Midha, Rajiv, Zager, Eric. Surgery of Peripheral Nerves: A Case-Based Approach. Thieme Medical Publishers, Inc. 2008.)

The radial nerve is one of the major nerves of the upper limb. It innervates all of the muscles in the extensor compartments of the arm. Injury to the nerve can therefore result in significant functional deficit for the individual. It is vulnerable to injury with fractures of the humeral shaft as it lies in very close proximity to the bone (it descends within the spiral groove on the posterior aspect of the humerus). Characteristic findings following injury will be as a result of radial nerve palsy (e.g. weakness of wrist/finger extension and sensory loss over the dorsum of the hand).

The vast majority of radial nerve palsies occurring as a result of humeral shaft fractures are neuropraxias (nerve conduction block as a result of traction or compression of the nerve), these nerve palsies can be expected to recover over a period of months. A minority of palsies occur as a result of more significant axonotmeses (division of the axon but preservation of the nerve sheath) or the even more severe neurotmeses (division of the entire nerve structure). As a result, it is important for individuals sustaining a Holstein–Lewis injury to be carefully followed up as if there is no evidence of return of function to the arm after approximately three months, further investigations and possibly, nerve exploration or repair may be required. The exception to this rule is if the fracture to the humerus requires fixing in the first instance. In that case, the nerve should be explored at the same time that fixation is performed.

There are many ways to acquire radial nerve palsy.

The term "Saturday Night Palsy" refers to an injury to the radial nerve in the spiral groove of the humerus caused while sleeping in a position that would under normal circumstances cause discomfort. It can occur when a person falls asleep while heavily medicated and/or under the influence of alcohol with the underside of the arm compressed by a bar edge, bench, chair back, or like object. Sleeping with the head resting on the arm can also cause radial nerve palsy.

Breaking the humerus and deep puncture wounds can also cause the condition.

Posterior interosseus palsy is distinguished from radial nerve palsy by the preservation of elbow extension.

Symptoms vary depending on the severity and location of the trauma; however, common symptoms include wrist drop (the inability to extend the wrist upward when the hand is palm down); numbness of the back of the hand and wrist, specifically over the first web space which is innervated by the radial nerve; and inability to voluntarily straighten the fingers or extend the thumb, which is performed by muscles of the extensor group, all of which are primarily innervated by the radial nerve. Loss of wrist extension is due to paralysis of the posterior compartment of forearm muscles; although the elbow extensors are also innervated by the radial nerve, their innervation is usually spared because the compression occurs below, distal, to the level of the axillary nerve, which innervates the long head of the triceps, and the upper branches of the radial nerve that innervate the remainder of the Triceps.

A Holstein–Lewis fracture is a fracture of the distal third of the humerus resulting in entrapment of the radial nerve.

In terms of prognosis radial neuropathy is not necessarily permanent, though sometimes there could be partial loss of movement/sensation.Complications may be possible deformity of the hand in some individuals.

If the injury is axonal (the underlying nerve fiber itself is damaged) then full recovery may take months or years ( or could be permanent). EMG and nerve conduction studies are typically performed to diagnose the extent and distribution of the damage, and to help with prognosis for recovery.

Axillary nerve palsy is a neurological condition in which the axillary (also called circumflex) nerve has been damaged by shoulder dislocation. It can cause weak deltoid and sensory loss below the shoulder. Since this is a problem with just one nerve, it is a type of Peripheral neuropathy called mononeuropathy. Of all brachial plexus injuries, axillary nerve palsy represents only .3% to 6% of them.

The radial nerve, like any other in the nervous system, is vulnerable to damage. This damage can originate when the nerve fibers experience pressure, stretching, or cutting. All of the aforementioned issues can prevent an action potential from continuing down the nerve, which would interrupt signal transduction to and from the brain. As a result of the interrupted signal, the patient may experience loss of feeling or motor control.

The hand of benediction, also known as benediction sign or preacher's hand, occurs as a result of prolonged compression or injury of the median nerve at the forearm or elbow.

The term "hand of benediction" refers to damage of the median nerve. However, the name is misleading as the patients with this median nerve problem usually can flex all fingers except for the index finger. The index finger is still flexed at the metacarpophalangeal joint (MCP joint) when the ulnar nerve innervated muscles (the interossei muscles) are still working. The index finger is not flexed at the proximal interphalangeal (PIP) and distal interphalangeal (DIP) joints, which looks like a pointing finger. Pointing Finger is therefore a much better term to recognize this condition.

The middle finger is flexed because of the connection between the flexor digitorum profundus (FDP) tendons, which is called the Quadriga phenomena.

The most common cause of scapular winging is serratus anterior paralysis. This is typically caused by damage (i.e. lesions) to the long thoracic nerve. This nerve supplies the serratus anterior, which is located on the side of the thorax and acts to pull the scapula forward. Serratus anterior palsy is a dysfunction that is characteristic of traumatic, non-traumatic, and idiopathic injury to the long thoracic nerve. Severe atrophy of the trapezius is seen with accidental damage to the spinal accessory nerve during lymph node biopsy of the neck. There are numerous ways in which the long thoracic nerve can sustain trauma-induced injury. These include, but are not limited to, blunt trauma (e.g. blow to the neck or shoulder, sudden depression of the shoulder girdle, unusual twisting of the neck and shoulder), repetitive movements (as observed in athletic activities such as weight lifting or sports that involve throwing), excessive compression of the shoulder area by straps (see backpack palsy), and various household activities (e.g. gardening, digging, car washing, prolonged abduction of the arms when sleeping, propping up the head to read, etc.). Sometimes, other structures in the body such as inflamed and enlarged subcorocoid or subscapular bursa press on the nerve. Clinical treatments may also cause injury to the long thoracic nerve (iatrogenesis from forceful manipulation, mastectomies with axillary node dissection, surgical treatment of spontaneous pneumothorax, post-general anesthesia for various clinical reasons, and electrical shock, amongst others).

Non-traumatic induced injury to the long thoracic nerve includes, but is not limited to, causes such as viral illness (e.g. influenza, tonsillitis-bronchitis, polio), allergic-drug reactions, drug overdose, toxic exposure (e.g. herbicides, tetanus), C7 radiculopathy, and coarctation of the aorta.

Secondary to serratus anterior palsy, a winged scapula is also caused by trapezius and rhomboid palsy involving the accessory nerve and the dorsal scapular nerve, respectively.

Though the most common causes of a winged scapula is due to serratus anterior palsy, and less commonly trapezius and rhomboid palsy, there are still other circumstances that present the ailment. These incidences include direct injuries to the scapulothoracic muscles (i.e. trapezius and rhomboid muscles), and structural abnormalities (e.g. rotator cuff pathology, shoulder instability, etc.).

A winged scapula due to serratus anterior palsy is rare. In one report (Fardin et al.), there was an incidence of 15 cases out of 7,000 patients seen in the electromyographical laboratory. In another report (Overpeck and Ghormley), there was only one case out of 38,500 patients observed at the Mayo Clinic. In yet another report (Remak), there were three diagnoses of serratus anterior paralysis throughout a series of 12,000 neurological examinations.

The mechanism of radial neuropathy is such that it can cause focal demyelination and axonal problems/degeneration (which is nerve fiber reaction to insult, and therefore axon death occurs). These would be caused via laceration or compression of the nerve in question.

The most common cause of Erb's palsy is dystocia, an abnormal or difficult childbirth or labor. For example, it can occur if the infant's head and neck are pulled toward the side at the same time as the shoulders pass through the birth canal. The condition can also be caused by excessive pulling on the shoulders during a cephalic presentation (head first delivery), or by pressure on the raised arms during a breech (feet first) delivery. Erb's palsy can also affect neonates affected by a clavicle fracture unrelated to dystocia.

A similar injury may be observed at any age following trauma to the head and shoulder, which cause the nerves of the plexus to violently stretch, with the upper trunk of the plexus sustaining the greatest injury. Injury may also occur as the result of direct violence, including gunshot wounds and traction on the arm, or attempting to diminish shoulder joint dislocation. The level of damage to the constituent nerves is related to the amount of paralysis.

Anterior interosseous syndrome or Kiloh-Nevin syndrome I is a medical condition in which damage to the anterior interosseous nerve (AIN), a motor branch of the median nerve, causes pain in the forearm and a characteristic weakness of the pincer movement of the thumb and index finger.

Most cases of AIN syndrome are due to a transient neuritis, although compression of the AIN can happen. Trauma to the median nerve have also been reported as a cause of AIN syndrome.

Although there is still controversy among upper extremity surgeons, AIN syndrome is now regarded as a neuritis (inflammation of the nerve) in most cases; this is similar to Parsonage–Turner syndrome. Although the exact etiology is unknown, there is evidence that it is caused by an immune mediated response.

Studies are limited, and no randomized controlled trials have been performed regarding the treatment of AIN syndrome. While the natural history of AIN syndrome is not fully understood, studies following patients who have been treated without surgery show that symptoms can resolve starting as late as one year after onset. Other retrospective studies have shown that there is no difference in outcome in surgically versus nonsurgically treated patients. Surgical decompression is rarely indicated in AIN syndrome. Indications for considering surgery include a known space-occupying lesion that is compressing the nerve (a mass) and persistent symptoms beyond 1 year of conservative treatment.

Ulnar tunnel syndrome, also known as Guyon's canal syndrome or Handlebar palsy, is caused by entrapment of the ulnar nerve in the Guyon canal as it passes through the wrist. Symptoms usually begin with a feeling of pins and needles in the ring and little fingers before progressing to a loss of sensation and/or impaired motor function of the intrinsic muscles of the hand which are innervated by the ulnar nerve. Ulnar tunnel syndrome is commonly seen in regular cyclists due to prolonged pressure of the Guyon's canal against bicycle handlebars. Another very common cause of sensory loss in the ring and pink finger is due to ulnar nerve entrapment at the Cubital Tunnel near the elbow, which is known as Cubital Tunnel Syndrome.

Injuries of the forearm with compression of the nerve is the most common cause: examples include

supracondylar fractures, often associated with haemorrhage into the deep musculature;

injury secondary to open reduction of a forearm fracture; or dislocation of the elbow.⁠⁠

Direct trauma from a penetrating injury such as a stab wound is a common cause for the syndrome.

Fibrous bands or arcuate (curved) ligaments may entrap the median as well as the anterior interosseous nerves, in which case a patient may experience numbness as well as pain.⁠⁠

Rheumatoid disease and gouty arthritis may be a predisposing factor in anterior interosseous nerve entrapment.

Very similar syndromes can be caused by more proximal lesions, such as brachial plexus neuritis.⁠

Anterior interosseous nerve entrapment or compression injury remains a difficult clinical diagnosis because it is mainly a motor nerve and the syndrome is often mistaken for finger ligamentous injury.⁠

Supracondylar humerus fractures account for 55%-75% of all elbow fractures. They most commonly occur in children between ages 5–8, because remodeling of bone in this age group causes a decreased supracondylar anteroposterior diameter.