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.

BPI has shown to occur in 44% to 70% of traumatic injuries, such as motorcycle accidents, sporting activities, or workplace accidents. With 22% being motorcycle injuries and about 4.2% having plexus damage. People that have accidents with riding motorcycles and snowmobiles, have higher risks of getting BPI.

Trauma is the most frequent cause of peripheral nerve lesions. There are two classifications of trauma which include civilian trauma and military trauma. Civilian trauma is most commonly caused by motor vehicle accidents but also by lacerations caused by glass, knives, fans, saw blades or fractures and occasionally sports injuries. Of the civilian injuries, stretch injuries are the most common types and are considered to be a closed injury, where the tissue is unexposed. Stretch injures are commonly the result of dislocation, such as a shoulder dislocation that stretches nerves. Opposite of civilian trauma, there is military trauma which most commonly results in open injuries from blasts often by bombs or improvised explosive devices. Other mechanisms of injury are less common but include ischemia, thermal, electric shock, radiation, adverse reactions to certain chemotherapy medications, percussion and vibration.

Vehicle-related SCI is prevented with measures including societal and individual efforts to reduce driving under the influence of drugs or alcohol, distracted driving, and drowsy driving. Other efforts include increasing road safety (such as marking hazards and adding lighting) and vehicle safety, both to prevent accidents (such as routine maintenance and antilock brakes) and to mitigate the damage of crashes (such as head restraints, air bags, seat belts, and child safety seats). Falls can be prevented by making changes to the environment, such as nonslip materials and grab bars in bathtubs and showers, railings for stairs, child and safety gates for windows. Gun-related injuries can be prevented with conflict resolution training, gun safety education campaigns, and changes to the technology of guns (such as trigger locks) to improve their safety. Sports injuries can be prevented with changes to sports rules and equipment to increase safety, and education campaigns to reduce risky practices such as diving into water of unknown depth or head-first tackling in association football.

Spinal cord injuries are most often caused by physical trauma. Forces involved can be hyperflexion (forward movement of the head); hyperextension (backward movement); lateral stress (sideways movement); rotation (twisting of the head); compression (force along the axis of the spine downward from the head or upward from the pelvis); or distraction (pulling apart of the vertebrae). Traumatic SCI can result in contusion, compression, or stretch injury. It is a major risk of many types of vertebral fracture. Pre-existing asymptomatic congenital anomalies can cause major neurological deficits, such as hemiparesis, to result from otherwise minor trauma.

In the US, Motor vehicle accidents are the most common cause of SCIs; second are falls, then violence such as gunshot wounds, then sports injuries. In some countries falls are more common, even surpassing vehicle crashes as the leading cause of SCI. The rates of violence-related SCI depend heavily on place and time. Of all sports-related SCIs, shallow water dives are the most common cause; winter sports and water sports have been increasing as causes while association football and trampoline injuries have been declining. Hanging can cause injury to the cervical spine, as may occur in attempted suicide. Military conflicts are another cause, and when they occur they are associated with increased rates of SCI. Another potential cause of SCI is iatrogenic injury, caused by an improperly done medical procedure such as an injection into the spinal column.

SCI can also be of a nontraumatic origin. Nontraumatic lesions cause anywhere from 30 to 80% of all SCI; the percentage varies by locale, influenced by efforts to prevent trauma. Developed countries have higher percentages of SCI due to degenerative conditions and tumors than developing countries. In developed countries, the most common cause of nontraumatic SCI is degenerative diseases, followed by tumors; in many developing countries the leading cause is infection such as HIV and tuberculosis. SCI may occur in intervertebral disc disease, and spinal cord vascular disease. Spontaneous bleeding can occur within or outside of the protective membranes that line the cord, and intervertebral disks can herniate. Damage can result from dysfunction of the blood vessels, as in arteriovenous malformation, or when a blood clot becomes lodged in a blood vessel and cuts off blood supply to the cord. When systemic blood pressure drops, blood flow to the spinal cord may be reduced, potentially causing a loss of sensation and voluntary movement in the areas supplied by the affected level of the spinal cord. Congenital conditions and tumors that compress the cord can also cause SCI, as can vertebral spondylosis and ischemia. Multiple sclerosis is a disease that can damage the spinal cord, as can infectious or inflammatory conditions such as tuberculosis, herpes zoster or herpes simplex, meningitis, myelitis, and syphilis.

Common causes of head injury are motor vehicle traffic collisions, home and occupational accidents, falls, and assaults. Wilson's disease has also been indicative of head injury. According to the United States CDC, 32% of traumatic brain injuries (another, more specific, term for head injuries) are caused by falls, 10% by assaults, 16.5% by being struck or against something, 17% by motor vehicle accidents, 21% by other/unknown ways. In addition, the highest rate of injury is among children ages 0–14 and adults age 65 and older.

People who suffer from neurotmesis often face a poor prognosis. They will more than likely never regain full functionality of the affected nerve, but surgical techniques do give people a better chance at regaining some function. Current research is focused on new ways to regenerate nerves and advance surgical techniques.

Neurapraxia is most commonly observed in athletes involved in collision sports, such as American football. Athletes participating in collision sports most often suffer from cervical cord neurapraxia, also known as transient neurapraxia. Cervical cord neurapraxia is the result of a severe collision in which a blow to the crown of the athlete’s head forcefully extends or compresses the neck. Numbness, stinging, and/or weakness in the arms, legs or both, distinguish cervical cord neurapraxia. Typical episodes of transient nuerapraxia only last a few seconds and symptoms dissipate entirely. Though the severity of the injury can range, transient neurapraxia does not lead to permanent paralysis of the affected muscles. Subsequent spinal cord injury after an episode of cervical cord neurapraxia has not been observed. However, athletes who experience an episode of transient cervical neurapraxia face an approximately 50% chance of a repeat episode if they continue to participate in collision sports.

In children with uncomplicated minor head injuries the risk of intra cranial bleeding over the next year is rare at 2 cases per 1 million. In some cases transient neurological disturbances may occur, lasting minutes to hours. Malignant post traumatic cerebral swelling can develop unexpectedly in stable patients after an injury, as can post traumatic seizures. Recovery in children with neurologic deficits will vary. Children with neurologic deficits who improve daily are more likely to recover, while those who are vegetative for months are less likely to improve. Most patients without deficits have full recovery. However, persons who sustain head trauma resulting in unconsciousness for an hour or more have twice the risk of developing Alzheimer's disease later in life.

Head injury may be associated with a neck injury. Bruises on the back or neck, neck pain, or pain radiating to the arms are signs of cervical spine injury and merit spinal immobilization via application of a cervical collar and possibly a long board.If the neurological exam is normal this is reassuring. Reassessment is needed if there is a worsening headache, seizure, one sided weakness, or has persistent vomiting.

To combat overuse of Head CT Scans yielding negative intracranial hemorrhage, which unnecessarily expose patients to radiation and increase time in the hospital and cost of the visit, multiple clinical decision support rules have been developed to help clinicians weigh the option to scan a patient with a head injury. Among these are the Canadian Head CT rule, the PECARN Head Injury/Trauma Algorithm, and the New Orleans/Charity Head Injury/Trauma Rule all help clinicians make these decisions using easily obtained information and noninvasive practices.

Nerve injury is injury to nervous tissue. There is no single classification system that can describe all the many variations of nerve injury. In 1941, Seddon introduced a classification of nerve injuries based on three main types of nerve fiber injury and whether there is continuity of the nerve. Usually, however, (peripheral) nerve injury is classified in five stages, based on the extent of damage to both the nerve and the surrounding connective tissue, since supporting glial cells may be involved. Unlike in the central nervous system, neuroregeneration in the peripheral nervous system is possible. The processes that occur in peripheral regeneration can be divided into the following major events: Wallerian degeneration, axon regeneration/growth, and nerve reinnervation. The events that occur in peripheral regeneration occur with respect to the axis of the nerve injury. The proximal stump refers to the end of the injured neuron that is still attached to the neuron cell body; it is the part that regenerates. The distal stump refers to the end of the injured neuron that is still attached to the end of the axon; it is the part of the neuron that will degenerate but that remains in the area toward which the regenerating axon grows. The study of peripheral nerve injury began during the American Civil War and has greatly expanded to the point of using growth-promoting molecules.

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.)

In cases of neurapraxia, the function of the nerves are temporarily impaired. However, the prognosis for recovery from neurapraxia is efficient and quick. Recovery begins within two to three weeks after the injury occurs, and it is complete within six to eight weeks. There are instances when function is not completely restored until four months after the instance of injury. The recovery period of neurapraxia is not an entirely ordered process, but the recovery is always complete and fast.

CES is often concurrent with congenital or degenerative diseases and represents a high cost of care to those admitted to the hospital for surgery. Hospital stays generally last 4 to 5 days, and cost an average of $100,000 to $150,000, unless the patient lives in a country where healthcare is free at the point of delivery.

Various etiologies of CES include fractures, abscesses, hematomas, and any compression of the relevant nerve roots. Injuries to the thoracolumbar spine will not necessarily result in a clinical diagnosis of CES, but in all such cases it is necessary to consider. Few epidemiological studies of CES have been done in the United States, owing to difficulties such as amassing sufficient cases as well as defining the affected population, therefore this is an area deserving of additional scrutiny.

Traumatic spinal cord injuries occur in approximately 40 people per million annually in the United States, resulting from traumas due to motor vehicle accidents, sporting injuries, falls, and other factors. An estimated 10 to 25% of vertebral fractures will result in injury to the spinal cord. Thorough physical examinations are required, as 5 to 15% of trauma patients have fractures that initially go undiagnosed.

The most frequent injuries of the thoracolumbar region are to the conus medullaris and the cauda equina, particularly between T12 and L2. Of these two syndromes, CES is the more common. CES mainly affects middle-aged individuals, particularly those in their forties and fifties, and presents more often in men. It is not a typical diagnosis, developing in only 4 to 7 out of every 10,000 to 100,000 patients, and is more likely to occur proximally. Disc herniation is reportedly the most common cause of CES, and it is thought that 1 to 2% of all surgical disc herniation cases result in CES.

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.

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 prognosis is usually good in terms of recovery. Rate of recovery depends on the distance from the site of injury, and axonal regeneration can go up to 1 inch per month. Complete recovery can take anywhere from 6 months to a year

Radial neuropathy (or radial mononeuropathy) is a type of mononeuropathy which results from acute trauma to the radial nerve that extends the length of the arm. It is known as transient paresthesia when sensation is temporarily abnormal.

Axonotmesis is an injury to the peripheral nerve of one of the extremities of the body. The axons and their myelin sheath are damaged in this kind of injury, but the endoneurium, perineurium and epineurium remain intact. Motor and sensory functions distal to the point of injury are completely lost over time leading to Wallerian Degeneration due to ischemia, or loss of blood supply. Axonotmesis is usually the result of a more severe crush or contusion than neurapraxia.

Axonotmesis mainly follows a stretch injury. These stretch injuries can either dislocate joins or fracture a limb, due to which peripheral nerves are severed. If the sharp pain from the exposed axon of the nerve is not observed, one can identify a nerve injury from abnormal sensations in their limb. A doctor may ask for a Nerve Conduction Velocity (NCV) test to completely diagnose the issue. If diagnosed as nerve injury, Electromyography performed after 3 to 4 weeks shows signs of denervations and fibrillations, or irregular connections and contractions of muscles.

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.

This is the least severe form of nerve injury, with complete recovery. In this case, the axon remains intact, but there is myelin damage causing an interruption in conduction of the impulse down the nerve fiber. Most commonly, this involves compression of the nerve or disruption to the blood supply (ischemia). There is a temporary loss of function which is reversible within hours to months of the injury (the average is 6–9 weeks). Wallerian degeneration does not occur, so recovery does not involve actual regeneration. There is frequently greater involvement of motor than sensory function with autonomic function being retained. In electrodiagnostic testing with nerve conduction studies, there is a normal compound motor action potential amplitude distal to the lesion at day 10, and this indicates a diagnosis of mild neuropraxia instead of axonotmesis or neurotmesis.

Among the causes of ulnar neuropathy are the following-

Much more commonly, ulnar neuropathy is caused by overuse of the triceps muscle and repetitive stress combined with poor ergonomics. Overused and hypertonic triceps muscle causes inflammation in the tendon and adhesions with the connective tissue surrounding that tendon and muscle. These in turn impinge on or trap the ulnar nerve. Ulnar neuropathy resulting from repetitive stress is amenable to massage and can usually be fully reversed without cortisone or surgery.

Center for Occupational and Environmental Neurology , Baltimore, MD has this to say:

“Repetitive Strain Injuries (RSI) refers to many different diagnoses of the neck/shoulder, arm, and wrist/hand area usually associated with work-related ergonomic stressors. Other terms used for Repetitive Strain Injuries are overuse syndrome, musculoskeletal disorders, and cumulative trauma disorders. Some of the more common conditions under these headings include:

Cubital Tunnel Syndrome-compression of the ulnar nerve in the cubital tunnel at the elbow.”

A stinger is an injury that is caused by restriction of the nerve supply to the upper extremity via the brachial plexus. The brachial plexus is formed by the anterior rami of the nerves at the 5th cervical level of the spinal cord all the way to the nerves at the 1st thoracic level of the spinal cord. The brachial plexus innervates the upper extremity as well as some muscles in the neck and shoulder. Damage to the brachial plexus can occur when the nerves are stretched too far from the head and neck; specifically the upper trunk of the plexus –nerve roots at the 5th and 6th cervical level –are primarily affected. The upper trunk provides part of the nerve to supply to the upper extremity via the Musculocutaneous, Axillary, Radial and Median nerves. It is for this reason that stingers do not affect both arms simultaneously, however it is possible for both arms to accrue injuries. Repeated nerve trauma can cause recurring stingers, chronic pain, and muscle weakness, while recovery can take weeks to months in severe cases.

In regards to the pathophysiology of ulnar neuropathy:the axon, and myelin can be affected. Within the axon, fascicles to individual muscles could be involved, with subsequent motor unit loss and amplitude decrease. Conduction block means impaired transmission via a part of the nerve. Conduction block can mean myelin damage to the involved area, slowing of conduction or significant spreading out of the temporal profile of the response with axonal integrity is a hallmark of demyelination.

Most often the radiculopathy found in the patients are located in the cervical spine, most commonly affecting C6-C8 spinal nerves.

Certain injuries can also lead to radiculopathy. These injuries include lifting heavy objects improperly or suffering from a minor trauma such as a car accident. Less common causes of radiculopathy include injury caused by tumor (which can compress nerve roots locally) and diabetes (which can effectively cause ischemia or lack of blood flow to nerves).