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.

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

Certain maternal health issues can cause birth injuries. For example, gestational diabetes can cause premature birth, macrosomia, or stillbirth.

Complications such as placenta previa, placental abruption, anemia, and preeclampsia can limit the supply of oxygen and nutrients to the fetus, increasing the risk of birth defects. Severe cases may be fatal to the fetus.

About 16% of deliveries where shoulder dystocia occurs will have conventional risk factors.

There are well-recognized risk factors, such as diabetes, fetal macrosomia, and maternal obesity, but it is often difficult to predict, despite recognised risk factors. Despite appropriate obstetric management, fetal injury (such as brachial plexus injury) or even fetal death can be a complication of this obstetric emergency.

Risk factors:

- Age >35

- Short in stature

- Small or abnormal pelvis

- More than 42 weeks gestation

- Estimated fetal weight > 4500g

- Maternal diabetes (2-4 fold increase in risk)

Factors which increase the risk/are warning signs:

- the need for oxytocics

- a prolonged first or second stage of labour

- turtle sign

- head bobbing in the second stage

- failure to restitute

- No shoulder rotation or descent

- Instrumental delivery

Recurrence rates are relatively high (if you had shoulder dystocia in a previous delivery the risk is now 10% higher than in the general population).

Although the definition is imprecise, it occurs in approximately 0.3-1% of vaginal births.

While any number of injuries may occur during the birthing process. A number of specific conditions are well described. Brachial plexus palsy occurs in 0.4 to 5.1 infants per 1000 live birth. Head trauma and brain damage during delivery can lead to a number of conditions include: caput succedaneum, cephalohematoma, subgaleal hemorrhage, subdural hemorrhage, subarachnoid hemorrhage, epidural hemorrhage, and intraventricular hemorrhage.

The most common fracture during delivery is that of the clavicle (0.5%).

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.)

Sequelae can occur in both the mother and the infant after a traumatic birth.

Birth trauma is uncommon in the Western world in relation to rates in the third world. In the West injury occurs in 1.1% of C-sections.

In babies that are born at term risk factors include problems with the placenta, birth defects, low birth weight, breathing meconium into the lungs, a delivery requiring either the use of instruments or an emergency Caesarean section, birth asphyxia, seizures just after birth, respiratory distress syndrome, low blood sugar, and infections in the baby.

After birth, other causes include toxins, severe jaundice, lead poisoning, physical brain injury, stroke, abusive head trauma, incidents involving hypoxia to the brain (such as near drowning), and encephalitis or meningitis.

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.

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.

Preventing or delaying premature birth is considered the most important step in decreasing the risk of PVL. Common methods for preventing a premature birth include self-care techniques (dietary and lifestyle decisions), bed rest, and prescribed anti-contraction medications. Avoiding premature birth allows the fetus to develop further, strengthening the systems affected during the development of PVL.

An emphasis on prenatal health and regular medical examinations of the mother can also notably decrease the risk of PVL. Prompt diagnosis and treatment of maternal infection during gestation reduces the likelihood of large inflammatory responses. Additionally, treatment of infection with steroids (especially in the 24–34 weeks of gestation) have been indicated in decreasing the risk of PVL.

It has also been suggested that avoiding maternal cocaine usage and any maternal-fetal blood flow alterations can decrease the risk of PVL. Episodes of hypotension or decreased blood flow to the infant can cause white matter damage.

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.

There are many causes of TOS. The most frequent cause is trauma, either sudden (as in a clavicle fracture caused by a car accident), or repetitive (as in a legal secretary who works with his/her hands, wrists, and arms at a fast paced desk station with non-ergonomic posture for many years). TOS is also found in certain occupations involving lots of lifting of the arms and repetitive use of the wrists and arms.

One cause of arterial compression is trauma, and a recent case involving fracture of the clavicle has been reported.

The two groups of people most likely to develop TOS are those suffering from neck injuries due to traffic accidents and those who use computers in non-ergonomic postures for extended periods of time. TOS is frequently a repetitive stress injury (RSI) caused by certain types of work environments. Other groups which may develop TOS are athletes who frequently raise their arms above the head (such as swimmers, volleyball players, dancers, badminton players, baseball pitchers, and weightlifters), rock climbers, electricians who work long hours with their hands above their heads, and some musicians.

Erb's palsy or Erb–Duchenne palsy is a paralysis of the arm caused by injury to the upper group of the arm's main nerves, specifically the severing of the upper trunk C5–C6 nerves. These form part of the brachial plexus, comprising the ventral rami of spinal nerves C5–C8 and thoracic nerve T1. These injuries arise most commonly, but not exclusively, from shoulder dystocia during a difficult birth. Depending on the nature of the damage, the paralysis can either resolve on its own over a period of months, necessitate rehabilitative therapy, or require surgery.

Plexopathy is a disorder affecting a of nerves, blood vessels, or lymph vessels. The region of nerves it affects are at the brachial or lumbosacral plexus. Symptoms include pain, loss of motor control, and sensory deficits.

There are two main types of plexopathy: brachial plexopathy and lumbosacral plexopathy. They are usually caused from some sort of localized trauma such as a dislocated shoulder. The disorder can also be caused secondary to a compression, co-morbid vascular disease, infection, or may be idiopathic with an unknown cause. Both plexopathies can also occur as a consequence of radiation therapy, sometimes after 30 or more years have passed, in conditions known as Radiation-induced Brachial Plexopathy (RIBP) and Radiation-induced Lumbosacral Plexopathy (RILP).

In the industrialized world, the incidence of overall cerebral palsy, which includes but is not limited to spastic diplegia, is about 2 per 1000 live births. Thus far, there is no known study recording the incidence of CP in the overall nonindustrialized world. Therefore, it is safe to assume that not all spastic CP individuals are known to science and medicine, especially in areas of the world where healthcare systems are less advanced. Many such individuals may simply live out their lives in their local communities without any medical or orthopedic oversight at all, or with extremely minimal such treatment, so that they are never able to be incorporated into any empirical data that orthopedic surgeons or neurosurgeons might seek to collect. It is shocking to note that—as with people with physical disability overall—some may even find themselves in situations of institutionalization, and thus barely see the outside world at all.

From what "is" known, the incidence of spastic diplegia is higher in males than in females; the Surveillance of Cerebral Palsy in Europe (SCPE), for example, reports a M:F ratio of 1.33:1. Variances in reported rates of incidence across different geographical areas in industrialized countries are thought to be caused primarily by discrepancies in the criteria used for inclusion and exclusion.

When such discrepancies are taken into account in comparing two or more registers of patients with cerebral palsy and also the extent to which children with mild cerebral palsy are included, the incidence rates still converge toward the average rate of 2:1000.

In the United States, approximately 10,000 infants and babies are born with CP each year, and 1200–1500 are diagnosed at preschool age when symptoms become more obvious. It is interesting to note that those with extremely mild spastic CP may not even be aware of their condition until much later in life: Internet chat forums have recorded men and women as old as 30 who were diagnosed only recently with their spastic CP.

Overall, advances in care of pregnant mothers and their babies has not resulted in a noticeable decrease in CP; in fact, because medical advances in areas related to the care of premature babies has resulted in a greater survival rate in recent years, it is actually "more" likely for infants with cerebral palsy to be born into the world now than it would have been in the past. Only the introduction of quality medical care to locations with less-than-adequate medical care has shown any decreases in the incidences of CP; the rest either have shown no change or have actually shown an increase. The incidence of CP increases with premature or very low-weight babies regardless of the quality of care.

Plexopathy symptoms often resemble spinal cord disorders. A neurosurgical consultation is usually undertaken to ensure proper diagnosis, management, and treatment. Patients with chronic symptoms will likely be advised to follow up with outpatient care from either their health care provider or specialist.

A pseudomeningocele is an abnormal collection of cerebrospinal fluid (CSF) that communicates with the CSF space around the brain or spinal cord. In contrast to a meningocele, in which the fluid is surrounded and confined by dura mater, in a pseudomeningocele, the fluid has no surrounding membrane, but is contained in a cavity within the soft tissues.

Pseudomeningocele may result after brain surgery, spine surgery, or brachial plexus avulsion injury.

Treatment for pseudomeningocele is conservative or may involve neurosurgical repair.

Other causes may include:

- Diabetes mellitus

- Facial nerve paralysis, sometimes bilateral, is a common manifestation of sarcoidosis of the nervous system, neurosarcoidosis.

- Bilateral facial nerve paralysis may occur in Guillain–Barré syndrome, an autoimmune condition of the peripheral nervous system.

- Moebius syndrome is a bilateral facial paralysis resulting from the underdevelopment of the VII cranial nerve (facial nerve), which is present at birth. The VI cranial nerve, which controls lateral eye movement, is also affected, so people with Moebius syndrome cannot form facial expression or move their eyes from side to side. Moebius syndrome is extremely rare, and its cause or causes are not known.

Despite its wasting and at times long-lasting effects, most cases resolve themselves and recovery is usually good in 18–24 months, depending on how old the person in question is. For instance, a six-year-old could have brachial neuritis for only around 6 months, but a person in their early fifties could have it for over 3 years.

Klumpke's paralysis (or Klumpke's palsy or Dejerine–Klumpke palsy) is a variety of partial of the lower roots of the brachial plexus. The brachial plexus is a network of spinal nerves that originates in the back of the neck, extends through the axilla (armpit), and gives rise to nerves to the upper limb. (see picture - click to enlarge). It is named after Augusta Déjerine-Klumpke.

The fetal and neonatal brain is a rapidly changing, developing structure. Because neural structures are still developing and connections are still being formed at birth, many medications that are successful for treatment and protection in the adult central nervous system (CNS) are ineffective in infants. Moreover, some adult treatments have actually been shown to be toxic to developing brains.