Brachial Plexus Injuries

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Brachial plexus injuries

Definition

Brachial plexus injuries affect the nerves that originate from the spinal cord behind the head and neck (cervical nerves).

Description

The brachial plexus are nerves that leave the cervical vertebrae (but originate in the brain) and extend to peripheral structures (muscles/organs) to transmit motor and sensory nerve impulses. The brachial plexus consists of several cervical nerve roots, which include: C4, sending fibers to the shoulder and trapezius muscle; C5, sending fibers to the deltoid muscle and sides of upper arm or distal radius and involved with shoulders abduction; C6, involved with elbow flexion and fibers in the biceps and lateral forearm and thumb; C7, fibers to the triceps muscle, index and middle finger tips and involved with elbow extension; and C8, involved with extension of thumb and 4th and 5th fingers. Injury to the brachial plexus can involve avulsion injuries (nerve torn from attachment to the spinal cord), which are the most serious type of injury; neuroma injuries, due to injury causing scar formation tissue, which compresses nerves; rupture injuries, nerve is torn, but not at the spinal cord; and stretch injuries, nerve is damaged, but not torn.

Sports related injuries to the the cervical spine are common, especially injury to cervical vertebra 5 (C5) and C6. Erb described this condition with paralysis in 1874. Other names for the disorder include "burner" or "stinger" syndrome and cervical nerve pinch syndrome. Traumatic sports injury to the brachial plexus is characterized by a classical symptom—burning sensation that radiates down an upper extremity. The sensation may be short lived (2 minutes) or in chronic cases may last as long as two weeks. There are three common mechanisms that cause BPI, which include: direct impact to Erb point resulting in brachial plexus compression; traction caused by lateral flexion opposite from affected side; and nerve compression caused by hyperextension of the neck.

Obstetrical brachial plexus paralysis (OBPP) refers to injury to all or part of the brachial plexus during delivery. The condition was first described by Smellie in 1764 who described bilateral (both arms) paralysis in the newborn. Klumpke described paralysis (of the lower plexus) in 1885. Erb described paralysis of the upper brachial plexus (upper C5-C6 nerve damage) in 1874. Lower brachial plexus injuries are called Klumpke palsies and upper brachial plexus injury are termed Erb palsies. Injury is rare but is more prevalent in neonates born by cesarean delivery.

Demographics

In the United States a true measurement of new and existing cases is undetermined largely due to the significant underreporting of injuries. Approximately 5% of all peripheral nerve injuries results from trauma to the brachial plexus. Research studies conducted on college football players reported approximately 45% to 65% experience BPI during their collegiate careers. Additionally, it is estimated that there is an 87% recurrence rate. Estimates in other countries are not possible due to significant underreporting.

The incidence (number of new cases) of OBPP ranges from 0.2–4% of live births globally. The World Health Organization estimates the worldwide incidence is approximately 1–2%. In the United States it is rare and the incidence is 0.2% of live births. Every year 1–2 babies per 1000 live births are affected by obstetrical brachial nerve injury.

Causes and symptoms

BPI typically occurs as a result of a blow to the head, shoulder, and/or Erb point in an athlete during a contact sport. There are two grades of BPI. Grade 1 occurs when there is an interruption of nerve function due to demyelination. Muscle weakness is often detected soon after injury. Grade 2 describes more extensive damage to deeper and vital nerve areas (axons). Muscle weakness is often present and if persistent could mean a higher-grade lesion. Further tests for grade 2 BPI are indicated to fully assess the extent of nerve degeneration.

The causes of OBPP include shoulder dystocia, large birth weight, and breech delivery (vertex presentation accounts for 94–97% of cases). Maternal diabetes (mother has diabetes) is associated as a risk factor. Mothers who have had several children who were recorded to be large babies have an increased risk for delivering neonates with OBPP.

Commonly, affected athletes complain and describe burning and/or numbness in the neck, shoulder, or upper extremity (affected arm). Symptoms typically occur after a blow to the head or shoulder. These symptoms include burning sensation in the neck, pain in the neck, (also called dysesthesias ), and a feeling of weakness or "heaviness" in the affected arm. Bilateral (on both arms) numbness possibly indicates a more severe form of cervical cord injury. Symptoms can last from a few seconds to weeks.

Infants affected by OBPI may present with flail arms at birth. The affected arm may be internally rotated and pronated and devoid of elbow and shoulder movement (Erb palsy). If brachial plexus paralysis is present the entire hand and arm is flail with no movement ability.

The symptoms of OBPP can be grouped according to Sunderland's classification, which was proposed in 1951. A first-degree injury (also called neuropraxia or "stretch injuries") involves nerve injury that can completely resolve within 12 weeks. A second-degree injury results in severe trauma and nerve compression, but essential nerve elements are still intact and complete recovery is expected. A third-degree nerve injury is more severe, and essential nerve structures have been damaged as well as possible muscle damage. Some nerves and muscles may be permanently damaged. A fourth-degree injury results from extensive nerve damage that affects muscles, and typically it requires corrective surgical repair. The most severe form of obstetrical brachial plexus injury is fifth-degree injury, which is complete transaction of the nerve (the nerve is completely cut).

Diagnosis

A careful history, physical examination, and testing are essential for diagnosis. The clinician must suspect cervical fracture and/or spinal cord injury in an athlete presenting with altered consciousness. If the patient is awake and alert a complete neurological examination is indicated. The patient's mental status should be immediately assessed. Cervical nerve root assessment for detection of motor and sensory deficits is essential. A special test called the Spurling test is performed. During the Spurling test, the cervical spine is extended and head rotated toward the affected shoulder while loading axial weight. The purpose of manipulating the neck in this fashion is to reproduce the symptoms of the BPI. A positive Spurling test will reproduce symptoms. Clinical examination on-site at the time of injury typically includes; grip strength, identification of specific symptoms, duration of symptoms; assessment of motor impairment; assessment of cervical range of motion (only if no cervical fracture is present). Lab tests are generally not required and imaging studies are routinely limited to radiographic (x-ray) studies, taken from different views. Higher resolution studies such as MRI and CT scans can be utilized in cases where cervical spine or cervical nerve root damage is suspected. Use of a special test to detect the extent of muscle damage (electromyography ) can help to localize lesions and confirm the diagnosis. No specific lab tests are useful in the diagnostic process.

For infants with BPI due to delivery complications an assessment scale called the Active Movement Scale (7-point scale) can determine impairment from no contraction to full motion in the absence of or against gravity. This scale can help to assess arm movement impairment caused by nerve damage. The extent of nerve damage can be classified according to Sunderland. Typically, a lack of clinical evidence of elbow flexion by the 3rd or 4th month of life is indication for surgical repair of damaged nerves.

Treatment team

The treatment team for sports-related BPI typically includes the immediate responders (coach, team physician). Further consults from a comprehensive team can include a primary care practitioner, neurologist , physical therapist, and possibly a medical pain specialist.

For patients with OBPP a complete team of special nursing care and specialists is usually indicated. For surgical candidates, a specialist in neurosurgery or an orthopedic spine surgeon is essential. The pediatrician and pediatric neurologist play a vital role in assessment and provide information to parents. Long-term rehabilitation may be necessary in severe cases.

Treatment

On-site treatment for sports-related BPI typically includes mobilization and icing of the affected region. Treatment of BPI can be divided into three phases: the acute phase, recovery phase, and maintenance phases. Treatment during the acute phase typically involves physical therapy and medical issues (i.e., further imaging studies). Surgery may be required. During the recovery phases, physical therapy continues and the patient is monitored to continue follow-up care. During the maintenance phase of treatment physical therapy continues. The goal for medication is to prevent complications and help alleviate pain. Typically analgesics such as the anti-inflammatory type or an opiate narcotic are recommended. Analgesia may also help the affected person to cope better with physical therapy sessions. Typical opiate-narcotics include Lortab, Norcet, or Vicodin. Nonsteroidal anti-inflammatory drugs (NSAIDs, e.g., Motrin, Ibuprin) have both anti-inflammatory and analgesic effects.

For infants with OBPI medical treatment initially focuses on protection of ligaments, joints, and tendons from stress. Physical therapy may be indicated for movement exercises. Surgical intervention may be necessary if patients do not show recovery of neurological function by four months of age. Some controversy exists in the United States, with some surgeons advocating surgery on patients younger than 4 months.

Recovery and rehabilitation

Rehabilitation for BPI primarily entails physical therapy (PT) during the entire treatment course (acute, recovery, and maintenance treatment phases). The focus of PT during the acute phases primarily involves early mobilization and icing. Patients attempt to improve cervical range of motion to strengthen cervical muscles. During the recovery phases, special PT programs attempt to strengthen cervical muscles to a level of performance prior to injury. Special focus on muscles supporting the injured brachial plexus nerve (i.e., cervical and shoulder regions) is emphasized. Treatment for the maintenance phases primarily focuses on continuation of cervical muscle strength and conditioning. Clinical findings during examination and testing are key factors for determining return to play and recovery. A full recovery of affected muscle is necessary to prevent recurrence of burner syndrome and further injury. An athlete in a contact sport, who has fully recovered, is capable of supporting his or her weight at the neck leaning at a 45 degree angle. Some athletes may have some asymmetry of affected muscles that persists, and care should be taken as the athlete returns to contact sport participation.

Most infants with OBPI spontaneously recover (92-95% of reported cases) because the nerve injury is usually minor. Initial rehabilitation can include physical therapy to maintain passive range of movement. Surgery may be necessary for severe cases that require special postoperative care, monitoring, and physical therapy. Recovery for children with OBPP depends on the severity of nerve injury. Recovery after surgery is variable given that results depend on extent of damage to nerves and successful repair if surgery is indicated.

Prognosis

Prognosis for sports-related BPI is generally good. Some athletes develop a chronic complicated condition with symptoms called chronic burner syndrome. Most cases of nerve injury in infants are self-limiting and spontaneously resolve. Severe cases may require surgery. Surgical candidates typically have severe nerve injury and must undergo microsurgery to repair nerve damage.

Special concerns

In sports-related injury medical/legal problems can exist because cervical spine injury is sometimes not considered the cause of symptoms. Overlooking BPI can result in further damage to peripheral nerves.