The brachial plexus is a network of nerves that originate from the neck region and branch off to give rise to most of the nerves that control movement and sensation in the upper limbs.
Brachial plexus injury (BPI) is the umbrella term for a variety of conditions that may impair function of the brachial plexus. This may result in loss of sensation, muscle weakness, or paralysis of some or all of the muscles of the shoulder and upper limb. Some patients may experience avulsion pain in the distribution of the injured nerves. The degree of functional impairment and potential for recovery depend on the mechanism, type, and complexity of the brachial plexus injury.
The majority of pediatric and adult brachial plexus injuries are caused by trauma. The most common inciting events are high speed vehicular accidents, especially motorcycle accidents. Other causes include blunt trauma, stab or gunshot wounds, inflammatory processes (brachial plexitis), compression caused by a growing tumor, and neuropathies. Obstetric brachial plexus palsy occurs in less than one percent of live births. During delivery, the baby's shoulders may become impacted on the pubic bone causing the brachial plexus nerves to stretch or tear (shoulder dystocia). Several patterns of obstetric brachial plexus palsy have been described including Erb's Palsy and Klumpke's palsy. The prognosis for recovery depends on the pattern, complexity, and severity of injury.
Due to the complex spectrum of brachial plexus injuries, a detailed and comprehensive understanding of the exact nature of injury in each patient is required for proper management.
Multiple modalities are utilized to diagnose a brachial plexus injury including clinical examination, electrodiagnostic studies (EMG, NCV, SNAP,SSEP) and imaging studies (CT, MRI). These studies may need to be repeated on a regular basis to track the progression of recovery of function. Used in combination, these modalities provide valuable insights into the elements of the brachial plexus that have been injured and some information about the severity of the injury.
Due to the broad spectrum of brachial plexus injuries, it is difficult to estimate the rate of spontaneous recovery. The potential for spontaneous recovery depends on the type and severity of injury. Therefore prognosis must be assessed for each patient individually based on the type and severity of their injury and the progression of any spontaneous recovery that may be occurring.
The most important decision that must be made is determining if and when surgical intervention should occur. Proper diagnosis is essential for deciding which patients have the potential for spontaneous recovery. If it is apparent that the severity and type of injury precludes the potential for spontaneous recovery (e.g., avulsion), immediate surgery is indicated. Otherwise surgery is typically delayed for several months to allow for spontaneous recovery.
Serial physical examinations and diagnostic studies play a key role in tracking the progression of recovery. After a few months surgery is indicated if there is no recovery or if recovery has plateaued at an unacceptable functional level.
Surgical intervention serves two functions: confirmation of diagnosis and repair of injury. Several factors determine the type of intervention performed including: preoperative diagnosis, interval between injury and surgery, and intraoperative diagnosis. Procedures to restore function include neurolysis, neurotization, tendon transfers, and free muscle transfers.
Brachial Plexus Injury Recovery
Recovery of function is a lengthy process. Nerves grow at about one inch per month, so it may take several months before the first signs of recovery are apparent. Recovery progresses from muscles of the shoulder, to those of the arm, and finally the hand. Unfortunately it not possible to predict the degree of recovery that will occur following surgery. Physical therapy is essential to strengthen recovering muscles and maintain flexibility of joints. Pain from surgery is usually minimal and can be managed by analgesics. Additional interventions, including the DREZ procedure, may be indicated to address avulsion pain.
The determination of whether the surgery was successful is usually not made until enough time has passed for complete reinnervation and strengthening (about 1.5 to 2 years). Recovery may continue to occur for up to four years. If there is incomplete recovery, patients should be evaluated for the further interventions. These may include muscle or tendon transfers or releases to optimize movement of the limb.