What is a Brachial Plexus Injury?
The brachial plexus (BRAY-key-el PLEK-sis) is a network of nerves that provides movement and feeling to the shoulder, arm and hand. The nerves supporting the arm exit the spinal column high in the neck; those that support the hand and fingers exit lower in the neck.
This nerve complex is composed of four cervical nerve roots (C5-C8) and the first thoracic nerve root (T1). These roots combine to form three trunks. C5-C6 form the upper trunk, C7 continues as the middle trunk and C8-T1 form the lower trunk.
Each trunk splits into a division. Half the divisions globally supply flexor muscles (that lift and bend the arm). The others supply the extensor muscles (that straighten the arm and bring it down).
Causes of Brachial Plexus Injury
A brachial plexus birth injury is thought to be caused by an injury involving the child's brachial plexus during the delivery process. This injury may result in incomplete sensory and / or motor function of the involved arm.
Per our published research, a brachial plexus injury was found to occur in 1.5 of every 1,000 live births.
Traumatic brachial plexus injuries may occur due to motor vehicle accidents, bike accidents, ATV accidents, sports, etc. Nerve injuries vary in severity from a mild stretch to the nerve root tearing away from the spinal cord.
Symptoms of Brachial Plexus Injury
- Patterns of muscle weakness or paralysis of the involved upper extremity depending on which nerves of the brachial plexus are involved
- Decreased sensation (feeling) in the involved upper extremity
Types of Brachial Plexus Injuries
The nerve is torn away from its attachment at the spinal cord; the most severe type. An eyelid droop suggests an avulsion of the lower brachial plexus (Horner's syndrome).
The nerve is torn, but not at the spinal cord attachment.
Scar tissue has grown around the injury site, putting pressure on the injured nerve and preventing the nerve from sending signals to the muscles.
The nerve has been stretched and damaged but not torn.
Risk Factors for Brachial Plexus Birth Injury
- Shoulder dystocia (the baby's shoulder being restricted on the mother's pelvis)
- Maternal diabetes
- Large gestational size
- Difficult delivery needing external assistance
- Prolonged labor
- Breech presentation at birth
- Over half of brachial plexus Injuries have no known risk factors
Conditions Related to Brachial Plexus Injuries
- C5, C6 and sometimes C7 nerves are involved
- Often presents with arm straight and wrist fully bent (waiter's tip)
- May have good hand function but not full movement of the arm
- May have instability of the shoulder joint
- Often presents with weak biceps and deltoid muscles (unable to bend elbow or lift arm at the shoulder)
- Includes about 75 percent of all brachial plexus injuries
- All five nerves of the brachial plexus are involved (C5-T1)
- Presents with no movement at the shoulder, arm or hand
- May have no sensations throughout the arm
- Result of nerve damage affecting the eye including constriction of the pupil (miosis) and eye drooping (ptosis)
- Sometimes seen with nerve root avulsions of the brachial plexus
The nerves of the brachial plexus originate in the neck, in the cervical spine. The nerves re-grow from the neck down the arm. This healing will occur at a rate of 1 mm per day or 1 inch per month.
A mixed or incomplete recovery may occur if the nerves do not fully reattach at their original motor and sensory targets.
Full recovery will occur only if sensory fibers reach their sensory end targets and motor fibers reach their muscle targets.
The ability to bend the elbow (biceps function) by the third month of life is an indicator of probable recovery. In addition to bicep function, active movement of the wrist in upward motion as well as thumb and fingers straightening is an even stronger indicator of excellent spontaneous improvement. Gentle range of motion exercises performed by parents, along with repeated exams by the doctor, may be all that is necessary for patients with strong indicators of recovery.
About two-thirds of children with brachial plexus birth injury get better on their own with minimal treatment. The remaining patients may have limitations related to their brachial plexus birth injury that are not resolving. Limitations may include incomplete range of motion with one or more movements, weak muscles, or decreased sensation (feeling) through the arm. It is for these children that the remainder of our treatment efforts are focused.
Surgery for Brachial Plexus Injuries
The timeframe of surgical repair is an important factor in recovery. Within 18 months, the muscles that have not already connected to nerves may have weakened to the point where it is no longer possible.
For avulsion and rupture injuries, there is no potential for full recovery unless surgical repair is done in a timely manner. For neuroma and neurapraxia injuries, the potential for improvement varies. Most patients with neurapraxia injuries have a fair prognosis of recovering spontaneously with a 90-100 percent return of function.
If surgery is needed, microsurgical nerve repair may be undertaken as early as three months post injury. Primary nerve repair is typically completed by approximately six months of age following the injury.
Removal of the constrictive scar tissue surrounding the nerve.
When the neuroma is large it must be removed and the nerve is then reattached either with end-to-end techniques or with nerve grafts.
When the gap between the nerve ends is so large that it is not possible to have a tension-free repair using the end-to-end technique, nerve grafting is used.
This is used generally in those cases where there is an avulsion. Donor nerves are used for the repair. The parts of the roots still attached to the spinal cord can be used as donors for avulsed nerves.
Isolated Nerve Transfers
- Isolated transfer may be completed up to 12-18 months of age
- A nearby healthy nerve is attached to the damaged nerve, closer to the target muscle
Additional procedures are available to improve the overall function of the affected limb.
- Arthroscopic surgery and other minimally invasive techniques
- Tendon transfers
- Muscle transfers
- Shoulder reconstruction
- Rotational osteotomies
- Elbow reconstruction
Treatment for Brachial Plexus Injury
Nonsurgical management is also an important part of the treatment process.
Occupational and / or physical therapy is often recommended including range of motion, strengthening, neuromuscular electrical simulation, Kinesio Taping, joint mobilization, aquatic therapy and use of orthoses.
Because your child may not be able to move the affected arm alone, it is important for you to take an active part in keeping the joints limber.
A brachial plexus injury is a life-long condition. Management often focuses on preventing or minimizing deficits and maximizing the child's capabilities at home and in the community.
It is important to remember that your child is very adaptable. Be supportive and encouraging; focus on what your child can do. Positive reinforcement will help your child to develop a healthy sense of self-esteem and promote independence.
Look up additional information in the brachial plexus glossary.