 Brachial Plexus Birth Palsy
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The brachial plexus is a network of nerves which run from the cervical spinal cord to the muscles of the upper limb.
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Brachial plexus birth palsy refers to an injury to these nerves sustained during childbirth. The nerves of the brachial plexus may be stretched, compressed, or torn. This may result in loss of muscle function and subsequent paralysis of the upper limb. Injuries may affect all or only a part of the brachial plexus, resulting in varying degrees of upper extremity involvement. Injuries to the upper brachial plexus (C5, C6) affect muscles of the shoulder and elbow, while injuries to the lower brachial plexus (C7, C8, and T1) can affect muscles of the forearm and hand.
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Brachial plexus birth palsies are often divided into different categories, depending upon the type of nerve injury and the pattern of nerves involved.
There are four different types of nerve injuries that may occur:
- Avulsion - The nerve roots are torn from the spinal cord. This type of injury is less common. Avulsions cannot be surgically repaired.
- Rupture - The nerve is torn, but not where it attaches to the spine. These injuries are more common and may be surgically repaired.
- Neurapraxia - The nerve has been stretched but not torn. These injuries are the most common. In these cases, the affected nerve(s) may recover spontaneously.
- Neuroma - The nerve has tried to heal, but scar tissue has formed, interfering with nerve function. This may be surgically treated.
Many different terms have been used to describe different patterns of injury:
- Erb's palsy - This refers to involvement of the upper portion (C5, C6) of the brachial plexus. Patient's with Erb's palsies typically have weakness involving the muscles of the shoulder and biceps.
- Klumpke's palsy - This refers to involvement of the lower portion (C8, T1) of the brachial plexus. This pattern is less common and typically affects the muscles of the hand.
- Horner's syndrome - This term is used to describe a constellation of clinical findings, including ptosis (drooping eyelid), miosis (smaller pupil of the eye), and anhydrosis (diminished sweat production by the skin in part of the face). Patients with Horner's syndrome may have more severe injuries of the brachial plexus.
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Brachial plexus birth palsies occur in approximately 1-3 out of every 1,000 live births. Risk factors for the development of brachial plexus birth palsy include: large gestational size, breech presentation, prolonged or difficult labor, vacuum- or forceps-assisted delivery, twin or multiple pregnancy, and a history of a prior delivery resulting in brachial plexus birth palsy.
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Brachial plexus birth palsy is diagnosed by your physician after a thorough medical history and physical examination. Special imaging studies (e.g. MRI) or nerve conduction studies may be performed to obtain more information, but the diagnosis and treatment recommendations are made primarily based upon history and physical examination.
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The prognosis is dependant upon the extent of the injury, and for this reason, varies from patient to patient. The majority of patients will achieve near normal arm function without surgery. Not all children, however, recover fully. In the absence of adequate recovery, surgery can improve strength and/or motion and help optimize shoulder joint development. One of the common problems with brachial plexus birth palsies is the abnormal development of the shoulder joint; this may progress over time. Thus, in addition to periodic physical examinations, magnetic resonance imaging (MRI) and/or computed tomography (CT) scans may be performed.
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Most brachial plexus birth palsies will heal on their own (spontaneous recovery). Many children improve or recover by 3-12 months of age. During this time, serial examinations should be performed to monitor progress. During this time, occupational and/or physical therapy is recommended to help maximize use of the affected arm and prevent tightening of the muscles and joints. With the teaching and guidance of therapists, parents are instructed to perform range of motion exercises at home with their child several times a day. These exercises are important to keep the joints and muscles moving as normally as possible. In addition, Botox injections may be used to assist with joint motion and prevent contractures.
Patients who do not demonstrate adequate recovery benefit from surgical treatment. There are a number of different operations that may be performed for patients with brachial plexus birth palsy:
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Microsurgery - If there is inadequate recovery during the first 3 -6 months of life, microsurgery (which involves operating on small nerves) is recommended. Microsurgery involves exploring the brachial plexus and trying to repair or reconstruct the injured nerves. In many cases, this will require the use of nerve grafts, which are typically taken from the patient's leg(s). In general, microsurgery is not beneficial in children who are beyond one year of age.
Tendon Transfers - Tendons are comprised of connective tissue and connect muscles to bones. A tendon transfer involves separating the tendon from its normal attachment and reattaching it to a different place. This allows a healthy muscle to assist a weaker or injured muscle perform its desired function. In brachial plexus birth palsy patients, tendon transfers are usually performed around the shoulder to improve the ability to raise the arm, but may be utilized in the forearm, wrist, and hand as well. Tendon transfers are done between the age of one year and adulthood, as appropriate. Patients are usually placed in a cast for 4 to 6 weeks after surgery. Extensive post-operative therapy is required. In some instances, shoulder weakness may cause limitations in motion that are not amenable to tendon transfers.
Capsulorraphy - This term refers to the surgical tightening of loose tissue around the (shoulder) joint. This is usually performed in patients when persistent muscle weakness has caused instability or dislocation of the shoulder joint. This procedure may be performed through a surgical incision ( open capsulorraphy ) or with the use of arthroscopy, in which a pencil-sized camera is inserted into the shoulder via smaller incisions. Capsulorraphy is often performed in conjunction with other surgical procedures.
Osteotomy - An osteotomy is a surgical procedure in which bones are cut and reoriented. In brachial plexus birth palsy patients, osteotomies may improve upper extremity function by better positioning the hand and arm. Most commonly, osteotomies are performed of the humerus (upper arm bone) or forearm.
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