The brachial plexus is a network of nerves located in the neck and axilla, composed of the anterior branches of the lower four cervical and first two thoracic spinal nerves that supply the chest, shoulder, and arm. Injuries to the brachial plexus affect the nerves supplying the shoulder, upper arm, forearm and hand, causing numbness, tingling, pain, weakness, limited movement, or even paralysis of the upper limb. Brachial plexus lesions are classified as either traumatic or obstetric. Brachial plexopathy is the pathologic dysfunction of the brachial plexus. When the brachial plexus is injured during delivery, the nerves become damaged and result in loss of muscle control and paralysis. This condition is also known as Erb’s palsy.
Brachial plexus avulsion is the tearing away or forcible separation of nerves of the brachial plexus (a network of nerves that conducts signals from the spine to the shoulder, arm and hand) from the spine, the point of origin. Symptoms of brachial plexus injuries may include a limp or paralyzed arm, lack of muscle control in the arm, hand, or wrist, and lack of feeling or sensation in the arm or hand. Brachial plexus injuries may occur during birth: the baby's shoulders may become impacted during the birth process causing the brachial plexus nerves to stretch or tear.
Brachial neuroplasty (neurolysis or nerve decompression) is the surgical repair or restoration of nerve tissue. The release of adhesions around a nerve (freeing of intact nerve from scar tissue) is performed to relieve pain and disability. It is written in the 2008 textbook Frontera: Essentials of Physical Medicine and Rehabilitation, surgery is an option in cases of traumatic plexopathy but has variable results. Surgical techniques such as nerve grafting, free muscle transfer, neurolysis, and neurotization are used. Surgeons who use these techniques frequently differ considerably in their approach to them, making conclusions about their efficacy difficult. According to the textbook Bradley: Neurology, the surgical treatment of traumatic plexopathy depends on the extent of the lesion. Depending on the findings, neurolysis, nerve grafting or re-neurotization is performed. In the textbook Browner; Skeletal Trauma it is written in reference to nerve injuries of the brachial plexus, when a neuroma in continuity is found it may be resected and repaired or neurolysis may be performed.
Dorsal root entry zone (DREZ) coagulation (also known as dorsal root entry zone lesion) is a surgical procedure in which ablative lesions are made at the dorsal root entry zones of the spinal cord. These lesions are made with a radiofrequency lesion generator or laser through an open exposure of the cord via laminectomy. Pain-producing nerve cells are destroyed with radiofrequency heat lesions.
Computer-assisted dorsal root entry zone microcoagulation (CA-DREZ) is a surgical procedure in which ablative lesions are made at the dorsal root entry zones of the spinal cord. These lesions are made with a radiofrequency lesion generator or laser through an open exposure of the cord via laminectomy. It involves electrical recording inside the spinal cord at the time of surgery to identify regions of abnormally active pain-producing nerve cells. These abnormal cells are then destroyed with radiofrequency heat lesions.
The Triangle Tilt is a surgical procedure that addresses scapular elevation in children with obstetric brachial plexus injury (OBPI) through the bony realignment of the clavicle and scapula. This realignment, or tilting, is of the triangle formed by clavicle and scapula. As the scapula elevates, the plane of the triangle is steepened. The purpose of the triangle tilt, therefore, is to normalize the plane of this triangle or, to reduce the elevation of the scapula and normalize the spatial relationship between the sides of the triangle.
Nath et al write in 2010 the triangle tilt surgery restores the distal acromioclavicular triangle from an abnormal superiorly angled position to a neutral position, thereby restoring normal glenohumeral anatomic relationships. The findings of a study investigating the effects of triangle tilt surgery on glenohumeral joint anatomy in 100 OBPI patients were reported. Axial computed tomography and magnetic resonance images taken before and 12- to 38-months after surgery showed significant improvements in both posterior subluxation and glenoid version. Patients with complete posterior glenohumeral dislocation improved from 19% preoperatively, to 11% postoperatively. Glenoid shape was also improved, with 81% of patients classified as concave or flat after surgery compared with 53% before surgery. The authors concluded these anatomic improvements after triangle tilt surgery hold promise for improving shoulder function and quality of life for OBPI patients.
The Mod Quad procedure is considered a secondary surgery in children with brachial plexus injury used to correct muscle imbalances. Among the muscles injured in Erb's are the abductors of the shoulder (that lift the arm over the head), as well as the external rotators (that help to turn the upper arm outward and to open the palm of the hand). At the same time, the internal rotators (muscles that turn the arm and palm inward) and adductors (muscles that pull the arm to the side) of the arm are not involved in the injury because they are supplied by the lower roots of the plexus. These strong muscles overpower the weak muscles and over time the child cannot lift the arm over the head or turn the palm out, because of the muscle imbalance. In order to use the hand effectively, the elbow becomes bent, which eventually becomes fixed because of weakness of the triceps (the elbow straightening muscle). The elbow-bent posture (also known as the Erb's Engram) contributes to the appearance of the arm being shorter.
For this muscle imbalance, a group of muscle releases and transfers can put the arm in a more natural position and help to lift the arm over the head. Known as the "quad" procedure, it has four components:
- latissimus dorsi muscle transfer for external rotation and abduction
- teres major muscle transfer for scapular stabilization
- subscapularis muscle release
- axillary nerve decompression and neurolysis). Depending on the individual child, other nerve decompressions or muscle/ tendon transfers (such as pectoralis muscle releases) might be performed at the same time (the modified quad or "Mod Quad" procedure).
Louden, et al. (2013) conducted a metaanalysis and systematic review analyzing the clinical outcomes of neonatal brachial plexus palsy treated with a secondary soft-tissue shoulder operation. A literature search identified studies of NBPP treated with a soft-tissue shoulder operation. A meta-analysis evaluated success rates for the aggregate Mallet score (≥ 4 point increase), global abduction score (≥ 1 point increase), and external rotation score (≥ 1 point increase) using the Mallet scale. Subgroup analysis was performed to assess these success rates when the author chose arthroscopic release technique versus open release technique with or without tendon transfer. Data from 17 studies and 405 patients were pooled for meta-analysis. The success rate for the global abduction score was significantly higher for the open technique (67.4%) relative to the arthroscopic technique (27.7%, P<0.0001). The success rates for the global abduction score were significantly different among sexes (P=0.01). The success rate for external rotation was not significantly different between the open (71.4%) and arthroscopic techniques (74.1%, P=0.86). No other variable was found to have significant impact on the external rotation
outcomes. The success rate for the aggregate Mallet score was 57.9% for the open technique, a nonsignificant increase relative to the arthroscopic technique (53.5%, P=0.63). Data suggest a correlation between increasing age at the time of surgery and a decreasing likelihood of success with regards to aggregate Mallet with an odds ratio of 0.98 (P=0.04). The authors concluded that, overall, the secondary soft-tissue shoulder operation is an effective treatment for improving shoulder function in neonatal brachial plexus palsy in appropriately selected patients. The open technique had significantly higher success rates in improving global abduction. There were no significant differences in the success rates for improvement in the external rotation or aggregate Mallet score among these surgical techniques.