Introduction
Adult traumatic pan-brachial plexus injury (BPI) results in an immediate loss of function of the patient’s shoulder, arm, and hand and has lifelong after-effects on the patient’s physical, mental, social, and economic well-being. , Although the global incidence of this injury is unknown, , the reported incidences of traumatic BPI ranged from 0.17 per 100,000 persons in Japan to 1.5 per 100,000 persons in Brazil. It is estimated that the annual incidence of surgically treated BPI in the United States is 0.89 per 100,000 persons. Although traumatic BPI are uncommon when compared to other peripheral nerve injuries, they represent a significant economic burden for patients and health systems.
Treatment of brachial plexus injuries advanced with the introduction of the operating microscope. Millesi applied microsurgical techniques to neurolysis, interfascicular nerve grafting, and promoted tensionless repair. Narakas (1969) reported good outcomes with cable grafting of nerve roots to targets. Even though nerve transfers were performed as early as 1903, upper extremity nerves, intercostal nerves, spinal accessory nerve, phrenic nerve, and contralateral C7 root transfers widened the reconstructive options for BPI patients. The transfer of a normal ulnar nerve fascicle to the musculocutaneous nerve branch to biceps described by Oberlin successfully restored elbow flexion in adult upper trunk BPI patients. This procedure highlighted the benefit of performing distal nerve transfers closer to the target muscle. Among other distal nerve transfers, the transfer of triceps branch of the radial nerve to the axillary nerve branch of the deltoid, when performed with spinal accessory nerve transfer to the suprascapular nerve, resulted in the recovery of shoulder abduction in adult upper trunk BPI patients. , Apart from nerve grafting and transfer procedures, the microscope also facilitated successful free tissue transfers. Ikuta described the use of a free functioning gracilis muscle transfer to restore elbow flexion in an adult patient with a 10-year-old pan-brachial plexus injury. This concept was advanced by Doi, who restored prehension in adult traumatic pan plexus injuries with staged double free functioning gracilis muscle transfers. ,
Many permutations or combination of procedures are available for adult BPI. Regional differences in patient characteristics, economic conditions, societal perceptions of disability, surgeon training, and measurements of outcome determines each treatment center’s philosophy of care. The foundation of any reconstructive strategy is a detailed clinical examination to determine what has been injured/affected, directed radiographic imaging, electrophysiologic testing, and an understanding of the priorities of treatment. A multidisciplinary team of surgeons, physicians, nurses, and therapists focused on helping the patient leads to reconstructive outcomes that surpass what each could accomplish alone and is probably the single greatest advancement in BPI surgery.
Essential knowledge
Anatomy
The brachial plexus is formed from the ventral primary rami of the lowest four cervical nerve roots (C5-C6-C7-C8) and of the first thoracic nerve (T1). The five roots form three trunks. Each trunk gives rise to an anterior and posterior division. The six divisions form three cords that are named for their anatomical relationship to the axillary artery: lateral, medial, and posterior cords. The three cords form five terminal branches in the upper limb ( Fig. 20.1 ). Roots and trunks are found supraclavicularly in the interscalene and posterior triangles of the neck. The divisions are located behind the clavicle, while the cords and terminal branches are found below the clavicle.
Pan-plexus injuries involve all five roots of the brachial plexus. Each root is formed by the joining of dorsal (sensory) rootlets and ventral (motor) rootlets branching off the spinal cord as they pass through the spinal foramen. The cell bodies of the sensory nerves lie within the dorsal root ganglia (DRG) outside the spinal cord ( Fig. 20.2A, E ). The injury to a cervical root is classified as preganglionic when there is an avulsion of the rootlets from the spinal cord proximal to the DRG (see Fig. 20.2B, E ). Stretching or rupture of the cervical root distal to the DRG is classified as postganglionic (see Fig. 20.2C-E ). Whether an injury is pre- or postganglionic has significant implications on the available reconstruction options. The avulsed nerve root in a preganglionic injury cannot be successfully reattached to the spinal cord; thus it cannot be used to reanimate the upper limb. The ruptured root in a postganglionic injury is a viable source of motor axons and can be reconnected to distal targets with nerve grafts to restore some motor function in the upper limb.
Clinical presentation
Patients are predominantly males in their 20s who are typically involved in motorcycle or vehicle accidents and experienced closed brachial plexus injuries. , The prevalence of pan-plexus injury is estimated at 53% (95% CI: 47%–58%), followed by upper plexus injury with 39% (95% CI: 31%–48%), and lower plexus injury with 6% (95% CI: 1%–12%). Pan-plexus injury patients present with a completely flail and painful/numb upper limb, whereas upper plexus injury patients retain their hand function. Secondary to the high-energy mechanism of injury, 54% to 70% of BPI patients have associated injuries. , Pan-plexus and lower plexus injury were significantly associated with coma; fractures of the shoulder girdle, ribs, pelvis, and lower limbs; thoracic/abdominal organ injuries; and other head injuries. Associated injuries often delay the diagnosis and may limit the reconstructive options available.
Examination and diagnosis
The initial evaluation starts with a detailed history of the timing from injury, mechanism of injury, associated injuries, and treatments received. Stigmata of closed head injury are observed for. Neuropathic pain is documented using the visual analogue scale. Physical examination is performed in a systematic manner and should be documented on a standard form ( Fig. 20.3 ). A baseline exam should be performed as early as possible, followed by serial exams (if time from injury permits) to determine if there is any spontaneous recovery. A neurological exam that includes upper and lower limb reflexes should be performed to rule out spinal cord lesions. Examiners should use consistent examination techniques for more comparable results.
Physical examination starts as soon as the surgeon meets the patient. The patient’s stance and gait (spinal cord injury) are observed, as well as any asymmetry in the patient’s face (ptosis, enophthalmos, and meiosis of Horner’s syndrome) and abnormal posturing of the neck (torticollis from paraspinal muscle injury). The examination proceeds with an inspection for scars from the accident or previous interventions or inadvertent injuries due to lack of protective sensation, deformities from fractures or scapular winging, and muscle atrophy. A sensory exam of the autonomous zone in each cervical dermatome (see Fig. 20.3 ) delineates which roots are injured (pan-plexus or upper trunk or C5 to C7 or lower trunk injury). Patients are asked if they can detect light touch in these zones (partial or complete injury) and to grade the amount of sensation perceived in percentages of the uninjured side.
The active and passive range of motions of the shoulder, elbow, wrist, and fingers are documented. Systematic manual motor testing of each upper extremity muscle is facilitated by using the standard form (see Fig. 20.3 ). Muscle strength is recorded using a Mayo modification of the British Medical Research Council (MRC) grading system wherein the muscle graded must fulfill all criteria of a lesser grade before obtaining a higher grade. A muscle must have active range of motion equal to its passive range against gravity (MRC grade 3 or M3) before it can be assigned as being able to move against resistance (MRC grade 4 or M4).
The pan-plexus injury patient is likely to have a complete or almost completely flail upper limb with no active range of motion. Recording the passive range of motion for each joint is important for early detection and prevention of joint contractures that would limit the outcome of reconstruction. Manual motor testing entails stabilizing for the patient the joint that the muscle of interest moves, and then palpating that muscle for any contraction while the patient attempts to perform the muscle action with gravity eliminated. The focus of the examination is to determine whether the injury is pre- or postganglionic. Rhomboid function is evaluated by asking the patient to touch his or her shoulder blades together. The patient’s ability to retract his or her scapula signifies a postganglionic injury and a likely available C5 root for grafting. The serratus anterior is another important muscle to examine to determine if there is nerve root avulsion. This muscle is hard to examine in a patient who cannot push against a wall. The examiner is advised to palpate the inferior corner of the scapular blade while the other hand pushes the shoulder posteriorly. If the serratus anterior is functioning (postganglionic), the inferior corner of the scapula is felt to stabilize/move toward the thorax. The inferior corner and scapula moves posteriorly when the serratus anterior is not functioning in a preganglionic injury ( Fig. 20.4 ). Paralysis of the rhomboids (C5), serratus anterior (C5, C6, C7), deviation of the head toward the opposite side, and presence of Horner’s syndrome (T1)—meiosis (small pupil), enophthalmos (sinking of the eyeball), ptosis (lid droop), and anhidrosis (absence of sweating) of the ipsilateral face—indicate a preganglionic injury wherein roots are not available for grafting.
The Tinel sign is another important examination that helps differentiate preganglionic root avulsion from postganglionic rupture. A strongly positive Tinel sign elicited by lightly tapping at the location of injury likely indicates that axons are ruptured instead of avulsed. The Tinel sign is absent in neuropraxia or conduction block. The Tinel sign is also useful for monitoring nerve regeneration in subsequent visits.
The incidence of a major vascular injury in patients with BPI is reported to be between 10% and 28%. A high index of suspicion is necessary because 5% to 15% of patients with upper-extremity trauma and concurrent vascular injuries present with an initially normal pulse on examination. Aside from palpating distal pulses, capillary refill should be assessed. Other hard signs in closed injuries to look out for are a rapidly expanding hematoma or palpable thrill or audible bruit that would warrant surgical exploration. Soft signs of hematoma over the artery, neurological findings from nerve adjacent to artery, and other proximity-related injuries are already present in the context of a BPI. An arterial pressure index and Doppler ultrasound examination can be used to further evaluate patients with soft signs and suspected vascular injury. If findings are still doubtful, the angiogram is the gold standard for diagnosis.
In summary, the objectives of serial examination in a pan-plexus injury patient are to determine the time elapsed since injury, what function was lost (pre- or postganglionic and partial or complete), and what is present that can be used to restore some upper limb function.
Investigations
Neurodiagnostic studies
Baseline nerve conduction studies (NCS) and electromyography (EMG) should be performed at 3 to 4 weeks after the injury when Wallerian degeneration has set in. Neurodiagnostic studies localize the site of injury as pre- or postganglionic, define the severity of axon loss, eliminate other conditions or reveal unrecognized disorders, and detect early/subclinical recovery.
Preserved sensory nerve action potential (SNAP) in clinically insensate areas and EMG findings of fibrillations in proximal muscles such as the rhomboids indicate a preganglionic injury. The cell body of sensory nerves lies in the DRG, outside the spinal cord, and this remains in continuity with the axons, resulting in preserved SNAP in cases of root avulsions.
EMG is also useful in preoperative planning for selection of donor nerves. The donor nerves with muscles exhibiting full or decreased motor unit recruitment patterns correlated with higher postoperative MRC grade of shoulder abduction and elbow flexion after distal nerve transfers in upper trunk type injuries.
Chest radiographs and sniff test
Plain chest radiographs are ordered to check for clavicular fractures and rib fractures. Displaced clavicular fractures requiring fixation may influence the timing of surgery. Rib fractures at the side of the affected extremity may limit the use of intercostal nerves (ICN) as donors. Inspiratory and expiratory films showing hemi-diaphragmatic elevation indicate an injured phrenic nerve and that the C5 root is not available for nerve grafting. However, the sensitivity of chest radiographs for detecting unilateral diaphragm paralysis is only 66.6%. The fluoroscopic sniff test is the current imaging gold standard for diagnosing hemidiaphragm paralysis. Hemidiaphragm paralysis is seen on fluoroscopy as the absence of downward diaphragm motion during inspiration with paradoxical upward motion when sniffing.
Computed tomography myelography or magnetic resonance imaging
Advanced imaging to detect preganglionic injuries should be performed at 3 to 4 weeks after injury when blood products in the spinal canal clear up and pseudomeningoceles have formed. CT myelography using a multidetector row CT scanner is the institutional preference for visualizing nerve root avulsions preoperatively. This scanner allows for submillimeter resolution of approximately 0.5 mm; hence, cervical rootlets that measure 1 mm in thickness can be seen. The CT myelogram would show asymmetric or absent nerve rootlets or a pseudomeningocele in preganglionic injuries ( Fig. 20.5A ). This is dependent on the contrast injected through lumbar puncture to flow to the craniocervical junction. Thus this study is also limited by any flow limiting stenosis in the spinal canal that would impede the flow of contrast.
Specialized MRI sequences, such as fast imaging employing steady-state acquisition (FIESTA) on General Electric magnets, can also be used to visualize absent nerve rootlets or pseudomeningoceles (see Fig. 20.5B ) and is noninvasive when compared to the CT myelogram. A retrospective review of CT myelogram and MRI (overlapping coronal oblique images taken parallel to the neural foramen using turbo spin–echo T2-weighted imaging techniques) of 175 cervical roots in 35 BPI patients found the same sensitivity (93%) for detection of the cervical nerve root avulsion in both modalities. MRI, when performed with gadolinium, can also demonstrate enhancement of spinal cord parenchyma at nerve root exit zone or denervation changes in cervical paraspinal muscles in a preganglionic injury. However, patients with implants about the neck and shoulder area would have imaging artifacts on MRI.
Angiography
Angiography is indicated in patients with suspected vascular injury. Magnetic resonance angiography (MRA) is the institutional preference for evaluating the patency of the thoracoacromial trunk in patients undergoing reconstruction with a free functioning muscle transfer.
Treatment
Timing of surgery
Interstitial fibrosis occurs to an appreciable degree in denervated muscle as early as 3 months postinjury. By 11 months postinjury, more than half of the denervated muscles would be fibrotic. Time from nerve reconstruction to the expected recovery of target muscle should be less than 11 months postinjury.
Sharp open injuries should be explored at the time of injury and primary nerve repair or grafting performed if the patient is stable. Blunt open injuries should also be explored acutely. Ruptured or lacerated nerve ends are tagged at physiologic length for delayed repair at 3 to 4 weeks postinjury when the zone of injury has demarcated.
Patients with closed pan-plexus injury have a dismal chance of spontaneous recovery, especially if there are nerve root avulsions. If the injury is incomplete or likely postganglionic, a 3-month delay to observe for recovery is advisable because, at present, there is no other method to differentiate a neuropraxia from axonotmesis or neurotmesis. Good results were reported when nerve reconstruction for pan-plexus injury was undertaken after the third month but before the sixth month postinjury. Results declined drastically when surgery was performed more than 9 months after trauma.
Priorities of reconstruction and setting patient expectations
Reconstruction after a pan-plexus injury will not result in a normal upper limb. Patients benefit from repeated discussions to understand the severity of their injury, the natural history of such injuries, and what can be realistically achieved with current surgical techniques. The widely accepted priorities of reconstruction from highest to lowest are:
- 1.
Elbow flexion
- 2.
Shoulder stability with external rotation
- 3.
Elbow extension
- 4.
Rudimentary grasp and release
- 5.
Protective sensation
The goal is to have the best possible helper arm that the patient could control so that the upper limb would not get in the way of the activities of daily living. A frank discussion of expected outcomes prevents future disappointments after a devastating injury. In a pan-brachial plexus injury with limited donor nerves, most surgeons give precedence to restoring elbow flexion and shoulder stability and external rotation. , Elbow flexion allows for the hand to reach the face for feeding, cleaning, and so on. A stable shoulder improves the strength of elbow flexion and extension. Shoulder external rotation positions the hand away from the trunk so that it can reach out to manipulate one’s environment and clear the abdomen to reach the face. Elbow extension acts as an antagonist for a single free functioning muscle transfer (FFMT) passing anterior to the elbow to effect finger flexion. Rudimentary grasp and release is challenging to restore because of the limited donors in complete pan-plexus injuries and the long distance required for nerve regeneration to distal targets. The use of myoelectric prosthesis requires initial nerve surgery to have muscles for signal followed by transradial amputation is an option to achieve grasp and release for complete pan-plexus injury patients. , Recovery of protective sensation prevents inadvertent injuries and facilitates grasp.
Modern principles and methods of management
The need for a center of excellence for BPI in the United States was recognized in the early 2000s. Mayo Clinic’s primary value is emphasized by William J. Mayo’s 1910 quote: “The best interest of the patient is the only interest to be considered, and in order that the sick may have the benefit of advancing knowledge, union of forces is necessary.” The Mayo model of care fosters collaboration rather than competition. Given the nature of the quaternary referral practice, surgeons from different specialties work together. The culture is reinforced because doctors are salaried instead of being compensated by a fee for service or productivity-based model. The effect of this environment resulted in interdisciplinary cooperation to promote excellence in clinical care, education, and research. The cooperation of surgeons and physicians from different subspecialties (orthopedics, hand surgery, neuroscience, plastic surgery, trauma surgery, vascular surgery, anesthesia, radiology, rehabilitation medicine) as well as physical and occupational therapists, social workers, and prosthetists elevated the management of BPI in the Mayo Clinic. A dedicated Brachial Plexus Team nurse coordinator is the glue that organizes and facilitates consultation schedules, testing, operative schedules, follow-up care, video/photography documentations, outcome data recording, and research coordination. ,
Patients are initially evaluated by a neurologist specializing in the care of peripheral nerves on Day 1, along with a prescheduled EMG and other necessary tests. The Brachial Plexus Team surgeons evaluate the patient and review the investigations together on Day 2. The surgeons and neurologists formulate a unified plan regarding the need for surgery, timing of surgery, and technical strategies for reconstruction. A group of ancillary surgeons and physicians associated with the team is readily available to address pain management, paralytic shoulder issues, stiff joints, and myoelectric prothesis needs. The availability of two or three surgeons and two or three starting operating rooms at any one time allows some flexibility in the scheduling of surgery for the patient who has traveled far for treatment. This team approach to managing a life-changing injury improves communication, surgical efficiency, and decision making. It brings the best innovations of each specialty to the patient in a single setting. ,
After the preoperative evaluation detailed above, the patient and accompanying persons are involved in a discussion about the natural history of pan-brachial plexus injuries and the options available for reconstruction. This is facilitated by using illustrations that patients can bring home to review ( Fig. 20.6 ) and motivates patients’ active involvement in their care. Patients are encouraged to ask questions and consider their long-term goals. The nuances of each reconstruction are openly discussed with the patient until a surgical plan is finalized. It is during these critical discussions that modifications in techniques or strategies have developed and led to advances in our practice. This conversation, more importantly, builds rapport with patients and their families, who are likely to be overwhelmed by the amount of information they are receiving. Having different surgeons with different styles of communication gives patients the opportunity to hear the information explained in different ways to facilitate their understanding. A sense of security from having an entire team supporting them through this difficult time of their lives is also afforded.
Pain affecting quality of life was found in 78% of BPI patients, and 68% had neuropathic pain. Patients are educated on the etiology of neuropathic pain and are actively managed by the pain specialist. Pain is modulated with medications (anticonvulsants, tricyclics, selective serotonin inhibitors, or muscle relaxants) and other modalities such as pain therapy with behavioral medicine techniques, transcutaneous electrical nerve stimulation, spinal cord stimulators, or neural ablation (dorsal root entry zone ablation). Therapy is crucial in strengthening possible donor muscles and in teaching patients how to activate donor nerves in preparation for transfer.
The rationale for the priorities of reconstruction is reviewed with the patient. The number of options to achieve each action can be disconcerting to the patient. The surgeon explains the rationale behind each procedure, its expected outcome, and the impact on future choices to help the patient make an educated decision. The patient is made familiar with the slow process of nerve regeneration. The implications of saving a donor nerve/vessel for future salvage is discussed as this limits the resources available during the initial reconstruction. Backup plans in case of no recovery and possible secondary procedures are discussed at onset.
The available surgical treatment options for pan-brachial plexus injury are as follows:
- a.
Ipsilateral intraplexal nerve root grafting, phrenic nerve transfer
The supraclavicular brachial plexus is explored to determine if any ipsilateral intraplexal nerve root is available for nerve grafting. A graftable nerve root was present in 15% to 32% of cases for some centers and was available in 87% of cases in another center. In our practice, the viability of any visible nerve root is confirmed using intraoperative neurophysiologic monitoring. Somatosensory evoked potentials (SSEP) are obtained with stimulation at the intervertebral foramen and are recorded at the cervical spine, nasopharynx, or scalp ( Fig. 20.7A ). The presence of a central SSEP response indicates continuity of the dorsal sensory roots. Motor evoked potentials (MEP) are obtained with transcranial electrical stimulation and recording at the intervertebral foramen (see Fig. 20.7B ). A present MEP response corresponds to intact ventral motor roots. The continuity of the ventral motor roots, as evidenced by an MEP response, indicates that the proximal root stump can be used for grafting.
Fig. 20.7
Intraoperative neurophysiologic monitoring. (A) Measurement of somatosensory evoked potentials with stimulation of the nerve root close to the intervertebral foramen and recordings obtained from the scalp. (B) Measurement of motor evoked potentials obtained with transcranial electrical stimulation and recordings at the nerve root exiting the intervertebral foramen.
(From Zelenski NA, Oishi T, Shin AY. Indications and technique for the use of intraoperative neuromonitoring in brachial plexus surgery. J Hand Surg Am . 2023;48(7):726-731; used with permission of Mayo Foundation for Medical Education and Research, all rights reserved).
There are limited reports on outcomes of nerve root grafting in complete pan-plexus injuries. Grafting one viable root to the anterior division of the upper trunk resulted in antigravity elbow flexion in 17 of 22 (77%) complete pan-plexus injury patients. Using longer grafts from the C5 root to musculocutaneous nerve, the same group obtained full elbow flexion of at least British Medical Research Council grade 3 (M3) strength in 20 out of 22 (91%) complete pan-plexus injury patients. This was attributed to poor root quality, disrupted coaptation, a more distal injury or double lesions, or traumatize biceps muscle in the shorter graft cohort. Regardless, a viable nerve root adds one more donor to an already limited armamentarium in this severe injury, and using it has the potential to restore one more function in the flail upper limb.
The phrenic nerve is not routinely utilized in our practice because a great majority of our patients are pan avulsions. Additionally, the generally high BMI of the patients in our region and our frequent use of ICN may put respiratory function at risk if a normal phrenic nerve is used as a donor.
- b.
Ipsilateral extraplexal nerve transfer – spinal accessory, motor and sensory intercostal nerves
The spinal accessory nerve lies in close proximity to the upper part of the brachial plexus in the supraclavicular fossa. It is usually uninjured and was available for use as a donor nerve in 94% of patients with upper or pan-brachial plexus injury. Taking the spinal accessory nerve in the supraclavicular fossa, after it has given a few muscular branches to the under surface of the trapezius muscle, preserves upper trapezius function. Transfers with or without interposition grafts to musculocutaneous nerve, upper trunk, suprascapular nerve, and radial nerve had been described since 1972 with inconsistent results. At present, options for use of the spinal accessory nerve in complete pan-plexus injury include direct neurotization of a free functioning muscle transfer, direct transfer to the suprascapular nerve to provide shoulder stability and limited abduction and external rotation, or preservation of lower trapezius function for later tendon transfer for shoulder external rotation.
Intercostal nerves also have a long history of use for transfers in brachial plexus injuries. The motor component of the ICN can be accurately isolated for a relatively long length to allow for direct coaptation with an isolated recipient motor nerve. This has the advantage of earlier reinnervation compared to donors requiring nerve grafts. However, each ICN is small and contains only 500 to 700 myelinated motor fibers, so more than one ICN is required for a successful transfer. Harvesting ICNs has a perioperative complication rate of 15%, the most common of which is a iatrogenic pleural tear (9%). This is usually managed by inserting a small chest tube. The rate of complications increased with the number of ICNs transferred. Rib fractures are common associated injuries in BPI. Rib fractures were not associated with an increased risk of overall complications of ICN harvest. In total, 92% of ICNs harvested from previously fractured ribs were suitable for transfer based on intraoperative nerve stimulation.
ICNs have also been transferred to a variety of recipients. The most common application is to restore elbow flexion by transfer to the musculocutaneous nerve ( Fig. 20.8 ). In complete pan-plexus injuries, biceps strength after ICN transfer was ≥M3 in only 48.8% of the patients. This is comparable to a previous outcome of 41.9% of patients obtaining M3 or M4 elbow flexion. The number of ICNs used for the musculocutaneous nerve (MCN) transfer did not correlate with better elbow flexion grade. The sensory component of intercostal nerves can be used to restore protective sensation in the median nerve distribution by transfer to the lateral cord contribution of the median nerve.
Fig. 20.8
Diagram of nerve transfer for elbow flexion using direct transfer of intercostal nerves to musculocutaneous nerve.
(From Guiffre JL, Kakar S, Bishop AT, Spinner RJ, Shin AY. Current concepts of the treatment of adult brachial plexus injuries. J Hand Surg Am . 2010;35(4): 678-688; used with permission of Mayo Foundation for Medical Education and Research, all rights reserved).
- c.
Contralateral C7 transfer (CC7)
Because of the cross-innervation by C6 and C8 roots, the uninjured C7 can be transferred to the injured side as a high motor axon count donor for reconstruction. This transfer has been described for different targets, but it is most known for restoring hand function in complete pan-plexus injuries. Gu and his coworkers first reported this transfer in 1991. In 1998, the group reported that 5 out of 8 (62%) CC7 transfers to the median nerve with more than 2 years follow-up had at least M3 recovery of wrist and finger flexors. Six of the 21 (29%) patients from another center obtained at least M3 wrist and finger flexors 24 to 51 months after transfer of the posterior superior half of CC7 to the median nerve. Only one patient had independent wrist and finger flexion. Selective transfer of anterior division fibers of CC7 to wrist and finger flexors by yet another group had 10 of 29 patients (34%) reaching M3 motor recovery. In our practice in Mayo Clinic, 3 of the 15 patients (20%) with hemi-CC7 transfer to the median nerve group demonstrated electromyographic evidence of reinnervation, but none developed M3 or greater composite grip. None of the patients who recovered some motion of the median nerve muscles could activate it independently of the contralateral muscles innervated by the CC7 nerve. All patients experienced donor-side sensory or motor changes that were mild and transient except for one patient who sustained severe, permanent donor-side motor and sensory losses. Our experiences with hemi-CC7 have been poor, and as such we have abandoned its use in adult patients.
Although good outcomes for CC7 transfers have been published, results are inconsistent across different centers globally. In patients with one flail upper limb, the surgical trauma and donor side morbidity to the remaining functioning upper extremity needs careful consideration before undertaking this transfer.
- d.
Free functioning muscle transfer
Doi et al described using a double gracilis FFMT that enabled prehension to patients with complete pan-brachial plexus injuries. The first gracilis is neurotized by spinal accessory nerve and restores elbow flexion and finger extension. The second is powered by fifth and sixth ICN for finger flexion. Elbow extension is achieved by transfer of third and fourth ICN to triceps. A variety of muscles can be transferred, but the gracilis is commonly used because of its reliable proximally based neurovascular pedicle that allows for earlier reinnervation and long tendon length that can be used to restore elbow and wrist motion. In 36 patients with complete pan-plexus injury followed up for at least 24 months after the second FFMT, 25 patients had M4 elbow flexion and 11 had M3 elbow flexion. Total active motion of the fingers was 46 degrees (range, 0–98 degrees), with a mean hook grip strength of 4 kg (range, 0–12 kg).
Comparing the use of FFMT to ICN to MCN transfer for elbow flexion in complete pan-plexus root avulsion injury, 68% of patients in the FFMT group achieved M3 or M4 elbow flexion compared to 42% of patients in the ICN nerve transfer group. The number of ICNs used did not correlate with better elbow flexion grade. The gracilis FFMT achieved significantly better elbow flexion strength after pan-plexus root avulsion injury and should be considered to restore elbow flexion in acute reconstruction.
In our practice, patients prefer a single-stage procedure to obtain rudimentary grasp. A single gracilis FFMT secured proximally to the clavicle and distally to the flexor digitorum profundus (FDP) and flexor pollicis longus (FPL) tendons restores elbow flexion and finger flexion ( Fig. 20.9 ). Adding an ICN to MCN nerve transfer to the gracilis FFMT did not improve elbow flexion strength. A more distal attachment of the gracilis to FDP/FPL (M3/M4 = 85%) was significantly stronger than gracilis to biceps (M3/M4 = 53%).
