Traumatic Brachial Plexus Injuries: Surgical Techniques and Strategies

Reinnervation Priorities

It must be stated as a preliminary remark that complete injuries rule out the possibility to restore the whole function of the upper limb: the reconstruction scheme follows priorities, generally assuming that elbow flexion and shoulder function (stabilization, abduction, and extrarotation) are the primary goals of surgical reinnervation. Elbow extension and restauration of protective sensitivity in the hand are less unanimously advocated. ¹ Reinnervation of the distal extremity of the upper limb is still out of our reach, in spite of some promising reports published by Asian surgeons; ² however, it must be emphasized that even in the best cases, only a basic function can ultimately be regained, certainly incomparable with the flexible refinement of the normal hand.

17.1.2 Surgical Approach

Brachial plexus exploration was considered mandatory until recent times, when some surgeons started to challenge its validity advocating the remarkable progress of imaging and the fact that nerve transfers have replaced graft reconstruction whenever possible; ³^, ⁴ especially in cases of partial injuries, distal neurotization aiming to restore the function could be the only repair strategy, the evaluation of the extension and severity of the injury at root level therefore ceasing to be a major concern. However, in our opinion, surgical exploration still retains its value and we regularly perform it. We also reckon that, regardless the overall successful outcome of nerve transfers, anatomical graft reconstruction still retains its advantages and should not be abandoned.

Brachial plexus exploration can be performed via two basic approaches: a posterior and an anterior approach. In spite of the initial wave of enthusiasm, the posterior approach proved to be limited in indications. Nowadays surgical exploration is regularly carried out via an anterior approach with few exceptions.

17.2 Repair Strategies

A clear evaluation of the type of injury suffered by the plexus is necessary to choose the repair strategy that can offer the best possible functional restoration; thus, each procedure involves an individually designed reconstruction according to the surgical findings. No guidelines are stated and surgeons mostly rely on their personal knowledge and expertise.

Surgical techniques basically imply two options: graft reconstruction and neurotization. Graft reconstruction ¹^, ⁵^, ⁶^, ⁷ can be applied when root continuity with the spinal cord is maintained, such as in cases of complete nerve rupture or severe stretch injuries resulting in the formation of neuromas. Sural nerves are usually harvested (in cases of complete injuries, radial sensory nerve, medial cutaneous nerve, or even the ulnar nerve can become suitable) and used to prepare cable grafts that bridge the two stumps of the nerve whose function must be restored.

Graft reconstruction is obviously not appropriate in avulsive injuries and neurotization techniques (also called nerve transfers) are the viable options. ⁸^, ⁹^, ¹⁰^, ¹¹^, ¹²^, ¹³^, ¹⁴^, ¹⁵^, ¹⁶^, ¹⁷^, ¹⁸^, ¹⁹^, ²⁰^, ²¹^, ²² The main concept behind neurotization techniques is that the proximal stump of a nerve (“donor”) still in continuity with the spinal cord is coapted to the distal stump of the nerve (“recipient”) considered the priority to restore. The donor nerve function is obviously estimated of lesser utility or it can be performed by another muscle. The donor and recipient nerves should preferably be in close proximity, thus avoiding the need for an interposition nerve graft or at least reducing its length as much as possible. Three forms of neurotization are available: plexoplexual neurotization, extraplexual neurotization, and distal neurotization.

In plexoplexal neurotization, ³^, ⁵ one of the roots is found ruptured after its exit from the foramen. The most common scenario is C5 root found in continuity with the spinal cord, whereas the other roots are likely to be avulsed: from C5 proximal stump, an interposition graft is bridged to the anterior division from the upper trunk to restore biceps contraction.

In extraplexual neurotization, the donor nerve does not belong to the plexus. ▶ Table 17.1 shows the most frequently used donors and their preferable recipients in relation with the most favorable outcome.

**Table 17.1** Extraplexual donor nerves most commonly used for brachial plexus repair
Donor nerve	Historical background	Recipient nerve/s	Pros	Cons	Remarks	The author’s experience
Spinal accessory nerve (XI)	First mentioned by Tuttle in United States in 1913, largely popularized in Japan by Kotani in 1963	Suprascapular nerve (SS)/musculocutaneous nerve (MC)	Excellent donor for the SS	Interposition graft in XI-MC transfer is required	XI-SS nerve transfer can be performed via anterior or posterior approach; according to some authors, the latter provides better results, due to its proximity to the target muscles and the decompression of the SS at the first notch	Routinely used to reinnervate the spinati muscles, by an anterior approach. The posterior approach is used only when anterior exploration revealed distal rupture of the SS that rules out direct XI-SS nerve transfer.
Phrenic nerve	Introduced by Gu in China in the 1980s	Mostly used to restore the biceps	Valid donor	Contraindicated in babies for the high rate of complications if used in patients younger than 3-y-old (respiratory infections, thoracic cage deformities, etc.). No available follow up studies of respiratory function in elderly patients	Harvest can be performed from the supraclavicular area or via video-assisted thoracoscopy at the thorax	Not used for fear of onset of respiratory complications when the patient reaches the third age
Pectoral nerve	Largely popularized by Kline in United States	Mostly used to restore the biceps	Valid donor	Denervation of the pectoral muscles, thus ruling out possibilities of secondary muscle transfer	Adduction is unaffected as supported by other muscles	Seldom used as complete denervation remarkably affects cosmetics
Thoracodorsal nerve	Introduced by Foester in the late 1920s	Axillary nerve Musculocutaneous nerve	Valid donor	Denervation of the latissimus dorsi ruling out possibilities for secondary muscle transfer	Adduction is unaffected as supported by other muscles	Routinely used to reinnervate the axillary nerve being preferred to Somsak’s procedure
Subscapular nerves	Introduced by Foester in the late 1920s and popularized in the 1940s in United States by Steindler	Axillary nerve Musculocutaneous nerve	Valid donor	No cons	Adduction is unaffected as supported by other muscles	Routinely used to reinnervate the axillary nerve being preferred to Somsak’s procedure
Intercostal nerves	First used by Casserini in Italy attempting to restore motor function in paraplegic patients. Popularized by Kotani, Hara and Tsuyama	Mostly the musculocutaneous nerve Other recipients: radial nerve, axillary nerve, long thoracic nerve	Valid donor	Cannot be used in cases of multiple rib fractures, cervical cord injury or Brown Sequard’s injury	Movement in the reinnervated muscle is initially elicited and synchronous with inspiration, autonomization takes about 1 y	Largely used in panavulsive injuries (see text)
Contralateral C7 (cC7)	Introduced by Gu in Shanghai at the end of the 1980s. His original technique has been later on modified by Xu Lei and Wang Shu Feng (“prespinal way”) According to the different surgical variants, the surgeon can harvest the whole of cC7 or one of the two divisions (anterior or posterior) from the splitting of the middle primary trunk	Mostly advocated to restore hand function.	Valid donor due to the high number of axons	Although safely harvested in the majority of the patients, cC7 can occasionally result in deficits of the extensors.The Asian surgeons describe the possibility of a later recovery Pain and paresthesias in the radial territory of the hand in the donor limb can be permanent	Autonomization of the reinnervated limb from synchronous movement of the donor limb can require more than 5 y and is not guaranteed	Used in lesions with multiple avulsions if the following criteria are met: patient younger than 30 y, slim, no major head injury, surgery within 6 mo after the traumatic event. Indication given in panavulsive injuries with no possibilities to use the intercostal nerves. Used to restore reinnervation in the territory of the upper trunk or in lesions with lower root avulsions to attempt hand rehanimation. Harvest of cC7 is always performed under intraoperative electrodiagnostic tests in order to avoid possible damage to the donor limb. Experience with Gu’s technique mainly

Distal neurotizations were introduced after the genial intuition of the French surgeon Christophe Oberlin, ¹⁴ who designed a technique to certainly be considered the Copernican revolution in brachial plexus surgery: fascicles selected from a sound nerve are intraneurally isolated thanks to direct stimulation, severed and coapted with the distal trunk of the recipient nerve. ▶ Table 17.2 illustrates the most frequently used techniques labeled as distal neurotization. ¹⁵^, ¹⁶^, ¹⁷^, ¹⁸^, ¹⁹^, ²⁰^, ²¹

**Table 17.2** Most frequently used distal neurotizations
The technique and its historical background	Donor fascicles	Recipient nerve	Pros	Cons	Remarks	The author’s experience
The ulnar to musculocutaneous nerve transfer. Introduced by Oberlin in the beginning of the 1990s has revolutionized brachial plexus surgery Universally known as “Oberlin’s transfer”	Fascicles for the flexor carpi ulnaris (FCU) from the ulnar nerve at the arm	The muscular branches of the musculocutaneous nerve	It can be used even in cases of avulsions of the upper roots regaining excellent biceps function	Only reinnervation of the biceps	It can successfully be used even in late referral cases	We started to apply this nerve transfer according to the original description, later on we modified it using the whole musculocutaneous nerve as recipient and occasionally choosing the median nerve as donor
The double neurotization: modified technique of the above procedure introduced by Oberlin in 2004, largely popularized by Mc Kinnon	Fascicles for the FCU from the ulnar nerve and fascicles for the pronator muscles form the median nerve	FCU fascicles are coapted to the muscular branches of the MC, whereas the fascicles from the median nerve are coapted to the brachialis muscle	Valid reinnervation of biceps and brachialis with increased strength in elbow flexion of the hand	Possibility of complications in the hand	It can be used in late referral cases	No personal experience
The medial cord to musculocutaneous infraclavicular transfer. Introduced by Ferraresi and Garozzo in Italy	Fascicles for the pronator or wrist flexors from the medial part of the medial cord	The whole musculocutaneous nerve cut at its origin form the lateral cord	Valid reinnervation of both biceps and brachialis at the same time	Not possible in those cases of anatomical variants of the lateral cord that branches off for the biceps at the arm level	Although the reinnervation time takes a few months longer than with Oberlin’s transfer, this does not influence the outcome	After the development of this variant of Oberlin’s technique, we have used it routinely and we consider it the best option
The brachialis branch to the median nerve transfer. Introduced by Accioli, popularized in Spain by Palazzi with the development of technical variants	Branch for the brachialis muscle from the musculocutaneous nerve	Fascicles for the AIN (anterior interosseous nerve) and FDS (flexor digitorum superficialis) in the median nerve	Valid reinnervation of finger flexors	Denervation of the brachialis muscle	The fascicles for the AIN and FDS are located in the posterior portion of the median nerve The lateral cutaneous nerve of the forearm can be added in the procedure to improve sensitivity in the median nerve territory	Limited experience but valid results
The triceps to deltoid nerve transfer, generally known as Somsak’s procedure. Introduced by Leechavenvongs (Somsak is his first name) in Thailand in the 1990s, technical variants introduced by Mckinnon in United States and Bertelli in Brazil later on	Branch to the long head of the triceps In the technical variant introduced by Mckinnon, the branch for the medial head	Axillary nerve	Valid reinnervation of deltoid	Reduced strength in the triceps in the early weeks/months after the procedure, not to be used in cases of weak triceps	Usually performed via a posterior approach, via an anterior approach at the axilla level in the technical variant by Bertelli	Limited experience and results less favorable than reported in the literature

17.2.1 Repair Strategies Depending on the Injury Pattern

In upper brachial plexus injuries, surgery aims to reinnervate shoulder muscles (spinati and deltoid) and biceps. Surgeons usually rely on the spinal accessory to suprascapular nerve transfer to regain spinati muscles; biceps is reinnervated via Oberlin’s technique ¹⁴ or its variants ¹⁵^, ¹⁶ and deltoid is restored via Somsak’s procedure. ¹⁷^, ¹⁸ Alternative options for biceps are pectoral to musculocutaneous nerve transfer and subclavius or thoracodorsal to axillary nerve transfers for deltoid. ¹³ If valid proximal root stumps are available, some surgeons prefer to associate graft reconstruction of the upper trunk with nerve transfers, claiming the outcome is more favorable as it allows restoration of pectoral muscles and median hand sensitivity.

Avulsions of the three upper roots are rare; in such case, the repair strategy could encompass the spinal accessory to suprascapular nerve transfer for the spinati muscles, Oberlin’s technique for the biceps, and an intercostal nerve transfer to the long thoracic nerve to functionally restore dentatus anterior (consequently providing a more stable shoulder) and to the axillary nerve to reinnervate the deltoid muscle.

If a wrist drop is also present due to C7 injury, tendon transfers have been classically considered the standard option, but recently distal transfers (e.g., median nerve to posterior interosseous nerve transfer) have been advocated. ²¹

In (C7), C8, T1 brachial plexus injuries, muscle transfers were the choice in the past, but nowadays nerve transfers (e.g., the brachialis muscle branch of the musculocutaneous to the median nerve transfer to regain finger flexion; ▶ Fig. 17.1) are the preferred option according to many surgeons. ¹⁹^, ²⁰^, ²¹^, ²²

Fig. 17.1 Findings at brachial plexus exploration. (a) C5 root avulsion: the tip of the scissors is showing the avulsed rootlets. (b) T1 root avulsion. (c) Posttraumatic pseudomeningocele of the upper roots. (d) Bulky neuroma of the upper trunk: note the splitting into the terminal branches of the upper trunk (anterior and posterior contributions, suprascapular nerve) at its distal end. (e) Neuroma-in-continuity of the lateral cord in a gunshot injury in association with a vascular injury (previously repaired by a vascular surgeon): the humeral insertion of the pectoralis major was detached to allow better control of the surgical field. Note that this patient presented an anatomical variant: the splitting of the lateral cord into its terminal branches occurred at the level of the proximal arm instead of infraclavicularly, as usual. (f) Neuroma-in-continuity of the origin of the median nerve, affecting both the lateral and medial roots. (g) Stretch injury of the median nerve associated with an infraclavicular lesion. (h) Neuroma on the proximal stump of the axillary nerve following a rupture at the inlet into the quadrangular space. (i) Rupture of the suprascapular nerve at supraclavicular level.