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Thoracodorsal to triceps nerve transfer (following brachial plexus injury)

    Overview

    Learn the Thoracodorsal to triceps nerve transfer (following brachial plexus injury) surgical technique with step by step instructions on OrthOracle. Our e-learning platform contains high resolution images and a certified CME of the Thoracodorsal to triceps nerve transfer (following brachial plexus injury) surgical procedure.
    Restoration of triceps function following a brachial plexus injury is increasingly recognised as a desirable aim of reconstructive surgery. Although restoration of elbow flexion is rightly prioritised over other motor functions the triceps must be given consideration wherever feasible.
    Active triceps control opens up the potential for more refined elbow flexion, improved active control of elbow extension (compared to mere gravity control) as well as improved shoulder stability. Co-contraction of triceps during elbow flexion also improves fine control of hand position by permitting locking of elbow position. Furthermore the restoration of active extension against gravity increases a persons reach space by 800%.
    Historically the results for nerve grafting for elbow extension have been poor. Nerve transfer results have been variable and depend upon the availibility of suitable donor nerves.
    For partial plexus injuries involving the upper plexus, intra-plexal donor nerves will be available and I have found the lateral branch of the thoracodorsal nerve to be a suitable donor due to a well matched axon count, a synergistic contraction that readily permits re-learning, and a reliable length with a short re-innervation distance.
    The thoracodorsal nerve is also a suitable donor in isolated high radial or distal posterior cord injuries where nerve grafting is deemed unsuitable.
    This technique illustrates the key surgical steps required to perform this nerve transfer successfully. Thorough pre-operative examination and investigation, as well as post-operative rehabilitation by therapists experienced in peripheral nerve reconstruction are also integral to the success of this technique.
    Another relevant OrthOracle operative technique that readers will find of use is Brachial plexus reconstruction (intercostal to radial nerve transfer)
    Some relevant surgical anatomy may also be found by reading the Modified Somsak nerve transfer (medial head of triceps nerve transfer to anterior division of the axillary nerve through a posterior approach)

    Indications

    INDICATIONS
    A thoracodorsal to triceps nerve transfer is used where an injury to the upper brachial plexus has also involved the innervation to the triceps which is transmitted predominantly through C7, the middle trunk and the posterior cord. This is typically in root avulsion injuries of C5,6 and 7. It may also be considered for a nerve ruptures deemed unsuitable for nerve grafting or where attempted grafting has failed. It may also be used to treat isolated injuries to the posterior cord or high radial nerve where triceps function has failed to recover and a salvage option is required.
    For this transfer to be viable, the injury must have spared the innervation to latissimus dorsi which derives its supply predominantly from C8. There is some variation in neuroanatomy between patients and careful examination is required to confirm the suitability of the donor.
    The timing of nerve transfer surgery is a key consideration. In complete injuries such as upper plexus root avulsions, the diagnosis and lack of potential for recovery is clear and therefore surgery should be undertaken as soon as possible after injury. In cases where a continuity lesion has failed to undergo recovery within an expected timeframe, there is likely to be a delay to surgery. Delayed nerve transfer is similarly considered where an early attempt at repair or grafting has failed, or when the patient has presented late. In such cases nerve transfer can be offered within the 6-9 month window, allowing enough time for reinnervation to occur within the commonly accepted 1 year timeframe.
    Results of nerve transfer surgery beyond this timeframe are unpredictable but on the whole are much worse. One exception to this though is the longer window for nerve transfer afforded by a continuity lesion that has resulted in some, though sub-functional, reinnervation or a radiculopathy resulting in triceps paralysis.
    SYMPTOMS & EXAMINATION
    Patients with an upper plexus injury that includes C7 will have lost the ability to abduct or externally rotate the shoulder, or flex and extend the elbow. There will be accompanying sensory loss in the C5, C6 and C7 dermatomes. There may also be dry skin and loss of sweating in the affected territory.
    These patients often have varying degrees of nerve pain, which often requires input from a pain specialist.

    INVESTIGATIONS
    Nerve conduction studies and electromyography are the mainstay of investigation, allowing localisation and grading of nerve injury. The timing of these studies are of vital importance. The changes seen following denervation take approximately 3 weeks to appear and studies performed prior to this period are less informative about prognosis.
    An experienced neurophysiologist working closely with the peripheral nerve surgeon will also confirm the availability of potential donor nerves such as the thoracodorsal nerve in the current case. It is not uncommon for a potential donor nerve to have suffered a lesser degree of injury that may be expected to recover within the treatment window. Equally there may be other potential donor nerves that have escaped injury and should be considered.
    Imaging in the form of an MRI scan is a useful adjunct that may help to localise injury and differentiate nerve rupture from root avulsion.
    ALTERNATIVE OPERATIVE TREATMENT
    Reconstruction of triceps function in the context of brachial plexus injury has historically occupied a lower priority than reconstruction of elbow flexion. In extensive injuries, the few donors that are available have already expended by the time the lack of triceps is considered. These patients will often be left to soldier on with gravity assisted elbow extension. Its limitations are mentioned above.
    Alternatives to nerve transfer in general include excision and nerve grafting.
    Alternative donor nerves for nerve transfers include a fascicle transfer from the ulnar nerve, a medial pectoral nerve (often requiring an inter-positional nerve graft), intercostal nerves, Brachial plexus reconstruction (intercostal to radial nerve transfer ,the contralateral C7 nerve, the nerve to levator scapulae or the phrenic nerve.
    NON-OPERATIVE MANAGEMENT
    Non operative treatment is indicated where there is thought to some potential for spontaneous recovery. This requires careful examination and investigation and the outset coupled with close follow up to ensure timely intervention where required. As mentioned above, the lack of elbow extension can be left untreated due to patient choice or the lack of suitable donors in extensive injuries.
    CONTRAINDICATIONS
    Complete denervation for a period of 1 year is unlikely to benefit from nerve transfer surgery. Other patient factors such as fitness for anaesthetic or the patients ability to tolerate rehabilitation are also important factors.

    Setup

    The patient is under a general anaesthetic without muscle relaxant since it is helpful to have reliable nerve stimulation.
    Once the procedure is complete, a local anaesthetic catheter can be left in situ to provide intermittent post operative analgesia for the first 24 hours.
    The patient is positioned supine with an arm table and the shoulder abducted 70 to 90 degrees to allow access to the axilla. A support is placed under the ipsilateral scapula to allow the upper body to rotate a few degrees to the contralateral side.
    Thromboprophylaxis and prophylactic antibiotics should be considered according to local protocol.
    Bipolar and unipolar diathermy and suction are available.
    Once nerves are exposed, a pair of mixter forceps and several sloops of various colours will be required. A set of micro-instruments with jewellers forceps and serrated nerve scissors.
    A microscope which should be checked and setup for the correct focal length, inter pupillary distance and working position prior to starting the procedure.
    Nerve coaptation is made using 9/0 nylon and fibrin glue (Tisseal – Baxter).

    Operation – 1

    The patient is positioned supine with the arm on an arm table
    The shoulder abducted 70 to 90 degrees to allow access to the axilla and the forearm is supinated. A support is placed under the ipsilateral scapula to allow the upper body to rotate a few degrees to the contralateral side.
    The surgical field includes the hand and includes the shoulder and ipsilateral nipple.

    The incison will follow a line placed between the posterior border of biceps and the anterior border of triceps, running proximally towards the axilla.In this case there is a more distal inner arm incision for an Oberlin nerve transfer. This is not the focus of the current technique, but the two incisions will be combined for ease of access in this approach.
    The neurovascular bundle is often palpable in this interval. The incision will extend across the axilla in a zig-zag fashion to avoid the risk of contracture. This may result by crossing the skin fold at 90 degrees.
    The shoulder should be moved into adduction to confirm the position of the skin folds to aid in this step.
    The incision then joins a line placed along the anterior margin of the latissimus dorsi muscle as it lies against the lateral chest wall.

    The skin is incised with a size 15 blade

    The incision is developed to the deep fascia.
    The epitome blade is used to divide the skin and coagulate traversing vessels, dissecting down to the deep fascia

    The loose subcutaneous tissue of the axilla is carefully seperated using the Jamiesons scissorsThe subcutaneous tissues of the axilla may contain one or more branches of the intercostobrachial nerves. These branches they should be identified to avoid inadvertent injury.
    These supply sensation to the skin of the axilla and medial upper arm.
    It is often seen at the level of the second intercostal space emerging through the fibres of serratus anterior. It may be accompanied by a second nerve arising from the third intercostal nerve.

    A mixter and sloop are used to protect the intercostobrachial nerve.
    The intercostobrachial nerve is a lateral cutaneous branch of the second intercostal nerve and is often seen, and needs to be protected, in the proximal extent of the exposure once through the deep fascia.
    In some individuals the intercostobrachial nerve joins with the medial cutaneous nerve of the arm to supply a greater sensory territory.
    The rubber sloop is placed using a mixter. This helps to protect the nerve and safely retract it.
    Injury can lead to debilitating nerve pain.

    The nerve is slooped and the dissection proceeds in the mid axillary line in between the pectoralis major and minor anteriorly and the teres major and latissimus dorsi posteriorly.

    The axilla is entered using blunt dissection with a pair of Jamieson scissorsThe axilla is the pyramidal space that lies inferior to the glenohumeral joint, at the junction of the arm and thorax.
    The axillary inlet is the apex and is formed by the lateral border of the first rib, the superior border of scapula, and the posterior border of the clavicle. The axillay artery and vein, as well as the major nerves that will be exposed shortly pass through the apex.
    The anterior wall contains the pectoralis major, pectoralis minor and subclavius.
    The posterior wall consists of the the subscapularis, teres major and latissimus dorsi. It extends more inferiorly than the anterior wall.
    The medial wall consists of ribs 1-4 as well as their intercostal muscles and part of the serratus anterior.
    The anterior and posterior walls converge to form a narrow lateral wall consisting of the humerus, coracobrachialis and the biceps.

    This is a better image demonstrating the entire axillary space from later on in the same procedure.
    A -The anterior wall has been lifted using the Langenbeck retractor to improve exposure of the neurovascular structures in the apex
    B The medial wall here is covered by the serratus anterior
    C The latissimus dorsi seen here is the main component of the posterior wall in this image
    D The lateral wall is covered by the swab, but one can see how the anterior and posterior walls converge onto it.

    The cords of the plexus are identified as they enter the apex of the axillaThe entire neurovascular bundle is tightly bound together and may be palpated in the apex before exposure with gentle blunt dissection.
    The first identifiable structure is the axillary vein labelled A) lying most superficially in the dissection. This can be seen as the pale structure in the apex.
    Just deep to this will be the axillary artery surrounded by the cords that are named in their relation to the artery.
    These structures pass through the axilla into the arm.
    There are two other two exits from the axilla.
    1. The quadrangular space – a defect in the posterior wall, through which the axillary nerve and posterior circumflex humeral artery exit.
    2. The clavicopectoral space – an anterior wall defect through which the cephalic vein enters and the lateral and medial pectoral nerves exit.

    The axillary vein is traced distally in line with the cords and proximal nerve branches.The incision has been extended to join the upper arm incision used for the Oberlin transfer.
    The line of this incision can be seen in slide 2. It lies along the medial/posterior margin of the biceps and the neurovascular bundle is palpable within this interval.
    This is not a necessary step but for a few extra centimetres has allowed better exposure in this case where a double nerve transfer is being performed.

    Before identifying the radial nerve and the appropriate recipient branches, it is necessary to assess the donor nerve for integrity and length.Dissection proceeds along the posterior wall of the axilla over the surface of latissimus dorsi (A).
    The muscle is closely related to the slips of the serratus anterior that make up the medial wall of the axilla (B).
    Once the muscle is identified, the lateral branch of the thoracodorsal is usually easily seen running along the surface of the muscle from superior to inferior, parallel to its lateral edge.
    The long thoracic nerve that supplies serrarus anterior runs parallel to this nerve along the medial wall of the axilla. Provided the dissection is in the correct plane the two are often seen running a few centimetres apart. They are easy enough to differentiate but stimulation is a useful adjunct to identification.

    The nerve stimulator aids identification of the thoracodorsal nerve
    A twitch of latissimus dorsi muscle fibres using the nerve stimulator confirms that this small structure is a branch of the thoracodorsal nerve.The nerve stimulator used is a Plexygon (TM) peripheral nerve stimulator typically used for regional anaesthesia.
    It allows fine adjustment of the stimulation current and detection of altered stimulation thresholds in nerve surgery.
    The needle is applied as close as possible to the epineurium of the nerve. Here a current of 0.5mA is used, which is suitable for identification of an uninjured nerve, in this case the thoracodorsal nerve.
    Occasionally stimulation of the nerve produces no twitch until a higher current is applied, usually because of inadequate exposure but possibly raising the possibility of undiagnosed injury to this nerve.
    Once identified, the nerve, often a side branch, is exposed and traced proximally to locate the main trunk.

    The lateral branch of the thoracodorsal nerve is exposedJamiesons scissors and Debakeys forceps are used to gently neurolyse the side branch and expose the main lateral branch.

    The thorocodorsal nerve is slooped to aid further exposure and neurolysis

    The donor is handled with the sloop and exposed further proximally and distallyThe sloop allows gentle traction to be placed upon the nerve.
    Exposing the donor proximally allows a more proximal pivot point and again aids reach from donor to recipient.

    Exposing the nerve as distally as possible obtains greater donor length and a better reach to the recipient nerve. Excess length can be trimmed later if required.
    Here the sloop allows gentle lifting of the main trunk of the nerve up to allow neurolysis of the nerve more distally
    As this is done, small side branches can be sacrificed in order to obtain a main trunk of adequate length and calibre.

    The recipient nerve branches to triceps are identified by identifying the cords and nerves of the brachial plexus.In the roof of the axilla the brachial plexus lies closely related to the axillary artery and vein.
    With the donor exposed and neurolysed, the recipient is identified. The radial nerve and its branches to the triceps nerve will emerge from the posterior cord which is closely related to the posterior surface of the axillary artery.
    Here the axillary vein, artery and medial and lateral cords are lifted to visualise the posterior cord and radial nerve at the posterior aspect of the artery.

    This drawing demonstrates the arrangement of the structures passing through the roof of the axilla seen in the previous slide.
    A – Axillary vein
    B – Axillary artery
    C – Medial cord contributing to the median nerve and ulnar nerve
    D – Posterior cord
    E – Lateral cord giving rise to the musculocutaneous nerve

    The structures of the infraclavicular plexus are identified and sloopedA – Axillary artery, red sloop
    B – Median nerve blue sloop
    The musculocutaneous nerve may be seen just lateral to the median nerve.
    C – Fibres of the coracobrachialis muscle through which the musculocutaneous nerve passes can be seen overlying the plexus in the distal part of the exposure.
    Anatomical variations are common. Stimulation with the nerve stimulator confirms the identity of each nerve.

    The posterior cord and radial nerve are exposed lying posterior to the axillary arteryThe posterior cord / high radial nerve has now been slooped in a second blue sloop.
    Stimulation of this nerve produces a flicker in wrist and hand extension.
    There is no discernible flicker in any of the components to triceps which is consistent with the injury pattern and preclinical examination findings.

    The wound is irrigated.

    The posterior cord / radial nerve is traced distally to identify the triceps branches.The radial nerve passes distally over the latissimus dorsi and teres major towards the triangular interval. This is a space just inferior to the teres major muscle. Its boundaries are as follows:
    Superiorly – teres major
    Medially – the long head of triceps
    Laterally – the lateral head of triceps / the humerus
    A posterior view of this area of anatomy is seen from step 20 onwards of Modified Somsak nerve transfer (medial head of triceps nerve transfer to anterior division of the axillary nerve through a posterior approach)and will provide a useful cross reference.
    2-3cm distal to the current exposure these will pass posteriorly through the triangular interval.
    The long and medial head branches tend to run together as a single trunk until the lateral border of the latissimus dorsi where they separate just prior to passing through the triangular interval.

    The radial nerve branches into the long and medial head of triceps are sloopedThe distal red sloop now contains a common trunk containing both the long and medial head branches to triceps. This will be our recipient nerve.
    This common branch to triceps separates away from the rest of the radial nerve within the axilla and can therefore be neurolysed proximally in order to gain length where needed.

    The recipient nerve branch is neurolysed as proximally as possibleThe donor branches are stimulated up to a maximal current to ensure that there is no residual or recovered function. No muscle contraction is seen.
    Stimulating the rest of the radial nerve demonstrates contraction in the distal radial motors that include extensor carpi radialis longus and brevis, which extend the wrist and extensor digitorum comminis which effects finger metacarpophalangeal joint extension.
    Once again the assistant holds the sloop which permits gentle traction and neurolyis.

    Operation – 2

    The thoracodorsal nerve is mobilised and divided as distally as possible.Neurolysis helps to mobilise the donor nerve taking care to minimise direct handling. The sloop is used to manoeuvre the nerve.
    All of the mobilisation of the nerve should be completed before the distal end is divided.
    This includes exposing the nerve as far proximally as feasible to gain as much reach as possible.
    Clearly, the total number of axons is higher in the more proximal donor nerve, before they branch off to supply the muscle, but getting the two nerve ends to reach for a tension free direct coaptation is the initial priority.
    Once mobilised the nerve is divided sharply as distally as possible.

    The common branch into triceps branch is divided as proximally as possible.Both donor and recipient are placed side by side.
    Taking the donor as distally as possible and the recipient as proximally as possible ensures that a tension free coaptation can be performed.
    At this stage there may be excessive length. Trimming the recipient nerve back allows the coaptation to be performed closer to the muscle thus reducing time to reinnervation.
    Donor and recipient are placed side by side on a piece of coloured background material.
    The field is irrigated with normal saline.

    The microscope is brought into the fieldThe microscope position is adjusted to allow a full view of the surgical field with comfortable access for surgeon and assistant.

    Working in the axilla can make optimal positioning of the scope difficult and usually requires the assistant to stand whilst the operating surgeon is seated.
    Focal length and and any lens correction are dialled in.
    The arm is placed into 90 degrees of abduction during neurorrhaphy ensuring that tension is minimised during the initial post operative recovery.

    The two nerve ends are placed on the background ready for coaptation.
    A – Branch to long head and medial head of triceps
    B – Lateral branch of the thoracodorsal nerve

    The nerve coaptation is completed using 9/0 nylon suture4 circumferential epineural sutures are placed.
    An ideal coaptation should be tension free throughout a normal range of movement of the limb.
    This particular suture line will be placed under maximal tension in full shoulder abduction and external rotation position.

    Fibrin glue is used to augment the repair.This adds some extra support and resistance to traction at the coaptation site.
    An initial layer of glue is placed around the repair site to seal the epineurium.

    The background is then rolled over the repair site and held in a position whilst the glue sets in a cylinder around the epineurium.

    Both nerve trunks are then anchored to the surrounding bed with more fibrin glue.
    The wound is irrigated and haemostasis ensured.

    A layered closure is performed.Deep dermal sutures are placed usung 3/0 monocryl is used.

    4/0 monocryl is used to perform a subcuticular closure.Local anaesthetic is infiltrated around the wound edges to provide some post-operative analgesia.

    The wound is sealed with tissue glue.
    This allows the patient to shower normally after 3-4 days, and removes the need for suture removal.

    Soft non-adherent dressings are used to provide padding in the axilla.The arm is placed in a polysling with a bodystrap to support the arm and prevent excessive tension on the nerve transfer.

    Post Operative

    The patient is discharged home on the day of surgery if well and pain well controlled.
    The polysling is used to support the arm. The patient is seen at 10 -14 days for a wound check and to see a physiotherapist to commence shoulder mobilisation out of the sling. Full shoulder abduction is permitted after 8 weeks.
    Therapy includes our nerve transfer retraining protocol with a physiotherapist trained in peripheral nerve rehabilitation an the use of functional electrical stimulation (FES).
    In the early period isometric contraction of latissimus dorsi are perfomed with an attempt to visualise simultaneous elbow extension.
    This is accompanied by neural gliding excercises.
    The first sign of reinnervation is expected at about 3 months and is commonly preceded by tenderness within the recipient muscle. This may be elicited by gently squeezing the muscle.
    At this stage, excercises to inititate activation of triceps with latissimus dorsi contraction are performed.
    As the triceps gains strength and can be activated independently the focus is turned to independent triceps activation, strengthening and useful function.
    This stage takes 12 months but further gains in strength and control are ongoing over 1-2 years beyond this.

    Recommended Reading

    Soldado, F., Ghizoni, M. F., & Bertelli, J. (2015). Thoracodorsal nerve transfer for triceps reinnervation in partial brachial plexus injuries. Microsurgery, 36(3), 191–197. doi:10.1002/micr.22386
    The largest series published using this transfer. Bertelli used the entire thoracodorsal nerve instead of just the lateral branch. The series contains 8 patients with 7 achieving grade M4 elbow extension and 1 achieving grade 3.
    Pet, M. A., Ray, W. Z., Yee, A., & Mackinnon, S. E. (2011). Nerve Transfer to the Triceps After Brachial Plexus Injury: Report of Four Cases. The Journal of Hand Surgery, 36(3), 398–405.
    Mackinnons group used an FCU fascicle in this series but it does contain a report of a single case of a thoracodorsal nerve transfer using an interpositional nerve graft.
    Flores, L. P. (2013). Reanimation of elbow extension with medial pectoral nerve transfer in partial injuries to the brachial plexus. Journal of Neurosurgery, 118(3), 588–593.
    An alternative strategy to reinnervate triceps is to use the medial pectoral nerve. Flores reports the results in 12 patients. Half of these cases required an interpositional nerve graft. All cases obtained grade M3 or M4 power.

    Reference

    • orthoracle.com

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