//

Thoracodorsal nerve to long thoracic nerve transfer for scapula winging

    Overview

    Learn the Thoracodorsal nerve to long thoracic nerve transfer for scapula winging surgical technique with step by step instructions on OrthOracle. Our e-learning platform contains high resolution images and a certified CME of the Thoracodorsal nerve to long thoracic nerve transfer for scapula winging surgical procedure.
    The serratus anterior is supplied by the long thoracic nerve from C5,6 and 7. Long thoracic nerve palsy may follow traction injury, viral neuritis or nerve entrapment. Paralysis of the serratus anterior leads to winging of the scapula with poor scapula elevation, poor scapula control and impaired upper limb function, particularly with the arm in the forward elevated position. Exploration and decompression in the [osterior triangle of the neck, at the lateral border of the upper ribs or within the axilla may identify a cause of dysfunction that may be amenable to decompression. This is described elsewhere on OrthOracle. Failed recovery following decompression or persistent dysfunction at 6 months may be treated with a distal nerve transfer from the thoracodorsal nerve to the lower serratus anterior. Nerve transfer offers a reliable method of reinnervating paralysed muscles and utilises the proximity and redundancy of adjacent motor nerves close to the motor point of the paralysed muscle. Reinnervation distances are typically short resulting in good functional outcomes even when there is a delay to presentation or when other initial treatment modalities have failed.

    Indications

    INDICATIONS:
    The long thoracic nerve arises from the C5,C6 and C7 nerve roots and has a long course from the posterior triangle of the neck, through the costoclavicular space to the axilla and the lateral chest wall where it supplies the serratus anterior which arises from the ribs 1-8. There are a number of innervation variants and the well described pattern of individual root contributions combining to a common trunk in the neck is only seen in approximately 1/3 of cases. Common variants are low contributions from the C7 within the costoclavicular space, contributions from the dorsal scapular nerve and aberrant innervation including contributions from C8.
    The main indication for exploration of the long thoracic nerve is a persistent dysfunction with altered scapulothoracic motion and scapula winging. Entrapment of the long thoracic nerve can occur in the scalenus medius due to fibrous bands, aberrant vascular pedicles, points of tether from variant innervation patterns, at the lateral border of the first rib or in the axilla.
    Loss of long thoracic nerve function may follow injury to the nerve, entrapment or viral neuropathy. The result is winging of the medial border of the scapula due to paralysis of the serratus anterior. This results in loss of scapula stability, control and elevation. Winging due to long thoracic nerve palsy should be distinguished from winging due to spinal accessory palsy or from loss of dorsal scapular nerve function. Poor scapula control may be associated with myopathic changes rather than neurogenic features and consideration should be given to rare conditions including facioscapulohumeral dystrophy.
    Serratus anterior dysfunction from neurogenic causes may be amenable to physiotherapy rehabilitation, however persistent denervation on electromyography and persistent motor dysfunction may suggest nerve entrapment and consideration should be given to decompression in the neck, at the lateral border of the upper ribs and the axilla. Absent function after decompression and denervation for at least six months can be salvaged with a distal nerve transfer from the thoracodorsal nerve.
    SYMPTOMS & ASSESSMENT:
    There is a paralysis of the long thoracic nerve resulting in scapula winging and impaired scapula elevation. There is prominence of the scapula when the arm is lifted, incomplete abduction and forward elevation plus limited endurance with the arm elevated. A viral prodrome should be sought in the history with a typical history of severe neuropathic pain. A history of injury, traction or compression from carrying heavy shoulder bags may be elicited. The patient may report pain deep in the posterior triangle, high in the axilla or in the lateral chest wall.
    Pain may be elicited when tapping over the course of the nerve, particularly at points of entrapment. There is no cutaneous innervation and so no sensory symptoms are reported.

    INVESTIGATION:
    MRI scan of the brachial plexus and cervical spine can exclude other causes of upper cervical root dysfunction including cervical root compression, tumours and some anatomical variants. Unfortunately not all anatomical variants are apparent on imaging and fibrous bands, intramuscular course of nerves and aberrant vascular pedicle compression are really only made during surgical exploration.
    Neurophysiological investigations including electromyography (EMG) are essential components of the preoperative assessment of patients prior to consideration of nerve transfer surgery. EMG recording from the serratus anterior carries a small risk of pneumothorax and patients should be informed of this prior to referral for investigation. Electromyography can assess the extent of denervation of the potential target muscle as well as the integrity of the function within the donor. This is important when the cause is unknown and can confirm neurogenic pathology isolated to the LTN or part of a wider pattern typical of a brachial plexopathy or viral brachial neuritis.
    OPERATIVE ALTERNATIVES:
    The alternatives to nerve transfer surgery include simple decompression for an entrapment neuropathy, musculo-tendinous transfer or the lower pectoralis major to stabilise the scapula or scapulothoracic arthrodesis.
    NON-OPERATIVE ALTERNATIVES:
    Non-operative treatment strategies include physiotherapy rehabilitation to strengthen any residual serratus anterior function and restoration of normal rhthym through recruitment of accessory scapula stabilising muscles.
    CONTRAINDICATIONS:
    The main contraindication to nerve transfer surgery is a muscle that has been denervated for too long, typically between 9 and 12 months for a lower motor neurone complete injury and no donor muscle of sufficient strength in the vicinity with an intact nerve supply available for nerve transfer. Patients must be able to understand the planned treatment and be able to comply with the extensive period of post operative rehabilitation necessary to achieve a good functional outcome.

    Setup

    The patient is under general anaesthesia without neuromuscular blockade. The arm is placed on a side table and the chest elevated with a gel pad under the ipsilateral scapula. The chest wall is prepped and included in the surgical field as well as the whole upper limb.
    In addition to basic instruments, a deep-jawed self-retaining retractor is required.
    An operating microscope, nerve sloops, microinstruments, serrated nerve scissors, jeweller’s forceps and nerve stimulator plus needle are essential.
    Tisseel fibrin glue may be used to support the neurorraphy.
    Bipolar diathermy is needed for cautery near the nerves. In the superficial part of the wound monopolar diathermy may be used and so a diathermy plate should be placed on the patient in addition to an electrode to complete the nerve stimulator circuit.

    Operation – 1

    The patient is positioned on an operating table with an arm table allowing shoulder abduction and access to the axilla and the chest wall. The mid axilary line is marked which is the surface anatomy of the course of the long thoracic nerve (LTN) from the first rib to the serratus anterior. The course of the thoracodorsal nerve from the posterior cord to the latissimus dorsi muscle is also marked. The surgical incision is either a longitudinal incision along the mid-axillary line or as is marked here an oblique incision extending from the axilla anteriorly and distally. This latter incision affords ready access to both nerve trunks.

    A an oblique incision is made in the lower axilla extending to the lateral chest wall at the mid-axillary line. This is a vascular area and meticulous haemostasis with bipolar diathermy is needed throughout the procedure.

    A West self-retaining retractor is placed in the wound edges. The axilla is exposed with blunt dissection using Jamieson scissors and initially fine toothed Adson’s forceps.

    The intercostobrachial nerve (lateral branch of the 2nd intercostal nerve (T2)) is identified and tagged with a blue sloop.

    Diathermy cautery of superficial vessels crossing this vascular plane.

    Gentle traction on the blue sloop helps to identify the deeper course of the intercostobrachial nerve which should be protected to prevent iatrogenic injury, nerve pain or numbness in the axilla and upper medial arm.

    A deeper Travers self-retaining retractor is positioned transversely within the wound. Dissection continues with Jamieson scissors in the mid-axillary line distal to the ICBN.
    ICBN: Intercostobrachial nerve
    MAL: Mid-axillary line

    The long thoracic nerve (LTN) is identified running along the mid-axillary line with the lateral thoracic artery. A fine tipped mixter (90 degree) forceps is passed under the LTN in preparation to receive the end of a surgical loop. Extreme care must be taken when passing a mixter and when closing the jaws to avoid inadvertent injury to the LTN or snagging with a sloop on the posterior aspect as the mixter is withdrawn. For this reason the sloop should be introduced to the jaws by the tip and no excess should protrude.

    The yellow sloop is used to gentley elevate and retract the LTN for a limited external neurolysis.

    The nerve stimulator is used to confirm just a flicker of contraction in the lower serratus anterior at 5mA. The normal stimulation threshold for contraction is 0.1mA. This is indicative of a severe denervation with only limited residual axon function.

    The LTN is traced proximally and any abnormal crossing bands that could contribute to compression are divided. A large Langenbeck retractor can be positioned carefully in the upper wound to aid this exposure. Ensure that the ICBN is not under the retractor to prevent a traction injury.

    Palpate the lateral border of the latissimus dorsi in the posterior axillary line and using Jamieson scissors explore the axillary aspect of the latissimus dorsi 3cm posterior to the mid-axillary line. The thoracodorsal neurovascular bundle runs obliquely to meet the latissimus dorsi and the nerve runs along this border before branching into terminal branches, typically a major lateral and medial branch and then multiple smaller direct muscle branches.

    Separating this tissue should be done cautiously to avoid vessel injury as it is an extremely vascular plane with vessels supplying the deeply sited latissimus dorsi.

    The thoracodorsal nerve main trunk is identified at the level of the ICBN and a mixter passed deep to it in preparation for passing a sloop.

    A red sloop is passed around the main thoracodorsal nerve proximally at the level of the ICBN.

    The thoracodorsal nerve is traced distally with limited external neurolysis to define the branching anatomy. This anterograde dissection is preferable to distal to proximal retrograde dissection where inadvertent dissection in the axilla of a side branch can cause an iatrogenous neurotmesis of side branches.
    A vascular pedicle is seen crossing the TDN and will need to be divided between ligaclips or the dissection of the LTN will need to continue distal to this vessel pedicle. I prefer to avoid unnecessary bipolar cautery near nerves.
    LTN: Long thoracic nerve
    TDN: Thoracodorsal nerve
    VP: Vascular pedicle
    ICBN: Intercostobrachial nerve

    Distal to the crossing vessel the sloop is reapplied. A small vein away from both the LTN and the TDN is cauterised with bipolar diathermy on the lowest possible functional setting.

    The TDN and its terminal branches are traced distally. It is intimately related to the thoracodorsal vessels at this point and careful mobilisation is necessary to expose the nerve branching anatomy.

    Another crossing vascular pedicle prevents complete elevation of the TDN to the wound.

    Following careful division of the vascular pedicle across the nerve the terminal branching anatomy of the TDN can be clearly defined.

    A broad Langenbeck retractor carefully positioned affords a clear view of the branching TDN.
    LTN: Long thoracic nerve
    TDN: Thoracodorsal nerve
    ICBN: Intercostobrachial nerve

    The upper LTN neurolysis continues to the lateral border of the 3rd rib. The LTN is sectioned just distal to the branch to the serratus anterior muscle slip arising from the second rib. This allows sufficient distal LTN stump to turn through 180 degrees distally to the co-aptation site with the TDN. In addition there is potential for some recovery of the upper 1st and 2nd rib origins of serratus to recover following the concomitant decompression of the LTN in the posterior triangle featured elsewhere on OrthOracle.

    The cut distal LTN is visible in the wound. The sloop on the TDN is used to elevate the branches for stimulation to define the best branch that will transfer directly to the cut LTN for a direct tension-free co-aptation.

    A large terminal motor branch from the TDN is chosen as the donor with sufficient length to rotate and co-apt directly to the distal LTN. The branch is sectioned after confirming a normal stimulation threshold of 0.1mA with good contraction.

    The TDN donor is reflected proximally and the distal LTN stump turned inferiorly for the transfer. There is sufficient length for the transfer with redundancy. Excess redundancy is removed by trimming the LTN stump so that the co-aptation is moved closer to the denervated serratus anterior allowing a more rapid reinnervation.

    Operation – 2

    The nerve transfer is sutured with 9’0 nylon under the operating microscope.

    After debriding loose connective tissue and excess epineurium there is a good size match of the donor and recipient fascicles.

    The neurorraphy is reinforced with Tisseel fibrin glue.

    The Tisseel is placed circumferentially around the co-aptation.

    The microsurgical background is rolled and used to help seal the nerve transfer.

    The completed nerve transfer.

    The sloop on the intercostobrachial nerve is removed and the wound is prepared for closure.

    Local anaesthetic infiltration to the wound edges.

    Closure in layers with a subcuticular 3’0 Monacril for the skin.

    Note that in this case there was a decompression of the LTN in the posterior triangle, however there was no useful residual function in the nerve and due to the length of denervation at 9 months the decision was made to undertake the distal nerve transfer from the TDN.

    Steristrips are applied to support the wound edges and an occlusive dressing is placed over the wound. The arm is immobilised in a polysling with a body strap for three weeks to prevent inadvertent disruption of the anastomosis.

    Post Operative

    A waterproof dressing with absorbent pad is applied to the wound. The wound should be kept clean and dry for 7 days after which the patient can shower then replace the dressing. A polysling is applied to the upper limb with a torso strap around the waist before the patient wakes from surgery. The polysling and torso strap should be maintained for 3 weeks to prevent excessive passive movement at the shoulder.
    During this phase the patient is encouraged to maintain isometric contraction of the donor latissius dorsi muscle in the sling and to visualise the combination of latissimus contraction an shoulder stabilisation and elevation.
    Nerve transfer rehabilitation involves a 6-phase programme of activity developed at the Centre for Nerve Injury and Paralysis, Birmingham, UK.
    Phase 1 – Pre-operative phase: Education and donor optimisation. Introduction to trophic stimulation and the concept for functional electrical stimulation (FES).
    Phase 2 – Protection phase: During the immediate post-operative period the nerve transfer is protected from inadvertent injury with the arm immobilised. Isometric contraction of the donor and visualisation of the combination donor-recipient action is performed during this period which typically lasts 3 weeks.
    Phase 3 – Prevention phase: During this phase the arm is mobilised and neural gliding is commenced. Joint range of motion exercises (active and passive) are commenced to prevent joint contractures developing. The isometric exercises are continued and isotonic and eccentric exercises are commenced for the donor muscle to maintain function and restore strength. Functional stimulation can be commenced on the donor muscle. Trophic stimulation can be maintained on the recipient muscle.
    Phase 4 – Power phase: During this period the donor muscle is strengthened and the recipient muscle starts to respond. Typically the first sign of reinnervation is a tender muscle squeeze sign due to small fibre reinnervation. Typically this is 3 months following transfer but is affected by the distance of the co-aptation from the recipient motor point.Visible flickers of contraction follow within 6 weeks and donor activation potentiate the recipient response. FES continues and the phase lasts for approximately 6-12 months during which useful motor grade returns: Medical Research Council – (MRC) Grade 3-4.
    Phase 5 – Plasticity: During this phase the patient works on activation of the recipient muscle without activation of the donor. This phase can overlap with phase 4 and is guided by a therapist specialised in nerve transfer rehabilitation.
    Phase 6 – Purpose: During this phase the patient introduces function tasks discussed as objectives during the pre-operative phase. This period of training is tailored to the individual and includes work hardening. Improvements are typically found in power and functional performance for at least 2 years following nerve transfer surgery.

    Recommended Reading

    Author’s note:
    Th eTDN transfer is a useful method of restoring function to the lower 2/3 of the serratus after axonal degeneration. It can be combined with a decompression when there is insufficient time for full reinnervation. The optimum time to undertake the nerve transfer is when it is established that there is no spontaneous recovery after 6 months and before 9 months to allow sufficient time for the nerve transfer to reinnervate the lower serratus anterior.
    References:
    1: Raksakulkiat R, Leechavengvongs S, Malungpaishrope K, Uerpairojkit C, Witoonchart K, Chongthammakun S. Restoration of winged scapula in upper arm type brachial plexus injury: anatomic feasibility. J Med Assoc Thai. 2009 Dec;92 Suppl 6:S244-50
    2: Uerpairojkit C, Leechavengvongs S, Witoonchart K, Malungpaishorpe K, Raksakulkiat R. Nerve transfer to serratus anterior muscle using the thoracodorsal nerve for winged scapula in C5 and C6 brachial plexus root avulsions. J Hand Surg Am. 2009 Jan;34(1):74-8
    3: Ray WZ, Pet MA, Nicoson MC, Yee A, Kahn LC, Mackinnon SE. Two-level motor nerve transfer for the treatment of long thoracic nerve palsy. J Neurosurg. 2011 Oct;115(4):858-64
    4: Noland SS, Krauss EM, Felder JM, Mackinnon SE. Surgical and Clinical Decision Making in Isolated Long Thoracic Nerve Palsy. Hand (N Y). 2017 Oct 1:1558944717733306. doi: 10.1177/1558944717733306
    5: Novak CB, Mackinnon SE. Surgical treatment of a long thoracic nerve palsy. Ann Thorac Surg. 2002 May;73(5):1643-5

    Reference

    • orthoracle.com

    Tags:

    You might be interested in

    Dark mode powered by Night Eye