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Brachial plexus exploration and long thoracic nerve decompression

    Overview

    Learn the Brachial plexus exploration and long thoracic nerve decompression surgical technique with step by step instructions on OrthOracle. Our e-learning platform contains high resolution images and a certified CME of the Brachial plexus exploration and long thoracic nerve decompression surgical procedure.
    The long thoracic nerve arises from the C5,6 and 7 roots in the neck and passes posterior to the brachial plexus across the lateral border ofthe first rib to enter the costoclavicular space. The anatomy has many variants and these abnormal innervation branches render the nerve susceptible to traction injury, compression or iatrogenous injury.
    Long thoracic nerve palsy results in paralysis of the serratus anterior muscle with loss of scapula stabilisation, elevation and rotation. Diagnosis of the condition is straightforward due to the obvious wasting of the muscle and the winging of the medial border of the scapula on arm lateral and forward elevation.
    The underlying pathology is difficult to diagnose. Common causes are neurogenic from viral neuritis, injury, traction or compression. Neuritis may have a painful prodrome and wider changes within the plexus on electormyography. The differential is myopathic winging due to primary motor pathology and weakness. EMG is useful in diagnosis and planning surgery. Tenderness over the course of the nerve at the scalene interval in the posterior triangle , the apex of the axilla or the mid-axillary line can guide the surgeon towards the primary site of pathology for exploration and decompression.
    The case presented here had tenderness over the scalene interval and the lateral border of the first rib and so the first part of the decompression was to explore and stimulate the nerve origin and proximal course in the neck.

    Indications

    INDICATIONS
    Persistent painful long thoracic palsy of at least 6 months without spontaneous recovery with tenderness over the origin and proximal course of the nerve in the posterior triangle of the neck and the costoclavicular space plus supportive electromyographic evidence of axonopathy,
    SYMPTOMS & EXAMINATION
    The typical patient will report prominence of the scapula border on forward elevation of t he affected arm. In cases of mild weakness the prominence is more obvious on slow descent of the arm from the forward elevated position and there is alteration of the scapulo-thoracic rhythm with intermittent control and loss of control due to co-traction of other stabilising muscles. There is a loss of elevation of the scapula due to seratus paralysis. The scapula will be pulled in a medial direction towards the midline due to the unopposed force of the trapezius muscle. This distinguishes it from the the rare form of lateral displacement and winging due to paralysed trapezius action in the case of a spinal accessory nerve palsy with unopposed action of the serratus anterior.
    IMAGING
    Plane xrays or CT may define other scapula pathology that may present with asymmetrical abnormal prominence of a scapula such as bone tumours, osteochondromata of the posterior ribs or a Sprengel shoulder. MRI imaging of the neck may exclude structural abnormalities such as intrinsic nerve tumours, extrinsic tumours compressing the plexus or anomalous boney anatomy such as cervical ribs. Fibrous bands in the scalene muscles or anomalous vascular pedicles crossing the nerves will not be seen and so MRI is of rather limited benefit. Following brachial neuritis there make be signal changes, constrictions or swelling in the nerves of the plexus. Cervical spine MRI will define the severity of any degeneration disc disease and nerve root compression. This doesn’t normally present with scapula winging however because of the widespread innervation of the serratus anterior from the C5,6 and 7 roots.
    ALTERNATIVE OPERATIVE TREATMENT
    The long thoracic nerve can be explored and decompressed in the neck or high in the axilla as it crosses the lateral border of the upper three ribs. If there is an iatrogenic transection the damaged segment of the nerve can be reconstructed using autologous nerve graft or a distal nerve transfer undertaken from the thoracodorsal nerve. The proximal nerve for the upper 2-3 serratus slips can be reinnervated from the nerve to subclavius as long as this nerve is stimulating normally and not involved in the pathology.
    Salvage of winging can be achieved with musculotendinous transfer of the pactoralis major lower fibres to the serratus anterior or with tenodesis or arthrodesis of the medial scapula border to the ribs.
    NON-OPERATIVE MANAGEMENT
    Functional rehabilitation using therapy to improve motor power and co-ordination of the per-scapular muscles can help in cases of partial recovery.
    CONTRAINDICATIONS
    Exploration of the neck is straightforward for a brachial plexus surgeon and should be contemplated if there is pain associated with the dysfunction and tenderness over the course of the long thoracic nerve in the scalene interval and over the lateral border of the first rib. It is controversial whether nerve reconstruction should be contemplated beyond 12 months from onset of paralysis, however in the author’s experience there is frequently some attempt at reinnervation following neuritis or some preservation of function following a compression and in such cases it may be possible to improve a persistent conduction block affecting the nerve through decompression and neurolysis.
    A contraindication is myopathic winging such as is seen in fasciscapulohumeral dystrophy. This will not respond to decompression. In such cases genetic screening, muscle biopsy and referral to a neurologist specialised in myopathy will help to confirm this suspected diagnosis.

    Setup

    Operation – 1

    The patient is positioned on an operating table with the arm abducted at the shoulder to a narrow arm board. The head is elevated 30 degrees to reduce congestion of the neck veins and the head is rotated slightly to the contralateral side and supported on a head ring. The ipsilateral torso is exposed.
    The exposure of the neck may be sufficient but in cases of long thoracic palsy access to the axilla and the lateral chest wall may be required for a decompression of the lower long thoracic nerve or for nerve transfer from the thoracodorsal nerve.

    The hand is prepped and then grasped by the scrub team to facilitate preparation of the rest of the upper limb, posterior shoulder, neck and ipsilateral upper chest.

    The limb is prepped over the posterior neck and shoulder so that the important muscles can be directly visualised and palpated by the operating surgeon during nerve stimulation.

    The limb is draped from the midline of the neck, just below the ear, across the posterior shoulder and across the mid chest. The ipsilateral limb is fully prepped and exposed to monitor contractions during nerve stimulation. The drapes are secured with sterile adhesive tapes.

    The exposed area of the neck for access to the posterior triangle, the costoclavicular space and the shoulder.

    The skin incision is marked. In elective surgery for long thoracic nerve exposure and decompression a low transverse incision parallel and 2cm above the clavicle approximately 5cm long is sufficient for access to the brachial plexus and long thoracic nerve.

    The skin is incised to platysma. I do not use local anaesthetic and adrenaline because I do not want to introduce uncertainty should the local anaesthetic cause a block to the deeper nerves and nerve stimulation thresholds are unreliable.

    The platysma is divided with cutting diathermy and a west self-retaining retractor is place in the wound.

    The external jugular vein is visible just deep to platysma. The scissors are used to develop the plane posterior to the vein to identify the supraclavicular nerves which should be protected.

    Fine tipped 90 degree mixter forceps are used to develop a plane deep to the supraclavicular nerves (SCNs).

    The SCNs are elevated in the mixter forceps.

    The end of the sloop is delivered to the mixter jaws. Carefully open and close the mixter jaws to capture the tip of the sloop without damaging the nerves. Avoid excess sloop material catching on the nerve as the mixter is withdrawn.

    The sloop in position identifies the supraclavicular nerves and can be used to provide gentle traction during external neurolysis.

    A tributary of the external jugular vein(EJV) is clipped and cut prior to tying of feach end with 3’0 vicryl ties. Meticulous haemostasis is essential during a neck dissection.

    The vein tributary is cut.

    Each end is secured with vicryl ties.

    The sternocleidomastoid is visible in the medial end of the wound and must be retracted medially. If there is a large lateral insertion to the clavicle, this can be elevated from the clavicle to improve access.

    The tied vein is mobilised medially to deepen the exposure.

    The sternocleidomastoid is mobilised medially exposing the omohyoid medial muscle belly on the fat pad overlying the scalenus anterior and the brachial plexus.

    The medial belly of the omohyoid is elevated over the jaws of mixter forceps to reveal the laterally placed central tendon. A sling holds the central tendon low in the neck posterior to the sternoclavicular joint. The sling must be released to fully expose the central tendon which is then divided.

    The central tendon is now visible. In this case there is muscle across the central point. Care should be taken during division to ensure that there is no bleeding in case the muscle retracts into the neck and bleeding continues. The ends can be tied but usually diathermy is sufficient. I do not repair the omohyoid at the end of the procedure.

    The omohyoid has been divided and has retracted exposing the fat pad medial to the external jugular vein.

    Large tributaries of the external jugular vein cross the fat pad. the fat pad must be elevated with careful haemostasis.

    The fat pad is moved medially and the fascial sheath over the upper trunk is identified in continuity with the fascia over the scalenus anterior beneath.

    The C5 contribution to the phrenic nerve is seen on the lateral edge of the scalenus anterior. The phrenic nerve traverses the scalenus anterior from lateral to medial as it passes distally in the neck.

    Operation – 2

    Nerve stimulation confirms that this is the C5 contribution to the phrenic nerve. A normal stimulation threshold of 0.1mA is achieved.

    Further exposure demostrates the scalenus anterior (SA), the phrenic nerve (P) and the C5 contribution to the phrenic nerve (C5P).

    The phrenic nerve is mobilised using mixter forceps. The DeBakey forceps are pointing to the C5 nerve root beneath the fascia posterior and lateral to the scalenus anterior.

    The phrenic nerve is mobilised.

    A blue sloop is passed around the phrenic nerve to isolate it and tag it to prevent inadvertent injury with retractors.

    The sloop is carefully passed deep to the phrenic nerve from medial to lateral.

    Nerve stimulation confirms that this is the main phrenic nerve.

    The anatomy of the blood vessels in the posterior triangle is variable. Typically the transcervical trunk arises anteriorly and crosses the plexus. One variation is a deep branch crossing between the upper and middle trunks known as the deep cervical artery. The transcervical may branch into the superficial ascending cervical and the deep cervical arteries. The suprascapular artery passes laterally and posteriorly with the suprascapular nerve. A deep dorsal cervical artery variant my cross the lateral first rib and the long thoracic nerve origin to exit withthe dorsal scapular nerve posterior to scalenus medius.
    Here the transcervical artery and veins cross the plexus and must be divided. Ligaclips are used to achieve safe division.

    A second ligaclip is applied medial to the first.

    The transcervical artery is divided between the ligaclips with scissors.

    A small nerve lies on top of the C5 root. This is the nerve to subclavius which passes under the fat pad inferiorly towards the undersurface of the clavicle.

    A second large vascuclar pedicle is seen here and has been divided between a double row of ligaclips. This is an unusual variant.

    The nerve to subclavius is insulated in a red sloop and the anatomy is confirmed with nerve stimulation.

    Deep to the nerve to subclavius the upper trunk is identified and the red sloop is repositioned around both the upper trunk and the nerve to subclavius.

    Leaving the upper trunk is the suprascapular nerve (SSN).

    A second red sloop is passed around the suprascapular nerve (SSN).

    The SSN is gently retracted superiorly to expose the anterior (AD) and posterior (PD) divisions of the upper trunk.

    Nerve stimulation confirms the anatomy. The key muscles are seen to contract in the exposed arm and can be readily palpated.

    The upper trunk is moved anteriorly. The red sloops have been removed. The C7 nerve root lies beneath with a more transverse orientation. Usually a deep branch of the transcervical artery passes through this interval. This is not present in this case.

    The sloops from the upper trunk and the SSN are removed to allow exploration of the posterior aspects of the C5 and C6 roots looking for contributions to the long thoracic nerve (LTN). The contribution to the long thoracic nerve (CLTN) is tagged in the upper yellow sloop. The second laterally placed yellow sloop remains around the supraclavicular nerves. The scalenus medius muscle is now seen posterior to the brachial plexus. The nerve stimulator is being used to identify a nerve posterior to the scalenus medius.This is the area where the dorsal scapular nerve is typically identified.

    The nerve stimulator is confirming the anatomy or the origin of the dorsal scapular nerve (DSN) to the rhomboids and levator scapulae as it exits posterior to scalenus medius.
    This nerve is not always identified at this point. The DSN may take origin from the C4 root in a “pre-fixed” brachial plexus.

    Another major vascular pedicle, most likely a deep dorsal scapular artery aberrant vessel is seen cross ing the posterior triangle at the level of the lateral border of the first rib. This vessel is larger and directly contacts the C5 and C6 contributions from the roots to the long thoracic nerve (LTN). The LTN in this cases has low union of the C5 and C6 contributions distal to the first rib and the C7 contribution joins even lower in the upper axilla. The later formation ofthe main LTN trunk renders these small branches vulnerable to compression. This vascular leash compresses the nerves against the lateral border of the first and second ribs.
    The vessels are divided between ligaclips.

    Following decompression the nerves lie in a normal position in the posterior triangle.

    The upper blue sloop identifies the suprascapular nerve from the upper trunk and the lower the long thoracic nerve contributions forming the C5 and C6 component now freed in the interval posterior to the plexus and travelling distally lateral to the ribs. the course is now direct.

    Increasing stimulation of the LTN from 0.1-5mA shows only a flicker of contraction in the upper serratus. This is in keeping with the clinical and neurophysiological pre-operative diagnosis of severe axonopathy in a continuity lesion. The longstanding nature of the compression and paarlysis makes it doubtful whether there is the possibility for reinnervation. In such cases the upper serratus may recover but the innervation distance to the lower serratus makes it unlikely that recovery will be useful. in such cases a distaal nerve transfer from the thoracodorsal lateral branch to the lower LTN is advised. This is illustrated elsewhere on OrthOracle.

    Operation – 3

    A layered closure is performed with vicryl to the platysma and subcuticular 4’0 Monacril to the skin.

    Steristrips are applied to support the wound edges. An occlusive waterproof dressing is then applied over the top.

    Post Operative

    The arm is rested in a polysling for 1 week for comfort. the wound is kept clean and dry for 1 week after which the patient can shower and replace the dressing.
    Start gentle range of motion exercises and neural glide exercises with a physiotherapist. The physiotherapist should commence place and hold serratus strengthening exercises and introduce training to improve scapulothoracic movements when there is sufficient recovery.

    Recommended Reading

    The long thoracic decompresion is beneficial if performed early. In such cases neurolysis alone may achieve good functional recovery in the serratus. Later presentation treated with nerve transfer achieved function in 3/3 in a series by Mackinnon et al. and 5/5 in the series by Leechavengongs et al. although in the latter series only 2 were graded as good function, 2 fair and 1 poor.

    References:
    1: Soldado F, Ghizoni MF, Bertelli J. Thoracodorsal nerve transfer for triceps reinnervation in partial brachial plexus injuries. Microsurgery. 2016 Mar;36(3):191-7
    2: Bertelli JA, Ghizoni MF. Long thoracic nerve: anatomy and functional assessment. J Bone Joint Surg Am. 2005 May;87(5):993-8
    3. Horwitz MT, Tocantins LM. An anatomic study or the role of the long thoracic nerve and the related scapular bursae in the pathogenesis of local paralysis of the serratus anterior muscle. Anat Rec. 1938;71:375-85
    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
    5: Maire N, Abane L, Kempf JF, Clavert P; French Society for Shoulder and Elbow SOFEC. Long thoracic nerve release for scapular winging: clinical study of a continuous series of eight patients. Orthop Traumatol Surg Res. 2013 Oct;99(6 Suppl):S329-35
    6: 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. doi: 10.3171/2011.5.JNS101615
    7: 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
    8: Novak CB, Mackinnon SE. Surgical treatment of a long thoracic nerve palsy. Ann Thorac Surg. 2002 May;73(5):1643-5. PubMed PMID: 12022573.

    Reference

    • orthoracle.com

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