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Common peroneal nerve ganglion; decompression and neurectomy

    Overview

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    Learn the Common peroneal nerve ganglion; decompression and neurectomy surgical technique with step by step instructions on OrthOracle. Our e-learning platform contains high resolution images and a certified CME of the Common peroneal nerve ganglion; decompression and neurectomy surgical procedure.

    Intraneural ganglia are benigin mucinous cysts that occur within peripheral nerves. They are a rare cause of foot drop when they occur in the common peroneal nerve, causing a local compressive neuropathy as they expand within the epineurium.
    Although they have been recognised and treated surgically for many decades, their exact pathogenesis remains unknown. It has become increasingly apparent that they have an intra-articular origin which, due to a defect in the proximal tibiofibular joint capsule, permits communication with the main nerve trunk through an articular nerve branch.
    This intra-articular, neural communication between the nerve and the proximal tibiofibular joint is often identifiable on a T2 weighted MRI image and should be carefully identified on surgical exploration.
    Early surgical intervention is recommended to decompress the common peroneal nerve in order to allow motor recovery and improve neuropathic pain. Extraneural excision with an decompressive epineurotomy has been described but current evidence suggests that the articular branch should also be ligated to eliminate the potential for recurrence.
    Where denervation is acute and the motor end plates are preserved, motor recovery may be expected following decompression. However this is difficult to predict and some groups have combined decompression with a tibial motor fascicle transfer.
    Where the tibiofibular joint has undergone degenerative change and is the source of pain one may consider a concomitant joint procedure such as an arthrodesis or excision arthroplasty.
    The following technique illustrates the surgical approach, and peripheral nerve surgical techniques required to perform an intraneural decompression of the common peroneal nerve as well as a neurectomy of the articular branch.
    Readers will also find the following associated OrthOracle techniques of interest:
    Common peroneal nerve decompression, neurolysis and wrapping with the AxoGen AxoGuard nerve protector
    Peroneal Nerve exploration and decompression
    Common peroneal nerve decompression and application of NeuroCap device (Polyganics)
    Tibialis posterior transfer (through interosseous membrane )for foot drop

    Indications

    PRESENTATION
    Peroneal nerve intraneural ganglia are typically diagnosed after intrusive symptoms become apparent. These may include neuropathic pain or sensory disturbance in the deep peroneal nerve territory. Motor symptoms include weakness of ankle dorsiflexion or toe extension. Motor and sensory loss in the superficial peroneal nerve territory are less common but are described and involve weakness of ankle eversion.
    Close questioning may reveal a longer time course over which symptoms have evolved, such as mild weakness or recurrent trips on the affected side. Symptoms may also arise acutely after trauma around the knee. Symptoms may at first be intermittent with episodic dysfunction related to activity level.
    In some cases a mass overlying the fibular neck is noticed by the patient.
    The patient in this example technique had presented to his local hospital with a palpable mass and an acute loss of deep peroneal sensory and motor function.
    He underwent an ultrasound guided aspiration of the swelling before referral for a peripheral nerve opinion. Since this condition is rare, surgery or aspiration elsewhere prior to diagnosis or referral is common and can make subsequent decision making difficult, particularly if there has been transient or partial improvement.
    EXAMINATION
    A complete neurological examination is essential. One must exclude the presence of a cause within the lumbar spine or proximal sciatic nerve both of which present with a different pattern of pain and sensory / motor loss to a common peroneal nerve lesion.
    Each muscle should be examined and graded according to the MRC system. Subtle motor deficits may be detected by comparison to the contralateral limb. Joint stiffness may result from longstanding weakness and loss of range of motion particularly of ankle dorsiflexion is common.
    Sensory examination using either a visual analogue scale or a Semmes-Weinstein monofilament is sensitive enough to pick up clincially important variations. Tapping over the course of the peripheral nerves of the lower limb may elicit a Tinel-Hoffman sign where the patient experiences pain radiating into the corresponding sensory territory. Palpating over the fibular neck may reveal a palpable swelling within the nerve. This may extend proximally into the popliteal fossa and is usually associated with a positive Tinels.

    INVESTIGATIONS
    A plain X-ray film may show evidence of cystic change in the proximal tibiofibular joint.
    An ultrasound may demonstrate a multilocular swelling along the course of the common peroneal nerve.
    An MRI is essential and a T2 weighted scan demonstrates a hyperintense lesion extending along the course of the nerve. In many cases a pedicle can be identified on one of the slices extending into the tibiofibular joint. Occasionally this extends proximally enough to involve the tibial nerve. Finally, denervation changes, such as loss of muscle volume and increased signal on T2 or STIR representing oedema. In more chronic denervation muscle atrophy may be combined with fatty infiltration seen as increased signal on a T1 weighted image.
    MR arthrography, whilst not essential, can be helpful in confirming communication with the joint.
    Other investigations include nerve conduction tests which will detect conduction abnormalities commonly in the deep peroneal nerve but also occasionally in the superficial peroneal nerve. Typically the tibial and sural nerves should be normal.
    Electomyography will delineate the distribution and extent of any muscle denervation and will aid differentiation between acute and chronic denervation which is useful for planning surgery and the need for further reconstructive surgery. It is therefore essential that the neurophysiologist is part of the MDT discussion.
    ALTERNATIVE OPERATIVE TREATMENT
    Some groups report the addition of an immediate nerve transfer alongside the initial decompression. The rationale for this is to reanimate tibialis anterior within an appropriate therapeutic timeframe, which may be lost if recovery remains poor after decompression alone. The results of such a transfer remain speculative and should be discussed in a multi-disciplinary meeting and with each individual patient, in order to arise at an informed surgical strategy.
    Failure to recover ankle dorsiflexion may necessitate a tibialis posterior tendon transfer or consign the patient to lifelong dependence upon an ankle foot orthosis.
    In recurrent cases where the local soft tissue bed is poor and liable to encase the nerve in dense scar, a nerve wrap may limit scar tether over the epineurium and allow the nerve to glide with knee and ankle motion. The Axoguard nerve wrapping technique is described here:
    Common peroneal nerve wrapping technique

    NON-OPERATIVE MANAGEMENT
    Whilst decompression and neurectomy of the articular branch remain the mainstay of surgical treatment in patients with neurological symptoms, one may elect to watch and wait if patients present with an asymptomatic ganglion, for example if the lesion is an incidental finding. The natural history of asymptomatic lesions remains unknown.
    CONTRAINDICATIONS
    The general contraindications to surgery apply and the soft tissue envelope and local skin condition should be suitable for surgery. However even in advanced lesions with widespread chronic denervation changes, there may be merit in decompression to treat pain and prevent further sensory or motor loss.

    Setup

    The patient is posititoned in a lateral position with the operated leg facing up. Surgery is performed under general anasthaesia with short acting muscle paralysis to allow intraoperative nerve stimulation.
    The entire leg and thigh are prepped and draped and a thigh tourniquet is applied.
    The patient is positioned in a lateral position with the operated side facing up. The entire foot, leg and thigh are prepped and draped to allow extension of the approach into the popliteal fossa if necessary. A thigh tourniquet is positioned. The foot is left exposed to provide clear visual confirmation during intra-operative nerve stimulation.
    The consent should include the options of treating any pathology within the proximal tibiofibular joint, as well as nerve wrapping, and nerve transfer should these be deemed necessary after intra-operative assessment of the nerve.
    A nerve stimulator is set up.
    Basic instruments, including Jamiesons scissors and Debakeys forceps along with a Mixter and sloops are all required for nerve handling. In addition, microinstruments and an operating microscope are needed for the intraneural dissection.
    Bipolar diathermy is used.
    Local thromboprophylactic guidance is followed with a TED stocking and Flotron on the non-operated leg.

    Operation – 1

    The sagittal T2 weighted MRI images demonstrate a hyperintense multiloculated lesion within the common peroneal nerve(A)as it crosses the fibular neck.

    An axial T2 weighted image demonstrated the lesion crossing the fibular neck and closely related to the articular branch into the proximal tibiofibular joint.
    Denervation changes in the anterior compartment can be seen with increased signal in these muscle groups.

    The drapes are applied to leave the entire lower limb below the thigh exposedThe entire foot will need to be visualised during the steps requiring nerve stimulation.
    The nerve may need to be exposed into the popliteal fossa if the ganglion tracks proximally.
    The surgeon should stand facing the posterior aspect of the leg.

    An extensile approach directly along the course of the common peroneal nerve as it traverses across the fibular neck is marked and incised.The surface anatomy is marked out along with the planned incision.
    As it leaves the popliteal fossa, the common peroneal nerve lies immediately deep to the investing fascia, running along the upper border of the lateral gastrocnemius and medial to the biceps tendon.
    It then runs along the fibular neck, giving off a number of articular branches. The nerve then passes under a thickened septum to lie under the fibres of peroneus longus. At this point it branches into its main superficial and deep components.

    The proximal tibiofibular joint is palpated and marked out.
    In this case there is a palpable swelling within the common peroneal nerve.
    Its proximal extent is ill defined but distally it appears to disappear over the fibular neck.
    The tourniquet if used, is inflated (to 300mmmHg) at this point to allow a bloodless field during the approach and nerve exposure.
    The tourniquet time is minimised as nerve stimulation is unreliable after about 20 minutes of tourniquet inflation.

    Skin, fat and fascia are incised taking care to keep full thickness flaps.
    The oblique incision runs along the line of the nerve and can be extended along the course of the nerve if a more proximal or distal nerve exposure is required.

    The fat is incised in the line of the skin incision . In this plane traversing vessels can bleed as they are divided. They are coagulated carefully with bipolar diathermy.

    Sharp dissection through the deep fat exposes the investing fascia of the leg.
    Bipolar diathermy is used to coagulate any traversing vessels and to maintain a bloodless surgical field.

    The deep fascia of the leg is incised along the line of the common peroneal nerve using Jamieson’s scissors.The nerve is usually palpable just under the fascia. In this case the incision in the fascia is centred over the palpable swelling within the nerve.
    In larger individuals the nerve may not be palpable.
    Palpation of the biceps femoris tendon insertion into the fibula head is helpful in this scenario. The nerve lies just posterior to this tendon as it leaves the popliteal fossa.
    A cross section of the nerve traversing this area is seen in slide 2.

    The peroneal tunnel is where the nerve runs across the fibular neck, under the intra-muscular septum and peroneus longus. This tunnel is de-roofed along the course of the nerve proximally and distally to ensure adequate access above and below the ganglion.
    Spreading the scissors in the plane under the fascia and over the nerve allows the nerve to fall away from the fascia which can then be divided safely.
    The assistant ensures that the nerve is protected during a proximal to distal exposure, which carries a greater risk of avulsing a nerve branch as it arises from the main nerve trunk.

    The exposed common peroneal nerve is inspected once the tunnel is opened.Any adherent tissue is peeled away from the nerve.

    Two separate areas of fusiform swelling within the nerve can be seen and palpated.
    The branching anatomy is now inspected, in particular the presence of an articular branch which may be seen to arise in the proximal part of this exposure, running parallel to the nerve trunk along superio-medial surface.

    To inspect the nerve circumferentially a Mixter is used to pass a sloop around it proximally.
    This minimises trauma to the nerve as it is handled.
    The articular branch may be passing through the area marked A on this slide and this area will be inspected and any potential nerve branches traced back to the main trunk.

    The posterior crural intermuscular septum, a thickening of fascia that marks the lateral border of the peroneus longus muscle, is a common site of compression of the nerve and must be divided to continue the exposure.The swelling within the nerve appears to come to an abrupt end where an oblique fascial band runs along its superficial surface. This is the posterior crural intermuscular septum, a thickening of fascia that marks the lateral border of the peroneus longus muscle.
    This is a common site of compression of the nerve and must be divided to continue the exposure.
    To divide it a plane between it and the underlying nerve needs to be developed before the septum is divided in a line that over lies the nerve.
    Ordinarily the plane is easy enough to enter and perform the division safely but here the septum was tightly pressed against the nerve and required development with the Jamieson’s scissors, as shown in this slide.

    The posterior crural intermuscular septum is divided.
    The peroneus longus muscle fibres can then be seen.
    An assessment of the hue of the muscle is a guide to whether it has been denervated for any length of time.
    This muscle appears to be a healthy red/pink colour, in keeping with the clinical and EMG findings which suggested normal function within the superficial peroneal nerve.

    There is a corresponding septal edge just deep to the nerve at the same level.
    This is also a potential source of compression and should therefore be divided.

    The nerve stimulator is used to identify the two main components of the nerve, the superficial and deep peroneal nerves.The nerve stimulator needle is gently applied to the epineurium. This stimulated motor fibres and a corresponding twitch is seen in the leg or foot. The needle can be applied to different parts of the nerve to map out the fascicle arrangement within the nerve trunk as well as the identity of key branches. Sensory fibres do not elicit any response.
    After the two motor components and sensory components have been mapped out, the current is gradually reduced to give a measure of the minimum current required to elicit discernable motor activity.
    In this case, laterally the superficial peroneal component stimulates the peroneus longus at a threshold of 0.5mA.
    The more medial fascicles leading to the deep peroneal nerve stimulate at higher threshold of 2mA.
    Tibialis anterior and extensor digitorum longus both show a flicker at this current and both fail to demonstrate increased activity as the stimulation current is gradually increased. This is indicative of some intact motor fibres but significant loss preventing normal recruitment at higher current levels.
    This may be due to a partial conduction block or loss of a significant number of the motor axon population.

    The articular branches are dissected out and a sloop passed around themOnce isolated, the swelling within the main nerve trunk can be seen entering this articular branch and running along its length towards the proximal tibiofibular joint which can be palpated.
    This branch can be seen within the second red sloop.
    Further distally there appears to be a second articular branch with a similar intraneural swelling communicating with the main nerve trunk.
    Stimulation of these two branches confirms that they contain no motor component and are likely two articular branches through wich the intraneural ganglion communicates with the proximal tibiofibular joint.
    The presence of a second branch raises the possibility that it may be a branch into tibialis anterior. Further confirmation of the identity of both articular branches is made after clear identification of a more distal branch to tibialis anterior that is readily identifiable under stimulation.
    In the next few steps these branches are dissected out distally further confirming their connestion into the joint.

    Once identification is complete each component of the nerve is slooped individually
    The second articular branch is slooped.

    The superficial peroneal nerve is slooped

    The deep peroneal nerve is slooped.
    A Articular branch
    B Articular branch
    C Superficial peroneal nerve
    D Deep peroneal nerve

    The deep peroneal nerve is traced further into the muscles anteriorly.
    Some muscle fibres are divided using bipolar diathermy. Two small langenbeck retractors are used to retract the muscles to reveal the course of the deep peroneal nerve and its motor branches under the muscle fibres in the anterior compartment.

    This image is taken from the other side of the table and so the anterior leg is towards the bottom of the screen and the right side is proximal.
    The nerve is traced distally as it passes through a number of intermuscular fascial bands which have been divided in this image to decompress the nerve and visualise it passing through.
    The anterior crural intermuscular septum lies between peroneus longus and extensor digitorum longus (EDL).
    There is a further septal band between EDL and tibialis anterior.
    As this is divided one can see extensor hallucis longus (EHL) just deep to EDL.
    The pale pink of the EHL is suggestive of complete denervation.
    The tibialis anterior looks a little less denervated but is still paler than the peroneus longus and EDL which are normal in appearance.
    A – Peroneus longus / EDL
    B – EHL
    C – Tibialis anterior

    The articular branches are neurolysed and followed up to the proximal tibiofibular joint.The forceps are pointing out the location of the proximal tibiofibular joint.

    Micro-instruments are used to perform an epineurotomy of each of the articular branches in turn.

    Operation – 2

    Both nerves are filled with ganglion which is in continuity with the main nerve trunk of the common peroneal nerve.

    A separate epineurotomy is made over the proximal ganglion in the common peroneal nerve.
    To do this a fresh 15G blade is used to make a longitudinal incision through the epineurium.
    This incision is placed parallel to any fascicles that are visible just under the epineurium.
    The epineurotomy therefore enters directly into the cavity of the ganglion with intact fascicles seen to either side.
    In this particular case the ganglion is filled with fatty infiltration with a small amount of clear fluid which tracks into the articular branch.
    Much of the ganglion fluid has already been removed by the aspiration this patient underwent at his referring unit.
    In many cases the loculations are much more tensely filled with fluid.

    The nerve is gently palpated to demarcate further loculations.

    There are further smaller swellings within the nerve along the course of fibres leading into the deep peroneal component.

    The microscope is brought into the field and set up

    Under low magnification the ganglion is traced out into its connection to the second articular branch.

    After a second epineurotomy over the distal ganglion, the cavity is followed into the the second articular branch. Again it is clear that the ganglion is intimately related to an articular branch.

    The articular branches are both divided, severing the connection between nerve and joint and thus reducing the chances for reaccumulation of the ganglion over time.

    A section of the divided nerve is sent to the histology laboratory.

    The tourniquet is released and any bleeding controlled using bipolar diathermy.A further confirmation of stimulation thresholds should be delayed as this will be unreliable immediately after tourniquet deflation.

    The nerve stimulator is used to assess final nerve function prior to closure.The combination of extrinsic and intrinsic decompression will often result in some improvement in motor function by improving local conduction.
    In this case the stimulation thresholds for both the tibialis anterior and EDL improved to 0.5mA with some increased recruitment at higher currents.
    The EHL did not show any activity throughout, which is in keeping with the clinical and neurophysiological findings.
    This retesting is useful in providing some prognostic information about the potential for future recovery. An immediate improvement may correlate with a good potential for future motor recovery.

    The wound is washed out with normal saline.
    3/0 Monocryl is used to bring the deeper layers of the wound together.

    A 4/0 monocryl running subcuticular suture line is placed.

    The wound edges are supported by steristrips.

    A non adherent sealed dressing is placed
    This is followed by a wool and crepe bandage.

    Post Operative

    The patients post operative neurological function is assessed as this can often demonstrate evidence of early motor improvement and is documented.
    The patient is usually discharged home the same day after review by a physiotherapist to confirm safe independent mobilisation. Some patients require crutches to aid mobilisation for the first week.
    Simple oral analgesia usually controls post operative pain but a significant number of patients are already on neuropathic pain agents which should be continued and tapered down under appropriate medical supervision.
    In the UK the guidance is set out under the National Institute for Care Excellence (NICE) guideline 173.
    The patient returns to clinic at 1 week post surgery for a wound check and examination of sensory and motor function.
    Nerve gliding excercises are commenced to prevent restrictive scarring around the nerve.
    The patient is then reviewed at 6 weeks and 3 months post surgery to assess progress.

    Recommended Reading

    1. Peroneal intraneural ganglia: the importance of the articular branch. A unifying theory.
    Spinner RJ, Atkinson JL, Tiel RL.
    J Neurosurg. 2003 Aug;99(2):330-43. doi: 10.3171/jns.2003.99.2.0330.
    This review outlines the synovial theory of intraneural ganglia and describes the concepts covered in the introduction to this technique.
    2. Peroneal intraneural ganglia: the importance of the articular branch. Clinical series.
    Spinner RJ, Atkinson JL, Scheithauer BW, Rock MG, Birch R, Kim TA, Kliot M, Kline DG, Tiel RL.
    J Neurosurg. 2003 Aug;99(2):319-29. doi: 10.3171/jns.2003.99.2.0319.
    This is a multi-centre clinical series that describes 24 cases of common peroneal intraneural ganglia all of which were treated by experienced peripheral nerve surgeons. It suggests that the presentation , operative findings and results of treatment are alll predictable. It suggests possibly addressing the tibiofibular joint to prevent extraneural recurrence.
    3. Long-Term Functional Outcome After Surgical Treatment of Peroneal Intraneural Ganglion Cyst.
    Lucattelli E, Menichini G, Brogi M, Roselli G, Innocenti M.
    World Neurosurg. 2019 Dec;132:e217-e222. doi: 10.1016/j.wneu.2019.08.195. Epub 2019 Sep 5.
    A longitudinal series demonstrating excellent motor recovery following surgery with no intraneural recurrence, but a 25% extraneural recurrence. Over 80% of patients had a history of knee trauma.

    Reference

    • orthoracle.com

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