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From eMedicine; Nerve Entrapment Syndromes of the Lower Extremity
DEEP PERONEAL NERVE ENTRAPMENT Section 7 of 10
Author Information Proximal Entrapments Of The Lower Extremity Obturator Nerve Entrapment Common Peroneal Nerve Entrapments Posterior Tibial Nerve Entrapment: Tarsal Tunnel Syndrome Superficial Peroneal Nerve Entrapment Deep Peroneal Nerve Entrapment Interdigital Neuritis Patient Education Bibliography
The deep peroneal nerve is 1 of the terminal branches of the common peroneal nerve, originating just distal to the fibular head. The deep peroneal nerve enters the anterior compartment in front of the interosseous membrane. It courses lateral to the TA muscle. It travels along with and usually lateral to the anterior tibial artery and vein.
It courses between the TA and the EDL in the proximal third, and between the TA and EHL in the middle third of the leg and anterior to the anterior tibial vessels. At approximately 3-5 cm proximal to the mortise, the EHL crosses over the nerve, and the nerve is then seen between the EHL and EDL in the distal part of the leg an average of 1.25 cm above the ankle joint. Occasionally, the nerve does not enter this interval until just distal to the ankle mortise. At this level, the nerve is about 3 mm in size and may be under the extensor retinaculum since the inferior extensor retinaculum can be centered, above, or below the ankle mortise level.
Approximately 1 cm distal to the ankle mortise, the nerve divides into lateral and medial branches. The terminal lateral branch curves laterally and supplies the EDB, extensor hallucis brevis (EHB), the adjacent tarsal and tarsometatarsal joints, including 2-4 branches innervating the anterolateral part of the subtalar joint, and occasionally the second and third dorsal interosseous muscles.
The terminal medial branch is just medial to the dorsalis pedis artery and just lateral to the first tarsometatarsal joint. It travels between EHL tendon and EHB muscle on the dorsum of the foot. At approximately the metatarsophalangeal (MTP) joint level, the EHB crosses over the nerve, and the nerve is then between the EHB and the EDL to the second toe. It then divides into the dorsolateral cutaneous nerve of the great toe and the dorsomedial cutaneous nerve of the second toe. It supplies the sensation to the web between the first and second toes, dorsalis pedis artery, the adjacent MTP and interphalangeal joints, and usually the first dorsal interosseous muscle. It occasionally supplies the second and third interosseous muscles.
This entrapment is most commonly due to compression of the deep peroneal nerve and repetitive mechanical irritation of the nerve at the ankle beneath the extensor retinaculum. The entrapment of the deep peroneal nerve in this location has also been called the anterior tarsal tunnel syndrome. Within the anterior tarsal tunnel, there are 4 tendons, one artery, one vein, and the deep peroneal nerve. Typically, the nerve is entrapped beneath the superior edge of the retinaculum. In this location, it is compressed by the crossing EHL tendon and under the EHB muscle, and directly over osteophytes, exostosis, or bony prominences of the talotibial, talonavicular, naviculocuneiform, or cuneiform metatarsal joints. Presence of an os intermetatarseum between the first and second metatarsal base has also been associated with entrapment symptoms.
Space-occupying lesions, such as ganglia, also contribute to symptoms in this tight canal. Repeated dorsiflexion and plantarflexion of the ankle contributes to this mechanical condition by pinching the nerve in this tight space, and inversion trauma has been shown to lower the motor conduction velocity of the deep peroneal nerve.
Postural causes such as wearing high-heeled shoes in which the nerve is stretched over the midfoot joint and prolonged or repetitive sitting on the plantarflexed feet such as is necessary for performing the Namaz in Islam are other commonly seen etiologies. Other etiologies include anomalies of the EHB distal to the retinaculum.
Entrapment of the deep peroneal nerve, however, can occur anywhere along the course of the nerve including just distal to the neck of the fibula, anterior to the ankle joint, and distal to the inferior extensor retinaculum but would not be considered anterior tarsal tunnel syndrome. Common etiologies for proximal entrapment of the deep peroneal nerve include space-occupying lesions about the proximal fibula, surgical procedures about the lateral knee (including proximal tibial osteotomy), and chronic anterior exertional compartment syndrome, seen in athletes.
The usual complaint of patients with deep peroneal nerve entrapment includes vague pain, burning sensation, or cramp over the dorsum of the foot, which may or may not involve the first web space. Patients may have associated sensory changes in the first dorsal web space. Some patients may present with neuritic symptoms along the course of the nerve such as unrelenting pain at rest and during sleep. There may be pain in the ankle region even if only the motor nerve is involved. Symptoms may only be present or be worse with a certain shoe or boot or with certain activities. Although less common, patients with more proximal entrapment may present with frequent tripping due to foot drop or weakness of the EHL.
With proximal entrapment, motor dysfunction may be demonstrated on regular gait examination, with presentations such as a dramatic foot drop. However, symptoms are usually more subtle and are noted only on heel walk or a hop test. With long-standing dysfunction, plantarflexion of the ankle with extension of the toes can compress the nerve as it passes beneath the extensor retinaculum, which can worsen the symptoms. Muscular atrophy may also be noted in the anterior compartment or of the EDB with distal entrapment of the nerve.
With distal entrapment, tenderness may be elicited along the entrapped segment of the nerve over the anterior ankle or just distal to it, and an underlying bony prominence is usually present. Provocative dorsiflexion and plantarflexion of the ankle may bring on or increase symptoms. A sensory deficit in the first web space may also be detectable. Most patients have a positive Tinel test result over the entrapment site of the nerve, commonly around the fibular neck or over the anterior ankle.
Incomplete involvement can also occur, affecting isolated sensory or motor branches. Temporary resolution of the neuritic symptoms following an injection of the nerve with plain lidocaine in the site of entrapment is a good indicator verifying the diagnosis.
Bony impingement can usually be seen on conventional lateral ankle or foot radiographs. Different angle oblique radiographs are necessary to better define smaller osteophytes, exostosis, or other bony masses about the anterior ankle or the dorsomedial midfoot. Knee radiographs are needed for suspected proximal involvement. If necessary, a CT scan will provide more detailed information on the bony anatomy of the area.
Ultrasonography has been useful for diagnosis and localization of cystic masses causing an impingement of the nerve. Occasionally, MRI is necessary to obtain additional information about soft tissue masses, synovial reaction, adjacent bone, and chondral and soft tissue involvement.
Electrodiagnostic studies are helpful in further defining the zone of compression and evaluating for concomitant radiculopathy or peripheral neuropathy. In deep peroneal nerve injury or entrapment, the results may show a decrease in the amplitude of the response if axonal involvement is present or conduction block occurs from demyelination. The distal latency may be prolonged if entrapment is present in the anterior tarsal tunnel region, and the NCV is decreased across the leg region if the entrapment or injury is more proximal. An accessory may also be present. The accessory peroneal nerve originates from the superficial peroneal nerve and traverses posterior to the lateral malleolus to provide variable innervation to the EDB. This anomaly is identified when the response is recorded from the EDB that is larger with proximal stimulation (at the fibular head) than with distal stimulation (at the ankle).
Needle examination may reveal the presence of fibrillations and positive sharp waves in the EDB only if present at the anterior tarsal tunnel. If entrapment is present more proximally, the denervation is present in the TA as well as the EDB.
Denervation may be present, however, with other neurological conditions. The short head of the biceps femoris as well as the medial gastrocnemius, tensor fascia lata, and lumbar paraspinal muscles should be tested if there are findings in the deep peroneal muscles to rule out a more proximal problem such as a radiculopathy. The absence of findings in these muscles and the peroneus longus and brevis confirms the presence of a deep peroneal motor-nerve injury.
Some reports have stated that there may be a high percentage of denervation present in the foot intrinsic muscles in healthy subjects, but recent reports have found that the actual percentage of abnormal findings in healthy subjects is low for a well-trained electromyographer. Many times, electrodiagnostic test findings are normal because these dynamic syndromes frequently improve or resolve at rest.
Nonsurgical care most importantly involves patient education to eliminate the predisposing factors. For example, padding of the tongue of the shoe or elimination of shoes with laces or use of alternative methods for lacing and avoidance of high heels may be sufficient to resolve symptoms.
Physical therapy is useful for strengthening the peroneal muscles in cases associated with weakness and in individuals with chronic ankle instability; the use of modalities may also improve symptoms.
In-shoe orthotic devices are helpful in certain instances, such as for correction of a biomechanical malalignment in gait, for example for patients with severe flatfoot or cavus foot.
The use of NSAIDs and antineuritic medication may be helpful as an adjunct to other treatment modalities. Injection of steroids plus lidocaine near the site of involvement can reduce symptoms in some individuals.
In addition, consideration should be given to a metabolic workup to rule out thyroid dysfunction and diabetes in select individuals. Further workup may be necessary to rule out lumbar radiculopathy.
Surgical options can be considered once symptoms are deemed refractory to nonoperative measures. Options include surgical release of the deep peroneal nerve in primary and idiopathic cases to excision of the nerve in cases of direct nerve injury due to previous surgery, direct trauma, or in revision cases. Surgical decompression of the nerve can provide immediate improvement of symptoms.
In 1990, Dellon reported on surgical release of the deep peroneal nerve in 20 patients. With a mean follow-up time of more than 2 years, he reported excellent results in 60% of patients, good in 20% of patients, and not improved in 20% of patients.
The surgical procedure can include part or all of a longitudinal straight or S-shaped incision on the dorsum of the foot, starting between the bases of the first and second metatarsals and extending proximally to the anterior ankle, depending on the predicted location of entrapment. The deep fascia overlying the deep peroneal nerve and the dorsalis pedis artery is released, as is the inferior part of extensor retinaculum, and the superior part can be preserved to maintain the function of extensor tendons. The deep peroneal nerve is followed proximally and distally to verify a full release. Nerves that appear to be normal in consistency and size can be released.
It is important to remove other underlying etiologies for entrapment or stretch, such as complete excision of underlying osteophytes during surgery. The decision to perform a neurolysis versus an excision, transposition, or both is dependent on the severity of injury to the nerve. Excision of the nerve in cases in which the nerve is abnormal, such as those directly manipulated during surgery or entrapped in scar tissue, is indicated. Neuroma in continuity is best excised and allowed to retract into deep tissues, and transposition of the stump into muscle belly may be possible depending on the level of excision. In 1998, Dellon and Aszmann reported on excision of the superficial and deep peroneal nerves in the lateral leg with translocation of the nerves into a muscle with excellent results in 9 of 11 patients.
When entrapment of the nerve is caused by the EHB muscle, the muscle is hypertrophied and has thick fibrous bands that compress the deep peroneal nerve. Decompression of the nerve and excision of the muscle and fibrous band can lead to complete resolution of pain, but numbness in the first web space may be persistent.
Entrapment of the deep peroneal nerve can occur anywhere through its course, from just distal to the fibular head to the dorsal first web space. The most common location of entrapment is just anterior to the ankle under the extensor retinaculum. Entrapment at this site is also called anterior tarsal tunnel syndrome. The most common etiologies for entrapment include prominent bony or soft tissue masses such as exostoses, osteophytes, or ganglion cysts, acute direct trauma, or chronic compression or stretch, such as with lace up shoes or high heels.
The most common presenting symptom is a vague pain on the dorsum of the foot with occasional associated numbness or weakness. Treatment options are aimed at eliminating underlying etiologies of entrapment
Anne, what do you think is the mode of action of acupuncture in such cases?
According to GerAc studies http://www.gerac.de/ (The German Multicenter, Randomized, Partially Blinded, Prospective Trial of Acupuncture) is unknown. It does not matter where o how you put the needles; you will achive the same results using "real acupuncture" or "sham acupuncture". You can find a recent article about acupuncture and knee osteoarthritis in Annals of Internal Medicine. Does this sound familiar?
I, and many others who practice acupuncture wish we had a complete answer to that Simon.
I have only recently completed my basic acupuncture training and am 'finding my way' at present. I have already found it to be very beneficial in plantar fasciitis, heel pain, plantar digital neuritis and many other conditions.
There is an increasing amount of reliable acupuncture research coming to the fore and there is certainly sufficient to move acupuncture from the realm of fantasy to that of serious science.
One postulation widely accepted is the gate theory of pain. Simply put, this suggests the existence of gates or filters in the posterior horns of the spinal cord (A new way of thinking about pain, Wall and Melzack, 1984; Wall, 2000). When the gates are open, pain information can be sent upwards to the brain; but when the gates are closed, transmission is stopped . The control of these gates is supposed to be by incoming messages from the periphery. Simply put, these gates are closed by impulses coming from the large diameter fibres acting like a brake and opened by the small-diameter fibres, acting like an accelerator.
This theory is the basis of TENS for the relief of pain. It has changed and expanded throughout the years but the basic features are still widely accepted.
The small-diameter nerves in muscles send impulses to the spinal cord, the midbrain and pituitary. Once these areas are stimulated they release endorphins and monoamines, which ‘block pain messages’, and thus analgesia is initiated.
The limbic system is also more than likely involved in acupuncture analgesia. By needling directly into the tender area one may simply block 'pain messages' to the brain.
There are several overlapping theories as to the mechanisms of acupuncture in pain relief. I would recommend you read 'Acupuncture in Practice - Beyond Points and Meridians' Butterworth Heinemann 2005, ISBN 0-7506-5242-X, written by Dr Anthony Campbell. This is a well-written and easy to read book on the subject, which removes a lot of the mysticism of acupuncture.
Yes it is true that you will achieve the same results using "real acupuncture" or "sham acupuncture", although there are a few exceptions to that rule. This is however, generally true of foot problems.
There is a 'double entendre' in the trial you mention, as this means using the traditional method versus the modern method of acupuncture.
The jury is still out on which is the best method to use. Whilst this paper found no difference, others have found that sham points seem to work in 33-50% of subjects and true points work in 55-85% of cases (Vincent CA, Richardson PH  The Evaluation of Therapeutic Acupuncture: concepts and methods. Pain 24: 1-13). With the traditional method you have to identify the acupuncture point for the problem you are treating (the true acupuncture points). In modern acupuncture you insert the needles into the troublesome area (the sham acupuncture points). Both appear to work equally well, possibly for the reasons I postulated in my previous post?
The benefit of acupuncture is that it is comparatively safe, is easy to use in conjunction with Podiatry and often works in disorders for which there is little or no effective treatment.
1) Inject a large amount of Bupivicaine under the retinaculum in the area of the entrapment. The fluid pressure may release adhesions as the tissues are stretched, and the local anesthetic may have a sustaining affect. It is a rather benign procedure to try, and I have seen *dramatic* results. (Steroids in this region must be used with caution, or even avoided, due to potential damage of nearby tendons.)
2) Try neural tension testing, and if positive, have the patient do nerve gliding techniques.
3) Of course, the basics.... no lace pressure over the area, address pathomechanics if relevent, NSAIDs, Lidocaine patches for night pain.
I don't see any benifit from accupuncture for this problem, unless it is unresponsive to local treatments. Would you suggest accupuncture for someone with a splinter, or would you first try to remove it???
Of course you address any mechanical problems at the same time as using any treatment modality. I perhaps naively assumed that Simon had already tried the ‘basics’ and was looking for another 'gem' to enhance the outcome.
Nerve pain is always difficult to treat, but cannot in any way be compared to treating a splinter. Do you practice acupuncture?
I would prefer to try acupuncture before injecting anaesthetics or NSAIDs into the body.
I don't practice accupuncture, but we do have a physiatrist in our group who is certified in it. We usually reserve accupunture for chronic cases.
I do realize that a splinter is different from a nerve lesion, but in an acute situation, there are some similarities. Both involved irritated tissue by mechanical means- certainly an irritated nerve will be more troublesome than irritated skin.
Perhaps I'm missing something, but how can accupunture help a single nerve exposed to repetative and ongoing compression and friction resulting in inflammation and swelling? I think a short course of NSAIDS may decrease the swelling and thereby lessen the entrapment, as well as fascilitate nerve glides and orthotic therapy.
I don't have anything against accupuncture but do question it's value in acute situations. Are there any studies on accupuncture for foot pain, or nerve lesions??
According to McGlamrys Textbook of Foot and Ankle Surgery,
Rx is " removal of any external aggravating factors, NSAIDs, and local steroid infiltration at point of entrapment. Immoblisation of the ankle is frequently necessary in the case of acute injury of the DP nerve. Rx of anterior tarsal tendonitis alleviates symptoms of DP neuritis when the neuropathy is caused by impingement resulting from edematous anterior tendon sheaths.
If conservative efforts fail, external neurolysis should be performed".
They go on to explain further the surgical procedure.
Personally, I practice acupuncture, and tend to reserve it for
osteoarthrosis of the knee, ankles and 1st MTPJs. Scar tissue ( cutaneous) can also be treated if symptomatic.
Acupuncture can be effective in acute conditions too. I have recently experienced, first hand, treatment for two different neurological conditions - sciatica and extremely tender scar tissue.
Although I admit to being sceptical about the outcome at the outset, I was agreeably surprised on both counts. The searing pain in my groin eased after the first visit, but the paraesthesia and pain in the thigh and knee didn't begin to subside until after the second visit.
Conventional treatments had previously been of no use. Physiotherapy had further aggravated the pain. NSAIDs had caused severe kidney function and bowel abnormalities.
In my experience, acupuncture reduced the inflammation far more effectively than the NSAIDs and had no nasty side effects.
There are a few studies beginning to emerge on foot pain and nerve lesions.
Some examples include:
· Clinical study on the wrist-ankle acupuncture treatment for 30 cases of diabetic peripheral neuritis; Jiang H, Shi K, Li X, Zhou W, Cao Y: J Tradit Chin Med. 2006 Mar; 26(1):8-12.
· Acupuncture Needling May Improve Pain of Knee Osteoarthritis; Ann Intern Med. 2006; 145:12-20.
· Can acupuncture contribute to the multi-disciplinary care of the patient with diabetic peripheral neuropathy? An overview of the current literature; CA Smith, Associate Professor Complimentary and Alternative Therapies, Adelaide, Australia: Australasian Journal of Podiatric Medicine, published in APJM 2005: 39(2): 41-44 & British Journal of Podiatry August 2005; 8(3): 83-86.
· Interventions for treating plantar heel pain: (Cochrane Review: Crawford F, Thomson C, The Cochrane Library, Issue 3, 2004. Chichester, UK: John Wiley & Sons, Ltd.
I would agree with the course you advise, if conservative treatment fails.
Whilst I would also concur that acupuncture works well for the conditions you mention, it can do a lot more than you are currently using it for. Dare I suggest that, to get the best possible advantage of this treatment modality, you try widening your scope?
I have tried acupuncture for many of thoses soft tissue conditions and haven't got the response I would have wanted. I'm not saying it doesn't work, its just more effective for other things.
In my experience.
That's fine. I accept that. Just didn't want to feel that you were missing out. I've found it generally unpredictable in all of these cases, but have had some surprising results that have made it worthwhile trying.
I am not "knocking" accupuncture, just questioning its efficacy. I have an open mind for all possible treatments, however, I am also open to discount something if I feel it has little value. In reading your posts to me and Peter, it appears that your outcomes with accupuncture are not that great overall (reading between the lines). If something is "generally unpredictible in all these cases", what does that tell you??
With regards to NSAIDs, I never keep a patient on them for more than 2-3 weeks. So far,the ONLY complications were dyspepsia and hives. Generally, a short course of NSAIDs are predictible for most people.
I still can't see physiologically, how tiny needles, placed distant to a site of inflammation, can make that inflammation go away. I can see how it would gate the pain, but not for long if the inflammation persists.
I appreciate where you're coming from. I felt equally sceptical before I took up acupuncture. The trouble with the written word is that it can be misinterpreted, or maybe it's just the way I use it? Re-reading what I wrote I would agree that I've been misleading in my support for acupuncture.
I wouldn't use it if I didn't find it useful. What I meant to say was that I couldn’t guarantee that it will work for every condition, but I am agreeably surprised by the number of times that it does prove beneficial.
I seldom place the needles distant to the site of inflammation. I was taught by the modern method, as I believe are the majority of podiatrists in the UK. I insert into or near the site of pain and this seems just as effective as using acupuncture points. Occasionally I will also work with corresponding trigger points.
There is a lot of literature on the mechanism of acupuncture in pain control. It is worth delving into it some time you have time to spare, as there are various explanations, some of which fit together quite neatly.
Having experienced it now from both sides of the fence, I'm certainly not prepared to knock it. As a recipient, I found that it achieved far more for me than 8 months of allopathic medicine had. I was reaching the stage where I would have tried almost anything within reason to alleviate the sciatica.
For me, the proof of the pudding was in the eating. My life had been on hold for 8 months. I have had the uncertainties of investigation for more sinister pathologies. In two visits, I've got my life back on track, had four pain free months and all's fine with the world.
I suspect that many of our patients are in similar predicaments by the time they reach us for guidance?
Have you tried simple Met-Cuneiform and 1st/2nd MTP mobilisation techniques for the Deep Peroneal nerve? If not why not try mobilising the Subtalar joint and the inferior tibiofibular joint? I have tried this sometimes and it works.