Forearm Arteries Entrapment Syndrome: a Rare Cause of Recurrent Angioaccess Thrombosis

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Forearm arteries entrapment syndrome: A rare cause of recurrent angioaccess thrombosis

Eric S. Chemla, MD,a Alain Raynaud, MD,b Benoît Mongrédien MD,a Myriam A. Combes, MD,a Nicola D’Attellis, MD,a Cyril F. Cardon, MD,a Pierre L. Julia, MD, PhD,a Jean-Fran¸cois Toussaint, MD, PhD,a and Jean-Noel Fabiani, MD,a Paris, France

Entrapment syndrome below or just above the elbow is uncommon. These rare causes of neurologic or vascular entrapment are linked to anomalous anatomical structures. No case of entrapment syndrome has been reported in patients with angioaccess for hemodialysis. We report, for the first time, forearm arteries entrapment in two patients presenting with recurrent angioaccess for hemodialysis thrombosis. Anatomical, radiologic, and surgical features of these uncommon syndromes are discussed. (J Vasc Surg 2001;34:743-7.)

Entrapment syndrome below or just above the elbow is uncommon. With few exceptions, compression at this level involves neurological structures.1-4 The rare cases of vascular forearm entrapment syndrome described in the literature are linked to an anomalous anatomical structure: the ligament of Struthers.5-9 We report, for the first time, forearm arteries entrapment in two patients with angioaccess for hemodialysis caused by a pronator teres syndrome and a fibrous arcade of the flexor digitorum superficialis muscle. Both patients presented with recurrent angioaccess failure; no cause was identified except artery occlusion by entrapment in the supinated position. We discuss anatomical, radiologic, and surgical features of these uncommon syndromes. CASE REPORT Patient 1. A 66-year-old woman was referred to our institu- tion for angiography of her vascular access for dialysis. Two days before, she had acute thrombosis, which was successfully treated with local fibrinolysis and manual aspiration thromboembolectomy. Her angioaccess was a 9-year-old ulnar-to-basilic artery graft Fig 1. Angioaccess angiogram in pronated position. Radial artery (polytetrafluoroethylene [PTFE]), which had already been treated is occluded, and ulnar artery is normally patent with no stenosis. four times for acute thrombosis: one time with surgery (thrombec- See two large aneurysms at cannulation site. tomy 5 years ago) and three times with local fibrinolysis and manual aspiration thromboembolectomy (4, 3, and 1 years ago). Angiograms performed by access route during these throm- repeated clinical examination showed an access with no thrill per- boses did not identify any cause of occlusion and especially no ceptible and two flat aneurysms. When the arm was set in prona- stenosis. A clinical examination performed before the opacifica- tion, angioaccess thrilled normally anew. An angiogram revealed tion revealed a normally thrilling angioaccess with two large that the access was patent without significant stenosis. A retro- aneurysms at the cannulation site. The arm was set in a supinated grade puncture of the brachial artery at the elbow was then per- position so that an access angiogram could be performed; then, formed to analyze the arterial tree of the forearm. Frames were taken in both the pronated and supinated posi- From the Department of Cardiovascular Surgery and Transplantation, tions. The radial artery was occluded. The ulnar artery was nor- a Hôpital Européen Georges Pompidou, and the Department of mally patent in pronation but occluded in supination because of Cardiovascular Radiology, Clinique Labrouste.b Competition of interest: nil. an external compression just below its takeoff (Figs 1 and 2). Reprint requests: Eric Chemla, département de chirurgie cardiovasculaire, Magnetic resonance imaging was also performed and revealed hôpital Européen Georges Pompidou, 20, rue Leblanc 75015 Paris, that the ulnar artery was compressed in a flexor digitorum France. fibrosous arcade (“sublimis bridge”), which is a slip connecting Copyright © 2001 by The Society for Vascular Surgery and The American the flexor digitorum superficialis and profundus muscles. Association for Vascular Surgery. 0741-5214/2001/$35.00 + 0 24/4/116973 Underneath this anomalous structure lay the ulnar artery. doi:10.1067/mva.2001.116973 Because of the two large aneurysms on the PTFE graft (Fig 2, A) 743 JOURNAL OF VASCULAR SURGERY 744 Chemla et al October 2001

A B

Fig 2. Angioaccess angiogram in supinated position. Ulnar artery is compressed by external structure. Arteriovenous fistula is occluded. Also shown are two aneurysms on PTFE graft.

and the absence of ischemic symptoms (an arterial reconstruction The ulnar artery had a high origin and was not able to feed was not necessary), angioaccess was ligated, and a new fistula was the access in a retrograde way through the palmar arch (Fig 3, A created at the other forearm. and B). The radial and interosseous arteries (the interosseous Patient 2. A 69-year-old man was referred for angiography artery has its origin on the radial artery) were normally patent in of his angioaccess for hemodialysis after he had several acute the pronated position but were occluded in supination by an thromboses treated with local fibrinolysis and manual aspiration external compression 2 cm below takeoff of the radial artery (Figs embolectomy. His angioaccess was a 4-year-old wrist radio 4 and 5). cephalic native fistula. This access had already been treated five Surgical exploration demonstrated pronator teres syndrome. times for acute thrombosis with local fibrinolysis and manual aspi- An anomalous fibrous band arising from the pronator teres mus- ration embolectomy. cle compressed the radial artery. An angiogram performed after these thromboses did not After resection of this fibrous band, the access was normally identify any cause of occlusion and especially no stenosis, which is patent, even in supination. The patient did not experience any extremely unusual for native fistulas. The clinical examination new episode of thrombosis at 1 year. performed before the arteriography showed a normally thrilling access. The patient did not have any ischemic symptom or pain at DISCUSSION rest during dialysis. Arterial upper-limb compression at the thoracic level is Once the patient had lain on the angiographic table, his arm a usual problem. Entrapment at other locations below or was set along his body in a supinated position. In this position, just above the elbow is uncommon. Nearly all of the pre- the angioaccess was flat, with no thrill detectable. The thrill reap- viously described patients with entrapment syndrome at peared after a slight rotation of the arm. this level presented with neurologic symptoms.1,10,11 We The angiogram was obtained by means of a retrograde punc- have described two cases of forearm arterial entrapment ture of the brachial artery at the elbow and showed the access syndrome in patients having angioaccesses for hemodialy- patent without significant stenosis (Fig 3). Patency of the forearm sis. One was due to a fibrosis arcade arising from the flexor arteries was studied with the patient in both the pronated and digitorum superficialis muscle; the other was due to supinated positions. pronator teres muscle syndrome (Fig 6, A and B). JOURNAL OF VASCULAR SURGERY Volume 34, Number 4 Chemla et al 745

A B

Fig 3. Angioaccess angiogram in pronated position. This is a normally patent wrist radio- cephalic arteriovenous fistula. Ulnar artery is occluded. A, Upper limb arteriography showing high origin of the ulnar artery. B, Angiogram showing that the ulnar artery cannot fill fistula through palmar arch.

Several causes of forearm entrapment syndrome are and claudication of the forearm after vigorous use are the described in the literature. The ligament of Struthers,5 most commonly observed signs.2,6 described in 1849, is a clinically significant entity running Pronator teres syndrome was first described in 1951 from the supracondylar process or spur of the humerus to by Seyffarth.15,16 It is generally considered a rare condi- the medial epicondyle. This anatomical variation is known tion. It is a neuropathy of the median nerve classically to occur in 0.7% to 2.7% of the population and has vari- caused by entrapment of the nerve as it passes between the ously been called “supracondylar,” “supracondyloid,” two heads of the pronator teres muscle. The resulting clin- “supraepitrochlear,” or “epicondylic.” This variation is ical picture includes some or all of the following features: usually asymptomatic. Occasionally, the pronator teres paresthesia in the median distribution in the hand, weak- muscle may have an anomalous origin at the bone spur, ness of the median innervated muscles distal to the site of the ligament, or both. The median nerve and the brachial, entrapment, pain in the proximal forearm, and tenderness radial, or ulnar artery travel underneath the process or the over the pronator teres muscle. Compression of adjacent ligament and may be compressed by either of them. vascular structures, which induces forearm claudication, Patients usually present with features of total or partial has been reported infrequently.3,4 median nerve palsy with or without ischemia of the fore- Other causes of entrapment are also infrequently arm.12-14 Weakness of the muscles supplied by the median described, such as the one in our second case, involving nerve in the forearm, paresthesia over the thenar muscles, compression by the fascia of the flexor digitorum superfi- JOURNAL OF VASCULAR SURGERY 746 Chemla et al October 2001

Fig 4. When forearm is in supinated position, the radial artery is compressed by an external process. Fig 5. Angioaccess angiogram in complete supinated position. Radial artery and arteriovenous fistula are occluded. Cubital artery cannot fill fistula in a retrograde way through palmar arch. cialis muscle (sublimis bridge).10 This anatomical variation has been found in 8% of the population.17 It represents a remnant of the connections between the flexor digitorum superficialis (sublimis) and the flexor digitorum profundus dysfunctions was found out to be related to a positional muscles. Other anatomical variations involving the flexor mechanism. With the patient in the supinated position, the digitorum superficialis muscle have been described by the flow was markedly reduced in the artery and led to iterative same author: a slip connecting with the flexor pollicis thromboses. The results of magnetic resonance imaging longus muscle and another one connecting with the examination and surgical exploration disclosed the under- pronator teres muscle. Another above-the-elbow com- lying cause of the forearm arteries entrapment: anomalous pression syndrome is related to an accessory bicipital anatomical structures and increased diameter of the feed- aponeurosis.18 ing artery.20,21 The clinical features of entrapment syndromes have In our opinion the frequency of arterial entrapment of been thoroughly discussed in the literature only at the the forearm artery is underestimated because it is asymp- thoracic level.19 In thoracic outlet syndromes, as in fore- tomatic in most patients. Entrapment involves only one of arm entrapment, the clinical presentation is usually neuro- the forearm arteries and cannot cause ischemia because of logic. Prevalence of vascular compression has been the patency of the palmar arches. In our two patients, one reported to be as low as 1%. At the level of the elbow, arte- of the forearm arteries was completely occluded, and the rial involvement has been exceptionally described.6,7 In other was the site of positional entrapment. These vascu- the cases we presented, no forearm claudication was lar lesions did not cause any ischemic symptoms despite observed and no neurologic symptoms occurred; thus, no the steal by the angioaccess. In our first patient the radial electromyogram was performed. artery was occluded, and in the supinated position the Both entrapment syndromes were revealed by angioac- ulnar artery was also occluded. The patient did not have cess iterative thromboses. Classical causes of angioaccess any ischemic symptom. In the supinated position the pal- failures were discussed and excluded. The etiology of these mar arch was not fed, and the lack of ischemic symptoms JOURNAL OF VASCULAR SURGERY Volume 34, Number 4 Chemla et al 747

drome must be ruled out. Responsibility of these anom- A alous anatomical structures in angioaccess thrombosis may be underestimated. The evaluation of patients presenting with recurrent angioaccess failure, with no cause identified, should include a dynamic clinical examination. In case of doubt, an arteriogram will confirm the diagnosis of entrapment.

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