Kurtis W. Martin, M.D., Gordon L. Hyde, M.D., Robert A. McCready, M.D., and David A. Hull, M.D., Lexington, Ky.

Transcription

1 Sciatic artery aneurysms: Report cases and review of the literature of three Kurtis W. Martin, M.D., Gordon L. Hyde, M.D., Robert A. McCready, M.D., and David A. Hull, M.D., Lexington, Ky. Sciatic artery aneurysms (SAAs) develop in a persistent sciatic artery, which is a congenital anomalous continuation of the internal iliac artery and may be the major blood supply to the lower extremity. SAAs may appear clinically with rupture, thrombosis, distal embolization, or compression of the sciatic nerve. We have reviewed our three cases and the literature to delineate those factors that permit correct preoperative diagnosis and appropriate surgical intervention. Our three patients (aged 54 to 82 years) appeared with severe ischemia that resulted in above-knee amputations. The literature reveals 21 patients ranging in age from 35 to 84 years (58% were women). Twenty of those patients had operations, one of which resulted in death, and five in above-knee amputations. Unexplained sciatic or buttock pain, or a palpable "pulsating" buttock mass, suggests an SAA. The diagnosis is confirmed by angiography. The recommended treatment is femoropopliteal bypass grafting followed by ligature or percutaneous endovascular thrombosis of the aneurysm. Early diagnosis and correct surgical therapy are the keys to successful management of SAA. (J VASc Sting 1986; 4: ) Sciatic artery aneurysms are rare but clinically important vascular problems. They develop in a persistent sciatic artery, which is a congenital anomalous continuation of the internal iliac artery and may be the major blood supply to the lower extremity) Persistent sciatic arteries are prone to aneurysmal dilatation and as such may have rupture, thrombosis, distal embolization, or compression of the sciatic nerve. This report describes the courses of our three patients and 21 cases from the literature, with particular reference to those features that should suggest the presence of a sciatic artery aneurysm and allow appropriate surgical therapy before catastrophic complications occur. CASE REPORTS Case 1. A 77-year-old white woman was admitted to the University of Kentucky Medical Center with a 2-day history of pain, numbness, and coolness in the left lower extremity. She had complained of left calf claudication for 1 year before admission. During physical examination the left foot was cool and cyanotic with no palpable pedal pulse and absent motor and sensory functions. The femoral and From the Department of Surgery, University of Kentucky College of Medicine. Presented at the Tenth Annual Meeting of the Southern Association for Vascular Surgery, Cerromar Beach, Puerto Rico, Jan. 30-Feb. 1, Reprint requests: Gordon L. Hyde, M.D., University of Kentucky Medical Center, MS-269, 800 Rose St., Lexington, KY popliteal pulses were normal. Arteriography revealed a hypoplastic left superficial femoral artery with poor runoff in the distal vessels and a sciatic artery aneurysm with intraluminal thrombus (Fig. 1). The right limb was normal. At popliteal artery exploration, embolectomy catheters could not be passed distally because of tibial artery occlusion. Four-compartment fasciotomy was performed by removal of the fibula and intravenous heparin therapy was begun. On the fourth hospital day the left extremity became more ischemic and an above-knee amputation was performed. Pathologic examination demonstrated occlusion of the popliteal artery with multiple emboli to the tibial vessels. At follow-up 1 month later the sciatic artery aneurysm was still patent and strongly pulsatile. The patient was readmitred to the hospital and the aneurysm was successfully thrombosed with Gelfoam and steel coils. The patient was doing well a year later. Case 2. A 54-year-old diabetic, hypertensive, white woman was admitted on May 31, 1979, with severe rest pain of the right lower extremity. Her past history was significant for right calfclaudication of unknown duration. She also complained of"pulsating" buttock and sciatic pain that had been evaluated a few months earlier by a neurosurgeon. Physical examination demonstrated a cool and cyanotic right lower extremity without motor or sensory fimction. The femoral and popliteal pulses were normal bilaterally; pedal pulses were absent on the right. Arteriography demonstrated a 3 4 cm aneurysm of the terminal branches of the right internal iliac artery and a hypoplastic right superficial femoral artery with poor runoff in the distal vessels (Fig. 2). The patient was taken to the operating room and the right internal iliac artery was ligated. After the internal iliac artery was surgically ligated, 365

2 366 Journal of VASCULAR SURGERY Martin et al. Fig. 2. Angiogram (case 2) demonstrates persistent sciatic artery aneurysm. Note small superficial and profimda femoral arteries. Fig. 1. Angiogram (case 1) demonstrates persistent sciatic artery aneurysm with intraluminal thrombus. Note small superficial and profunda femoral arteries. the popliteal pulse disappeared and the femoral pulse remained unchanged. A Fogarty catheter was passed into the distal internal iliac artery for a distance of 50 cm but no thrombus was retrieved. The superficial femoral artery was then opened and a Fogarty catheter was passed to a distance of 40 cm but could not be advanced further. No thrombus or emboli were retrieved. The popliteal artery was opened and noted to be flail of thrombus. The Fogarty catheter was passed proximally from the popliteal artery and passed into the internal iliac artery rather than into the common femoral artery as expected. It was then apparent that the popliteal artery was a continuation of the internal iliac artery. Although the foot was of questionable viability, an attempt to establish flow to the pedal arteries was made. A common femoropopliteal graft with 8 mm Gore-Tex yielded strong dorsalis pedis pulse. However, the graft thrombosed in the early postoperative period and a thromboembolectomy was performed with success. Four days later the graft again thrombosed, and an above-knee am- putation was performed. The patient recovered satisfactorily. Pathologic examination showed thrombosis of the popliteal, anterior tibial, and posterior tibial arteries. Case 3. An 82-year-old white man was admitted in 1977 with an ischemic right foot. A few days before admission the patient noticed the sudden onset of severe pain in the right foot. His past medical history was significant for foot and leg pain along the distribution of the sciatic nerve. In the past he had been evaluated by a neurologist but no cause for the pain was found. Physical examination demonstrated a 10 cm pulsatile right buttock mass with no popliteal nor pedal pulses in the right lower extremity. The patient underwent an above-knee amputation because of the far-advanced ischemia and the sciatic artery aneurysm spontaneously thrombosed the following day. The patient was discharged from the hospital and results of follow-up examination 6 months later were unremarkable. Pathologically, the specimen revealed thrombosis of all small vessels. COLLECTIVE REVIEW F r o m o u r review o f all original cases o f sciatic artery aneurysms reported in the literature, we identiffed 21 cases in which an aneurysm occurred in the persistent sciatic artery. Cases that were t h o u g h t to

3 Volume 4 Number 4 October 1986 Sciatic artery aneurysms 367 Table I. Presenting symptoms of 24 patients No. of Symptom patients % Pain Leg or foot Sciatic 5 21 Buttock 3 13 Back 1 4 Pulsatile sciatic 1 4 Mass Painful buttock 5 21 Pulsatile buttock 1 4 Buttock 1 4 Pulsatile painful buttock 1 4 Ischemia 7 29 Claudication 7 29 represent traumatic aneurysms of pelvic vessels and isolated gluteal aneurysms were excluded from this study. Only 3 of the 26 cases described by Bryan, 2 a frequently cited article, have been included. The ages in our total population ranged from 35 to 84 years (~aean, 59.5 years). There was a slight female predominahce (58%). Forty-six percent of the aneurysms occurred on the right side, 33% were on the left side, 12% were bilateral, and 9% were of unknown location. The most common symptoms on admission were pain in the leg or foot, a painful buttock mass, sciatica, claudication, ischemia, and a pulsatile buttock mass (Table I). The clinical data for all 24 patients are summarized in Table II. Twenty of the patients had surgical treatment. Four underwent ligation of the sciatic artery, resulting in the death of one patienp and a foot drop in another. 6 One patient had resection of the aneurysm 9 and another had aneurysmorrhaphy, 14 'both with good results. Five patients had excision of the aneurysm 7's'as or endoaneurysmorrhaphy, me followed by end-to-end sciatic artery bypass graft. Of these five, four patients had excellent results whereas the fifth required amputation of the toes as a result of gangrene, which was present preoperatively. Seven patients underwent ligation of the sciatic artery followed by femoropopliteal bypass, 12'1s'19"21 and all had excellent results except our case 2, who later required an above-knee amputation. Recently, two patients were successfully treated by femoropopliteal bypass followed by percutaneous endovascular thrombosis of the aneurysm. 21,22 Five patients (our three plus two from the literamre) required above-knee amputationsy 6 One patient from the literature was unsuccessfully treated by injection of ferric chloride in 1891 and later required an above-knee amputation as a result of gan- Fig. 3. Schematic drawing of persistent sciatic artery to right leg and normal pattern to left leg. Note that normal popliteal, peroneal, and anterior tibial arteries are derivatives of the sciatic system. (Modified from Steele Jr G, Sanders RJ, Riley J, Lindenbaum B. Pulsatile buttock masses: Gluteal and persistent sciatic artery aneurysms. Surgery 1977; 82:201-4.) Dotted area = primitive sciatic artery and its derivatives. Solid area = external iliac artery and its derivatives. grene.s One of our patients had a nonviable extremity and subsequently underwent an above-knee amputation (case 3). The other three patients had viable lower extremities on admission, but because of advancing ischemia they required above-knee amputations (cases 1 and 2, and Pignoli ct al.16). Of the four patients treated nonsurgically, one exsanguinated from rupture of the aneurysm, s one was not a surgical candidate, 2 another refused surgery with an unknown result, 18 and the outcome of the last is unknown} s

4 368 Martin et al. Journal of VASCULAR SURGERY Table II. Summary of clinical data for 24 patients with sciatic artery aneurysms Age (yr)/sex/ Angiographic and Author(s) side Symptoms Clinical findings operative findings Treatment Result Hilton 3 48/F/R Pain (R) thigh for Ruptured (1864) 3 mo Kade 4 50/M/L Painful mass Pulsatile mass Thrombosis Ligation (1876) Monta# 35/M/R Painful mass (R) Ptdsatile mass, bruit -- Injection ferric ( 1891) buttock chloride; gangrene; AKA Joffee 6 45/M/R Calf claudication 3 Pulsatile mass (R) Thrombosis and/or Ligation (1964) yr, painful swell- buttock, bruit embolus found ing (R) buttock 7 distal w/commo plete occlusion Hutchinson 63/F/L Painful (L) foot 6 Pulsatile mass (L) Embolization Exclusion and et al.7 yr, gangrene buttock, gangre- ISG, amputation (1968) of toes nous toes of toes Martinez 66/M/L Painful mass (L) Pulsatile mass Thrombosis Excision and ISG et al.8 buttock, calf clau- (1968) dication Clark, 72/M/L Pain in (L) buttock, Pulsatile mass -- Resection Beazley 9 sciatica (1976) Steele et al)0 65/F/R Fall, buttock mass, Pulsatile mass Thrombosis Aneurysmorrhaphy (1977) sciatica and ISG Thomas n 53/M/L Calfclaudication Pulsatile mass 10 cm ruptured Ligation (1978) (L) leg, pain aneurysm with thrombus present Tisnado 42/F/R Pain in buttock, Exclusion and et al.n sciatica FPG (1979) JuiUet et al.ls 66/F/? Kieffer 65 /F/L et al)4 Kim et al)s 66/F/? Ischemia -- Thrombosis -- Calf claudication, Pulsatile mass -- Endoaneuryssciatica, pulsatile morrhaphy mass Pain in buttock, Pulsatile mass -- Resection and ISG pulsatile mass Death Death Recovery Foot drop 11 mo without complications, died 3 yr later of prostatic cancer OK atdischarge OK atdischarge AKA = above-knee amputation i ISG = in situ graft of sciatic artery; FPG = femoropopliteal graft; SFA = superficial femoral artery. DISCUSSION Embryology. In the developing embryo, the sciatic artery develops along with the limb bud as the axial artery. Subsequently, the femoral artery, as an extension of the external iliac artery, normally supercedes and annexes the sciatic artery and its branches to the mid-thigh. 2 Interruption of this normal process results in atresia of the superficial femoral artery system and persistence of the sciatic artery (Fig. 3). Anatomy. The persistent sciatic artery is anatomically a continuation of the internal iliac artery. 2 After giving rise to the superior gluteal and internal pudendal arteries in the pelvis, the sciatic artery follows the inferior gluteal artery and courses through the greater sciatic foramen below the pyriformis mus- de where it then enters the thigh. 2 Once in the thigh, the persistent sciatic artery runs inferior to the gluteus maximus along the posterior aspect of the adductor magnus, finally passing into the popliteal fossa where it is continuous with the popliteal artery. 2 The sciatic artery is most frequently found within the posterior medial sheath of the sciatic nerve) although it may accompany the posterior cutaneous nerve or lie within, or adjacent to, the sheath of the sciatic nerve, z When the artery lies within the sheath of the sciatic nerve, the nerve is usually flattened out over the artery. 23 This flattening becomes more prominent when aneurysmal dilatation is present, creating a potential hazard to the nerve when the aneurysm is resected. 6"2s This anatomic relationship explains why patients frequently appear with sciatica and/or leg

5 - - Ligation Volume 4 Number 4 October 1986 Sciatic artery aneurysms 369 Table II. Cont'd. Age (yr) /sex/ Author(s) side Symptoms Clinical findings Pignoli 64/F/L Pain in foot, Ischemia et al.~6 ischemia Vimla 45/M/B Leg.pain, buttock Pulsatile mass, bruit et al.~7 pam (1981) McLellan, 60/F/B Thigh and hip pain, Edema, ischemia Morettin ls calf clandication (1982) McLeUan, 55/M/R Clandication, Edema, absent Morettin ~s ischemia distal pulses (1982) Mayschak, 60/F/B (R) leg pain, hip Flye 19 pain (1984) Mandell 65/M/R Painful mass in but- Pulsatile mass et al. 2 tock, sciatica, (1985) calf claudication Mandell 84/F/R Ischemia, rest pain Absent distal pulses et al.2o (R) foot (1985) Becquemin 43/F/R Pain (R) leg Ischemia et al.2~ (1985) Present study Case 1 77/F/L Pain in leg, ischemia Ischemic leg Case 2 54/F/R Back pain and leg Ischemic foot pain, ischemia, pulsatile sciatic pain Case 3 82/M/R Pain in feet, leg Pulsatile mass (10 ischemia cm), ischemic leg Angiographic and operative findings Treatment Result Thrombosis Embolectomy, AKA Thrombosis Aneurysmorrhaphy, and ISG 2 yr without complications Embofization (R), Exclusion and thrombosis (L) FPG in both limbs Thrombosis Refused surgery -- Embolization Exclusion and FPG in both limbs Poor distal runoff No surgery Thrombosis Ligation and FPG, balloon endovascular occlusion Thrombosis, Fibulectomy; embolization fasciotomy; AKA; embolized 1 mo later Embolization Popliteal ligation with FPG; AKA Embolization AKA, spontaneous thrombosis of aneurysm and foot pain. The most common site for aneurysmal dilatation is at the level of the greater trochanter just under the gluteus maximus muscle, although it may extend far down the posterior thigh. 23 The persistent sciatic artery is considered complete when it is the main supply to the extremity and changes little in its course to the popliteal artery (Table III). This configuration is present in 63% of all cases. It is considered incomplete 9,~ if its continuity is interrupted or if its connection to the internal iliac or popliteal artery is by small collateral vessels. ~8 When the sciatic artery is complete, the superficial femoral artery may be normal or entirely absent. 2. However, in 78% of the cases it is hypoplastic and provides flow to the lower limb through collateral vessels, which usually end just above the knee. a8 Surgically, the sciatic artery aneurysm may be eas- ily approached through a posterolateral buttock curvilinear incision, splitting the gluteus maximus muscle in the direction of its fibers. Again, minimal dissection near the aneurysm will decrease the potential for sciatic nerve injury. ~ If proximal control is not achieved through this incision, an anterior lower abdominal incision may be made, through which retroperitoneal control of the iliac artery can be obtained. ~ Pathologic conditions. The persistent sciatic artery may exist as a normally functioning vessel. However, early atheroscleromatous degeneration and aneurysm formation are common. The exact cause of aneurysm formation is unclear, but probably both congenital and acquired components play a role. 2 Pirker and Schmidberger 24 attribute the aneurysms to a congenitally hypoplastic vessel wall with reduced

6 370 Martin et al. Journal of VASCULAR SURGERY Table III. Relative incidence of the various anatomic configurations in the sciatic and femoral arterial systems seen with persistent sciatic artery aneurysms Anatomy No. % Sciatic artery (n = 27) Complete Incomplete 2 7 Unknown 8 30 Femoral arte~ (n = 27) Normal 0 0 Hypoplastic Absent 1 4 Unknown 5 18 elastic elements, both of which favor aneurysmal dilatation. Others believe the aneurysms are caused by the relatively exposed position of the artery in the buttock region, lending itself to frequent trauma from external forces, as well as its close approximation to the sharp edge of the sacrospinous ligament. 2 Diagnosis. Clinically, a sciatic artery aneurysm may be suggested by a painful buttock mass (Table I). Unexplained buttock or sciatic pain, particularly that with a "pulsating" character, should also raise suspicion of a sciatic artery aneurysm. In patients with these symptoms, one should always palpate the buttock to rule out sciatic artery aneurysm. In case 3, palpation of the buttock at the time of evaluation of sciatica several months earlier may have suggested the diagnosis and prevented limb loss. In some patients the uncommon but pathognomonic finding of an absent femoral pulse with strong popliteal and distal pulses should suggest a persistent sciatic artery. 2s To make the diagnosis of persistent sciatic artery noninvasively, one may use Doppler ultrasonography, following the course of the sciatic nerve down the posterior thigh. 24 Computed tomography may also be helpful. ~ To make the definitive diagnosis one must use angiography, which is valuable both in confirming the diagnosis and in the planning of appropriate surgical intervention. Without a complete peripheral vascular study surgical exploration could lead to disastrous results, is The most common approaches are translumbar aortography and retrograde femoral arteriography, both of which usually identify the sciatic artery aneurysm and anatomy of the femoral arterial system with its distal runoff vessels. Radiologically, the internal iliac artery usually appears larger in caliber than the external iliac artery and is nontapering; it courses laterally at the level of the femoral head and is recognized as an anomalous sciatic artery. 6 If a persistent sciatic artery is found, then a sciatic artery aneurysm is found in 45% of the arteries visualized.is If oblique views are obtained, the sciatic artery aneurysm is usually located at the level of the greater trochanter, and below this the persistent sciatic artery with its ectatic and irregular walls can be visualized. 2 Often, the sciatic artery appears dilated and runs a very tortuous course, which gives rise to the term "arteriomegaly. "1~ The superficial femoral artery is usually hypoplastic and appears in its normal position, although it gently tapers to an end above the knee without direct communication to the popliteal artery. This hypoplastic vessel may be mistaken for a normal-sized superficial femoral artery, which is occluded at the adductor canal. Therefore, an unusually small superficial femoral artery that is not continuous with the popliteal artery should suggest the possibility of a persistent sciatic artery. Another clue to sciatic artery aneurysm revealed by angiography is an aneurysm appearing to be in the groin region although it cannot be palpated there. Here (as in case 1) palpation of the buttock will confirm the diagnosis. It may be difficult to demonstrate patency of the popliteal and tibial arteries in the presence of a persistent sciatic artery, and routine arteriography may lead to the erroneous impression that they are occluded. The runoff vessels may not be visualized for two reasons. First, the sciatic artery is usually arteriomegalic (large, tortuous, and slow flowing), resulting in poor visualization of the runoff vessels. Second, retrograde femoral arteriography may fail to opacify the sciatic artery if the catheter is not proximal to the origin of the internal iliac artery. In either case, a selective internal iliac artery injection with delayed timing may be required to demonstrate adequate distal runoff and collateral flow. Therefore, exploration of distal vessels should be performed before amputation in patients with ischemia resulting from a sciatic artery aneurysm. When a sciatic artery aneurysm is diagnosed, the contralateral extremity should be examined carefully for the presence of a similar aneurysm since 12,6 of all cases are bilateral. In the differential diagnosis one must consider gluteal artery aneurysms, which require only ligation or endovascular thrombosis. Because gluteal artery aneurysms are usually clinically indistinguishable from sciatic artery aneurysms, arteriography will be needed to make the definitive diagnosis. Treatment. Treatment of sciatic artery aneurysms has varied markedly according to available techniques

7 Volum 4 Numbcl 4 October 1986 Sciatic artery aneurysms 371 and ir, genuity. Historically, they have been treated unsucc ssfully by injection of sclerosing agents, such as ferric chloride. 5 The more aggressive approach of ligation of the sciatic artery proximal to aneurysmal dilatation has proved successful in cases in which the femoral arterial system was developed sufficiently to maintain the leg's viabili~. 6'2 '26 However, in patients with a hypoplastic superficial femoral artery without adequate collateralization, ligation of the sciatic artery aneurysm must be followed by some form of bypass to avoid disastrous results. 4 In addition, the extremity already ischemic from a thromboembolic event can be worsened by ligation of the sciatic artery aneurysm (as evidenced in case 2). Excision of the sciatic artery aneurysm with endto-end interposition grafting has been successful. 7'8'1"~ However, this approach has the following disadvantages: (1) The sciatic nerve is frequently attenuated and stretched out over the surface of the aneurysm, and attempts at excision can lead to sciatic nerve injury~; (2) the remaining anomalous sciatic artery is still prone to further atheromatous degeneration18; and (3) blood flow may be compromised when the patient sits on the graft, is Endoaneurysmorrhaphy with end-to-end sciatic artery anastomosis has been successfup '~7 and more than likely would avoid nerve injury. However, it too is prone to atheromatous degeneration and compromised blood flow. Recently, the most favored approach has been proximal and distal ligation of the aneurysm with simultaneous femoropopfiteal bypass graft. 12'~s'~9'21 This approach fulfills all the goals of surgical treatment: (1) ablation of the aneurysm, (2) restoration of satisfactory arterial blood flow to the lower extremity, and (3) prevention of future complications from the diseased sciatic artery. Other successful alternatives include femoropopliteal graft followed by percutaneous endovascular occlusion of the sciatic artery aneurysmm. 2L22 These are appealing alternatives to ligation with femoropopliteal bypass because they limit manipulation near the sciatic nerve and thus decrease the chance for sciatic nerve injury. REFERENCES 1. Williams LR, Flanigan DP, O'Connor RJA, Schuler JJ. Persistent sciatic artery: Clinical aspects and operative management. Am J Surg 1983; 145: Bryan RC. Aneurism of the sciatic artery. Ann Surg 1914; 60: Hilton FC. Case of aneurism seated on an abnormal main artery of the lower limb. Guy's Hosp Rep 1864; 10(3): Kade E. Aneurysma der art. ischiadica, Unterbindung der art. iliaca communis sinistra. Petersb Med Wchnschr 1876; 1(8): Montaz L. Des anevrysmes de la region fessiere. Congres Franc de Chir 1891; 5: Joffe N. Aneurysm of a persistent primitive sciatic artery. Clin Radiol 1964; 15: Hutchinson JE, Cordice JWV, McAllister FF. The surgical management of an aneurysm of a primitive persistent sciatic artery. Ann Surg 1968; 167: Martinez LO, Jude J, Becker D. Bilateral persistent sciatic artery. Angiology 1968; 18: Clark FA, Beazley RM. Sciatic artery aneurysm: A case report including operative approach and review of the literature. Am Surg 1976; 42: Steele G, Sanders RJ, Riley J, Lindenbaum B. Pulsatile buttock masses: Gluteal and persistent sciatic artery aneurysms. Surgery 1977; 82: Thomas ML. Artetiomegaly. Br J Surg 1971; 58: Tisnado J, Beachley MC, Amendola MA, Levinson S. 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