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Original Report |
1 Department of Radiology, University Hospital of Bern, Inselspital, CH-3010
Bern, Switzerland.
2 Department of Plastic and Reconstructive Surgery, Kantonspital Aarau, 5000
Aarau, Switzerland.
3 Department of Orthopedics, University Hospital of Bern, Inselspital, CH-3010
Bern, Switzerland.
4 Department of Radiology, Hospital of the University of Pennsylvania,
Philadelphia, PA 19104.
5 Department of Pathology, University Institute of Bern, Inselspital, CH-3010
Bern, Switzerland.
6 IMAMED Radiologie Nordwest, 4058 Basel, Switzerland.
7 Department of Radiology, The James Cook University Hospital, Middlesborough,
TS4 4BW United Kingdom.
8 Department of Radiology, University of California San Francisco, San
Francisco, CA 94143.
Received December 21, 2001;
accepted after revision August 12, 2002.
Address correspondence to S. E. Anderson.
Abstract
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CONCLUSION. Awareness of the specific imaging appearances of pseudoaneurysms of the hand and their complications may improve the accuracy of radiologic diagnosis, advance the preoperative workup, and prevent possible clinical complications such as digital gangrene, nerve dysfunction, and aneurysm rupture.
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Our aim was to analyze the imaging features of 25 patients with pseudoaneurysms of the hand who presented with a mass or complications. The cases were collected from three countries (Switzerland, England, and the United States) over an 18-year period (1984-2002). Awareness of the specific imaging appearances of hand pseudoaneurysms and their complications may improve the accuracy of radiologic diagnosis by excluding a soft-tissue mass, advance the preoperative workup, and prevent possible clinical complications such as digital gangrene, nerve dysfunction, and aneurysm rupture.
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MR imaging was performed in nine patients on either a 1.5-T Signa unit (General Electric Medical Systems, Milwaukee, WI) or a 1.5-T Vision unit (Siemens, Erlangen, Germany). T1-weighted sequences (TR range/TE range, 500-560/14-17) and T2-weighted axial sequences (1800-4060/60-108) were available in all patients. Other sequences available included coronal T1-weighted and short tau inversion recovery images and sagittal T1-weighted images. IV gadolinium-enhanced (gadopentetate dimeglumine, Magnevist; Schering, Berlin, Germany) T1-weighted fat-suppressed imaging (460-700/14-17) was available in the axial and coronal planes in five patients. Two- and three-dimensional MR angiograms acquired using standard commercial sequences were available in six patients, and digital subtraction angiography was available in 13 patients. High-resolution sonography and Doppler sonography were performed with a Sequoia 512 unit (Acuson, Sunnyvale, CA) in two patients and with an Ultramark 9 unit (ATL, Bothell, WA) in two patients.
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All pseudoaneurysms resulted from either a single direct trauma (stabbing, fall with or without fracture) or, more commonly, chronic blunt low-grade trauma (labor-intensive work: glass blower, contractor, laborer). Seven patients had a history of a single direct trauma (direct trauma, n = 4; remote trauma, n = 3 [time since trauma: range, 9 months-37 years]). Eighteen patients had a history of chronic trauma to the ulnar artery (Figs. 1A, 1B, 1C and 2A, 2B, 2C, 2D, 2E).
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The radial pseudoaneurysms were located proximal to the wrist in two patients, at the level of the wrist joint in one patient, at the level of a nonunion of the scaphoid in one patient (Fig. 3A, 3B), between the first and second metacarpals in one patient (Fig. 4A, 4B), and in the mid thenar region in one patient. Eighteen of 19 ulnar artery pseudoaneurysms were located in Guyon's canal, typical for the hypothenar hammer syndrome, and one at the junction of the ulnar and fourth and fifth common digital arteries, which is not typical for the classical hypothenar hammer syndrome. Pseudoaneurysms ranged in size from 3 to 27 mm with a mean size of 10.5 mm, and wall thickness ranged from 1 to 4 mm with a mean thickness of 1.6 mm.
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MR imaging in nine patients revealed signal characteristics within the pseudoaneurysm on T1-weighted images to be decreased (n = 2), increased (n = 5), or isointense to muscle (n = 2) and on T2-weighting to be increased (n = 4), decreased (n = 4), or isointense to muscle (n = 1). After contrast material was administered, two of five pseudoaneurysms showed avid enhancement, which suggested a vascular origin. In three patients, focal enhancement suggested a mass (Fig. 5A, 5B, 5C). MR angiography of these three patients confirmed the diagnosis of pseudoaneurysm. Other features seen on MR imaging included a flow void in the central lumen (n = 3), phase-encoding artifact (n = 1), and hemosiderin synovitis associated with a fracture nonunion of the scaphoid (n = 1).
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MR angiography showed pseudoaneurysms in three of six patients and
thrombosis of the ulnar artery in three patients. Digital subtraction
angiography showed two patent pseudoaneurysms and 11 occluded ulnar artery
pseudoaneurysms. Combined imaging findings showed occlusion of the ulnar
artery pseudoaneurysms in 14 of 19 patients. In patients with hypothenar
hammer syndrome, a pseudoaneurysm is usually present with either partial
thrombosis with distal emboli or complete thrombosis. In our series, complete
thrombosis of the ulnar artery was the most common. Rarely, as shown in our
series in two cases, no obvious pseudoaneurysm formation is visible, but there
is thrombosis of the long segment of the ulnar artery (
8 cm), and
pseudoaneurysm is diagnosed using special stains at pathology. All six radial
artery pseudoaneurysms showed patent arterial flow.
Additional symptoms of finger paresthesia were investigated on MR angiography and digital subtraction angiography and were present in 10 patients with thromboemboli. One patient with a radial pseudoaneurysm had thromboemboli in the first three digits, whereas patients with ulnar pseudoaneurysms with occlusive thrombosis commonly had thromboemboli in the last three digits.
A diagnosis of pseudoaneurysm was made in three of the four patients who underwent sonography on the basis of the following findings: a cystic saccular formation arising directly from the adjacent artery; an irregular, thickened wall; and evidence of turbulent blood flow within the saccular mass. The sonographic diagnosis for the fourth patient was a focal cystic mass, with the diagnosis of a pseudoaneurysm being made on MR imaging. CT and nuclear medicine studies in one patient showed a mass with increased uptake in the vascular and soft-tissue phases, and diagnosis was confirmed with digital subtraction angiography. Conventional radiography in 21 patients showed associated fractures in these regions: one fracture nonunion of the scaphoid, one fracture of the hook of hamate, and one Colles' fracture of the distal radius. No curvilinear soft-tissue calcification or bone erosion was present in any of the patients.
Our study shows that typical imaging features of pseudoaneurysms include an anatomic site closely related to a neurovascular bundle, which was present in all patients (depicted on MR imaging, CT, or sonography); an eccentric saccular mass originating from an artery with vascular flow and an irregular thickened wall (shown on sonography, MR angiography, or digital subtraction angiography or suggested by flow void or phase-encoding artifact on MR imaging); or the indirect sign of arterial thrombosis with an absence of arterial flow (shown on sonography, CT, MR angiography, or digital subtraction angiography). In this series, 14 cases exclusively involved the ulnar artery. Varying MR signal intensities appear to reflect the status of vascular flow, hemorrhage, and thrombosis as evidenced in this study. A variety of imaging modalities were used in this study using the aforementioned features to diagnose pseudoaneurysm in 23 patients.
Two ulnar artery thromboses within Guyon's canal were shown, and the diagnosis of thrombosed pseudoaneurysm was highly suspected, but conclusive diagnosis was possible only with the use of special stains at pathology. One sonographic study revealed a cystic mass that was shown on MR angiography to be a patent ulnar artery pseudoaneurysm.
All modalities are capable of revealing findings for diagnosis. The variation in imaging protocol reflects the retrospective, multiinstitutional nature of this study. The aim of this study was to increase readers' awareness of the diagnosis of pseudoaneurysm of the hand, independent of an imaging modality. MR imaging with MR angiography yielded the best results for diagnosing pseudoaneurysm, revealing the status of local and peripheral vessels, and showing soft-tissue anatomy. Digital subtraction angiography yielded the best results for showing the fine details of the peripheral vessels and complications.
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Pseudoaneurysms of the hand may present as a soft-tissue mass, which occurred in this series in 10 of 25 patients; a mass and peripheral symptoms, as seen in nine patients; or peripheral symptoms alone, as shown in six patients. Although this entity is uncommon, correct diagnosis is clinically important because patients with these lesions are at increased risk of distal thrombosis with digital ischemia [1, 5], gangrene, nerve compression [1, 5], rupture [6, 7], or bone erosion and joint degeneration [1, 8]. Awareness of this entity and its diagnosis may also have implications for workers' compensation and preventive safety measures in the workplace [1].
Preoperative information should include confirmation of the diagnosis; presence of proximal or distal abnormalities, such as additional aneurysms or distal thromboembolic disease or thrombosis; and display of normal anatomy and anatomic variants [1]. If a pseudoaneurysm is clinically suspected, MR angiography or digital subtraction angiography is recommended first; however, sonography has been shown to be useful in the diagnosis of pseudoaneurysms and complications [9]. The visualization of a mass that originates from a neurovascular bundle and that has continuity with an artery of the wrist largely excludes all radiologic differential diagnoses. Ganglion cyst, which is cystic and nonvascular in nature with rim contrast enhancement, and malignant soft-tissue tumors, such as epithelioid or synovial sarcomas, can be excluded. Malignant soft-tissue tumors are largely solid tumors with irregular margins and occasional cystic or hemorrhagic components and are usually centered in soft tissues or paraarticular regions.
Pseudoaneurysms are more likely found on the palmar side, involving the superficial palmar arch rather than the deep arch [5]. True aneurysms are usually found on the dorsal side of the hand and wrist [6]. A 10-year review from the Baltimore Hand Center involving 30 upper extremity aneurysms revealed four radial and two ulnar pseudoaneurysms of the wrist [3]. A 10-year review from the department of surgery of Massachusetts General Hospital involving 10 ulnar aneurysms of the wrist revealed two pseudoaneurysms and two thromboses [2]. A large series of Korean War veterans who had arteriovenous fistulas and false aneurysms revealed that only 3.8% of the cases involved the distal radial and ulnar arteries [3]. A 13-year review from the department of surgery of the Louisville School of Medicine showed 46 ulnar artery thromboses that resulted from the hypothenar hammer syndrome [4].
Most pseudoaneurysms are caused by acute trauma with direct arterial injury [1, 5, 6]. However, chronic repetitive trauma may lead to pseudoaneurysm formation. The hypothenar hammer syndrome was originally described by Conn et al. [10] in 1970. This syndrome describes signs and symptoms associated with ischemia of the hand and fingers resulting from blunt repetitive injury of the ulnar artery and superficial volar arch against the hook of hamate. Arterial wall damage may lead to pseudoaneurysm formation with or without vessel thrombosis and to microemboli formation [5] and compression of the sensory branch of the ulnar nerve [5]. Usually described in men of working age with industrial occupations involving repetitive blunt trauma to the hands [1, 11], pseudoaneurysms of the hand has also been described in athletes with sports-related injuries such as handball players and baseball catchers [1, 5, 12]. Ulnar thrombosis caused by the pressure on the hands from walking canes rarely may be seen bilaterally in elderly women [1].
The thenar hammer syndrome was described by Janevski [13] in 1979. Acute or chronic compression of the radial artery between the first and second metacarpals where the artery is more superficial in location and covered only by the muscle of flexor pollicis brevis and subcutaneous fat. Less well known is a pseudoaneurysm that forms in the superficial branch of the radial artery, where it is relatively unprotected by skin; in subcutaneous tissues; and in a small portion of the abductor pollicis brevis tendon with compression against the trapezoid ridge [3]. The most common causes of radial artery thrombosis relate to indwelling radial artery catheters for cardiovascular monitoring. Presenting symptomatology is similar to the hypothenar hammer syndrome but usually is restricted to the thumb and second digit. Other rare causes associated with wrist pseudoaneurysm are Okihios syndrome with hypothenar muscle hypoplasia, atherosclerosis, tumor, arteritis, osteogenesis imperfecta, and infection [1, 2].
Most authors recommend surgical treatment for pseudoaneurysm of the hand [1, 4, 10, 14]. Resection of the involved arterial segment and reconstruction—either by direct anastomosis, if possible, or by a venous interpositional graft—are usually performed [1, 4, 14]. The choice of method depends on site, size, and complications. For embolic occlusion of the digital arteries, local sympathectomy with or without thrombolysis may be discussed.
Limitations of this study include the lack of a uniform imaging protocol, which reflects the rarity of the lesion and the retrospective and multiinstitutional nature of this study over an 18-year period. Surgical follow-up was not available in five of the 25 patients. However, the imaging findings were deemed classical for the diagnosis, and histology was not performed in three patients who underwent surgery with diagnostic confirmation.
Awareness of the unique imaging features of hand pseudoaneurysms and their complications, as presented in this study, allows improved diagnosis and advanced preoperative workup. The presence of a mass in the thenar or hypothenar region of the hand should alert the radiologist to consider pseudoaneurysm in the differential diagnosis.
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