Neurovascular compromise due to true brachial artery aneurysm at the site of a previously ligated arteriovenous fistula: Case report and review of literature

Introduction

Arterial aneurysms of the upper extremity are rare and are most commonly false aneurysms resulting from blunt trauma, iatrogenic complications, or infection. ¹ True aneurysms are even less common and may result from repetitive trauma or atherosclerosis. Brachial artery aneurysms (BAAs) have also been described in the setting of vasculitis and after ligation of an arteriovenous fistula (AVF).^2–15 Our case is unique as it presented with median neuropathy and distal vascular compromise 4 years after ligation of a brachiocephalic AVF. We describe our approach and present a review of the relevant literature.

Case report

Our patient is a 48-year-old man with a history of end-stage renal disease on hemodialysis via a left brachiocephalic AVF, which was ligated in 2009 after his cadaveric renal transplant. Four years later, he presented complaining of 2 days of left hand numbness and pain. He denied a history of trauma, atrial fibrillation, or prior clotting disorders. His left hand was cool but pink. Brachial and ulnar pulses were palpable, and a triphasic Doppler signal was present in both palmer arch and digital arteries. Thrombosis of the previously ligated fistula was noted. The left hand had significantly diminished strength relative to the contralateral side, and sensation was blunted in the distribution of the median nerve.

A left upper extremity arterial duplex demonstrated aneurysmal dilatation of the brachial artery measuring approximately 1.9 cm with mural thrombus. Magnetic resonance angiography (MRA) demonstrated a hypertrophied brachial artery with focal aneurysmal dilatation measuring approximately 2.2 cm in diameter and 6 cm in length. The radial artery was found to have multifocal non-occlusive filling defects consistent with thrombus throughout its course, which was presumed to be embolic in nature. The ulnar artery filled briskly and constituted the only runoff to the hand. The deep palmar arch was patent, as were digital arteries.

The patient was started on intravenous heparin and his pain improved; however, he continued to have paresthesias of his left palm and fingertips, weakness, and poikilothermia suggestive of nerve compression. Given the urgent nature of the patient’s presentation, nerve conduction studies were not obtained prior to surgical intervention. Intra-operatively, the median nerve was found to be thickly encased by the aneurysm (Figure 1(a)). The nerve was dissected proximally and then freed distally along the 7 cm course of the aneurysm (Figure 1(b)). The brachial artery was dissected from the level of the junction with the axillary artery to the level of the trifurcation of the artery into the ulnar, radial, and interosseous arteries. The aneurysm was excised, and a 10-cm segment of the previously matured cephalic vein was harvested for use as an interposition graft. Attempts were made to remove the thrombus from the distally occluded radial artery; however, these were unsuccessful, and the vessel was ligated to prevent any propagation of clot into the anastamosis. He tolerated the procedure well and was discharged on postoperative day 2 in stable condition with significant improvement in his symptoms. OPEN IN VIEWER

Histopathologic examination of the resected aneurysm revealed calcified atherosclerotic plaque with recent organizing and recanalizing thrombus (Figure 2). At 3 months, the patient had returned to work and continued to endorse complete resolution of his symptoms. OPEN IN VIEWER

Discussion

The brachial artery normally measures 3.5–4.3 mm in diameter in women and 4.1–4.8 mm in men.^12,16 True aneurysms, defined as a focal increase in the diameter of the artery to more than 50% of normal, result from degeneration of the entire arterial wall. Aneurysms of the brachial artery may present as an asymptomatic pulsatile swelling in the upper extremity ¹⁷ or with symptoms resulting from compression of surrounding structures^3,4 or distal embolization,^9,13 and occasionally with ischemia or gangrene requiring amputation.^1,18 Similar to popliteal aneurysms, brachial aneurysms do not typically present with rupture. Pain is the most commonly reported symptom among cases described in the literature (Table 1). Duplex is the diagnostic modality of choice, and CTA may be used for operative planning.^3,19 While rupture of BAAs is uncommon, given the potential for significant neurovascular complications, most authors feel that these aneurysms should be resected whenever they present.^1,4,13,19

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Table 1.

Presenting symptoms associated with brachial artery aneurysms development after ligation of arteriovenous fistulae.

Presenting symptom	Number of cases
Pain	15
Swelling	10
Distal emboli	6
Paresthesias	6

True BAAs are rare and are most commonly caused by blunt trauma. ²⁰ BAAs may be seen in the setting of infection secondary to intravenous drug use or in patients with systemic connective tissue diseases, ¹⁷ but frequently are deemed idiopathic.^1,20 Twenty-four other cases of BAAs developing after AVF ligation have been previously described (Table 2).^2–15 Risk factors for developing BAAs proximal to iatrogenic AVFs include hypertension, smoking, diabetes, and dyslipidemia.

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Table 2.

Reported cases of true brachial arterial aneurysms developing after ligation of arteriovenous fistulae.

Author	Patient age (years) and sex	Type of AVF	Time since AVF ligation (years)	Prior renal transplant	Aneurysm size (diameter, cm)	Type of repair	Presenting symptoms
Hale 2	35 M	BC	3	N	7	GSV	Distal emboli
Nguyen 3	51 M	RC	8	Y	5	GSV	Paresthesias, digital emboli
Schunn and Sullivan 4	52 F	RC	19	N	7	Forearm vein	Pain, exercise-induced ischemia
Eugster et al. 5	–	RC	7	Y	–	GSV	Distal emboli
Battaglia et a. 6	58 M	RC	13	Y	5	PTFE	Swelling, mild pain
Ventura et al. 7	63 M	RC	–	Y	5	PTFE	Pain
Sultana et al. 8	57 M	RC	17	Y	3.7	GSV	Distal emboli, subjective coldness
Chemla et al. 9 a
	51 M	BC	2	Y	4	End-to-end	Swelling, pain
	42 M	BC	3	N	4	GSV	None
	73 M	BC	4	N	5	End-to-end	Swelling, pain
	50 F	BC	3	Y	8	GSV	Swelling, pain
	47 M	BC	6	Y	5	End-to-end	None
Murphy and Bakran 10	61 M	RC	11	Y	3	PTFE	Swelling, pain
Basile et al. 11	55 M	RC	9	Y	2.37	GSV	Swelling
Dinoto et al. 12	64 M	RC	21	Y	8.4	PTFE	Pain, paresthesias
Marzelle et al. 13 b
	44 M	BB	11	–	5.8	End-to-end	Pain
	42 M	BC	1.3	–	3.5	GSV	Subacute ischemia
	41 M	RC	7	–	3.5	PTFE	Pain, contained rupture
	42 F	RC	4	–	3.9, 5	GSV, PTFE	Swelling, pain, median nerve compression
	40 F	RC	5.8	–	4	Allograft	Swelling, pain
Sohawon et al. 14	33 F	BB	0.25	N	2.5	GSV	Pain, paresthesias
Khalid et al. 15
	44F	BC	4	Y	2.99	GSV	Pain, pulsatile mass
	50F	BC	3	Y	2.18	GSV	Paresthesias, distal emboli
	75M	BC	20	Y	5.32	Ligation of feeding vessel	Pain, pulsatile mass
Present case	48 M	BC	4	Y	2	Cephalic vein	Paresthesias, median neuropathy, distal emboli

Peripheral nerve compression at the site of AVF may contribute to distal paresthesias. As in this case, compression may be due to arterial aneurysm, but may also be a result of venous aneurysm, abscess formation, or hematoma. ²¹ Ultimately, our patient’s aneurysm was found to be compressing the median nerve. The initial differential diagnosis did, however, include ischemic monomelic neuropathy. Given the time course of his presentation and concern for distal ischemia secondary to both thrombosis within the aneurysm and distal thromboembolization, it was felt that immediate operative intervention precluded more invasive diagnostic testing such as nerve conduction studies. The preoperative Doppler and MRA studies did not clearly identify vascular compromise of the median nerve, and the intraoperative identification of the aneurysmal sac encasing the nerve led us to believe that this was a significantly contributing factor in his distal paresthesias.

The treatment of upper extremity aneurysms is often described as similar to that of false aneurysms, which are far more common, given the frequency with which interventions are performed in the upper extremity. Resection of the aneurysm and reconstruction with reversed vein graft (usually saphenous) or prosthetic material is the “gold standard.”^4,19 Vascular reconstruction is utilized to avoid later complications associated with brachial aneurysms such as microembolization and occlusion of the distal vasculature of the upper extremity. Endovascular repair can be used if the aneurysm occurs in a straight arterial segment that does not cross the joint. ²² Lifelong surveillance is required with ultrasound, as recurrence has occasionally been reported secondary to disease progression. Immunosuppression may well contribute to weakening of the arterial wall musculature and subsequent aneurysmal degeneration.^3,9,12,23

Conclusion

True BAAs are rare, but can develop following ligation of AVF used for hemodialysis access. The risk for complications including neurovascular compromise is significant. Surgeons should therefore maintain a high index of clinical suspicion when evaluating patients with ligated AVFs in long-term follow-up and offer therapy whenever an aneurysm is identified.