True brachial artery aneurysm: A systematic review

Objective: To identify and critically appraise literature on true brachial artery aneurysm, exploring its demographic characteristics, aetiologies, clinical manifestations and different methods of repair along with complication rates to determine future treatment strategies. Method: The systematic review was conducted at Liaquat National Hospital, Karachi, from September 30, 2021, to November 30, 2022, in line with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Literature was searched on MEDLINE, EMBASE and Cochrane databases for relevant studies in English language or with English translation published till May 31, 2022. The key words used for the search were “brachial artery aneurysm”. Data was noted on a proforma and was subjected to descriptive analysis. Results: Of 113 articles, 6 (5.3%) were retrospective studies, 7 (6.1%) were case series and 100 (88.4%) were case reports. The total number of patients involved was 157 with mean age 43.1±23.4 years (range: 2 months to 84 years). The gender was mentioned for 152(96.8%) patients; 111(73%) males and 41(27%) females. The mean diameter of true brachial artery aneurysm was 36.2 ±17.5mm and 106(67.5%) patients presented with localised swelling, 65(41.4%) with pain, 41(26.1%) with distal ischaemic symptoms, and 28(17.8%) with median nerve compression. True brachial artery aneurysms were more common in renal failure patients having a history of arteriovenous fistula creation in the affected limb and were on immunosuppressant drugs due to renal transplant 81(51.5%). Less common causes included primary/idiopathic


Introduction
True brachial artery aneurysms (TBAAs) are rare peripheral vascular aneurysms (0.17%) that usually present with a swelling in the upper extremity and a history that suggests local injury or inflammation. 1,2The normal brachial artery diameter is 3.5mm to 4.3mm for females and 4.1mm to 4.8mm for males. 3,4A "true aneurysm", compared to its counterpart, the "false or pseudo aneurysm", is defined as at least a 50% increase in the diameter of an artery compared to its normal diameter, and involving all 3 layers of the vessel wall. 4Although the natural course of this condition is unknown, once detected, therapy is essential to avoid complications, like rupture, thrombosis or distal embolisation. 5garding treatment of brachial artery aneurysms, they can be managed in the initial stages by surveillance alone, especially if they are asymptomatic and small in size, but the main mode of treatment is open surgical repair due to easy access to aneurysm and less morbidity associated with the operative treatment. 5,6Recently, with the evolving trend of endovascular treatment, some reports The initial screening filtered out papers that has nothing to do with TBAAs.Material related to pseudo or false aneurysms was excluded after full-text screening, and so was the case with articles that were not in English and their English translation was also not available in the institutional library.A secondary screening excluded articles for which full-text access was not available.
The Cochrane Handbook for Systematic Reviews of Interventions did not advocate meta-analysis because of the overall clinical diversity of the studies found in the current review. 12The experimental designs, treatment protocols, and methods of outcome assessment in each of the study examined were all distinct, therefore performance of meta-analysis was inapplicable.Due to these reasons, only a Systematic review and descriptive analysis of the existing data was performed.
The treatment primarily used was aneurysmectomy, which is resection of brachial aneurysm, 142(90.4%),followed by re-establishment of distal limb perfusion by inter-positional vascular grafts 122(77.7%).In grafts the most preferred one was reversed saphenous vein graft (RSVG) 79(50.3%).Other venous grafts were also used, including cephalic 8(5%), basilic 7(4.4%) and internal iliac artery 1(0.6%), femoral artery 1(0.6%).Use of Synthetic grafts was the last option to re-vascularise the distal limb in 17(10.82%)cases.In 17(10.82%)cases where sac of aneurysm was small and distance between the cut edges of native vessel was <2cm, primary end-to-end vascular repair was attempted to anastomose the remaining segments of native artery to restore its continuity and   Some modified surgical techniques in unsuitable cases were also noted, like surgical ligation of brachial artery, lateral aneurysmoraphy and partial aneurysmectomy (Table 3).
There were only 17(10.8%)cases of post-operative complications among whom 5(3.1%) developed recurrence of aneurysm in the venous graft, and 4(8.9%) in native brachial artery.Besides, 2(1.2%) patients complained of persistent neuropathy in the form of weakness of hand grip and paraesthesia even after 6-12 months.Ischaemic symptoms reversed almost in every patient except in 1(0.6%) patient who developed gangrene and amputation was done.Further, 2(1.27%) cases developed significant haematoma at the operative site that required surgical drainage.Also, 1(0.6%) mortality was noted in a patient having primary diagnosis of neurofibromatosis, due to uncontrolled bleeding from artery proximal to ligation of aneurysm on the 4th postoperative day.

Discussion
To the best of our knowledge, the current systematic review is among the first on brachial artery aneurysm and its treatment.TBAAs are rarely encountered in clinical practice with its frequency being as low as 0.17 % in all peripheral arterial aneurysms. 1Aetiology of TBAAs include genetic pathologies, such as connective tissue disorders, vasculitis, atherosclerotic disease and trauma. 1185][16][17][18][19][20][21][22][23][24]119 Findings noted in the current review also confirmed of the above theory.It was found that 51.5% patients with TBAA had a history of CRF with AVF creation in the affected limb and received 1-2 RTs.
4][15] Another proposed theory states that the increased release of reactive oxygen species (ROS) results in an increase in negative ions that stimulates an up-regulation of metalloproteases, resulting in the degradation of the internal vessel wall. 16,17oreover majority of CRF patients receive renal transplant/s and take steroid and immunosuppressive drug therapy to prevent rejection.Steroids can also pose a threat to the integrity of the muscular walls of vessels and increase the risk of aneurysm disease. 17However, development of aneurysm after AVF creation and steroids is a slow process and takes years to progress (11.3 ± 5 years) and the risk of development of aneurysm persists even after ligation of fistula and cessation of steroids. 18other finding that supports the association of AVF with brachial aneurysm is that the left-sided TBAA (50.3%) was almost twice as common (1.79: 1) as the right-sided (28.0%).The left upper arm is a preferable site for AVF creation.
Regarding risk factors, it was found that handicapped patients who had history of long-term use of crutches for their mobility had more chance of developing TBAA compared to other cohorts.0][21][22][23][24] These findings shed light on the risk of aneurysm development associated with prolonged use of such walking aids and warrant caution to be taken by physicians and physiotherapists. 19maining aetiologies / risk factors that were found included primary/idiopathic aneurysm, connective tissue  118 Symptoms observed were mostly upper extremity swelling and pain.These classical findings were usually followed by ischaemic and median nerve compression symptoms.The presence of swelling usually manifested as a palpable mass, but was subjected to the size of aneurysm, as a small-size aneurysm may not present with a palpable mass on examination and could be completely asymptomatic.Similarly, palpable brachial aneurysm was not always pulsatile as generally understood.
Diagnostics and investigations included a physical examination of any palpable swelling, and application of the Allen test to assess arterial blood supply.The results can be confirmed by a Duplex scan.The radiological modalities available for further detailed imaging are computed tomography (CT) scan and magnetic resonance imaging (MRI). 3However, in regard to imaging, some studies have debated whether or not it is necessary as majority of the aneurysms are easily detectable on physical examination. 15,18This statement, however, should be subjective to the case of the patient as not all the aneurysms can present with a palpable mass. 25anagement strategies are subject to the severity of the pathological process and morphological change that the aneurysm has caused.Common factors to take into consideration include the severity of symptoms, size of aneurysm, load of thrombus in aneurysmal sac, distal ischaemia of limb and any compression of the nerves of the upper limb. 267][8][9] Aneurysmectomy was the primary procedure chosen by most of the vascular surgeons 142(90.4%).After aneurysmal sac resection vascular continuity was maintained by either using grafts or by direct end-to-end anastomosis.
Alternative pathway of endovascular repair, which is gaining popularity very rapidly among vascular surgeons now-a-days, has shown little role in the management of TBAA, as reflected in earlier studies. 7,8ter successful treatment of TBAA, complications were noted only in 17 (10.82%)patients, among whom the most common was recurrence of aneurysmal degeneration (95.7%).However, 1 patient died due to uncontrolled bleeding.
The good outcome in TBAA patients was due to effective management and timely surgical intervention that helped the patients in recovering from ischaemic and neurological symptoms within a relatively short hospital stay.Due to the same reasons long-term follow-up (>1 year) was not available or mentioned in most cases, which is a limitation of the current systematic review.
Among other limitations is the fact that the review was initially registered with PROSPERO as the initial plan was to compare surgical and endovascular treatments, but later it was found that there were only 8 case reports on endovascular treatment which made comparison impossible.Also, no trial or comparative study was found to conduct meta-analysis.As such, the current study was only a systematic review.

Conclusion
Due to rare presentation of TBAAs, the available literature is limited.Arteriovenous fistula (AVF) in CRF patients and immunosuppression therapy in renal transplant patients were found to be significant risk factors for TBAA development.Patient with above risk factors need longterm follow-up (10-15 years) even after the ligation of fistula and cessation of immunosuppressive therapy.Surgical aneurysmectomy and revascularisation by venous grafting was the major mode of treatment due to relatively superficial location of aneurysm and having good outcome.Further studies are needed to explore the risk factors and generate comparative data for the selection of the best mode of treatment.

Figure :
Figure: Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) flowchart.