Clinical History
A 25 year old male patient presented with complaints of pain and swelling near medial aspect of left cubital fossa following a blunt trauma two weeks prior. On examination the swelling was pulsatile in nature and a systolic bruit was appreciable on auscultation.
Imaging Findings
Colour doppler ultrasound of left upper arm revealed a patent pseudoaneurysm originating from the brachial artery measuring approx 10 by 6mm. The aneurysm was surrounded by a hypoechoic soft tissue (probably a haematoma) of 8mm thickness. Distally the radial and ulnar artery showed normal flow velocity with no evidence of stenosis. These findings were also appreciable on CT angiography of upper limb.
Discussion
Pseudoaneurysm of the upper extremity is rarer as compared to the lower extremity. Pseudoaneurysms or false aneurysms are formed usually as a sequelae to trauma resulting in penetration of the vessel followed by haemorrhage and extravasation. They lack all the 3 layers of the arterial wall. True aneurysms are formed when the vessels are damaged and lead to dilatation and have all the 3 layers- intima, media and adventitia.
In most cases, brachial artery aneurysms are psedoaneurysms. Causes for brachial artery pseudoaneurysms are broadly classified into 3 castegories: [1] Congenital; [2] Traumatic e.g iatrogenic, penetrating or blunt injury, humerus fracture, supracondylar fracture, crutch use etc; and [3] Systemic causes e.g. Ehler Danlos syndrome, Kawasaki Disease, Mycotic aneurysm, Behcet's disease, Giant cell arteritis etc.
It takes weeks to months for a brachial artery pseudoaneurysm to form. Patients usually present with induration, pain and an expanding pulsatile swelling which is accompanied by a systolic bruit on auscultation. There are various modes of diagnostic imaging including doppler ultrasonography, Angiography, CT Angiography and MRI. Selective arteriography is considered the gold standard, but because doppler ultrasound is faster, cost effective, non-invasive, and more readily available, it is the preferred modality of choice. Doppler ultrasound usually demonstrates a turbulent flow with vessel dilatation.
Early Diagnosis of upper limb pseudoaneurysms is of utmost importance as they are known to cause thromboembolism, leading to ischaemia and gangrene, and finally resulting in amputation. Other complications include neurapraxia, compartment syndrome, rupture and haemorrhage. [1, 2, 3]
There are several treatment options for pseudoaneuryms based on size, location and accessibility. Small pseudoaneuryms can be treated by Ultrasound Guided Compression (USGC). It is also the first line treatment for non-operative pseudoaneurysms. In this technique pressure is applied by the transducer over the center of the neck of the pseudoaneurysm until flow is stopped for about 10-20min and then slowly released. If the flow resumes, the pressure is immediately reapplied. This is repeated until the flow into the pseudoaneurym has completely stopped. The success rate for USGC is between 60-90%. However it has several disadvantages- the compressions are painful and time consuming, high failure and recurrence rates in patients on anticoagulation. Other newer non-invasive techniques include- percutaneous injection of thrombin and endovascular covered stent exclusion. When pseudoaneurysms are large, open surgery is required and these options include primary repair with sutures or a patch angioplasty, pseudoaneurysm excision, or embolisation. [3, 4, 5]
Differential Diagnosis List
Left Brachial Artery Pseudoaneurysm
Pulsating Haematoma
Abscess
Arterio-venous malformation
Final Diagnosis
Left Brachial Artery Pseudoaneurysm
