Surgical significance of brachial arterial variants in a Kenyan population

Authors: Pulei A BSc (Anat), MBChB, Obimbo M MBChB, MSc (Anat), Ongeti K BSc (Anat), MBChB, Kitunguu P BSc (Anat),

MBChB, Inyimili M, HND, OgengÕo J BSc, MBChB, PhD. Correspondence and reprints requests: Dr. Anne Pulei, Department of

Human anatomy, University of Nairobi PO Box 30197 00100 Nairobi. Email:

Abstract

Background: Knowledge of the variant anatomy of the brachial artery is important in radial arterial grafts for coronary bypass, percutaneous trans-radial approach to coronary angiography, angioplasty and flap surgery. These variations show ethnic differences but data from black populations are scarce. This study therefore describes the course in relation with median nerve, level and pattern of termination of brachial artery in a black Kenyan population.

 

Methods: This was a cadaveric dissection study of 162 upper limbs at the Department of Human Anatomy University of Nairobi, Kenya. The brachial artery was exposed entirely from the lower border of teres major to its point of termination. The course in relation to the median nerve and the level of termination were recorded. The results were analyzed using SPSS version 17.0 for Windows.

Results: 72.2% of the brachial arteries followed the classical pattern described in Gray’s Anatomy. Superficial brachioradial and superficial bra-    chial arteries were present in 12.3% and 6.1% of the cases respectively. Brachial artery terminated at the radial neck in 79% of the cases, radial tuberosity (8.6%), and proximal arm (11.1%), mid arm (1.2%). Pattern of termination was either a bifurcation into the radial and ulnar arteries (90.1%) or trifurcation into radial, ulnar and common interosseous arter-ies (9.3%). We also report a case of trifurcation of the brachial artery into the profunda brachii, radial and ulnar arteries (0.6%).

 

Conclusion: Variations of the brachial artery in its relationship with the median nerve, level and pattern of termination are common. These may complicate arm surgical exposures, flap and vascular surgery. Pre-opera-tive angiographic evaluation is recommended.

 

Keywords: brachial artery, bifurcation, trifurcation, superficial brachiora-dial artery

 

Introduction

The brachial artery, a continuation of the axillary, usually begins at the lower border of teres major muscle courses deep to the median nerve and ends at the level of the neck of the radius by dividing into ulnar and radial arter-ies (1). Variations occur in course of the artery in relation to the median nerve (2, 3), pattern and level of bifurca-tion (4-6). Variant anatomy is important in trans-radial percutaneous coronary angiography or when using ra-dial artery for coronary bypass grafts (7, 8). Complica-tions as a result of the variant pattern of this artery have been reported in surgical procedures (9). Knowledge of these variations is important to avoid complications of accidental intra-arterial injection of medication into su-perficial arteries that may lead to clinically important se-quelae such as to paraesthesias, severe pain, motor dys-function, compartment syndrome, gangrene, and limb loss (10). This study reports surgically relevant variants of the brachial artery in a black Kenyan population.

 

Materials And Methods

This was a dissection study carried out on 162 upper limbs from 81 cadavers of adult black Kenyans in the Department of Human Anatomy, University of Nairobi. Vertical incisions were made on the lateral and medial borders of the arm from the coracoid process and ax-illa proximally to the mid forearm. These incisions were joined by transverse ones and the skin flaps removed. The biceps brachii was sectioned in the middle, the ends retracted and the fascia split to expose the brachial artery in its entire extent from the axilla to the cubital fossa. The artery was traced proximally to its continuity with the axillary artery at the lower border of teres major and distally to its point of termination. The course in relation to the median nerve, level and pattern of termination were identified as follows; normal (classical pattern), an artery with a classical origin, course and branching pattern as described in Gray’s Anatomy (1). This artery originates from the lower border of Teres major muscle and coursed deep to the median nerve, terminating at the level of the radial tuberosity into the ulnar and ra-dial arteries. Superficial brachial artery described an ar-tery with a course superficial to the median nerve (3, 11, 12). Brachioradial artery described a proximal origin of the radial artery in the arm which courses superficial to the median nerve. Photographs of the representative pat- terns were taken using a Sony cybershot ® camera 14.1 mega pixels, 4x optical zoom. The results were analysed using the Statistical Programme for Social Scientists (SPSS) version 17 for Windows and presented in tables and macrographs.

 

Results

Brachial artery was present bilaterally in all 162 upper limbs studied. Variations were observed in course, level and pattern of termination. The usual anatomical de-scription of the brachial artery occurred in 72.2% (117 of the cases) of the cases. The artery was found to course superficial to the median nerve mainly as the brachiora-dial artery (12.3%) in which case the artery bifurcated in the arm, and the radial artery coursed superficial to the nerve. A superficial brachial artery existed in 6.1% of the cases.

 

Regarding the point of termination of the brachial ar-tery, 79% terminated at the radial neck (Fig. 1A). Twenty brachial arteries (12.3%) had a proximal bifurcation in which case the radial artery coursed distally at first medial to the median nerve then arching superficial to the median nerve from medial to lateral (Fig.1B). These proximal bifurcations occurred either in the proximal third of the arm, 18 cases, 11.1%, (Fig. 1B) or mid arm level 2 cases, 1.2% (Fig 1C). Fourteen brachial (8.6%) arteries took a longer course and terminated at the level of the radial tuberosity (Fig.1D). The mode of termi-nation observed in this study was either a bifurcation of the brachial artery into ulnar and radial arteries 146 (90.1%) or a trifurcation into the ulnar, radial and com-mon interosseous arteries 9.3% (Fig. 1D, E). In one case (0.6%), the brachial artery terminated in the arm as a trifurcation into the radial, ulnar and profunda brachii arteries (Fig. 1F).

 

Discussion

In the present study, 72.2% of the limbs displayed the classical pattern of the brachial artery. This is lower than the 82% reported (6) in an Indian population. The ex-istence of such variations of the upper extremity is clini-cally important. They may complicate intravenous drug administration as well as percutaneous brachial cath-eterization. For instance, in the present study, 10 (6.1%) brachial arteries coursed superficial to the median nerve, higher than 3.6% reported by Keen (1961) [Table 1] (2). Miller (1939) suggested the superficial brachial artery

 

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Click to view table 2

 

was an atavistic feature as he considered a brachial artery passing anterior to the median nerve to be the usual arrangement in pri-mates (13). Such an artery may be mistaken for a vein. Its superficial course makes it more prone to injury, which may result in profuse bleeding. On the other hand, t