Topographic Sonoanatomy of Infraclavicular Brachial Plexus: Variability and Correlation with Anthropometry

The aim of the study was to assess the effectiveness of ultrasound in analyzing topographic relationship of nerve cords with axillary artery at lateral infraclavicular level, their variations, and the distance from the skin and to correlate findings with anthropometric parameters.

Two hundred patients aged 18-75 years were enrolled for the study after informed written consent. A 7-12 MHz linear ultrasonic transducer was used for scanning of the brachial plexus at lateral infraclavicular fossa. The results of the cord positions were expressed on a 12-section pie chart, and the number of arteries and veins was reported. Measurements included the vertical distance from the upper part of the artery to the skin, diagonal distance to the apical corner of the ultrasound image, and distances from center of cords to the center of artery. Age, sex, weight, height, body mass index, and biceps girth were recorded. Data were expressed as mean with standard deviation or frequency and percentage for categorical variables, and statistical analysis was done using correlation analysis and two-sample t-test.

The most frequent positions of the cords were observed in 2-4 sections (92%) for the medial cord, 6-7 sections (92%) for the posterior cord, 10-11 sections (89%) for the lateral cord, and 4-5 sections (95%) for the axillary vein. More than one axillary vein was seen in 12.5% and two axillary arteries were seen in 1.5% of cases. Cord visibility and distance between artery and apical corner of the ultrasound image correlated with anthropometric parameters.

A topographical study of brachial plexus at lateral infraclavicular fossa showed anatomical variations and abnormal vascular formations. This sonoanatomic knowledge can be helpful in improving safety and success of nerve blocks.