Ultrasound Verification Of Safe Needle Examination Of The Rhomboid Major Muscle

Abstract

INTRODUCTION: Palpation of a thoracic rib is a common method for reducing the risk of pneumothorax during electromyographic examination of the rhomboid major muscle, but its accuracy is unknown. METHODS: Two physicians palpated healthy subjects to attempt to identify the center of a rib located beneath the rhomboid major muscle. The identified location was examined with ultrasonography to examine its accuracy and the subject's anatomical depths. RESULTS: Forty-four subjects (88 ribs) were studied. Palpation demonstrated a 66.3% accuracy rate, with significantly more incorrect palpations seen with greater muscle thickness (P = 0.004) and body mass index (P = 0.037), but not adipose thickness, age, or skin thickness (P > 0.05). DISCUSSION: Palpation of the ribs in an attempt to avoid inadvertent pneumothorax while examining the rhomboid major may be inaccurate, primarily in patients with large muscle bulk. We suggest a brief ultrasound evaluation before electromyography to gauge correct needle depth. Muscle Nerve 57: 61-64, 2018.