Ultrasound Verification Of Safe Needle Examination Of The Rhomboid Major Muscle.

Abstract

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. 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. 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). 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.