Can High Resolution Ultrasound probes (5-12, 18, 22 MHz) performed by Medical Students Identify the Median Nerve In the Wrist and Hand Region from Donor Cadavers and Healthy Individuals

TRAN Jenny1, Brion BENNINGER1-9. Medical Anatomy Center1, Departments of Medical Anatomical Sciences2, Neuromuscular Medicine3, Family Practice4, Western University of Health Sciences, COMP–Northwest, Lebanon, OR. USA.... [ view full abstract ]

TRAN Jenny1, Brion BENNINGER1-9. Medical Anatomy Center1, Departments of Medical Anatomical Sciences2, Neuromuscular Medicine3, Family Practice4, Western University of Health Sciences, COMP–Northwest, Lebanon, OR. USA. Departments of Orthopaedics5, General Surgery6 and Sports Medicine7, Samaritan Health Services, Corvallis, OR. USA. Departments of Surgery8, Orthopaedics & Rehabilitation9, Oregon Health & Science University, Portland, OR. USA.

INTRODUCTION. The median nerve is the most commonly injured nerve in the forearm and wrist region. It anastomoses significantly with the ulnar nerve, affecting innervation patterns to the hand. MRI demonstrates low sensitivity and specificity while ultrasound (US) reveals high sensitivity and specificity for detecting median nerve lesions. The objective of this study was to investigate if medical students (MS) could identify the median nerve using multiple US probes. METHODS. Literature search was conducted regarding use of US on the median nerve of donor cadavers and healthy subjects by MS. Recently deceased unembalmed donor cadavers (RDUD) received 432 (144 per probe) trials from MS using 3 different US probes (5-12 MHz, 18 MHz, 22 MHz) and 42 trials on healthy individuals. All MS conducted timed trials bilaterally. RESULTS. Literature search revealed no known studies. 432/432 trials successfully identified the median nerve with all 3 probes (100%). 144 trials with 5-12MHz probe were more difficult to visualize than 18&22MHz probes. 42 trials with 18MHz probe on a healthy individual revealed 33% accuracy on the left side and 52% accuracy on the right. The high resolution probes allowed MS to identify the median nerve from cadaveric specimens and healthy volunteers more clearly than the 5-12 MHz probe. DISCUSSION. Carpal tunnel syndrome is the most common nerve entrapment syndrome in the upper limb. Mobile devices have increased prevalence of carpal tunnel syndrome significantly, reported to represent 90% of all entrapment neuropathies. Literature search revealed no known studies regarding MS identifying the median nerve with multiple US probes on RDUD and healthy subjects. US can be used to diagnose carpal tunnel syndrome by assessing the morphologic characteristics and caliber of the median nerve. High resolution US probes can reveal considerable median nerve detail, including its fibers in situ. CONCLUSION. This study demonstrated MS with novice ultrasound skills identified the median nerve using high-resolution probes (18&22 MHz).