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American Association for Hand Surgery

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Gray Scale and Power Doppler Ultrasound Findings Predictive of Cubital Tunnel Syndrome Severity
David M Brogan, MD1, Tony Y Lee, BS2, Dale Colorado, DO2, Wilson Ray, MD3 and Christopher J Dy, MD2, (1)Washington University School of Medicine, St. Louis, MO, (2)Washington University in St. Louis, St. Louis, MO, (3)Department of Neurological Surgery, Washington University School of Medicine, St. Louis, MO

Purpose: The use of ultrasound to aid in the diagnosis of cubital tunnel syndrome (CuTS) is an attractive alternative to electrodiagnostic studies, but the diagnostic utility is considered binary with poor correlation of severity. Our hypothesis is that increasing cross sectional area (CSA) and Power Doppler measurement of intraneural vascularity may predict extent of disease.

Methods: We identified a symptomatic cohort of 20 patients with a clinical examination and history consistent with cubital tunnel syndrome, and 20 elbows in 10 asymptomatic controls. Nerve conduction studies and needle electromyography were performed in the symptomatic group. Maximum CSA of the ulnar nerve and power Doppler imaging were performed to detect intraneural vascularity in all participants (Figure 1). Functional outcomes measured for all patients included: grip and key pinch strength, and Semmes-Weinstein monofilament (SWM) testing and patient reported outcomes questionnaires, such as the Boston Carpal Tunnel Questionnaire (BCTQ) and PROMIS surveys.


A strong positive correlation was found between CSA and decrease in motor nerve conduction velocity, which increased when BCTQ>2 was used as a screening criterion. Increased CSA also demonstrated a high positive predictive value (PPV) in predicting changes in motor conduction velocity, but poor ability to predict axonal loss. In contrast, Power Doppler ultrasound demonstrated 100% PPV and 94% negative predictive value (NPV) in predicting severe CuTS (defined as CMAP amplitude < 6 mV and EMG findings) (Figure 2).

Conclusions: CSA is a sensitive method of identifying changes in nerve conduction velocity and amplitude but does not stratify disease severity, as defined by diminished CMAP amplitude values and/or evidence of denervation changes on EMG. The presence of increased intraneural vascularity is relatively sensitive but highly specific for axonal loss. The combination of nerve cross sectional area, BCTQ screening and Power Doppler ultrasound may provide an alternative assessment of CuTS to electrodiagnostic studies.

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