Boon, Andrea J.

Introduction : Real time ultrasound imaging of the diaphragm is an under‐used tool in the evaluation of patients with unexplained dyspnea or respiratory failure. Methods : We measured diaphragm thickness and the change in thickness that occurs with maximal inspiration in 150 normal subjects, with results stratified for age, gender, body mass index, and smoking history. Results : The lower limit of normal diaphragm thickness at end expiration or functional residual capacity is 0.15 cm, and an increase of at least 20% in diaphragm thickness from functional residual capacity to total lung capacity is normal. A side to side difference in thickness at end expiration of > 0.33 cm is abnormal. Diaphragm thickness and contractility are minimally affected by age, gender, body habitus, or smoking history. Conclusions : This study confirms previous findings in much smaller groups of normal controls for quantitative ultrasound of the diaphragm and provides data that can be applied widely to the general population. Muscle Nerve 47: 884–889, 2013

Introduction: Median nerve ultrasound shows increased cross‐sectional area (CSA) in carpal tunnel syndrome (CTS) and diabetic peripheral neuropathy (PN). The role of ultrasound in diagnosing CTS superimposed on diabetic PN is unknown. The objective of this study is to evaluate ultrasound for diagnosis of CTS in diabetic PN. Methods: Prospective recruitment of diabetics with electrodiagnostically proven PN, subdivided into cases (with CTS) or controls (without CTS). The gold standard for CTS was clinical diagnosis. NCS were correlated with blinded median nerve CSA ultrasound measurements. Results: Eight cases (CTS) and eight controls (no CTS) were recruited. Nerve conduction studies (NCS): Median nerve distal latencies (antidromic sensory; palmar; lumbrical motor; and lumbrical motor to ulnar interosseous difference) were significantly prolonged in CTS cases. No ultrasound measurement (distal median CSA, wrist‐forearm ratio, wrist‐forearm difference) reached significance to detect CTS. Area under the curve was greatest for lumbrical distal latency by receiver operator characteristic analysis (0.85). Conclusions: In this pilot study, NCS may be superior to ultrasound for identification of superimposed CTS in diabetic PN patients, but larger numbers are needed for confirmation. Muscle Nerve 47: 437–439, 2013