Ultrasonography of longus colli muscle: A reliability study on healthy subjects and patients with chronic neck pain.

In this study, the reliability of the longus colli muscle (LCM) size was assessed in a relaxed state by a real time ultrasonography (US) device in a group of healthy subjects and a group of patients with chronic neck pain. Fifteen healthy subjects (19-41 years old) and 10 patients with chronic neck pain (27-44 years old) were recruited for the purpose of this study. LCM size was measured at the level of thyroid cartilage. Two images were taken on the same day with an hour interval to assess the within day reliability and the third image was taken 1 week later to determine between days reliability. Cross sectional area (CSA), anterior posterior dimension (APD), and lateral dimension (LD) were measured each time. The shape ratio was calculated as LD/APD. Intraclass correlation coefficients (ICC) and standard error of measurement (SEM) were computed for data analysis. The ICC of left and right CSA for within day and between days reliability in healthy subjects were (0.90, 0.93) and (0.85, 0.82), respectively. The ICC of left and right CSA for within day and between days reliability in patients with neck pain were (0.86, 0.82) and (0.76, 0.81), respectively. The results indicated that US could be used as a reliable tool to measure the LCM dimensions in healthy subjects and patients with chronic neck pain.