Reliability of Longus Colli Muscle Size Measurement Using Ultrasonography

The deep cervical flexor muscles have a major role to play in neck stabilization and evidence suggests that these muscles especially longus colli muscle (LCM) becomes dysfunctional in the presence of neck pain. Therefore, measurement of these muscles in healthy subjects and patients may be of great value to understand the stabilization function of the muscles. The purpose of this study was to assess within and between days reliability of LCM size measurement using ultrasonography (US) in a group of healthy subjects and a group of patients with chronic neck pain. This methodological research was performed on 10 patients with chronic neck pain (27-44 years old) and 15 healthy subjects (19-41 years old). Neck LCM size was measured at the level of thyroid cartilage using a real time US device. Two images were taken on the same day with an hour interval to assess the within- day reliability and the third image was taken one week later to determine between- days reliability. Cross sectional area (CSA), anterior posterior dimension (APD), and lateral dimension (LD) were measured at each time. The shape ratio was calculated as LD/APD. Then data were compared using statistical tests. The ICC measurements for within day and between days reliability in healthy subjects were varied ranging from 0.8 to 0.9 for CSA, 0.9 to 1 for APD, and 0.6 to 0.9 for LD. In patients group it was also ranged between 0.8 to 0.9, 0.8 to 0.9, and 0.7 to 0.9, respectively. The highest reliability score were found for CSA measurement in healthy subjects (ICC= 0.90-0.93). The results indicated that US could be a reliable tool to measure the LCM dimensions in healthy subjects and patients with chronic neck pain. Therefore, the non invasive method can be used to follow up the effect of exercise therapy interventions.