Reliability of deep cervical fascia and sternocleidomastoid thickness measurements using ultrasound imaging

Abstract

BACKGROUND: Recent literature has provided a hypothetical framework for the possible role of fascia within myofascial pain. This hypothesis involves structural alteration of deep cervical fascia within the loose connective tissue layer, as observed through ultrasound imaging (USI). This structural alteration has been termed ‘densification’, and has been associated with increased fascia thickness and reduced tissue compliance. Whilst increased cervical fascia thickness has been reported in one study to be significantly thicker within people with chronic neck pain compared to controls, a study assessing the reliability of cervical fascia measurements has not been conducted to date.

OBJECTIVE: To investigate the reliability of deep cervical fascia and sternocleidomastoid thickness measurements utilising USI.

METHODS: High-resolution, B-mode ultrasound was utilised to execute a standardised protocol for repeated thickness measurements of deep cervical fascia enveloping SCM muscle, and the SCM muscle itself. A convenience sample of 10 participants (5 males, 5 females, mean ± SD age = 26.2 ± 5.8 years, height 172.9 ± 13.2 cm, body mass 76.4 ± 16.6 kg, and median NDI score was 7% (range: 0 to 34 %) attended a single session. Intra-operator and inter-operator reliability was calculated for all thickness measurements obtained by a novice and an experienced USI operator.

RESULTS: Both operators demonstrated ‘very high’ intra-operator and inter-operator reliability for SCM muscle thickness measurements (all ICCs >0.7). The experienced operator demonstrated ‘moderate’ reliability (ICC = 0.312; 95%CI 0.357 - 0.770) to ‘very high’ (ICC = 0.821; 95%CI 0.434 - 0.952) intra-operator reliability for cervical fascia measurements. The level of intra-operator reliability for the novice operator was inconsistent for both the SDF and DF measurements, ranging from ‘very low’ to ‘very high’. Inter-operator reliability for all fascia thickness measurements was ‘low’ (ICC = 0.033; 95%CI 0.581 - 0.623) to ‘moderate’ (ICC = 0.428; 95%CI 0.235 - 0.819).

CONCLUSION: Within this study, the experienced operator demonstrated acceptable reliability for cervical fascia measurement with USI, whilst the novice operator was not reliable. Both the novice and experienced operators demonstrated high intra-operator and inter-operator reliability for SCM muscle thickness measurements.