The purposes of this research were to investigate the effect of age and chronic neck pain on cervical proprioception, the change of ultrasonographic (USD) patterns in deep neck muscle and superficial neck muscles.

The hypotheses of this research included: 1) the alteration of neck proprioception is determined predominantly by the changed activation deep neck muscles and superficial neck muscles. 2) Age factor contributes to the alteration of cervicocephalic sensibility, USD pattern of deep and superficial muscles. 3) Chronic pain contributes to the alteration of cervicocephalic sensibility, USD pattern of deep and superficial muscles.

Neck proprioception is measured by an ultrasound-based coordinate measuring system (CMS 70P, Zebris, Germany) by asking the subjects to performed head repositioning to the neutral head position or to a target position in three cardinal plane. These repositioning error expressed in root mean square errors could represent the craniocervical kinesthetic sensibility. The change of muscle thickness (mm) of the superficial (Trapezium, Splenius) and deep (semispinalis cervicis and multifidus) dorsal neck muscle is measured by a real-time ultrasonographic scanner (HDI 5000, ATL Ultrasound, USA). Image is obtained for each cervical level, and the thickness of the muscle is identified manually using a custom-written C++ computer graphic program. The measurements of pain intensity and pain frequency are modified from the symptoms questionnaire to indicate the intensity, location, frequency and duration of pain and disability of the subjects. The age and pain effects for each independent variables measured in patients with chronic neck pain (pain: intensity, location, frequency, and duration, NDI), will be tested with the General Linear Model (GLM; age and pain factors). The confounding factors such as gender, range of motion, body height and weight are controlled in the regression model.