RESUMO
Multifidus muscle is one of the short and deep posterior Paraspinal muscles, which gives stability to the spine during various activities. Studies have shown that in people with neck pain, weakness and atrophy of neck muscles are major factors in the incidence of neck pain. Measurement of muscle's dimensions by ultrasonography provides an opportunity to be able to objectively assess muscle atrophy or hypertrophy. This study aimed to assess symmetry of cervical multifidus muscle size in females with chronic non-specific neck pain and healthy by ultrasonography apparatus. Twenty five women with unilateral chronic nonspecific neck pain and 25 healthy women were participated in this study. All subjects were employed and more than 4 hours working with computers or paying office in a day. Imaging of the cervical multifidus muscles were done bilaterally in the level of the fourth vertebra. Anterior-Posterior Dimension [APD], Lateral Dimension[LD], Cross-Sectional Area [multiplied of two diameters[APD and LD]] and the Shape ratio [Lateral diameter divided by the Anterior-Posterior diameter[LD/APD]] of the muscle were measured and recorded. Multifidus muscle size in patients group was smaller than the healthy group. In patients group, size of multifidus muscle in the painful side was smaller than the opposite side. Asymmetry of muscle size between the two sides, in the patient group was higher than the control group [P < 0.05]. The ratio of smaller size to the larger size of the muscle, in the healthy group was higher than the ratio in the patient group [P < 0.05]. In patients group, asymmetry of the muscle size between two sides, also smaller size of the muscle in the painful side, showed that muscle atrophy has happened in the involved side