RESUMO
Background: cervicogenic headaches are common and are believed to be the cause of dysfunction in the upper cervical spine. The mobility and the position of the atlas have been identified as a cause of upper cervical dysfunction. The mobility of the atlas is entirely under the control of the suboccipital muscles. The oblique capitis inferior muscle has a rotatory effect on the atlas when contracted. This study evaluated the immediate effects of a dry needling electrical stimulation-induced contraction of the left oblique capitis inferior muscle on the position and mobility of the atlas in the atlantoaxial joint. Methods: thirty-one subjects participated in this within-subject repeated measure study design. Each subject underwent a pre-measures neck flexion rotation test, palpation of the atlas position, and measurement of the length of the right oblique capitis inferior muscle with musculoskeletal ultrasound imaging. The pre-measures were repeated after two five-second tetanic contractions of the oblique capitis inferior muscle. Results: post-intervention analysis revealed significant changes in the length of the right oblique capitis inferior muscle. This length change correlated with the palpated positional default position immediately after the intervention. Conclusions: two five-second tetanic contractions of the left oblique capitis inferior muscle immediately affected the position of the atlas in the atlantoaxial joint. In our subjects, 90% displayed a positional default in the left rotation, and this was correlated with a change in the neck flexion rotation test. This study supports the notion that suboccipital muscle tonicity can result in mobility dysfunction and, thus, conditions such as cervicogenic headaches.
