Head repositioning accuracy and posturography related to cervical facet nerve blockade and spinal manipulative therapy in healthy volunteers: a time series study.

Objective: The aim of the study was to investigate if changes in head repositioning accuracy (HRA), and standing balance could be evoked by unilateral facet nerve blockade (FNB) or spinal manipulative therapy (SMT).
Methods: This time series research study (n = 6) was chosen because of the viability of the experiment, sample characteristics, and small sample size. Cervical proprioceptive functions were assessed by exploring HRA and static posture by computerized posturography. All participants were subjected to 2 interventions, unilateral FNB using local anesthetic and SMT.
Results: No significant trends were seen in the subjects over the period of the study. All measurements were taken approximately 3 weeks apart. Visually, it was detected that most of subjects appeared to be greatly affected by the FNB, thus, increasing their deviation from the center point of measurement in extension and flexion movements. When comparing the changes with respect to the baseline after SMT, all subjects showed some differences, though there was a great deal of variation between the subjects. These trends were also seen when comparing the changes from baseline measurements to those after FNB.
Conclusions: Data from this time series research design suggest there was no uniform response to unilateral FNB or to SMT. However, differences indicate that there may be important effects of unilateral FNBs for some of the HRA aspects measured. Balance testing using computerized posturography did not show clear differences between baseline assessments and interventions. A future larger clinical study to detect changes in HRA evoked by unilateral FNB or SMT appears feasible.