Sympathetic nervous system effects in the hands following a grade III postero-anterior rotatory mobilisation technique applied to T4: a randomised, placebo-controlled trial.

Joint mobilisation to the T4 vertebra has been advocated as a treatment for T4 syndrome. To date no controlled studies have investigated the effects of thoracic spinal manual therapy (SMT) applied to T4 on sympathetic activity in the hands. This study investigated whether a grade III postero-anterior rotatory joint mobilisation technique applied to the T4 vertebra at a frequency of 0.5 Hz had demonstrably greater effects than a validated placebo intervention on skin conductance (SC) in the hands of healthy subjects. A power analysis calculation was performed and using a double blind, placebo-controlled, independent groups design, 36 healthy subjects (18-35 years) were randomly assigned to two groups (placebo intervention or treatment intervention). A BioPac unit recorded continuous SC measures before, during and after each experimental intervention. An exit questionnaire was used to validate the expectancy effects of the placebo intervention. Results demonstrated a significant difference between groups in SC in the right hand during the post-treatment rest period (F = 4.888, p = 0.034); with the treatment intervention being sympathoexcitatory in nature. A trend towards a significant difference between groups was also demonstrated in the left hand during the rest period (F = 4.072, p = 0.052). This study provides preliminary evidence that joint mobilisation applied to the T4 vertebra at a frequency of 0.5 Hz can produce sympathoexcitatory effects in the hand. Further research is recommended in a patient population.