Sacroiliac joint manipulation decreases the H-reflex

Area of Science:

• Neuroscience
• Physiology
• Musculoskeletal Medicine

Background:

• Joint manipulation is a common clinical practice for pain relief and improving joint mobility.
• The underlying physiological mechanisms of joint manipulation, particularly on the nervous system, require further elucidation.

Purpose of the Study:

• To investigate the effect of sacroiliac joint manipulation on the Hoffman (H) reflex amplitude.
• To explore the afferent pathways involved in the reflex changes induced by sacroiliac joint manipulation.

Main Methods:

• Surface electromyography (EMG) was used to record H-reflexes from the soleus muscle in response to tibial nerve stimulation.
• H-reflex amplitudes were compared before and after sacroiliac joint manipulation or a sham procedure.
• Experiments were repeated with local anesthetic applied to the sacroiliac joint area to assess the role of cutaneous afferents.

Main Results:

• Sacroiliac joint manipulation significantly decreased ipsilateral H-reflex amplitude by 12.9% (p < 0.001).
• No significant changes in H-reflex amplitude were observed after the sham procedure or in the contralateral leg.
• The decrease in H-reflex amplitude persisted (10.6%) even when cutaneous afferents were anesthetized, suggesting non-cutaneous mediation.

Conclusions:

• Joint manipulation induces physiological effects on the central nervous system, likely at the segmental level.
• The findings suggest that joint and/or muscle afferents, rather than cutaneous afferents, mediate the observed reflex changes.
• This study provides evidence for the neurophysiological impact of sacroiliac joint manipulation.