Effect of Joint Mobilization on Alpha Motoneuron Reflex Excitability

Objective: To determine the effect of ankle joint mobilization on the alpha motoneuron reflex excitability of the soleus muscle in people with spasticity. Subjects and Methods: A controlled clinical trial with crossover design and simple masking was conducted in 24 randomized subjects to initiate the control or experimental group. Traction and rhythmic oscillation were applied for five minutes to the ankle joint. Alpha motoneuron reflex excitability was assessed by measuring H wave amplitude (Hoffmann reflex - H reflex), stimulating the tibial nerve at the level of the popliteal fossa and recording in the soleus muscle. In each subject 12 measurements were taken: basal rate, during and after mobilization. Changes in alpha motoneuron reflex excitability were calculated in relation to basal measurement. For each measurement a hypothesis test was performed (Student t test). Results: In groups of patients with brain injury (BI) and incomplete spinal cord injury (ISCI), a significant difference was found between measurements of both studies, concerning variation in alpha motoneuron reflex excitability during the application of joint mobilization techniques, with a decrease in the experimental group and an increase in the control group. In contrast, no significant differences were found after mobilization therapy. Patients with complete spinal cord injury (CSCI) showed no significant differences in any measurements. Conclusion: We demonstrate the effectiveness of passive movement in the decrease of muscle tone during the mobilization maneuver in patients with BI or ISCI, but no residual effect after completion of the trial. This research project showed no evidence regarding spasticity reduction in complete spinal cord injuries. This suggests that therapeutic interventions to decrease muscle tone, based on the passive exercise and stimulation of proprioceptors should be reconsidered.