Comparison of H-reflex and F-wave latencies of upper limbs and lower limbs before and after cervical manipulation in patients with mechanical neck pain.

One of the physiological effects of high velocity low amplitude (HVLA) manipulation is change in motor neuron activity, which can be evaluated by measuring the H reflex and F wave latencies. The lack of specific objective and measurable criteria in previous studies related to the treatment of neck pain may have caused bias in effectiveness of treatment options؛ For this reason, proper treatment plans cannot be made. Nevertheless, use of measurable prognostic criteria such as H-reflex and F-wave latencies can have a major role in treatment of mechanical neck pain with cervical HVLA manipulation. Therefore, in this study, we will examine and compare the onset latencies of H-reflex and F-wave parameters of the median and tibial nerves before and after cervical HVLA manipulation.

In this interventional study, patients with mechanical neck pain who referred to Imam Reza Hospital in Tehran during 2018-19 were selected. Before and- after the HVLA manipulation of the neck, the onset latency index related to the H-reflex and F-wave parameters in the upper and lower limbs were measured using an EDX EMG machine. Statistical analysis was performed to compare the before and after results with Kolmogorov-Smirnov and paired t-tests and p-value less than 0.05 was considered significant.

In this study, 35 patients were examined. F wave in the right median nerve did not change significantly after the intervention (p=0.295), but this amount had decreased significantly on the left side (p=0.048). There was no significant change in the tibial F wave latency (p=0.245 on the right side and p=0.133 on the left side). There was a significant change in H reflex in the median nerve after the intervention (p=0.001 for the right side and p=0.030 for the left side). In the tibial nerve, the H reflex decreased significantly after the intervention (p=0.026 for right side and p=0.036 for left side).

H reflex latencies in both left and right median and tibial nerves and F wave latencies only in the left median nerve had a significant decrease after the intervention. HVLA manipulation by inhibiting the motor system reduces muscle tone, and in this way can break the cycle of pain and spasm and is effective in treating neck pain.