Value Of H Reflex Elicited By Magnetic Stimulation And F Wave In The Diagnosis Of S1 Radiculopathy

【Objective】To explore a new electrodiagnostic approach for evaluating the nerve root function in patients with S1 radiculopathy.【Methods】Thirty normal subjects and 30 patients with unilateral S1 radiculopathy were recruited in this study. Bilateral H reflex and M response were recorded from soleus of all the subjects by magnetic stimulation of the first sacral nerve roots, F wave and M response to electrical stimulation of the bilateral tibial nerves at popliteal fossa were also recorded. The sensory root conduction time (SRCT) and motor root conduction time (MRCT) were calculated. Meanwhile, needle electromyographic examination was performed on the affected side to detect any possible EMG abnormalities. In addition, we tried to find out if age and height correlated with the SRCT in healthy subjects, and if there exists a correlation between the SRCT and pain in the patients with S1 radiculopathy.【Results】The norm we established with the normal subjects was 3.10±0.44ms for SRCT, and 0.29±0.36ms for the inter-side difference of SRCT. In 30 patients with S1 radiculopathy, H reflex was not elicited from 4 patients. For the remaining patients, the SRCT of the affected side significantly prolonged (3.90±0.65ms), and the mean value of the inter-side difference significantly increased (1.12±0.62ms). We developed a regression equation correlating SRCT with height,but no significant correlation between SRCT and age was found in our normal subjects. There was a positive correlation between SRCT and the severity of pain in patients. However, no significant difference was revealed between the normal subjects and the patients with S1 radiculopathy with regard to the MRCT and the inter-side difference of MRCT. The diagnosis agreement percentage between NEE and MRCT was 81.8%.【Conclusion】MRCT and SRCT can be used as the new electrodiagnostic parameters for estimation of the sensory nerve root function in patients with S1 radiculopathy.