Value of the H reflex elicited by magnetic stimulation and the F wave in the diagnosis of S1 radiculopathy / 中华物理医学与康复杂志

Objective To explore a new electrodiagnostic approach using the H reflex elicited by magnetic stimulation of the S1 nerve root and F waves to evaluate sensory nerve root function in patients with S1 radiculopathy.Methods Thirty normal subjects and 30 patients with unilateral S1 radiculopathy were recruited in this study.H reflex and M response were recorded from the bilateral soleus of all the subjects by magnetic stimulation of S1 nerve roots.F and M wave responses elicited by electrical stimulation of bilateral tibial nerves at the popliteal fossa were also recorded.The sensory root conduction time (SRCT) was calculated.Correlations of age and body height with SRCT in the healthy subjects,and between SRCT and pain in the patients with S1 radiculopathy were analyzed.Results The mean values of normal subjects were 3.10 ± 0.44 ms for SRCT,and 0.13 ± 0.19 ms for inter-side SRCT differences.In the 30 patients with S1 radiculopathy,H reflex could not be elicited from 4 patients.Among the remaining patients,the SRCT of the affected side was prolonged significantly (3.90 ±0.65 ms),and the mean value of the inter-side difference increased significantly (0.90 ±0.50 ms).A regression equation correlating SRCT with height was developed,but no significant correlation between SRCT and age in the normal subjects was revealed.There was positive correlation between SRCT and the severity of pain among the patients.Conclusion SRCT can be used as a new electrodiagnostic index in estimating sensory nerve root function in patients with S1 radiculopathy.

Value of magnetic stimulation in the non-invasive diagnosis of St radiculopathy / 中华物理医学与康复杂志

Objective To explore the value of a new electrodiagnostic approach for evaluating motor nerve root function in patients with S1 radiculopathy. Methods Thirty healthy subjects and 30 patients with clinical mani-festations of unilateral S1 radiculopathy were recruited. Bilateral compound muscle action potentials evoked by magnetic stimulation of the first sacral nerve root were recorded from the soleus of all the subjects. F wave and M responses to electrical stimulation of the bilateral tibial nerves at the popliteal fossa were also recorded. The peripheral motor conduction time (PMCT) and the motor root conduction time (MRCT) were calculated and compared between the two groups. In addition, needle electromyographic examination (NEE) was performed on the affected side to detect any possible EMG abnormalities. Results The norm established with the normal subjects was 3.45±0.39 ms for the MRCT, and 0.28±0.15 ms for the inter-side difference in the MRCT. In the 30 patients, the mean MRCT and PMCT values on the affected side were prolonged. Of the 23 patients who received NEE, 6 had EMG abnormalities. The agreement between the NEE and MRCT diagnoses was 82.6%. Conclusion MRCT can be used reliably for non-invasive estimation of motor nerve root function and to help diagnose the S1 radiculopathy.

Relation between Symptom Duration and Abnormal Spontaneous Activity in S1 Radiculopathy

OBJECTIVE: It is a widely accepted belief that paraspinal muscles tend to show spontaneous activity on needle electromyography early on in a radiculopathy and distal muscles become abnormal later on. But most studies have shown the limitations of using symptom duration when interpreting electrodiagnostic findings in radiculopathy. The purpose of this study was to determine the relationship between symptom duration and abnormal spontaneous activity in S1 radiculopathy confined to abnormal H-reflex. METHOD: A retrospective study that collected the informations on symptom duration and spontaneous activity in paraspinal muscle and gastrocnemius for 112 patients with S1 radiculopathy diagnosed by unilateral H-reflex abnormality was undertaken. RESULTS: Abnormal spontaneous activity in paraspinal muscle had shown a significant negative correlation with symptom duration, that is a tendency to decrease its expression over symptom duration. On the contrary abnormal spontaneous activity in gastrocnemius muscle was rare at first a few weeks and became to show after 7 weeks. Patients with symptom duration over 1 year had higher incidence of having no abnormal spontaneous activities both in paraspinal and gastrocnemius muscle. CONCLUSION: These results suggested that symptom duration had a potential role in the diagnosis of S1 radiculopathy when H-reflex were abnormal unilaterally.

Variability of the Side-to-Side Difference in H Reflex Latency

OBJECTIVE: To find the developing features of H reflex by the gradual increase of stimulation intensity, to evaluate the variability of each H reflex latency, and to verify the consistency of the side-to-side difference of bilateral H reflex latencies in normal population. METHOD: Fifty normal persons (100 limbs) were studied. H reflexes were elicited using standardized technique from Braddom and Johnson. RESULT: H reflex developed in the stimulation intensity at which M response was not evoked in 46 of total 100 limbs. The latency difference between the longest and shortest in each ipsilateral evoked potential was 0~2.1 ms (mean 0.65+/-0.44 ms). In the side-to-side latency difference between the variously evoked H waves, the mean value of maximal one was 1.28+/-0.63 ms (0.4~2.6 ms), and the mean value of the minimal one was 0.24+/-0.35 ms (0~1.5 ms). The mean side-to-side latency difference between the H waves of maximal amplitudes was 0.69+/-0.46 ms (0.1~1.6 ms), and the mean side-to-side difference between the shortest latencies was 0.61+/-0.53 ms (0~2.1 ms). Among these findings the latency difference of the maximal amplitude was observed in 47 cases with 0~1.5 ms, in 3 cases with more than 1.5 ms. CONCLUSION: In diagnosing the S1 radiculopathy with the side-to-side latency difference it will be reasonable to use the latency of maximal amplitude or the shortest latency as diagnostic tool, and reevaluation will be needed with the diagnostic criteria of 1.5 ms latency difference.

The Diagnostic Significance of H Reflex and Somatosensory Evoked Potential in S1 Radiculopathy

OBJECTIVE: To compare the diagnostic significance of H reflex and somatosensory evoked potential(SEP) in the diagnosis of S1 radiculopathy, and to explore the possible interpretations on the discrepancies of the test results. METHOD: Twenty-eight patients who were diagnosed as a S1 radiculopathy by the clinical and radiological correlations, and thirty-five controls with no evidence of S1 radiculopathy by the clinical or radiological studies were studied by the H reflex, sural SEP, and needle electromyography. RESULTS: The sensitivity of H reflex study was 64% for the S1 radiculopathy, and the specificity was 86%. The sensitivity and the specificity of the sural SEP study for the S1 radiculopathy were 50% and 80% respectively. Within 1 month from the onset, the sensitivity of H reflex increased to 75%. The needle electromyography showed 19% for the sensitivity and 100% for the specificity. The probability of the S1 radiculopathy was 70% in 10 cases who had the abnormal H reflex and normal SEP values and 36% in 8 cases who had the normal H reflex and abnormal SEP values. CONCLUSION: H reflex study was the most sensitive test in the electrodiagnosis of the S1 radiculopathy and the electrodiagnostic significance of sural SEP was obscure.