Electrodiagnostic Measurement of Posterior Tibial Reflex in Patients with L5 Radiculopathy

J Korean Assoc EMG Electrodiagn Med 2010;12(2):77-82.
Published online October 1, 2010.

Abstract

Objective: To evaluate whether the electrodiagnostical posterior tibial reflex (PTR) will play an adjuvant role in diagnosis of L5 radiculopathy. Methods: Fourteen L5 radiculopathy patients confirmed by routine electrodiagnostic study and age- and sex-matched 14 healthy controls were participated in this study. By using patellar hammer, latencies of PTR were evoked in both legs of each group. Average of 5 repeated PTR latencies were calculated and the difference of the PTR latencies between right and left leg (PTR-D) were compared between two groups. Receiver operating characteristic (ROC) curve was used to determine optimal cut off values of PTR-D in diagnosing L5 radiculopathy. Results: Mean PTR latency in affected legs showed significantly longer value than that in unaffected legs in unilateral L5 radiculopathy group (p<0.05). And, mean value of PTR-D in L5 radiculopathy group was significantly greater than that in control group (p<0.05). PTR-D threshold of 10.0 ms yielded the greatest sensitivity (93%) and specificity (93%) for the diagnosis of L5 radiculopathy. Conclusion: As the PTR latency represented large inter-individual differences, the PTR-D can be used as an optimal parameter for the inter-individual comparison. Furthermore, PTR-D with 10.0 ms threshold gives best diagnostic discrimination for the diagnosis of L5 radiculopathy.

Key Words: Posterior tibial reflex, Electrodiagnostic measurement, Radiculopathy