Clinical Utility of Flexor Carpi Radialis H-Reflex in the 7th Cervical Radiculopathy

Woo, Kyoung Bong; Park, Young Sook; Ryu, Dae Gul; Lim, Gyu Nam; Kim, Woo Jin; Chung, Seung Hyun; Lee, Yong Taek

Abstract

OBJECTIVE
To determine the clinical utility of flexor carpi radialis (FCR) H-reflex with and without facilitation in the diagnosis of 7th cervical radiculopathy. METHOD: Thirty-four subjects (27 men, 7 women) participated in this study showed symptoms and signs suggesitive of cervical radiculopathy and every subject had single herniated cervical disc on MRI study. All participants underwent electrophysiologic study including routine nerve conduction study (NCS), electromyography (EMG), FCR H-reflexes with and without facilitation in both arms. Abnormal parameters for FCR H-reflex were 1) side to side latency difference more than 1.0 msec, 2) absence of FCR H-reflex in one side, 3) side to side amplitude ratio below 33% for without facilitation and 22% for facilitation. If the subjects had at least one of the three abnormal parameters, we concluded as having abnormal FCR H-reflex.
RESULTS
In the FCR H-reflex without facilitation group, we were not able to elicit FCR H-reflex in both arms in 17 subjects. Among the 17 subjects with elicited FCR H-reflex, 7 had abnormal FCR H-reflex (C7 root; 4, other roots; 3). In the FCR H-reflex with facilitation group, FCR H-reflex was obtained in 32 subjects, 13 out of the 32 showed abnormal FCR H-reflex (C7 root; 6, other roots; 7). The sensitivity and specificity of FCR H-reflex without facilitation in the diagnosis of 7th cervical radiculopathy were 67%, 73%, with facilitation it were 50%, 65%.
CONCLUSION
Even though FCR H-reflex without facilitation is superior in its sensitivity and specificity, low elicitabiliy is the factor that limits its clinical utility. FCR H-reflex with facilitation with its good elicitability, seems to be a useful adjunctive method to routine NCS and EMG examination in the diagnosis of 7th cervical radiculopathy.