Flexor carpi radialis Hoffmann-reflex in the assessment of the responsible level of cervical radiculopathy

Abstract

Objective To identify abnormal Hoffmann-reflex (H-reflex) of the flexor carpi radialis (FCR) is mainly attributed by C7 or C6 nerve root lesion.Methods This study was performed on 41 normal subjects,20 patients with identified C6 radiculopathy(C5,6 level compression) and 24 patients with identified C7 radiculopathy (C6,7 level compression).The FCR H-reflex was performed in all patients bilaterally,and the concentric needle electrode was used to record the FCR H-reflex.The latencies of M wave and H-reflex were measured and compared bilaterally.All data were analyzed using SPSS version 15.0 (IBM,USA) for Windows.Results FCR H-reflexes were reliably recorded in all control group subjects bilaterally.On the involved side,the FCR H-reflex was abnormal in 22 of 24 patients with C7 radiculopathy (absent H-reflexes were seen in 9 patients,including 2 patients with bilateral absent H-reflexes,and 13 patients with siginificant prolonged H-reflex latencies),along with the abnormal FCR H-reflex in 2 of 20 patients with C6 radiculopathy (prolonged H-reflex latencies were seen in these 2 patients).On the uninvolved side,the FCR H-reflex was normal in 42 of 44 patients,and disappeared H-reflex was seen in 2 cases with C7 radiculopathy.The sensitivity of FCR H-reflex in assessing C7 nerve root lesions (C6,7 level compression) (83.4％; 20 of 24) was significantly higher than that in evaluating C6 nerve root lesions (C5.6 level compression) (10.0％; 2 of 20) Conclusion Abnormal FCR Hreflex may mainly suggest C7 nerve root lesion in the present study.The abnormal FCR H-reflex in the patients with cervical radiculopathy always suggests the responsible level is C6,7,which most often affect the C7 nerve root. Key words: Cervical vertebrae; Spinal cord compression; H-reflex; Spinal nerve roots