electromyographic assessment of F-wave in carpal tunnel syndrome: correlation study with MRI carpus and cervical spine

ABSTRACT

In this study we have analyzed the effect C.T.S. of focal median nerve injury carpal tunnel syndrome [CT] on F wave. We have determined the F wave parameters in C.T.S. patients and evaluate the relationship between F wave and severity of injury of CT and MRI finding of the wrist and cervical spine finding. The study was conducted on all patients[104] referred from out-patients clinic in the same hospital to electrophysiologic examination in Rheumatology, Physical Medicine and Rehabilitation Dep. and Radiology department, Al Hussein University Hospital as clinical assessed as a carpal tunnel syndrome, Standard electro diagnostic study was made on all of them bilaterally. MRI of carpal tunnel and cervical spine done for selected patients with C.T. S. According to F wave parameters, patients were divided into three groups, absent F-wave, abnormally prolonged F-wave and normal F-wave. According to electrophysiological testing results, the patients were grouped into mild, moderate or severe C.T.S. Absent F wave was presented in 8 hands [7.7%], prolonged latency in 9 hands [8.6%] and normal F wave in 87 of 104 hands [83.7%]. the mean F wave latency were statistically different between the C.T.S. patients and the normal values [CI 95%, p<0.0001]. Also, the entire F wave latencies were significantly prolonged in the severely injured group [p=0.0001]. F wave determination could show injury to proximal and also severe injury to distal parts of median nerve and especially axonal injury. According to abnormalities of this test the surgical release of nerve for prevention of irreversible changes must be considered. Results of our study supported the adding of F wave parameters study to standardize electrophysiological evaluation of C.T.S