H reflex and F wave latencies to soleus normal values and side-to-side differences.
OBJECTIVE
Electromyographers must reliably differentiate between H reflexes and F waves when recording from the soleus muscle in the evaluation of S1 radiculopathy. The use of F waves in root-level injuries is questioned, whereas H reflexes have shown value in the evaluation of S1 radiculopathy. We studied the relationship between the tibial H reflex and F wave latencies in the limbs of 40 subjects.


METHODS
After recording the H wave latency, we changed the gain to 200 microV/cm and increased the stimulation to supramaximal for ten additional responses without moving the recording or stimulating electrodes. We also calculated the predicted H wave latency with the standard formula. Forty subjects, mean age 32 yr, consented and participated.


RESULTS
The mean of the average F wave was 1.76 ms longer than the ipsilateral H reflex latency. The mean side-to-side difference of the average F wave was 0.56 ms. The H reflex latency side-to-side difference was 0.36 ms.


CONCLUSIONS
The findings suggest that the average F wave latencies have a predictive value in the clinical context similar to the H reflex.
Strakowski
J A
JA
Grant-Riverside Methodist Hospitals, The Ohio State University, Columbus, USA.
Redd
D D
DD
Johnson
E W
EW
Pease
W S
WS
D000200:Action Potentials / Q000502:physiology*; D000328:Adult; D004576:Electromyography / Q000379:methods*; D005071:Evoked Potentials / Q000502:physiology*; D005260:Female; D006181:H-Reflex / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009046:Motor Neurons / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology*; D011128:Polyradiculopathy / Q000175:diagnosis / Q000503:physiopathology; D011237:Predictive Value of Tests; D011843:Radiculopathy / Q000175:diagnosis / Q000503:physiopathology; D011930:Reaction Time / Q000502:physiology*; D012447:Sacrum / Q000294:innervation*; D013126:Spinal Nerve Roots / Q000293:injuries / Q000503:physiopathology