Prolonged F waves?

[QUOTE=slk]…. My nerve conduction study showed prolonged F-Waves. What does that mean?…[/QUOTE]

for what it means, study this:

[url]http://www.ispub.com/journal/the_internet_journal_of_neurology/volume_10_number_2_6/article/f_wave_clinical_importance.html[/url]

A summary from that site:

“In a typical F wave study, a strong electrical stimulus (supramaximal stimulation) is applied to the skin surface above the distal portion of a nerve so that the impulse travels both distally (towards the muscle fiber) and proximally (back to the motor neurons of the spinal cord)…”

“The distal motor latency ,Conduction velocity and the patients limb length are the parameters required for calculating F estimate. It is calculated by the theoretical time it should take for the F response to occur…”

“Therefore, if F response is prolonged as compared to the F estimate it is suggestive of proximal nerve segment injury…”

“It is a sensitive measure of polyneuropathy and radiculopathy.In Guillain Barré syndrome (GBS) even if the nerve conduction study in terms of distal motor latency and conduction velocity is normal, the F response could be the only parameter which would help in diagnosis. F wave latencies are prolonged in GBS affecting the proximal nerve segment. In amyotrophic lateral sclerosis, reduced persistence of F wave is attributed to the loss of anterior horn cell.”