F-wave
A late response recorded during nerve conduction studies reflecting conduction along the entire motor pathway.
Full Definition
The F-wave is a late motor response obtained during nerve conduction studies by supramaximal stimulation of motor nerves. Unlike the direct motor response (M-wave), the F-wave results from antidromic activation of motor neurons in the spinal cord, followed by orthodromic impulse transmission back to the muscle. F-waves evaluate the proximal portions of motor nerves and nerve roots, making them valuable for detecting radiculopathies and proximal neuropathies that might be missed by standard distal nerve conduction studies. The F-wave latency provides information about conduction velocity along the entire motor pathway from spinal cord to muscle.
Usage
Usage note: Always capitalize 'F' and hyphenate; distinguish from 'H-reflex' which tests different pathways.
In Context
- "F-wave latencies were prolonged bilaterally, suggesting proximal motor nerve involvement." — Electrodiagnostic report
- "The F-wave study revealed evidence of L5 radiculopathy with prolonged minimal latency." — Nerve conduction study interpretation