F-wave
A late electrophysiological response representing backfiring of motor neurons, used to assess proximal nerve conduction and anterior horn cell function.
Full Definition
The F-wave is a late response obtained during nerve conduction studies by supramaximal stimulation of a motor nerve. Unlike the direct motor response, the F-wave results from antidromic activation that travels back to the spinal cord and causes a small percentage of anterior horn cells to discharge orthodromically. This response provides valuable information about the entire length of the motor pathway, including proximal segments not assessable by standard nerve conduction studies. F-waves are particularly useful in diagnosing radiculopathies, proximal neuropathies, and motor neuron disorders.
Usage
Usage note: Capitalize the 'F' and hyphenate. Do not confuse with 'f-wave' in cardiology.
In Context
- "F-wave latencies were prolonged bilaterally in the median nerves." — Nerve conduction study report
- "The F-wave was absent in 80% of stimulations." — Electrodiagnostic findings