ephaptic transmission
Pronunciation: eh-FAP-tik
Abnormal electrical communication between nerve fibers through their membranes rather than synaptic connections, often seen in demyelinating conditions.
Full Definition
Ephaptic transmission is a pathological form of nerve conduction where electrical impulses spread laterally between adjacent nerve fibers through their cell membranes, bypassing normal synaptic transmission. This phenomenon typically occurs when the normal insulation provided by myelin sheaths is compromised, as seen in demyelinating diseases like multiple sclerosis. In clinical neurophysiology, ephaptic transmission can manifest as abnormal waveforms during nerve conduction studies and may contribute to symptoms like facial synkinesis after Bell's palsy or trigeminal neuralgia. Recognition of ephaptic patterns is crucial for accurate interpretation of neurophysiological findings and understanding of certain neurological symptoms.
Usage
Usage note: Often confused with volume conduction or electrical artifact; ensure proper context when describing abnormal nerve transmission mechanisms.
In Context
- "The abnormal muscle responses observed during facial nerve stimulation suggested ephaptic transmission between motor fibers." — Nerve conduction study report
- "Ephaptic transmission may explain the paradoxical muscle contractions seen in this patient with chronic demyelination." — Clinical interpretation note