Summating Potential
Also written as: SP — Summating Potential
A sustained DC electrical response generated by cochlear hair cells during acoustic stimulation, recorded via electrocochleography and used in diagnosing endolymphatic hydrops.
Full Definition
The summating potential (SP) is a direct-current baseline shift superimposed on the compound action potential waveform in electrocochleography. It reflects the asymmetric distortion of the basilar membrane and is thought to originate primarily from the outer hair cells. An elevated SP relative to the action potential (SP/AP ratio greater than approximately 0.4–0.5) is interpreted as evidence of abnormal endolymph pressure, consistent with Ménière's disease or other forms of endolymphatic hydrops. When editing ECochG reports, writers must ensure that SP amplitude and SP/AP ratio are clearly distinguished and that the laboratory's reference norms are cited.
Usage
Usage note: The abbreviation SP is heavily overloaded across medical writing (speech pathology, speech perception). Expand on first use in any document that spans disciplines.
In Context
- "The summating potential was disproportionately enlarged, yielding an SP/AP ratio of 0.48." — ECochG interpretation section of a diagnostic report
- "SP should always be reported alongside the AP amplitude and the resultant ratio, not in isolation." — Clinical report style guide