Crossed Acoustic Reflex
An acoustic reflex measured in the ear contralateral to the ear receiving the eliciting stimulus, testing the integrity of the crossed brainstem reflex arc.
Full Definition
The crossed (contralateral) acoustic reflex is elicited by presenting a loud pure tone or broadband noise to one ear and recording the resulting stapedius muscle contraction via an immittance probe in the opposite ear. This pathway traverses the brainstem, crossing at the level of the superior olivary complex, making it sensitive to pontine lesions and eighth-nerve pathology. Comparison of crossed and uncrossed reflex thresholds and decay patterns is a key component of the acoustic reflex battery used to differentiate cochlear from retrocochlear dysfunction. Editors should ensure 'crossed' and 'contralateral' are used consistently within a document and should verify that laterality labelling (probe ear vs. stimulus ear) is unambiguous.
Usage
Usage note: When editing reflex tables, confirm that the probe ear and the stimulus ear are identified separately; 'crossed' alone is insufficient without laterality information.
In Context
- "Absent crossed acoustic reflexes with intact ipsilateral reflexes pointed to a retrocochlear lesion on the right." — Differential diagnosis report
- "The table must clearly label whether reflex thresholds are crossed or uncrossed to avoid misinterpretation." — Editorial review note for clinical manuscript