Bilateral superior cervical sympathectomy and noise-induced, permanent threshold shift in guinea pigs.

The rich sympathetic innervation to the cochlea suggests its potential control of cochlear blood flow and activity during noise exposure, as part of the general and local stress sympathetic reaction evoked by noise. In a previous study, superior cervical sympathectomy prior to sound exposure in guinea pigs in an awake state, resulted in reduced temporary threshold shift. The present study was conducted to explore whether this potential protection would also be manifested in conditions producing permanent threshold shift (PTS).