Canal-plugging in the rhesus monkey a tool to study the contribution of individual canals to nystagmus generation

Plugging of the semicircular canals was first described by Ewald in 1892 (3). With a drill one makes a small opening in the bony canal and fills it with bone chips. The idea is to block any fluid movement or pressure build-up across the capula during angular acceleration without interfering with normal afferent activity in the hair cells of the capula. The following operations were successfully done in animals subjected to a battery of vestibular tests: 1. all 3 canals on both sides plugged; 2. both lateral canals plugged; 3. all vertical canals plugged; 4. paired anterior and controlateral posterior canals plugged.