Micrographic recordings in the caloric test

: We report 97 cases of micrographic nystagmus recordings elicited by the caloric test. This response was found in 27% of patients examined for dizziness. The main feature of these tracings was low amplitude. Patients had a mean age of 55 years, frequent episodes of instability related with head movements, and perception of imbalance during walking which was described as being like drunkenness. No noteworthy audiological findings were observed, but there were signs of cervical bone lesions on radiography, scanning, vertebral Doppler, and MRI. The special organization of the arterial system of the inner ear as a terminal system make it sensitive to hemodynamic effects of ischemic and hypoxic episodes, which explains the frequency and nature of the dizziness described. Although not pathognomonic, micrographic recordings or a low-amplitude nystagmus response to the caloric test suggest the existence of the hemodynamic phenomenon of vertebrobasilar insufficiency.