The Clinical Significance of the Failure to Perceive Vertigo in the Postcaloric Period Despite a Robust Caloric Response

Abstract

Purpose The purpose of this project was to explore the association between the perception of motion during caloric testing and two tasks associated with central vestibular processing: postural stability and visuospatial memory. Method This was a prospective study of 25 patients who were found to have nonvestibular etiologies of their symptoms and normal vestibular function test results and who underwent caloric testing with a mean maximum slow phase eye velocity for each irrigation of 15° or greater. Following each caloric irrigation, patients were asked whether they had any sensation of movement. Patients were grouped based on the presence or absence of motion during the caloric exam (motion perception vs. absent perception). Postural stability was assessed using computerized dynamic posturography, and visuospatial memory was assessed using a memory match card game application. Results There were no significant differences between groups on any measures of peripheral vestibular function. However, the Absent Perception Group showed greater postural instability during Condition 5 of posturography and performed significantly worse on a task of visuospatial working memory. Both age and absence of motion perception predicted abnormal performance on measures of postural stability and visuospatial working memory. Conclusions There appears to be clinical implications to a lack of motion perception during the caloric exam in patients with an otherwise normal peripheral vestibular system. Based on the current findings, we are unable to determine whether differences in postural stability and visuospatial memory were due to age or a central vestibular processing deficit.