Caloric Test versus Rotational Chair Test in Patients with Peripheral Vestibulopathy

OBJECTIVE: 1) To correlate caloric results with sinusoidal and step-velocity rotary chair gain, phase, asymmetry and time constant values in all patients; 2) To evaluate sensitivity, specificity, positive predictive value and negative predictive value of both tests in patients with vestibular dizziness. STUDY DESIGN: Retrospective case review. SETTING: Academic tertiary care vestibular function test center PATIENTS: Two hundred randomly selected patients (132 with clinically suspected vestibular dysfunction and 68 with suspected non-vestibular dizziness) evaluated in the Dizziness and Balance Center with bithermal binaural caloric and sinusoidal and step-velocity rotary chair tests. MAIN OUTCOME MEASURES: 1. Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of caloric and rotational chair testing in patients with and without suspected vestibular dysfunction. 2. Correlation of the following measures in all patients: a) degree of caloric weakness versus 0.025 Hz vestibule-ocular reflex (VOR) gain, b) degree of caloric asymmetry versus 0.025 Hz VOR phase, c) caloric asymmetry versus 100 deg/s step velocity time constants, d) total eye speed versus 0.025 Hz gain, and e) total eye speed versus 0.025 Hz phase. RESULTS: In patients with a suspected diagnosis of vestibular dysfunction, caloric testing demonstrated 68% sensitivity, 86% specificity, 95% PPV and 31% NPV. In similar fashion, rotary chair testing showed 44% sensitivity, 84% specificity, 88% PPV and 23% NPV value. Combining the two tests resulted in a slight increase in sensitivity (73%) with a consequent decline in specificity (74%) and no substantial change in PPV (94%) or NPV (33%). In all patients, significant correlations were noted between; 1) percentage caloric weakness and 0.025 and 0.05 Hz phase, 2) percentage caloric weakness and average step velocity time constant (Tc), 3) total eye speed and 0.025 and 0.05 Hz phase, and 4) 0.025, 0.05 and 0.25 Hz phase and Tc (Pearson coefficients, p<0.05). However, no significant relationships were noted with caloric testing and rotary chair gain, asymmetry or 0.5 Hz phase measurements. CONCLUSIONS: Both caloric and rotary chair test abnormalities are quite specific with high positive predictive value but only moderately sensitive in identifying patients with suspected vestibular disease. There is agreement between caloric asymmetry and total eye speed with lower frequency phase and Tc but not gain or asymmetry values. These results support the notion that a positive finding in either test alone or in combination is consistent with a suspected clinical diagnosis of vestibular disease (high specificity and PPV) whereas normal tests do not rule out a vestibular problem (low sensitivity). Finally, caloric abnormalities positively correlate with lower frequency phase and time constant tests. Received: February 8, 2014. Revised: March 19, 2014 Accepted: June 18, 2014