Relationship of the head impulse test and head-shake nystagmus in reference to caloric testing

The objective of this study was to determine the usefulness of the head impulse test (HIT) and head-shake nystagmus (HSN), two easily performed office maneuvers, in the evaluation of the dizzy patient with reference to caloric irrigation results.

This was a prospective double-blind trial conducted at an outpatient academic tertiary referral center.

The study population was composed of 105 patients (35 male, 70 female) who presented for evaluation of dizziness and ranged in age from 13 to 87 years (mean 52.1).

The intervention was HIT and HSN evaluation followed by bithermal binaural air caloric irrigations.

The main outcome measures were sensitivity, specificity, and predictive values of HIT and HSN evaluation (individually and in combination) in relation to caloric results.

Sensitivity of the tests was equally low (35%), whereas specificity was high (HIT 95%, HSN 92%). The positive predictive value for the two tests in combination (80%) was greater than for each individually (HIT 64%, HSN 50%). Negative predictive values remained stable when considering each test individually (HIT 86%, HSN 86%) or in combination (88%).

The low sensitivity renders both tests inadequate as a screening tool for peripheral vestibular disease based on caloric results. However, when HIT and HSN results are both abnormal, there is a high likelihood of a significant caloric deficit.