Dizziness based on sympathetic nervous disturbances is primarily due to either vasovagal reflex (VVR) or an orthostatic degegulation. The head up tilt test is useful for a differential diagnosis of them but it is not useful for a clinical diagnosis. We report a case where an exercise test was used to clinically confirm dizziness due to VVR.
A 13-year-old male visited our hospital complaining of recurring dizziness during exercise. He was examined by the pediatric department and underwent holter ECG, master ECG, brain MRI and head up tilt tests, but they were inconclusive. He was then examined in our department and we suspected VVR due to presenting symptoms and the negative clinical findings.
Thus, an exercise test was performed to confirm our diagnosis. The subject steps up and down on a stair until they complain of sensations such as dizziness and nausea. Vital signs and the plasma adrenaline level are checked every 5 minutes during exercise and pre and post exercise. At 25 minutes he complained of dizziness, bradycardia, low blood pressure and a high plasma adrenaline level. The attack recurred with severe bradycardia (28/min) and a high plasma adrenaline level at 10 minutes after the test.
We diagnosed it as a VVR attack. VVR is caused by excessive left ventricular contractions to adjust for blood volume retention in the legs while standing and/or sitting. The mechano-receptor also makes a paradoxical emission to the vagal nerve resulting in bradycardia, dizziness, and syncope. We recommend checking the plasma adrenaline level during VVR.
