Hyperventilation and vertigo

Area of Science:

• Neurology
• Vestibular System
• Physiology

Background:

• Dizziness is a common subjective sensation.
• Hyperventilation can provoke dizziness.
• The objective physiological correlates of hyperventilation-induced dizziness are not fully understood.

Purpose of the Study:

• To objectively assess the effect of hyperventilation on nystagmus.
• To determine if hyperventilation-induced dizziness correlates with objective nystagmus changes.

Main Methods:

• Electronystagmography (ENG) was performed on 19 healthy subjects.
• Subjects underwent a routine ENG followed by a test with 90-second hyperventilation periods.
• Post-caloric nystagmus and nystagmus in various positions were analyzed.

Main Results:

• Hyperventilation did not significantly affect the slow-phase velocity of post-caloric nystagmus.
• Hyperventilation significantly increased the number of positions in which nystagmus was elicited (p = 0.061).

Conclusions:

• Hyperventilation may induce dizziness through mechanisms involving cerebral hypoxia.
• Cerebral vasoconstriction and the Bohr effect are potential contributors to hyperventilation-induced cerebral hypoxia.
• ENG can objectively detect changes related to hyperventilation, although not consistently on post-caloric nystagmus slow phase.