Vertigo and acid-base imbalance

Abstract

There have been several reports about the relation between acid-base imbalance or arterial blood gas abnormalities and the occurrence of vertigo, including Meniere' disease. In animal experiments, respiratory acidosis induced by CO₂ inhalation or metabolic acidosis induced by injection of NH₄Cl has been shown to cause attacks of vertigo in rabbits with hemilabyrinthectomy. In clinical studies, approximately half of the patients with dizziness have arterial blood gas abnormalities when their dizziness occurs. An increase of HCO_3- is found in many patients with dizziness, and the frequency of attacks is higher in patients who have arterial blood gas abnormalities during the remission period. These patients are thought to have unilateral vestibular dysfunction, and it is suggested that arterial blood gas abnormalities cause temporary vestibular dehabituation that increases the frequency of dizziness. It has also been reported from a study that the middle ear pressure difference between both ears, which is larger during periods of dizziness or recurrent dizziness than at the time of remission, might be related to blood gas abnormalities in Meniere's disease. In the same study, a difference of more than 50 decapascals was significantly more common in the patient group with blood gas abnormalities. In addition, metabolic acidosis has been reported in patients with Meniere's disease, and the base excess and bicarbonate levels were also found to be beyond the normal range in Meniere's disease. Arterial blood gas abnormalities might develop for various reasons, including underlying diseases and middle ear pressure differences. The endolymph in the endolymphatic sac is acidic (pH6.6-7). It has been reported that carbonic anhydrase, vacuolar H⁺-ATPase, pendrin and aquaporin may participate in the acidification process or homeostasis. The role of acid-base disturbance or arterial blood gas abnormalities in dizziness, and the relation in acid-base balance between inner ear and arterial blood gas need to be investigated further.