Other evidence also implicates hypoxia (acute and chronic) in SIDS. Hypoxanthine, a marker of tissue hypoxia, is elevated in the vitreous humor of patients who die of SIDS as compared with control subjects who die suddenly. This adds biochemical support to the concept that in some cases, SIDS is a relatively slow process. In addition, a number of infants who die of SIDS manifest necropathologic evidence of chronic hypoxia, including changes in the bronchiolar walls, pulmonary neuroendocrine cells in the lungs, and elevated fetal hemoglobin levels.
The symptoms of Ménière’s disease are caused by the buildup of fluid in the compartments of the inner ear, called the labyrinth. The labyrinth contains the organs of balance (the semicircular canals and otolithic organs) and of hearing (the cochlea). It has two sections: the bony labyrinth and the membranous labyrinth. The membranous labyrinth is filled with a fluid called endolymph that, in the balance organs, stimulates receptors as the body moves. The receptors then send signals to the brain about the body’s position and movement. In the cochlea, fluid is compressed in response to sound vibrations, which stimulates sensory cells that send signals to the brain.