No evidence of intracranial hypertension in trekkers with acute mountain sickness when assessed noninvasively with distortion product otoacoustic emissions.

Aims: The role of intracranial hypertension in acute mountain sickness (AMS) is a matter of debate. Distortion product otoacoustic emissions (DPOAEs) can be used to monitor the intracranial pressure (ICP) noninvasively with a level decrease at the frequencies f2=1 and 1.5 kHz indicating elevated ICP.

Level alterations of the 2f (1)-f (2) distortion product due to hypoxia in the guinea pig depend on the stimulus frequency.

Increased intracranial pressure (ICP) is known to affect the levels of distortion product otoacoustic emissions (DPOAEs) in a frequency-specific manner. DPOAEs might, therefore, be used for monitoring the ICP non-invasively. Hypoxia can also cause alterations of DPOAE levels, which can be distinguished from ICP-related changes only, when their characteristics, in particular frequency specificity, are known in detail.

Complex level alterations of the 2f (1)-f (2) distortion product due to hypoxia in the guinea pig.

It is controversially discussed inasmuch acute hearing disorders might originate from impaired cochlear circulation. Hypoxia-specific alterations of inner ear parameters measurable in patients with acute sensorineural hearing loss would therefore be of great interest. Aim of this study was to characterize hypoxia-related alterations of the 2f (1)-f (2) distortion product.

Distortion product otoacoustic emissions for assessment of intracranial hypertension at extreme altitude?

The levels of distortion product otoacoustic emissions (DPOAEs) change at frequencies between 0.75 and 1.5 kHz along with intracranial pressure (ICP) and DPOAEs are suggested for monitoring ICP changes.