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[Noninvasive testing of intracranial pressure changes due to body position in infants]
Katalin Mertz1, Beáta Bencsik, Béla Büki
1Semmelweis Egyetem, Altalános Orvostudományi Kar, I. Gyermekklinika, Budapest.
Insights
Intracranial pressure changes affect the inner ear, altering otoacoustic emissions (OAE) phase in adults. This effect is significantly reduced in children and absent in infants, likely due to skull elasticity and lower pressure changes.
Area of Science:
- Otoacoustic Emissions (OAE)
- Inner Ear Physiology
- Intracranial Pressure (ICP) Dynamics
Context:
- Hydrostatic fluctuations in intracranial pressure transmit to the inner ear, altering stapes anular ligament tension and oval window impedance.
- Otoacoustic emissions (OAE), which travel through the oval window, reflect these impedance changes.
- Previous studies demonstrated OAE phase shifts in adults due to ICP variations during positional changes.
Purpose:
- To investigate whether otoacoustic emission (OAE) phase shifts, previously observed in adults due to intracranial pressure (ICP) changes, can be elicited in infants and children.
Summary:
- No reproducible OAE phase shift was observed in infants (2-4 months) during head-down positioning (Trendelenburg).
- Children (3-4 years) exhibited a significantly smaller OAE phase shift compared to adults.
- The reduced response in younger subjects is theorized to stem from smaller hydrostatic pressure changes and greater skull distensibility, which compensates for volume shifts.
Impact:
- This study highlights age-dependent differences in the transmission of intracranial pressure effects to the inner ear.
- Findings suggest that the developing skull's compliance plays a crucial role in mitigating ICP-induced changes in auditory function.
- Results provide insights into the maturation of the auditory system's response to physiological pressure variations.
Introduction:
The hydrostatic fluctuations of intracranial pressure are transmitted to the inner ear and then the tension of the anular ligament of the stapes changes. This causes a change of the impedance of the transmission apparatus in the oval window. This in turn can be shown by the measurement of otoacoustic emissions (OAE), since both the stimulus and the emissions travel through the oval window. It has been shown that in adults the phase of otoacoustic emissions changes due to changes in intracranial pressure (eg. during positioning from sitting to head-down (Trendelenburg) position).
Aims:
The aim of their study was to examine if these phase changes can be elicited in infants and children.
Results:
In young infants (between 2 and 4 months old) there was no reproducible phase shift during positioning into Trendelenburg position, in children (between 3 and 4 years old) there was a significantly smaller phase shift than in adults. According to their theory that difference is due to the smaller hydrostatic pressure change and the fact that the skull distents easily thereby compensating for the volume change.
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