The "Brain Stethoscope": A Non-Invasive Method for Detecting Elevated Intracranial Pressure

Area of Science:

• Neurosurgery
• Biomedical Engineering
• Physiology

Background:

• Minimally invasive intracranial pressure (ICP) screening is crucial for neurosurgical patients.
• Existing methods for ICP monitoring can be invasive and carry risks.
• A non-invasive technique using tympanic membrane (TM) pulsations is being explored.

Purpose of the Study:

• To investigate a novel technique for non-invasive ICP screening using TM pulsations.
• To assess the feasibility of using a modified stethoscope to measure TM pulsations.
• To evaluate an algorithm for distinguishing normal from elevated ICP based on TM waveform analysis.

Main Methods:

• A modified stethoscope with a magnetic reluctance pressure sensor was used to measure TM pulsations.
• The slope ratio of the TM pulsation waveform (downslope to upslope) was analyzed.
• Seventeen healthy subjects underwent hyperventilation and tilt table tests to simulate ICP changes.

Main Results:

• The slope ratio method demonstrated consistent changes corresponding to induced ICP alterations.
• A classification algorithm accurately identified elevated ICP in 100% of independent recordings (60/60).
• Physiologic trends from tilt and hyperventilation maneuvers were consistent with expectations.

Conclusions:

• The "brain stethoscope" can detect increased ICP via TM pulsation waveform analysis in healthy individuals.
• Slope ratio calculations effectively differentiate between normal and elevated ICP.
• Further clinical studies in patients with pathological ICP are necessary before widespread adoption.