B-waves in noninvasive capacitance signal correlate with B-waves in ICP

Area of Science:

• Neuroscience
• Biomedical Engineering
• Medical Diagnostics

Background:

• B-waves in intracranial pressure (ICP) recordings were crucial for diagnosing normal pressure hydrocephalus (NPH).
• The study investigated if B-wave equivalents exist in a noninvasive electric capacitance signal (W).

Purpose of the Study:

• To test the hypothesis that B-wave equivalents are detectable and quantifiable in the noninvasive W signal.
• To explore the potential of the W signal as a diagnostic tool for NPH and related disorders.

Main Methods:

• Simultaneous measurement of ICP and W in 15 patients undergoing infusion testing for suspected NPH or intracranial hypotension.
• Identification of B-waves in both ICP and W signals using wave-template matching.

Main Results:

• A very strong correlation was found between the duration of B-waves in ICP and W (R² = 0.86, p < 10⁻⁶).
• A weak correlation was observed between the average amplitudes of B-waves in ICP and W (R = 0.34, p = 0.02).

Conclusions:

• The presence of B-waves in W suggests it reflects vasogenic activity in cerebral autoregulation.
• The W signal, an indirect measure of cranial volume, could be a useful noninvasive triage tool for NPH and low compliance disorders.