Apparatus for measuring intracranial pressure

• US 4,984,567 A
• Filed: 04/17/1989
• Issued: 01/15/1991
• Est. Priority Date: 09/27/1986
• Status: Expired due to Fees

• Current Assignee: HIROJI KUCHIWAKI 12-6, Hitachi Construction Machinery Company Limited (Hitachi, Ltd.)
• Original Assignee: Hiroji Kuchiwaki, Hitachi Construction Machinery Company Limited (Hitachi, Ltd.)
• Inventors: Kageyama, Naoki, Ogura, Yukio, Sakuma, Nobumitsu, Kuchiwaki, Hiroji, Ito, Junki
• Primary Examiner(s): JAWORSKI, FRANCIS J
• Application Number:
  US07/350,705
• Time in Patent Office: 638 Days
• Field of Search: 128/660.01, 128/660.02, 128/661.05, 128/660.06, 73/599, 73/602
• US Class Current: 600/438
• CPC Class Codes: A61B 5/031 Intracranial pressure
• CPC Class Codes: A61B 5/7257 using Fourier transforms
• CPC Class Codes: A61B 8/0808 for diagnosis of the brain
• CPC Class Codes: A61B 8/0858 involving measuring tissue layers, e.g. skin, interfaces

Abstract

The present invention relates to an apparatus for measuring the intracranial pressure of a living body or patient utilizing ultrasonic waves. An ultrasonic pulse is transmitted as triggered by a trigger signal into the cranium from an ultrasonic probe placed outside the cranium of the living body, the data of an interference reflection wave caused by the multiple reflections of the incident waves at the interstital boundaries within the cranium is analyzed for frequency, and the time difference between the element waves of the interference reflection wave is calculated and delivered as output. Thus, the dura mater thickness and its change are measured, and the intracranial pressure and its change can be measured utilizing the correlation between the intracranial pressure and dura mater thickness.

The most of the conventional measurements of intracranial pressure are done with an invasion to the cranium, and some noninvasive techniques have been proposed but their accuracy and costs are far from the level at which they can be satisfactorily used. The apparatus according to the present invention permits to measure the intracranial pressure from outside the cranium, easily, safely, highly reliably, non-invasively and without any malinfluence on the brain inside. Furthermore, by periodically effecting such measurement, the intracranial pressure and the pattern of its change can be known and accurate diagnostic information on the pathology as well as legion-preventive information can be provided.

Claims

1. In an apparatus for measuring intracranial pressure, including an electrocardiograph for detecting a heartbeat of a living body having a cranium, a pulser means for generating a voltage pulse using the heartbeat detected by the electrocardiograph as a trigger, an ultrasonic probe means for receiving the voltage pulse generated by the pulser means and for transmitting an ultrasonic pulse into the cranium of the body from the outside thereof and for receiving an echo of an incident wave therefrom, a receiver means for amplifying the received echo and for providing an output corresponding thereto, a processor means for processing the output of the receiver means comprising:

an A/D converter means for digitizing discrete values of a waveform of the echo received by the probe means and for providing an output corresponding thereto; and

an arithmetic means for extracting from the output of the A/D converter means a range including a reflection wave from dura mater of a certain thickness contained within the cranium, and for determining a time difference between element waves from a quefrency value obtained through frequency analysis of the extracted range by an arithmetic algorithm of a cepstrum method so as to calculate the thickness of the dura mater, and for comparing the calculated dura mater thickness with a previously measured reference value so as to calculate a dura mater distortion factor having a correlation with an intracranial pressure within the cranium.

2. In an apparatus for measuring intracranial pressure, including an electrocardiograph for detecting a heartbeat of a living body having a cranium, a pulser means for generating a voltage pulse using the heartbeat detected by the electrocardiograph as a trigger, an ultrasonic probe means for receiving the voltage pulse generated by the pulser and for transmitting an ultrasonic pulse into the cranium of the body from the outside thereof and for receiving an echo of an incident wave therefrom, a receiver means for amplifying the received echo and for providing an output corresponding thereto, a processor means for processing the output from the receiver means comprising:

a gate circuit means for gating the echo received by the probe means to a range including reflection waves from dura mater of a certain thickness contained within the cranium and for outputting a waveform corresponding thereto;

an A/D converter for digitizing discrete values of the output waveform from the gate circuit means and for providing an output corresponding thereto; and

an arithmetic means for determining a time difference between element waves from a quefrency value obtained through frequency analysis of the output of the A/D converter by the arithmetic algorithm of a cepstrum method, so as to calculate the thickness of the dura mater and for comparing the calculated dura mater thickness with a previously measured reference value so as to calculate a dura mater distortion factor having a correlation with an intracranial pressure within the cranium.