Non-Invasive Intracranial Pressure Monitoring System and Method

Abstract

A system which includes a first sensor placed proximate to a perfusion field of an artery receiving blood which emanates from the cranial cavity is configured to monitor pulsations of the artery receiving blood which emanates from the cranial cavity artery. A second sensor placed proximate to a perfusion field of an artery which does not receive blood emanating from the cranial cavity configured to monitor pulsations of the artery which does not receive blood emanating from the cranial cavity. A third sensor configured to monitor pulsations of a distal artery. A processing system responsive to signals from the first, second, and third sensors is configured to determine intracranial pressure.

What is claimed is: 
     
         1 . A non-invasive intracranial pressure monitoring system comprising:
 a first sensor placed proximate to a perfusion field of an artery receiving blood which emanates from the cranial cavity configured to monitor pulsations of the artery receiving blood which emanates from the cranial cavity artery;   a second sensor placed proximate to a perfusion field of an artery which does not receive blood emanating from the cranial cavity and placed approximately the same distance from the heart as the first sensor configured to monitor pulsations of the artery which does not receive blood emanating from the cranial cavity;   a third sensor placed distally from the heart configured to monitor pulsations of a distal artery; and   a processing system responsive to signals from the first, second, and third sensors configured to determine intracranial pressure.   
     
     
         2 . The system of  claim 1  in which the first sensor is placed on the forehead. 
     
     
         3 . The system of  claim 1  in which the second sensor is placed on or near the temple. 
     
     
         4 . The system of  claim 1  in which the second sensor is placed on or near the ear. 
     
     
         5 . The system of  claim 1  in which the third senor is placed distally on a finger. 
     
     
         6 . The system of  claim 1  in which the third sensor is placed distally on a hand. 
     
     
         7 . The system of  claim 1  in which the third sensor is placed distally on a forearm. 
     
     
         8 . The system of  claim 1  in which the processing subsystem is configured to determine the intracranial pressure by correlating signals from the first sensor to signals from the third sensor and correlating signals from the second sensor to signals from the third sensor and combining the determined correlations. 
     
     
         9 . The system of  claim 1  in which the processing subsystem is configured to determine the intracranial pressure by determining the magnitude and phase of the spectral components of signals from each of the first, second, and third sensors and comparing the magnitude or the phase of the spectral components of the first sensor to the magnitude or the phase of the spectral components of third sensor and the magnitude or the phase of the spectral components of the second sensor to the magnitude or the phase components of the third sensor and combining the compared values. 
     
     
         10 . The system of  claim 9  in which the processing subsystem is configured to adjust the value of the component phases according to differences in magnitudes of associated spectral components. 
     
     
         11 . The system of  claim 1  in which the processing subsystem is configured to determine the intracranial pressure by combining the signals from the first sensor with the signals from the second sensor and combining the result with the signals from the third sensor. 
     
     
         12 . The system of  claim 1  further including a display coupled to the processing subsystem configured to display the intracranial pressure. 
     
     
         13 . A non-invasive intracranial pressure monitoring system comprising:
 a first sensor placed proximate to the supraorbital artery configured to monitor pulsations of the supraorbital artery;   a second sensor placed proximate to a branch of the external carotid artery and placed approximately the same distance from the heart as the first sensor configured to monitor pulsations of the external carotid artery;   a third sensor placed distally from the heart configured to monitor pulsations of a distal artery; and   a processing subsystem responsive to signals from the first, second, and third sensors configured to determine intracranial pressure.   
     
     
         14 . The system of  claim 13  in which the first sensor is placed on the forehead. 
     
     
         15 . The system of  claim 13  in which the second sensor is placed on or near the temple. 
     
     
         16 . The system of  claim 13  in which the second sensor is placed on or near the ear. 
     
     
         17 . The system of  claim 13  in which the third senor is placed distally on a finger. 
     
     
         18 . The system of  claim 13  in which the third sensor is placed distally on a hand. 
     
     
         19 . The system of  claim 13  in which the third sensor is placed distally on a forearm. 
     
     
         20 . The system of  claim 13  in which the processing subsystem is configured to determine the intracranial pressure by correlating signals from the first sensor to signals from the third sensor and correlating signals from the second sensor to signals from the third sensor and combining the determined correlations. 
     
     
         21 . The system of  claim 13  in which the processing subsystem is configured to determine the intracranial pressure by determining the magnitude and phase of the spectral components of signals from each of the first, second, and third sensors and comparing the magnitude or the phase of the spectral components of the first sensor to the magnitude or the phase of the spectral components of the third sensor and the magnitude or the phase of the spectral components of the second sensor to the magnitude or phase of the spectral components of the third sensor and combining those compared values. 
     
     
         22 . The system of  claim 21  in which the processing subsystem is configured to adjust the value of the component phases according to differences in magnitudes of associated spectral components. 
     
     
         23 . The system of  claim 13  in which the processing subsystem is configured to determine the intracranial pressure by combining signals from the first sensor with the signals from the second sensor and combining the result with signals from the third sensor. 
     
     
         24 . The system of  claim 12  further including a display coupled to the processing subsystem configured to display the intracranial pressure. 
     
     
         25 . A method for non-invasively determining intracranial pressure, the method comprising:
 monitoring pulsations of an artery receiving blood which emanates from the cranial cavity and generating first output signals;   monitoring pulsations of an artery which does not receive blood emanating from the cranial artery and generating second output signals;   monitoring pulsations of a distal artery and generating third output signals; and   in response to the first, second and third output signals, determining the intracranial pressure.   
     
     
         26 . The method of  claim 25  in which said monitoring pulsations of blood which emanates from the cranial artery is performed proximate a forehead. 
     
     
         27 . The method of  claim 25  in which said monitoring pulsations of blood which does not emanate from a cranial artery is performed on or near the temple. 
     
     
         28 . The method of  claim 25  in which said monitoring pulsations of blood which does not emanate from a cranial artery is performed on or near the ear. 
     
     
         29 . The method of  claim 25  in which said monitoring pulsations of the distal artery is performed on a finger. 
     
     
         30 . The method of  claim 25  in which said monitoring pulsations of the distal artery is performed on a hand. 
     
     
         31 . The method of  claim 25  in which said monitoring pulsations of the distal artery is performed on a forearm. 
     
     
         32 . The method of  claim 25  in which determining the intracranial pressure includes correlating the first output signals to the third output signals and correlating the second output signals to the third output signals and combining the determined correlations. 
     
     
         33 . The method of  claim 25  in which determining the intracranial pressure includes determining the magnitude and phase of spectral components of each of the first output signals, the second output signals, and the third output signals and comparing the phase of the spectral components of the first output signals with the magnitude or the phase of the spectral components of the third output signals and the magnitude or the phase of the spectral components of the second output signals to the magnitude or the phase of the spectral components of the third output signals and combining the compared values. 
     
     
         34 . The method of  claim 33  further including adjusting the value of component phases according to differences in magnitudes of associated spectral components. 
     
     
         35 . The method of  claim 25  in which determining the intracranial pressure includes combining the first output signals with the second output signals and combining that result with the third output signals. 
     
     
         36 . A non-invasive method for determining intracranial pressure, the method comprising:
 monitoring pulsations of the supraorbital artery and generating first output signals;   monitoring pulsations of the external carotid artery and generating second output signals;   monitoring pulsations of the distal artery and generating third output signals; and   in response to the first, second, and third output signals determining the intracranial pressure.   
     
     
         37 . The method of  claim 36  in which said monitoring pulsations of the supraorbital artery is performed on the forehead. 
     
     
         38 . The method of  claim 36  in which monitoring pulsations of the external carotid artery is performed on or near the temple. 
     
     
         39 . The method of  claim 36  in which monitoring pulsations of the external carotid artery is performed on or near the ear. 
     
     
         40 . The method of  claim 36  in which monitoring pulsations of the distal artery is performed on a finger. 
     
     
         41 . The method of  claim 36  in which monitoring pulsations of the distal artery is performed on a hand. 
     
     
         42 . The method of  claim 36  in which monitoring pulsations of the distal artery is performed on a forearm. 
     
     
         43 . The method of  claim 36  in which determining the intracranial pressure includes correlating the first output signals to the third output signals and correlating the second output signals to the third output signals and combining the determined correlations. 
     
     
         44 . The method of  claim 36  in which determining the intracranial pressure includes determining the magnitude and phase of spectral components of each of the first output signals, the second output signals, and the third output signals and comparing the magnitude or the phase of the spectral components of the first output signals with the magnitude or the phase of the spectral components of the third output signals and the magnitude or the phase of the spectral components of the second output signals to the magnitude or the phase of the spectral components of the third output signals and combining the compared values. 
     
     
         45 . The method of  claim 44  further including adjusting the value of component phases according to differences in magnitudes of associated spectral components. 
     
     
         46 . The method of  claim 36  in which determining the intracranial pressure includes combining the first output signals with the second output signals and combining that result with the third output signals.