Non-invasive method and apparatus for monitoring intracranial pressure

A method for continuous non-invasive monitoring of intracranial pressure of a subject comprising the steps of:

• a) generating a first audio output of frequency ƒ1 with a first audio output generator;
• b) generating a second audio output of frequency ƒ2, wherein ƒ2 is greater than ƒ1;
• c) communicating first and second audio outputs to a first and a second transducer;
• d) outputting first and second outputs with first and second transducers;
• e) receiving and converting an audio input into a response signal with an audio input transducer including a 2ƒ1-ƒ2 cochlear distortion;
• f) non-invasively coupling first and second audio output transducers and transducer with the human auditory canal of the subject;
• g) generating a validation signal;
• h) processing the response signal and the validation signal with a signal processor to determine the intracranial pressure of the subject, such processing further including the steps of
• i. isolating the 2ƒ1-ƒ2 cochlear distortion signal from the response signal;
• ii. measuring the phase of the isolated 2ƒ1-ƒ2 cochlear distortion signal;
• iii. validating the relationship between the phase of the isolated 2ƒ1-ƒ2 cochlear distortion signal and intracranial pressure of the subject, and
• iv. converting the phase to intracranial pressure;
• and
• i) displaying the intracranial pressure.

An apparatus for continuous non-invasive monitoring of intracranial pressure of a subject comprising:

• a) a first audio output transducer to output frequency ƒ1;
• b) a second audio output transducer to output frequency ƒ2, wherein ƒ2 is greater than ƒ1;
• c) an audio input transducer for converting an audio input into a response signal having a 2ƒ1-ƒ2 cochlear distortion, wherein the audio input is the otoacoustic emission signal of the cochlea;
• d) a non-invasive coupling between the first and second audio output transducers and the audio input transducer and the auditory canal of the subject;
• e) a signal processor to process the response signal to determine the intracranial pressure of the subject;
• and
• f) a display for displaying intracranial pressure.

An apparatus for continuous non-invasive monitoring of intracranial pressure of a subject comprising:

• a) a first audio output generator to generate frequency ƒ1;
• b) a second audio output generator to generate frequency ƒ2, wherein ƒ2 is greater than ƒ1;
• c) first and second audio output transducers in communication with first and second audio output generators;
• d) an audio input transducer for converting an audio input into a response signal having a 2ƒ1-ƒ2 cochlear distortion, wherein the audio input is the otoacoustic emission signal of the cochlea;
• e) a signal processor to process the response signal and a respiration signal to determine the intracranial pressure of the subject;
• and
• f) a display for displaying intracranial pressure.

An apparatus for continuous non-invasive monitoring of intracranial pressure of a subject comprising:

• a) an audio output burst generator;
• b) a first audio input transducer for converting an audio input into a response signal wherein the audio input is the otoacoustic emission of the cochlea in response to an audio output burst;
• c) a processor for processing the output burst response signal and determining the optimum OAE response frequency, ƒopt, of the patient;
• d) a first audio output transducer to output frequency ƒ1;
• e) a second audio output transducer to output frequency ƒ2, wherein ƒ2 is greater than ƒ1;
• and 2ƒ1-ƒ2 is equal to ƒopt;
• f) a second audio input transducer for converting an audio input into a distortion response signal having a 2ƒ1-ƒ2 cochlear distortion, wherein the audio input is the otoacoustic emission signal of the cochlea in response to first and second audio outputs;
• g) a signal processor to process the distortion response signal and convert the response signal into the intracranial pressure of the subject;
• and
• h) a display for displaying intracranial pressure.