Patent No. 5922016 Apparatus for electric stimulation of auditory nerves of a human being

 

Patent No. 5922016

Apparatus for electric stimulation of auditory nerves of a human being (Wagner, Jul 13, 1999)

Abstract

Apparatus for electric stimulation and diagnostics of auditory nerves of a human being, e.g. for determination of sensation level (SL), most conformable level (MCL) and uncomfortable level (UCL) audibility curves, includes a stimulator detachably secured to a human being for sending a signal into a human ear, and an electrode placed within the human ear and electrically connected to the stimulator by an electric conductor for conducting the signals from the stimulator into the ear. A control unit is operatively connected to the stimulator for instructing the stimulator as to characteristics of the generated signals being transmitted to the ear.

Notes:

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an improved apparatus for electrical stimulation and diagnostics of auditory nerves, which allows determination in advance, even in very sensitive and uncooperative patients such as infants, whether the transmission of stimuli of the auditory nerves is functional or at least sufficiently functional to justify an artificial stimulation through implantation of cochlea electrodes.

This object, and others which will become apparent hereinafter, are attained in accordance with the present invention by providing a stimulator which is adapted for detachable securement to the clothing of a human for generating signals, electrodes placed within the human ear and electrically connected to the stimulator by an electric conductor for conducting the signals from the stimulator into the human ear, and a control unit operatively connected to the stimulator for instructing the stimulator as to characteristics of the generated signals being transmitted.

As the stimulator for generating the required impulses is easy to handle, the person being examined is inconvenienced only in a very minor way. Suitably, the electrodes may be placed within the auditory meatus or in the middle ear.

The electrodes that are placed within the auditory meatus are formed by a body of electrically conducting material such as e.g. graphite, metal or the like and connected via an electric conductor to the stimulator, whereby the conductor is secured in place by an enveloping plastic body of elastically deformable material which bears upon the inside wall of the auditory meatus and may also be used for sealing the auditory meatus. Thus, the stimulation impulses can be transmitted in a particular effective manner to the auditory nerves while the elastic plastic body securely retains the electrode in place within the auditory meatus.

When being placed in the middle ear, preferably upon the promontory, the electrode are provided in form of a body of electrically conducting material such as graphite, metal or the like, which is situated at the end of an insulated metal rod with electrical conduction. The metal rod is formed preferably in crank-like manner and is secured in place by an enveloping plastic body of elastically deformable material that bears upon the inner wall of the auditory meatus. If necessary, the metal rod may further be secured by an adhesive strip upon the wall surface of the auditory meatus. A placement of the electrode in this manner is particularly effective to stimulate the auditory nerves.

Preferably, the control unit is of a type to enable a selection of the time pattern as well as intensity and frequency of the stimulation signals for wireless transmission, e.g. infrared transmission, to the stimulator. Thus, the stimulator becomes easy to manipulate while the person being examined retains full freedom of movement. The transmitter as well as receiver for wireless transmission can be produced in a simple manner while still affording the required range for use with young children.

According to another feature of the present invention, the stimulator is equipped with means for triggering an acoustic confirmation signal when receiving data from the control unit to effect the intended stimulation. The generation of the acoustic signal confirms the correctness of the data transmission in a simple manner. Preferably, the stimulator may further include means for triggering acoustic warning signals in case of malfunction of the intended stimulation or reception of incorrect data. Thus, the determination of characteristic audibility curves will not be adversely effected. Suitably, the triggered warning signal is differentiated in dependence on the cause for malfunction. This enables the user to pinpoint the error source as to whether it is based on apparative malfunction, or possible screening of the receiver diode of the stimulator, or misplaced electrodes, or even on discharged batteries.

In accordance with another feature of the present invention, the stimulator is provided with a separate optical signaling device which triggers an optical signal during transmission of a stimulation signal in one of both auditory meatus or in one of both middle ears. Thus, psychological conditioning methods as known from pediatric audiometry are employed for reinforcing the reaction during perception of a stimulus, with the an additional optical control of the stimulation being accomplished in a simpler manner. The optical signaling device may be a simple toy, such as a toy truck, which is suitable for infants. During examination, the transmission of a stimulation signal triggers at the same time an optical signal that draws the attention of the infant. This reaction provides the operator with a clear and unmistakable sign that the infant senses an auditive signal.

Suitably, the control unit includes a graphic display for illustration of determined audibility curves and associated numerical values. Thus, characteristic audibility curves can be monitored during examination, and obviously erroneous values can be corrected by renewed measurements. Advantageously, the control unit has a terminal for attachment of a printer to thereby provide the operator with a printout of the characteristic audibility curves as determined for the auditory meatus of a patient.