Method and apparatus for detecting and analyzing the swallowing activity in a subject

Abstract: An apparatus for analysing the swallowing behavior of a subject, comprises displacement and/or pressure-activated transducing means (2) which are positioned in relationship with the anatomical structure of the subject which is to be analysed during swallowing, e.g. the larynx. The signals generated by the transducing means (2) are processed to determine swallow beginning and ending times and the relative induced intensity of the sampled signals at the sampling times. Visual data or data points are displayed for carrying out biofeedback.

Description: Field of the Invention The present invention relates to the analysis of swallowing dysfunction, more particularly to a method and an apparatus for detecting and analyzing the swallowing activity in a subject. BACKGROUND OF THE INVENTION Swallowing dysfunction may occur in a human subject as a result of different physiological causes, and the analysis of the swallowing behavior of a subject may be useful in the diagnosis of a variety of illnesses. Furthermore, when abnormal swallowing behavior is found in a subject, it is important to recognize the problem and to educate the subject to properly perform the swallowing action. The Prior Art From IEEE Engineering in Medicine & Biology 7 (1988), No. 3, pages 16 - 20; N.P.Reddy et al. "Biomechanical Quantification for Assessment and Diagnosis of Dysphagia" it is known to measure acceleration at the throat by placing two ultra miniature piezo-resistive type semiconductor transducers over the throat. The throat acceleration pattern during swallowing is graphically plotted and gives rise to a typical pattern. An analysis of this type of problem has been carried out in the art. For instance, Shawker et al. ["Ultra Sound Analysis of Tongue, Hyoid and. Larynx Activity During Swallowing", Investigative Radiology, 1984, 9: 82-86] used a very complicated technique based on a combination of balloon pressure techniques and ultrasonic scanner techniques, to evaluate the behavior of a subject during swallowing. These authors followed the movement of the tongue with an ultrasonic scanner, and the activity of the larynx with an external device. The results they obtained, with respect to the movement of the larynx were difficultly repeatable, as in two out of ten subjects the first out of two swallows was used for measurements because of difficulties with the laryngeal pressure transducer display, while in eight out of ten subjects analyzed only two swallows were followed, and the second swallow was arbitrarily chosen for analysis. The reason for this procedure is that the heavy equipment employed does not afford repetition of the results and cannot be kept on a subject for a long period of time. As will be understood by a person skilled in the art, this is a very severe drawback, as long time measurement and analysis of the behavior of a human subject are often necessary in order to be able to draw meaningful conclusions. Furthermore, ultrasonic techniques can be employed to follow the first oral stage of the swallowing activity, but are not useful to follow the frequency, speed or depth of the swallow. In a recent review [Evaluation of Swallowing Pathophysiology, Otolaryngologic Clinics of North America, vol. 21, no. 4, November, 1988, pp. 637-647] Sonies and Baum reviewed the techniques available for the clinical evaluation of swallowing. The techniques detailed include the computerized axila tomography (CAT), ultrasound (US), x-rays (still and video fluoroscopy), magnetic resonance imaging (MRI), manometry and scintigraphy. All of these techniques are complicated, some of them require expensive and sophisticated apparatus, such as CAT, US, x-ray and MRI, some are invasive techniques such as manometry, and some require the injection of foreign substances. It is therefore clear that it would be highly desirable to be able to provide a simple method for effectively analyzing the behavior of a subject during swallowing activity, which method could be carried out using simple and non-expensive apparatus that exploits non-invasive techniques, thus rendering it possible to perform extensive analysis of a large number of patients. SUMMARY OF THE INVENTION It is an object of the present invention to provide such a method, which overcomes the drawbacks of available methods and which can be used by the specialized physician in his clinics, thus making it possible to analyze a large number of patients. It is another object of the invention to provide an apparatus for carrying out the method, which is relatively non-expensive and which is simple in operation. It is still another object of the invention to provide a method and apparatus which permit to carry out repetitive analyses of prolonged duration of swallowing activity, on the one hand, and detailed analysis of a single swallow and its stages on the other hand. It is a further object of the invention to provide a method by means of which swallowing activity can be followed, thus enabling generation of a signal to prime the patient to correct his swallowing performance. Correctable swallowing parameters include - but are not limited to - the frequency of deglutition, the amplitude of a single swallow, the coordination and continuity in laryngeal movement, and the movement of additional anatomical structures involved in swallowing, such as the tongue, hyoid and oral muscles. The method of analyzing the swallowing of a subject, according to the invention, is defined in claim 1. Different signals can be provided for different swallow parameters. The swallow parameters will include, e.g., swallow beginning and ending time, the form, sequency, continuity and coordination of the various anatomical structures involved in swallowing, e.g., the larynx, tongue, hyoid and oral muscles. As displacement and/or pressure-activated transducing means a piezo-electric film transducer is employed, because it responds to light pressures, is lightweight and can be easily positioned near the larynx or other anatomical structure of the subject. Suitable piezo-electric films are such as those manufactured by Pennwalt Corporation under the trade name Kynar. When piezo-electric films such as the Kynar film are used, it is also possible to provide matrix output in which different locations on the film independently produce a signal indicative of intensity and position when they are pressure-activated. In this way, it is possible to follow the movement of the larynx with time. Examples of the transducers and of various conventional uses of such transducers can be found, e.g., in European Patent Application No. 14,693, British Patent Application No. 2,138,144 and U.S. Patent No. 4,359,726. The article by Fraden, J. "Application of Piezo/Pyroelectric Films In Medical Transducers", J. Clin. Engg., March/April 1988, pp. 133-138, is also noteworthy. The transducer is a contact-activated device, and it should be positioned accordingly, in contact with the structure to be monitored. The appropriate positioning of the transducer, of course, is within the skill of the routineer. It should be understood that throughout this specification, unless otherwise indicated, whenever reference is made to the monitoring of the movement of the larynx, it is meant to include all anatomic structures which are involved in swallowing, such as the tongue, hyoid and the oral muscles. Thus, for instance, when it is desired to analyze the movement of the tongue during swallowing, a transducer, e.g., a Kynar film, may be positioned on the tongue and removed or replaced at the end of each swallow. Thus, in accordance with the present invention, there is also provided an apparatus for analyzing the swallowing of a subject, which apparatus is defined in claim 3. A preferred embodiment is claimed in claim 4. The elaborating means may comprise a microprocessor or a microcomputer. Preferably, a personal computer, such as an IBM PC, is employed for this purpose. Then, the signals generated by the transducing means and transmitted and received by the sampling means would be fed into the microcomputer by means known to the skilled person and which need not be discussed here. The display means may be any type of display which enables the physician to view the results of the analysis. Often a display such as the normal display of a personal computer will be used for first review, but it may be desirable, for more detailed analysis and for record keeping, to provide a printed record of the results of the analysis. For this purpose the display means will often comprise a printer or a plotter. Furthermore, the data created during the analyses can be stored, for future reference and elaboration, on any appropriate storage means, e.g., a magnetic or an optical disk, or the hard disk of a PC. The invention further embraces a method of signaling to a subject who does not correctly perform his swallowing activity, so that the subject may educate himself to perform an improved swallow, which method is defined in claim 5. Thus, for instance, in a subject who does not perform deep enough swallows, the value of the sampled signal will indicate the depth of the swallow, and the predetermined value of the signal will be the minimal acceptable depth of swallow. Thus, if the subject does not swallow deeply enough, the value of the sampled signal will be below the minimal predetermined depth of swallow and a signal will be generated to prime the subject to perform a deeper swallow. If, on the other hand, the sequence of the stages is incorrect, an appropriate signal will be generated, which may be different in type and/or intensity from signals generated, e.g., by a non-deep-enough swallow. DETAILED DESCRIPTION OF THE INVENTION Brief Description of the drawings Fig. 1 is a schematic representation of the set-up of an apparatus according to one embodiment of the invention; Fig. 2 schematically shows a number of swallows as displayed on a printer or on a display; and Fig. 3 illustrates the analysis of single swallows. Detailed Description of Preferred Embodiments To further illustrate the invention, reference is now made to Fig. 1 which schematically shows a representative set-up of an apparatus according to one embodiment of the invention, which can be used to carry out the method of the invention. The zone of the subject which is to be analyzed, e.g., the neck (larynx) or tongue, is schematically indicated by numeral 1, and the single piezo-electric film transducer, is indicated by numeral 2. The electric signals generated by piezo transducer 2 are transmitted, through wire 3, to sampling means 4, which may be, e.g., an amplifier, which may be further coupled to an A-to-D card. Normally, the A-to-D card will be contained within the computer, and if no amplifier is required it may be directly connected to the output of the transducer 2. A microprocessor, 5, receives the data from the sampling means 4 which, as said, may be integral with the microprocessor 5, and elaborates them. The data so elaborated, in form of data representing intensity versus time, can be displayed on a display 6, which may be the display of a personal computer, if microprocessor 5 is enclosed in a personal computer, and the same data may be additionally, or alternatively, printed out on a printer 7. If it is desired to employ the apparatus of Fig. 1 as an apparatus for effecting the bio-feedback education of a patient, display means 6 and 7 can be dispensed with, and signaling means 8, indicated in broken lines in the figure, can be provided, which will signal to the patient that the performance of the swallow is below a desired performance. The signaling means 8 may be, for instance, acoustic signaling means, such as a beeper, or visual signaling means, such as a display or touch signaling means such as vibration/touch stimuli placed in contact with the skin of the subject. Furthermore, two different types of signals as well as different intensities of the signal, may be provided, to indicate to the subject whether his swallow is deficient in frequency, depth, form, sequency, continuity or coordination, and to what extent. Of course, different signals can also be provided to indicate different deficiencies in swallowing. For instance, for the larynx and the hyoid the movement in two planes (AP/vertical), as well as the continuity of movement are important; the timing and sequence of events in swallowing will be considered with respect to all anatomical structures; the muscles the tensile contraction of the oral muscles can also be analysed, etc. The apparatus shown in Fig. 1 is an analysis apparatus which, as explained, can be used also as a bio-feedback apparatus. The invention, however, contemplates also providing simpler and cheaper devices that can be used by the patient to exercise, according to parameters preset by the physician as the result of the analyses effected. Thus, the simplified apparatus will still, broadly speaking, comprise the elements described with reference to Fig. 1, but will only be able to provide bio-feedback by way of signalling means. While, as explained, the analyzing apparatus of Fig. 1 can be employed "as is" as a bio-feedback device, this will normally be needlessly expensive and complicated for home exercise purposes. Fig. 2 schematically shows a number of swallows as can be displayed, e.g., on a printer or on the display of a PC. This figure shows the intensity of each swallow and all swallows occurring in the period of time examined. From the data points shown in the figure deficient swallowing, whether from the point of view of depth of swallowing or of frequency (time passing between two swallows) can be determined. Fig. 3 shows the analysis of single swallows, two swallows being shown. The first swallow, indicated by S10, begins at time t 1 and ends at time t' 1 . The maximum swallow is above the minimal intensity, MS, of the swallow which has been set for the specific subject. Thus, swallow S10 is a correct swallow, and will result in no signal from the system, if a bio-feedback system is employed. The second swallow, S20, begins at time t 2 and ends at time t' 2 . This swallow has a maximum which is below the minimal relative intensity which is desirable for the subject. Thus, if a bio-feedback system is employed, a signal indicating to the subject that the depth of swallow is insufficient will be generated. Furthermore, the time intervening between t' 1 and t 2 will be compared with a preset time interval. If the time interval t 2 - t' 1 is shorter than the maximal preset time interval, then swallow S20 will occur spontaneously. On the other hand, if the time interval reaches the value of the maximal permissible time interval, then a signal will be generated to prime the subject to effect the next swallow at the time t 2 , and swallow S20 will be the result of this priming produced by the bio-feedback apparatus. Additional information on the behavior of each swallow can be similarly obtained from the data for a single swallow. All the above description and examples have been given for the purpose of illustration. Many different modifications can be made in the apparatus and methods, without exceeding the scope of the invention as defined in the claims.

Claims: A method of noninvasive analyzing the swallowing of a subject, comprising the steps of: 1) Providing a single piezo-electric film transducer; 2) Positioning the transducer noninvasively in the desired position on the anatomical structure of the subject to analyze the swallowing of the subject; 3) Sampling signals generated by the transducer when swallowing is performed; 4) Elaborating the signals to determine swallow beginning and ending time and the relative induced intensity of the sampled signals at the sampling times; and 5) Providing visual data representing the induced intensity of the sampled signals representing the swallowing behavior of the subject A method according to claim 1, wherein the anatomic structure is selected from the larynx, hyoid, tongue and the oral muscles. Apparatus for noninvasively analyzing the swallowing of a subject, the apparatus comprising: 1) A single piezo-electric film transducer (2); 2) Means for positioning the transducer in a desired position on the anatomical structure of the subject, to analyze the swallowing of the subject; 3) Sampling means (4) for sampling the signals generated by the transducer; 4) Elaborating means (5) to elaborate the signals to determine swallow beginning and ending time, and the relative induced intensity of the sampled signals at the sampling times; and 5) Visual data display (6,7) means to display the data representing the pressure-induced intensity of the sampled signals. Apparatus according to claim 3, wherein the means for positioning are adapted to position the transducer directly on the larynx of the subject to detect the movement of the larynx during swallow. A method of teaching a subject to perform an improved swallow, comprising the steps of : 1) Positioning a single piezo-electric film transducer noninvasively in a desired position relative to the anatomical structure of the subject, the behavior of which during swallowing it is desired to analyze; 2) Sampling the signals generated by the transducer when swallowing is performed; 3) Elaborating the signals to determine the interval of time between the separate swallows and the relative induced intensity of the sampled signals at the sampling times; 4) Determining whether the interval between the two separate swallows exceeds a predetermined interval of time, and if the predetermined time is exceeded, generating a signal to prime the subject to perform a swallow; and 5) For each swallow parameter analyzed, determining whether the sampled signal departs from a predetermined value, and if the sampled signal departs from the said predetermined value, generating a signal to prime the subject to perform a correct swallow.

Inventors: YARKONY SHIRIT, YARKONY, SHIRIT
Applicants: YARKONY SHIRIT, YARKONY, SHIRIT
Application year: 1991
Main classification: A61B5
IPC codes: A61B5