US20050267547A1

US20050267547A1 - Microstimulator treatment for sleep apnea or snoring

Info

Publication number: US20050267547A1
Application number: US11/197,054
Authority: US
Inventors: Mark Knudson; Robert Nickoloff; Timothy Conrad
Original assignee: Restore Medical Inc
Current assignee: Medtronic Xomed LLC
Priority date: 1999-09-29
Filing date: 2005-08-03
Publication date: 2005-12-01
Also published as: US20040073272A1; WO2001023039A1; US6636767B1; AU7725700A

Abstract

The present disclosure relates to methods and apparatuses for treating snoring by implanting a stimulating electrode into a patient. The electrode is placed in stimulating contact with an airway passage-controlling muscle of the patient. The electrode is energized to contract the muscle and alter the airway passage.

Description

BACKGROUND

1. Field of the Invention
This invention is directed to method and apparatus for treating snoring.
2. Description of the Prior Art
Snoring has received increased scientific and academic attention. One publication estimates that up to 20% of the adult population snores habitually. Huang, et al., “Biomechanics of Snoring”, Endeavour, Vol. 19, No. 3, pp. 96-100 (1995). Snoring can be a serious cause of marital discord. In addition, snoring can present a serious health risk to the snorer. In 10% of habitual snorers, collapse of the airway during sleep can lead to obstructive sleep apnea syndrome. Id.
Notwithstanding numerous efforts to address snoring, effective treatment of snoring has been elusive. Such treatment may include mouth guards or other appliances worn by the snorer during sleep. However, patients find such appliances uncomfortable and frequently discontinue use (presumably adding to marital stress).
Surgical treatments have been employed. One such treatment is uvulopalatopharyngoplasty. In this procedure, so-called laser ablation is used to remove about 2 cm of the trailing edge of the soft palate thereby reducing the soft palate's ability to flutter between the tongue and the pharyngeal wall of the throat. The procedure is frequently effective to abate snoring but is painful and frequently results in undesirable side effects. Namely, removal of the soft palate trailing edge comprises the soft palate's ability to seal off nasal passages during swallowing and speech. In an estimated 25% of uvulopalatopharyngoplasty patients, fluid escapes from the mouth into the nose while drinking. Huang, et al., supra at 99. Uvulopalatopharyngoplasty (UPPP) is also described in Harries, et al., “The Surgical treatment of snoring”, Journal of Laryngology and Otology, pp. 1105-1106 (1996) which describes removal of up to 1.5 cm of the soft palate. Assessment of snoring treatment is discussed in Cole, et al., “Snoring: A review and a Reassessment”, Journal of Otolaryngology, pp. 303-306 (1995).
Huang, et al., supra, describe the soft palate and palatal snoring as an oscillating system which responds to airflow over the soft palate. Resulting flutter of the soft palate (rapidly opening and closing air passages) is a dynamic response generating sounds associated with snoring. Huang, et al., propose an alternative to uvulopalatopharyngoplasty. The proposal includes using a surgical laser to create scar tissue on the surface of the soft palate. The scar is to reduce flexibility of the soft palate to reduce palatal flutter. Huang, et al., report initial results of complete or near-complete reduction in snoring and reduced side effects.
Surgical procedures such as uvulopalatopharyngoplasty and those proposed by Huang, et al., continue to have problems. The area of surgical treatment (i.e., removal of palatal tissue or scarring of palatal tissue) may be more than is necessary to treat the patient's condition. Surgical lasers are expensive. The proposed procedures are painful with drawn out and uncomfortable healing periods. The procedures have complications and side effects and variable efficacy (e.g., Huang, et al., report promising results in 75% of patients suggesting a full quarter of patients are not effectively treated after painful surgery). The procedures may involve lasting discomfort. For example, scar tissue on the soft palate may present a continuing irritant to the patient. Importantly, the procedures are not reversible in the event they happen to induce adverse side effects not justified by the benefits of the surgery.
Electrical stimulation of the soft palate has been suggested to treat snoring and obstructive sleep apnea. See, e.g., Schwartz, et al., “Effects of electrical stimulation to the soft palate on snoring and obstructive sleep apnea”, J. Prosthetic Dentistry, pp. 273-281 (1996). Devices to apply such stimulation are described in U.S. Pat. Nos. 5,284,161 and 5,792,067. Such devices are appliances requiring patient adherence to a regimen of use as well as subjecting the patient to discomfort during sleep. Alternatively, these devices must be used during the day for a period of time causing disruption of daily activity, interference with daily life. This may generally be assumed to cause them to be prone to a significant risk of non-compliance by the wearer. Such devices, though have met with some success in treating disorders such as snoring and Obstructive Sleep Apnea.

SUMMARY OF THE INVENTION

According to a preferred embodiment of the present invention, a method and apparatus are disclosed for treating snoring of a patient. The invention includes implanting a stimulating electrode into a patient. The electrode is placed in stimulating contact with an airway passage-controlling muscle of the patient. The electrode is energized to contract the muscle and alter the airway passage.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side sectional view of a portion of a human head showing a soft palate in a relaxed state and in relation in adjacent anatomical features;
FIG. 2 is a portion of the view of FIG. 1 showing the soft palate in a flexed state;
FIG. 3 is a front view of an interior of the mouth shown in FIG. 1 and showing an area to be ablated according to a first prior art surgical procedure;
FIG. 4 is the view of FIG. 3 and showing an area to be scarred according to a second prior art surgical procedure;
FIG. 5 is a schematic representation of a spring-mass system model of the soft palate;
FIG. 6 is the view of FIG. 1 showing electrodes placed in the muscles of the soft palate, tongue and throat; and
FIG. 7 is a schematic representation of a pacing electrode inductively coupled to a control device.

DESCRIPTION OF THE PREFERRED EMBODIMENT

For ease of understanding the present invention, the dynamics of snoring are explained with reference to FIGS. 1-5. The hard palate HP overlies the tongue T and forms the roof of the mouth M. The hard palate HP includes a bone support B and does not materially deform during breathing. The soft palate SP is soft and is made up of mucous membrane, fibrous and muscle tissue extending rearward from the hard palate HP. A leading end LE of the soft palate SP is anchored to the trailing end of the hard palate HP. A trailing end TE of the soft palate SP is unattached. Since the soft palate SP is not structurally supported by bone or hard cartilage, the soft palate SP droops down from the plane of the hard palate HP in an arcuate geometry of repose.
The pharyngeal airway passes air from the mouth M and the nasal passages N into the trachea TR. The portion of the pharyngeal airway defined between opposing surfaces of the upper surface of the soft palate SP and the wall of the throat is the nasopharynx NP.
During normal breathing, the soft palate SP is in the relaxed state shown in FIG. 1 with the nasopharynx NP unobstructed and with air free to flow into the trachea TR from both the mouth M and the nostrils N.
During swallowing, the soft palate SP flexes and extends (as shown in FIG. 2) to close the nasopharynx NP thereby preventing fluid flow from the mouth M to the nasal passages N. Simultaneously, the epiglottis EP closes the trachea TR so that food and drink pass only into the esophagus ES and not the trachea TR. The soft palate SP is a valve to prevent regurgitation of food into the nose N. The soft palate SP also regulates airflow through the nose N while talking. Since the soft palate SP performs such important functions, prior art techniques for surgically altering the soft palate SP can compromise these functions.
The majority of snoring is caused by the soft palate SP flapping back and forth. If breathing is solely through the nose N with the mouth closed, the trailing edge TE of the soft palate SP is sucked into the nasopharyngeal space NP obstructing the airway and subsequently falls opening the airway in a repeating cycle. When the mouth is open, air flows over the upper and lower surfaces of the soft palate SP causing the soft palate SP to flap up and down alternating in obstructing the oral and nasal passageways M, N. The snoring sound is generated by impulses caused by rapid obstruction and opening of airways. Huang, et al., state the airway passage opening and closing occurs 50 times per second during a snore. Huang, et al., utilizing a spring-mass model (FIG. 5) to illustrate oscillation of the soft palate in response to airflow (where the soft palate is the ball B of mass depending by a spring S from a fixed anchor A).
Huang, et al., analogize the shortening of the soft palate SP in uvulopalatopharyngoplasty as effectively raising the critical air flow speed at which soft palate flutter will occur. The shaded area SA in FIG. 3 shows the area of the trailing end TE of the soft palate SP to be removed during this procedure. The alternative procedure proposed by Huang, et al., reduces the flexibility of the soft palate SP through surface scarring which is asserted as effecting the critical flow speed. The shaded area SA′ in FIG. 4 shows the area to be scarred by this alternate procedure. In FIG. 4, dashed line L shows the demarcation between the soft and hard palates.
The present invention is directed to a method and apparatus for altering the dynamic response of the soft palate by altering airflow past the soft palate. With reference to the spring-mass model (FIG. 5), the soft palate is moved by airflow. Airflow through an orifice varies in response to the orifice size. The present invention alters the size of the air passage through a minimally invasive surgical implant to allow stimulation of airway defining muscles of the oro-pharynx (i.e., mouth and throat).
The present invention stimulates muscles of one or more of the soft palate SP, tongue T and back of the throat. In the soft palate SP, these muscles include, but are not limited to, the Levator veli paltini, the dextera, the Palatopharyngeous and the Palatoglossus muscles. At the back of the throat, these muscles include, but are not limited to, the Superior, Middle and Inferior pharyngeal constrictor, the Salpingopharyngeous and the Stylopharyngeous muscles. In the tongue T, these muscles include, but are not limited to, the Genioglossus and Geniohyoid muscles.
Stimulating the muscles of the soft palate, tongue and throat is intended to alter the dynamic response of the soft palate to airflow. Namely, stimulation of the soft palate SP causes the soft palate to move away from the tongue T, stimulation of the tongue T causes the tongue T to move away from the soft palate SP, and stimulation of the back of the throat causes the throat to move rearwardly. Alone or in combination, these actions increase the size of the airway thereby decreasing air velocity and the disrupting force which would otherwise cause oscillation of the soft palate SP.
Stimulation of the muscles is accomplished by implanted electrodes 10, 10′ and 10″ placed in the airway passage-defining muscles (identified above) of the soft palate SP, tongue T and back of throat (as illustrated in FIG. 6). Implantable muscle stimulating electrodes are well known and may be such as those used in cardiac pacing.
The implant 10, 10′, 10″ can be positioned and stimulated in a plurality of ways to alter the shape of the airway, to change the dynamic response of the airway tissues or a combination of both. Unlike the prior art surgical techniques, the electrodes 10, 10′, 10″ that will be described are easy to insert in a small incision resulting in reduced patient discomfort and are not exposed to the interior of the mouth (such as the surface scarring of Huang, et al.) as a patient irritant. Also, as will be described, the degree of dynamic remodeling and stimulation pattern can be fine tuned avoiding the need for excessive anatomical modification and are reversible in the event of adverse consequences.
The present invention permits the surgeon to apply stimulation to various muscles until the desired alteration in airway area and tone is achieved so that snoring inducing oscillation is abated at normal airflow. The individual electrodes 10, 10′, 10″ may be placed into the soft palate, tongue or throat muscles through small individual incisions closed by sutures which is much less traumatic than the gross anatomical destruction of uvulopalatopharyngoplasty or the large surface area scarring proposed by Huang, et al.
A control device 20 is provided for controlling the electrodes 10, 10′, 10″. The control device 20 is shown as a removable appliance (schematically shown in FIG. 6 with it being appreciated that appliances for placement in the mouth are well known) which fits the form of the hard palate or sub-lingual spaces.
The control device 20 is electrically coupled to the electrodes 10, 10′, 10″ through electromagnetic coupling which avoids the need for electrode leads being exposed from the implants 10, 10′, 10″. Specifically, the electrode 10 (shown in FIG. 7 and it being appreciated that electrodes 10′, 10″ are of similar construction) includes a pacing electrode 12 for stimulating muscle in response to a signal through the electrode 10. Leads 14 connect the pacing electrode 12 to an inductive winding 16. In use, the entire electrode 10 (i.e., each of the components of the pacing electrode 12, leads 14 and winding 16) are imbedded in the patient and not exposed.
The control device 20 is shown schematically and includes an inductive winding 22 connected to a control circuit 24. Control circuit 24 is only shown schematically. Control circuits for pacing electrodes are well known and widely used in cardiac pacing. In the present invention, preferably none of the components of the control device 20 (i.e., the winding 22 and circuit 24) are implanted. Instead, preferably such components are contained in the removable oral appliance control device 20 although some elements (e.g., a battery may be worn externally by the patient).
The control winding 22 is positioned on the control device 20 to be inductively coupled to the electrode winding 16 when the control device 20 is in place. In the event multiple electrodes 10, 10′, 10″ are placed in multiple muscles, the control device 20 may contain a plurality of windings 22 each uniquely tuned to the windings of the electrodes 10, 10′, 10″ such that each electrode 10, 10′, 10″ may be uniquely paced. Also, each of the electrodes 10, 10′, 10″ can be provided with filter circuits to pass only desired signals to the pacing electrodes.
The control device 20 sends a pulsitile signal to the electrode 10 through the inductive coupling of windings 16 and 22. In response, the electrode 10 causes pacing contraction of the muscle. Preferably, the pacing is selected to contract the muscle up to and including tetanic contraction.
With the present invention, the muscle is contracted to increase the size of the airway and reduce palatal flutter. The amount of pacing can be tuned to the unique physiology of the patient. The control device need only be used during sleep. It is anticipated that regular use of the control device 20 results in improved tone of the paced muscles reducing or eliminating future need to use the control device 20. Unlike the appliances of U.S. Pat. Nos. 5,284,161 and 5,792,067, the present device has more effective pacing since muscles are being paced directly by implanted electrodes rather than through less efficient surface stimulation. Further, the present invention contemplates pacing of all muscles defining the airway passage and not just the soft palate.
Having described the invention, alternatives and embodiments may occur to one of skill in the art. It is intended that such modifications and equivalents shall be included within the scope of the following claims.

Claims

1-12. (canceled)

13. A method of treating snoring comprising: a) monitoring the airway passage of a patient during sleep to identify at least one anatomical structure in the airway passage that vibrates during snoring; b) implanting at least one microstimulator in the proximity of the at least one anatomical structure identified in step a); c) energizing the microstimulator to deliver an electrical stimulation to the anatomical structure to cause at least one muscle to contract and reduce the vibrations of the airway passage.

14. The method of claim 13, further including inserting a distal end of a scope such that the distal end is located in an upper airway of the patient and monitoring the airway passage during sleep.

15. The method of claim 13, further including inserting a distal tip of an insertion tool into the anatomical structure, wherein the microstimulator is located in a lumen of the insertion tool, and activating the insertion tool to eject the microstimulator from the insertion tool, and removing the insertion tool from the anatomical structure.

16. The method of claim 13, further comprising delivering an electrical stimulation to the anatomical structure prior to step b), and observing the anatomical structure for decrease in vibration.

17. The method of claim 16, further comprising inserting a distal tip of an insertion tool into an anatomical structure, applying an electrical current to at least the distal tip of the insertion tool, and delivering an electrical current to the anatomical structure.

18. The method of claim 16, further including inserting a distal tip of an insertion tool into the anatomical structure, wherein the microstimulator is located in a lumen of the insertion tool, and energizing the microstimulator located within the lumen of an insertion tool.

19. The method of claim 13, further comprising testing the microstimulator by emitting electrical stimulations at a plurality of intensities, and observing the anatomical structure to determine the intensity which decreases the vibration of the anatomical structure.

20. The method of claim 19, wherein the electrical stimulation is of an intensity from about 8 to about 800 nC.

21. The method of claim 13, further comprising energizing the microstimulator at a selected frequency to deliver an electrical stimulation to the anatomical structure to cause at least one muscle to contract and reduce the vibrations of the airway passage.

22. The method of claim 21, wherein the frequency is about 1 to about 30 pulses per second.

23. The method of claim 21, further comprising providing interruptions of a selected duration and period in the electrical stimulation to permit the at least one muscle to relax.

24. The method of claim 23 wherein the duration of the interruption is from about 0.2 to about 2 seconds and the selected period is from about 5 to about 20 seconds.

25. The method of claim 13, further comprising: a) sensing when snoring is occurring; and b) generating an electrical stimulus from the microstimulator to contract an oropharyngeal muscle, in response to sensing snoring in step a).

26. The method of claim 25, wherein snoring is sensed by detecting mechanical vibrations of at least one anatomical structure.

27. The method of claim 25, wherein snoring is sensed by acoustically detecting sounds generated by vibrating at least one anatomical structure in the airway passages.

28. The method of claim 13, wherein the energizing includes delivering a control signal to a pair of electrodes, wherein the microstimulator includes the pair of electrodes.

29. The method of claim 13, wherein the anatomical structure is selected from the group comprising: the soft palate or the uvula.

30. The method of claim 13, wherein the anatomical structure is a muscle selected from the group comprising: palatoglossus, palatopharyngeal, musculus uvulae, genioglossus, geniohyoid, levator palati or tensor palati.

31. The method of claim 13, wherein the anatomical structure is a branch or terminal of a nerve selected from the group comprising: vagus X, hypoglossal, vagus pharyngeal branch, V3 branch trigeminal nerve.

32. The method of claim 13, further comprising implanting a second microstimulator proximate to at least a second anatomical structure, different than the at least one anatomical structure.

33. The method of claim 32, wherein at least one anatomical structure and a second anatomical structure are muscle pairs selected from the group comprising: geniohyoid and genioglossus; tensor palati and palatoglossus; tensor palati and musculus uvulae.

34. The method of claim 32, wherein at least one of the microstimulators includes a sensor and a telemeter configured to generate a signal indicative of a sensed condition, and at least one of the microstimulators includes a circuitry configured to generate an electrical stimulation pulse.

35. The method of treating snoring comprising: a) implanting a microstimulator within at least one of the soft palate or the uvula; and b) activating the microstimulator to deliver an electrical stimulation to at least one of the soft palate or the uvula to cause at least one muscle to contract.

36. The method of claim 35, wherein the microstimulator includes an electrical circuit configured to generate an electrical stimulus and a pair of electrodes configured to apply the electrical stimulus to the at least one of the soft palate or uvula.

37. The method of claim 35, further comprising transmitting from a controller to the microstimulator power, control signals, or power and control signals.

38. The method of claim 35, further comprising transmitting an acknowledgement signal from the microstimulator to a controller, wherein the acknowledgement signal indicates that the microstimulator has received a control signal from a controller.

39. The method of claim 35, further comprising activating the microstimulator in a temporal pattern to deliver the electrical stimulation to the at least one of the soft palate or the uvula to cause at least one muscle to contract, wherein the temporal pattern includes periods of an absence of electrical stimulation to permit the at least one muscle to cease from contracting.

40. The method of claim 35, further comprising testing the microstimulator by emitting electrical stimulations at a plurality of intensities, and observing at least one of the uvula or soft palate to determine the intensity which decreases the vibration of the uvula or soft palate.

41. The method of claim 40, wherein the electrical stimulation is of an intensity from about 8 to about 800 nC.

42. The method of claim 35, further comprising sensing when snoring is occurring; and electrically stimulating at least one microstimulator implanted within the soft palate or the uvula in response to sensing snoring.

43. The method of claim 42, wherein snoring is sensed by detecting mechanical vibrations of at least on anatomical structure.

44. The method of claim 42, wherein snoring is sensed by acoustically detecting sounds generated by at least one vibrating anatomical structure in the airway passages.

45. The method of claim 35, wherein the microstimulator is implanted in a muscle selected from the group comprising: palatoglossus, palatopharyngeal, or musculus uvulae.

46. The method of claim 35, wherein the microstimulator is implanted proximate to a branch or terminal of the vagus X nerve.

47. The method of claim 35 further comprising implanting a second microstimulator in the proximity of an anatomical structure selected from the group comprising: palatoglossus, palatopharyngeal, musculus uvulae, genioglossus, geniohyoid, levator palate, tensor palati, vagus X, hypoglossal, vagus pharyngeal branch, V3 branch trigeminal nerve.

48. The method of claim 35, further comprising: a) inserting a distal tip of an insertion tool including a microstimulator through the oral mucosa of the soft palate; b) inserting the distal tip of the insertion tool into the uvula; c) activating the insertion tool to deposit the microstimulator from the insertion tool; and d) removing the insertion tool from the uvula.

49. The method of claim 48, further including positioning the microstimulator in or in the proximity of the musculus uvulae.

50. The method of claim 48, further including positioning the microstimulator in the proximity of the terminal branches of the motor axons to the musculus uvulae, wherein the microstimulator includes a cathode and an anode; and positioning the microstimulator cathode in the proximity of the terminal branches of the motor axons to the musculus uvulae.

51. The method of claim 48, further comprising advancing a distal tip of an insertion tool through the oral mucosa to the soft palate to the uvula, wherein the distal tip of the insertion tool includes a microstimulator within a lumen of the distal tip; and testing microstimulator by emitting electrical stimulation from the microstimulator within the lumen of the distal tip; and withdrawing the insertion tool leaving the microstimulator within the uvula.

52. The method of implanting a microstimulator into the genioglossus muscle comprising: a) inserting a distal tip of an insertion tool through the epidermis under the mandible b) passing the distal tip of the insertion tool through the geniohyoid muscle; c) inserting the distal tip of the insertion tool into the genioglossus muscle; d) depositing the microstimulator in the genioglossus muscle; and e) removing the insertion tool from the body.

53. The method of claim 52, further including positioning the microstimulator in the proximity of the endplate zone of the radially oriented sagittal muscle fibers of the genioglossus muscle, wherein the microstimulator includes a cathode and an anode; and positioning the microstimulator cathode in the proximity of the endplate-zone of the radially oriented sagittal muscle fibers of the genioglossus muscle.

54. The method of claim 52, further comprising advancing a distal tip of an insertion tool through the geniohyoid muscle to the genioglossus muscle, wherein the distal tip of the insertion tool includes a microstimulator within a lumen of the distal tip; and testing microstimulator by emitting electrical stimulation from the microstimulator within the lumen of the distal tip; and withdrawing the insertion tool leaving the microstimulator within the genioglossus.

55. The method treating snoring in a patient comprising alternately stimulating at least a first and second muscle in the oropharynx to contract so that an airway passage remain substantially free of vibrating soft tissue during sleep.

56. The method treating snoring in a patient comprising alternately stimulating at least a first and second muscle in the oropharynx to contract so that an airway passage remains substantially free of vibrating soft tissue during sleep, and selecting a pattern of stimulation such that while the first muscle is being contracted the second muscle may have a period of relaxation, and while the second muscle is being contracted, the first muscle may have a period of relaxation.

57. The method of claim 43 wherein the first and second muscles are selected from the group comprising: palatoglossus, palatopharyngeal, musculus uvulae, genioglossus, geniohyoid, levator palati, tensor palati.

58. The method of claim 55, wherein the first and second muscles are selected from the groups of pairs comprising: tensor palati and palatoglossus; tensor palati and musculus uvulae; and geniohyoid and genioglossus.

59. The method of claim 55, further comprising monitoring an airway passage of the patient during sleep to identify at least one anatomical structure in the airway passage that vibrates during snoring.

60. The method of claim 55, further comprising: a) sensing when snoring is occurring; and b) generating an electrical stimulus from the microstimulator to contract an oropharyngeal muscle, in response to sensing snoring in step a).

61. The method of claim 60, wherein snoring is sensed by detecting mechanical vibrations of at least one anatomical structure.

62. The method of claim 60, wherein snoring is sensed by acoustically detecting sounds generated by at least one vibrating anatomical structure in the airway passages.

63. The method of claim 60, further including implanting at least a first microstimulator and a second microstimulator, and wherein the first and second microstimulators are alternately activated to cause the contraction of the at least first and second muscle in the oropharynx

64. The method of claim 63, further comprising alternately applying electrical stimulations of an intensity from about 8 to about 800 nC to stimulate at least the first and second muscle in the oropharynx to contract.

65. The method of claim 55, further comprising applying electrical stimulations for a selected duration to stimulate at least the first muscle in the oropharynx to contract, and interrupting the electrical stimulation for a selected duration at a selected period to permit the first muscle in the oropharynx to relax.