Method and process for placement and fixation of a surgical implant

Abstract

Methods of treating obstructive sleep apnea according to the disclosure can include providing an implant comprising: a substantially planar central body portion having a top side and a bottom side; at least two adjustable wing portions; and at least two connecting members each extending from opposite sides of the central body portion, each of the at least two connecting members configured to flexibly connect each of the at least two wing portions to the central body portion on opposite sides; forming a surgical opening to expose a genioglossus muscle; exposing a hypoglossal nerve branch on at least one side of the genioglossus muscle for stimulation by the implant; forming at least one pocket on at least one side of the genioglossus muscle; sizing the pocket to receive at least one of the at least two wing portions of the implant device; inserting the implant device through the surgical opening such that the central body extends over the genioglossus muscle and each of the wing portions is received in a respective at least one pocket; and securing the implant device to the muscle.

Description

TECHNICAL FIELD

[0001] The disclosed subject matter relates to methods and procedures for placing and securing surgical implants for treating sleeping disorders and in particular sleep apnea. BACKGROUND

[0002] Obstructive sleep apnea is a common and heterogenous disorder characterized by repetitive partial or complete obstruction of the pharyngeal airway during sleep. In most patients, there is an anatomic predisposition to the disorder. Complicating this can be abnormalities in ventilatory control (e.g. high loop gain) and increased arousal threshold during sleep. Pharyngeal muscles respond to inputs from mechanoreceptors in the airway as well as changes in oxygen and C02levels in the blood. The genioglossus muscle is the primary dilator muscle of the pharyngeal airway. Failure of the upper airway dilator muscles to respond appropriately to airflow restriction and or changes in C02and 02levels can result in obstructive OSA.

[0003] Hypoglossal nerve stimulation as a means to dilate the pharyngeal airway was first described by Schwartz et al in a feline model in 1993.

[0004] Since then, several devices (Apnex, Inspire Medical, Imthera) have been developed to stimulate the hypoglossal nerve unilaterally in patients with OSA. The Inspire Medical device has now been in use for over 5 years and is approved for use in both Europe and North America. Key study results for the Inspire hypoglossal nerve stimulator were published in 2014. Despite the efficacy of this technology having been proven, potential difficulties arise due to MRI compatibility issues, long leads, the need for a lead to be tunneled from the chest to the submandibular region, and an implanted battery and processor implanted in the subcutaneous tissue of the subclavicular region in a subcutaneous manner.

[0005] REFERENCES

[0006] • Neelapu BC, Kharband OP, Sardana HK et al, Craniofacial and upper airway morphology in adult obstructive sleep apnea patients: A systematic review and meta-analysis of cephalometric studies. Sleep Med Rev. 2017 Feb; 31 :79-90. doi: 10.1016 / j.smrv.2016.01.007. Epub 2016 Jan 30

[0007] • Eckert DJ, White DP, Jordan AS, Malhotra A, Wellman A Am J Respir Crit Care Med. 2013 Oct 15; 188(8): 996-1004. doi: 10.1164 / rccm.201303-04480C

[0008] • Schwartz AR1, Bennett ML, Smith PL, De Backer W, Hedner J, Boudewyns A, Van de Heyning P, Ejnell H, Hochban W, Knaack L, Podszus T, Penzel T, Peter JH, Goding GS, Erickson DJ, Testerman R, Ottenhoff F, Eisele DW. Therapeutic electrical stimulation of the hypoglossal nerve in obstructive sleep apnea. Arch Otolaryngol Head Neck Surg. 2001 Oct; 127(10): 1216-23.

[0009] • Schwartz AR, Thut DC, Russ B, Seelagy M, Yuan X, Brower RG, Permutt S, Wise RA, Smith PL. Effect of electrical stimulation of the hypoglossal nerve on airflow mechanics in the isolated upper airway. Am Rev Respir Dis. 1993 May; 147(5): 1144-50.

[0010] • B. Tucker Woodson, MD, Kingman P. Strohl, MD, Ryan J. Soose, MD, M. Boyd Gillespie, MD, Joachim T. Maurer, MD, Nico de Vries, MD, Tapan A. Padhya, MD, M. Safwan Badr, MD, Ho-sheng Lin, MD, Olivier M. Vanderveken, MD, PhD, Sam Mickelson, MD, and Patrick J. Strollo, Jr, MD. Upper Airway Stimulation for Obstructive Sleep Apnea: 5-Year Outcomes. Otolaryngology-Head and Neck Surgery, March 2018. https: / / doi.org / 10.1177 / 0194599818762383

[0011] • Strollo PJ Jr, Soose RJ, Maurer JT, de Vries N, Cornelius J, Froymovich O, Hanson RD, Padhya TA, Steward DL, Gillespie MB, Woodson BT, Van de Heyning PH, Goetting MG, Vanderveken OM, Feldman N, Knaack L, Strohl KP. Upper-airway stimulation for obstructive sleep apnea. N Engl J Med. 2014 Jan 9; 370(2): 139-49. doi: 10.1056 / NEJMoal308659.

[0012] • Heiser C, Hofauer B, Lozier L, Woodson BT, Stark T. Nerve monitoring- guided selective hypoglossal nerve stimulation in obstructive sleep apnea patients. Laryngoscope. 2016 Dec; 126(12):2852-2858. doi: 10.1002 / lary.26026. Epub 2016 Jun 27

[0013] • Bassiri Gharb B., Tadisina K.K., Rampazzo A., Hashem A.M., Elbey H., Kwiecien G.J., Doumit G., Drake R.L., Papay F. 2015. Microsurgical Anatomy of the Terminal Hypo-glossal Nerve Relevant for Neurostimulation in Obstructive Sleep Apnea.

[0014] • Neuromodulation 2015; E-pub ahead of print. DOI: 10.1111 / ner.12347

[0015] The devices disclosed in PCT / EP2018 / 054913 and Applicant’s other numerous applications, including US 9,415,216, WO 2013 / 046048, US 8,577,466, which are incorporated by reference herein, describe hypoglossal nerve stimulators and related systems that have been designed to circumvent some of these issues. By stimulating the hypoglossal nerve bilaterally and simultaneously, airway opening is potentially more effective than achieved with unilateral nerve stimulation. Furthermore, there is no need to pass a wire down from the neck into the chest, and there is no need for an implanted battery or processor, nor dissection in the chest. SUMMARY

[0016] In one aspect, a method of treating obstructive sleep apnea comprises:

[0017] providing an implant, the implant comprising:

[0018] a substantially planar central body portion having a top side and a bottom side;

[0019] at least two adjustable wing portions; and

[0020] at least two connecting members, each of the at least two connecting members extending from opposite sides of the central body portion, each of the at least two connecting members configured to flexibly connect each of the at least two wing portions to the central body portion at opposite sides;

[0021] forming a surgical opening to expose the genioglossus muscle;

[0022] exposing a hypoglossal nerve branch on at least one side of the genioglossus muscle for stimulation by the implant;

[0023] forming at least one pocket superior to the nerve on at least one side of the genioglossus muscle; such that the pocket size is configured to fit at least one of the at least two wing portions of the device;

[0024] inserting the implant device through the surgical opening such that the central body extends over the genioglossus muscle and each of the wing portions is received in the respective at least one pocket; and

[0025] securing the implant device to the muscle.

[0026] In one embodiment, at least one of the at least two adjustable wing portions comprises at least one pair of electrodes. According to this example, the electrodes are mechanically or electronically coupled to an antenna configured to receive a signal, and wherein the electrodes are configured to receive an electrical current in response to the signal received by the antenna, such that at least one of the pair of electrodes is configured to emit an electric field. In one embodiment, the at least one pair of electrodes extends within the at least one pocket, such that when the electric field is emitted, the hypoglossal nerve is stimulated.

[0027] The method can include using a fastening element to secure the implant to the muscle. Such a fastening element can be a suture, an adhesive, or any other type of fastening element, including mechanical, chemical, or adhesive. In one example, a parachuting technique is used to secure the at least adjustable wing portion. In this embodiment, a suture is used to mark the location of one or more suture points, and can then be used to secure the wing portion at the pre-marked location. In another embodiment, a biodegradable fastening element can be used. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 is an illustration of an implantable device according to embodiments of the disclosed subject matter.

[0029] Figure 2 illustrates placement of an AC-DP on the chin according to examples of the disclosed subject matter;

[0030] Figure 3 is an image of a set up of a patient prior to a surgical procedure according to the disclosed subject matter;

[0031] Figure 4 is an illustration of a patient marking and set up for a surgical procedure prior to a surgical procedure;

[0032] Figure 5 is an illustration of a surgical step of exposing the GH muscle;

[0033] Figure 6 is an illustration of a surgical opening in which the hypoglossal nerve and left GG muscle are exposed;

[0034] Figure 7 and 8 is an illustration of the exposed nerve;

[0035] Figure 9 is an illustration of an external stimulator (ES) according to the disclosed subject matter;

[0036] Figure 10 illustrates the post-surgical incision area;

[0037] Figure 11 illustrates a surgical implant according to the disclosed subject matter (e.g. Figure 1 ) positioned on the genioglossus muscle, in which the DP and AC are provided in an external manner; and Figure 12 illustrates a screenshot of a PSG result. DETAILED DESCRIPTION

[0038] Implantable devices and systems

[0039] An example of an implantable stimulator (IS) consists of two sets of paired stimulating electrodes (one on each side of the device - see Figure 1 ) and a receiving antenna in the center, encapsulated in a silicon envelope to protect the antenna and circuitry. The two sets of electrodes are located on two flexible legs to accommodate not only the movement of the genioglossus muscle and hyoid bone skeleton, but also a variety of nerve anatomies. The implant according to the disclosed subject matter comprises:

[0040] a substantially planar central body portion having a top side and a bottom side;

[0041] at least two adjustable wing portions;

[0042] at least two connecting members, each of the at least two connecting members extending from opposite sides of the central body portion, each of the at least two connecting members configured to connect each of the at least two wing portions to the central body portion in a flexible manner on opposite sides.

[0043] The IS structure allows placement on both genioglossus muscles, with the paddle electrodes facing the medial branches of the hypoglossal nerve on each muscle. The flexibility of the wing portions and connecting member allows adjustment of the implant on the muscle, and further adjustment of each of the wing portions, respectively, to accommodate the respective anatomical structures of the muscle and nerve. The IS is provided sterile. The IS is a passive device, as it contains no battery according to this example.

[0044] In use, and in the post-surgical procedure, the patient connects an activation chip (AC) to a disposable patch (DP) (both from Nyxoah SA, BE) before going to sleep, and then places the DP and AC submentally (see Figure 2 and 11 ). Examples of the activation chip and disposable patch are disclosed in Applicant’s other applications, such as US 8,577,468, US 2014-0052219, etc., which are incorporated herein by reference.

[0045] The DP is a single-use biocompatible adhesive device; the AC allows activation of the IS by transferring energy wirelessly. Each morning, the patient removes the AC from the DP and disposes of the DP.

[0046] The storage of the AC contains user-specific stimulation parameters, which are programmed by the treating physician.

[0047] Patient Setup

[0048] Under general anesthesia with nasotracheal intubation, the patient is placed in a supine position, and his neck is extended with a shoulder roll. Four electrodes connected to a nerve integrity monitoring system are inserted into the tongue to locate the medial branches of the hypoglossal nerve and or their terminal fibers, and to verify normal muscle contraction: one set in each genioglossus muscle, and another in each styloglossus muscle i (see Figure 3 ).

[0049] A bipolar electrode was sutured to the tongue mucosa using 3 / 0 vicryl (Ethicon Inc, USA) to prevent it from moving. The electrode was carefully gathered to one corner of the mouth and secured to the skin of the face near the mouth using adhesive tape. A roll of gauze was inserted between the teeth to keep the mouth open so that tongue movements could be observed during stimulation. Finally, a video nasendoscope was inserted and a view of the epiglottis and base of the tongue was achieved. At the level of the nostril, a tape was placed around the scope to mark the depth at which the epiglottis was seen. The scope was then placed on a table beside the patient's head and unplugged from the monitor. This was covered with a drape and the anaesthetist still had access to it. Some gauze was placed on the scope near the nose to prevent the sterile drape from sticking to the scope. Alternatively, a nasopharyngeal airway could be inserted to facilitate easy insertion of the nasendoscope at any time.

[0050] Implantation technique

[0051] The midline was marked with a dotted line from the chin down to the thyroid notch. The hyoid bone was marked using a horizontal line. The midpoint between the hyoid bone and the chin was marked. A horizontal skin incision was then marked at the level of the midpoint between the hyoid and the chin, 4 to 6 cm in length. In addition, dotted lines were drawn to mark the midline for reference (see Figure 4 ).

[0052] 5 ml of local anaesthetic and adrenaline (1% lidocaine with 1 / 100000 adrenaline) was injected into the skin along the line of the incision. Betadine was used to disinfect the skin from the sternal notch (jugular notch) to the nose and laterally as far as at least the greater horn of the hyoid bone.

[0053] A split sheet drape was placed from approximately the lower edge of the thyroid cartilage, the second sheet being placed under the nostrils, the mouth not being covered. A clear sterile plastic sheet was then placed over the mouth / nose / upper drape leaving the sterile neck exposed.

[0054] Following the intravenous cefazolin 2g, a transverse incision is made. A monopolar cautery with a needle or spatula tip is used to deepen the incision through the platysma muscle. The subplatysmal flap is lifted superiorly to the chin and inferiorly to the thyroid notch. Four Lone-star elastic stays (Cooper Surgical, Trumbull, CT, USA) or fish hooks are used to retract the flap. Subsequently, the cautery is used to vertically dissect at the midline, through the fat inferiorly to the mylohyoid muscle. The midline is aided by reference to the vertical skin marking indicating the midline. With the assistant providing countertraction, the careful dissection is continued through the mylohyoid muscle. The horizontal fibers of the mylohyoid muscle are easily identified and separated under magnification. When the mylohyoid muscle has been separated, the vertical fibers of the geniohyoid muscle (GH) will immediately appear (see Figure 5 ).

[0055] The GH muscle is usually apposed in the midline, and thus determining the midline between the two muscle bellies can sometimes be challenging. Lifting a small portion of the mylohyoid muscle from the GH muscle and subsequently superiorly to the mandible and inferiorly to the hyoid bone search can make it easier to identify the plane between the GH muscles. The GH muscles are carefully separated using tenotomy scissors and bipolar cautery (or monopolar diathermy to avoid bleeding) from the mandible to the hyoid bone. The assistant retracts the muscle bellies and continues to gently separate them in the midline until the genioglossal muscle (GG) is identified. The midline raphe of fat is easily identified. At this point, it is important not to dissect between the GC muscles, but to carefully dissect the geniohyoid muscle from them. If the surgeon is standing on the right side of the patient, it is initially easier to dissect the left / opposite GH from the CG, using tenotomy scissors, Leahy dab, and bipolar cautery as needed. The assistant uses retractors to lift the muscles. The lateral edge of the GG is then identified and the lateral fat to it is carefully explored to find the hypoglossal nerve. The nerve passes superiorly and medially, crossing the GG at an angle of approximately 70° (see Figure 6 ). The stimulator probe of the NIM can then be used to aid in the localization of the nerve. The stimulation intensity can be set quite high (0.5 to 1 mAmp) until the nerve is more precisely localized.

[0056] Almost invariably, there is a venous branch that runs alongside the nerve (companion vein) that interferes with the clear view of the superior aspect of the nerve. This can be gently dissected off the nerve, cauterized with a bipolar cautery, and then separated. The nerve should be dissected clean on its superior aspect and a deep pocket created superior to the nerve. The pocket needs to be made deep and wide enough to fit the leg of the device without any external force. Dissecting the nerve as close to the GG as possible will reduce the likelihood of the retrusor branch or the C1 branch being stimulated (see Figure 7 ).

[0057] If branches are seen, they should be stimulated with the NIM to determine if they are retrusor branches. When dissecting this pocket, occasionally the lingual artery will be seen. Bleeding is usually venous and can be controlled with local epinephrine on cottonoids and bipolar cautery.

[0058] Once the nerve has been exposed on its superior aspect and the pocket has been created, the NIM stimulator is used to confirm electrode placement. It is important to reduce the stimulation intensity to 0.1 mAmp. This will avoid retrograde stimulation of the hypoglossal nerve, which can result in spurious stimulation of the styloglossus muscle electrode. If significant stimulation of the styloglossus muscle still occurs at 0.1 mAmp, careful dissection is performed to find the upward going branch to this muscle (see Figure 8 ). If found, it should be gently dissected off the medial continuation of the hypoglossal nerve and the pocket medial to the branch.

[0059] According to examples of the disclosed subject matter, when positioning the electrode to induce contraction of the CG, it is advantageous to avoid stimulating any branches that can result in tongue contraction, i.e. retrusor muscles, such as the styloglossus or hyoglossus. In one example, the respective branch is placed in direct view.

[0060] Since the branch to the styloglossus muscle leaves the hypoglossal nerve close to the branch of the hyoglossus muscle, in one example the NIM electrode is placed directly in both the hyoglossus and genioglossus muscles during surgery and connected to the NIM monitor. This step can be performed in addition to placing the NIM electrode in the mouth. Such a combination will allow comparison of the responses of the two sets.

[0061] The procedure is then repeated on the right nerve with the surgeon switching sides and standing to the left of the patient.

[0062] After surveying and controlling any bleeds, the pocket is irrigated with saline to wash away any clots and to ensure there are no active or potential bleeds (bleeders). The implant is then placed in position and one electrode is inserted into its pocket. It is important to ensure that the nerve passes through both electrodes. If the device legs do not sit comfortably in the pocket, the pocket should be made slightly larger and the device reinserted. If the position is satisfactory, the external stimulator (ES) (see Figure 9 ) is turned on and placed vertically over the device antenna so that the implant can be activated and the treatment effect tested. Initially, the stimulator should be set at maximum distance using a retractor so that the minimum amount of energy is transmitted to the device.

[0063] The distance should then be gradually decreased until there is a strong contraction of the tongue. The NIM monitor should show a high potential in the genioglossus electrode, with a low reading in the hyoid tongue electrode. If the hyoid tongue electrode shows similar readings to the GG electrode, the position of the IS can be moved and this will usually result in a high GG and low SG reading. If this does not improve, the electrode position can need to be adjusted, with further medial sectioning of the nerve if possible, and separation of any caudal muscle branches and Cl branches if they can be identified. When the readings are satisfactory and the tongue contraction looks strong, the electrodes are fixed in position using 2x3 / 0 Ethibond suture (Ethicon Inc, NJ, USA) through the dedicated suture holes located on each device leg. Only toothless forceps must be used and the device electrodes should never come into contact with any metal. The IS legs should be held in the suture holes using only toothless forceps or by finger. The suture should be passed through the device first and then through the soft tissue, before knotting. This is to prevent accidentally pricking the device in a position other than the dedicated suture holes, which can cause damage to the circuit and result in a malfunction.

[0064] The same procedure is repeated for the other side. The antenna portion of the IS is then sutured to the genioglossus muscle. Again, it is important to pass the suture through the dedicated suture holes in the device first and then through the soft tissue. A small right-angled clamp (Mixter) can be used to support the device on its deep surface, which makes it easier to push the suture needle through the suture holes.

[0065] Subsequently, the device should be tested with AC stimulation. To do so, the skin edges are temporarily closed using a single suture and a large sterile drape is placed over the neck and face to cover the sterile field. The technician then holds the patch (DP) and external stimulator (AC) on the implant and uses the endoscope to observe the response on the NIM monitor as well as tongue, epiglottis and palate movement. If there is a threshold or a severe asymmetry in movement, the electrodes can need to be repositioned. Once the response is satisfactory, the plastic sheet is lifted off the sterile field, the temporary skin suture is removed to reopen the neck and the wound is irrigated with sterile saline. The depth between the implant receiver and the skin should be measured. If it is greater than 4 cm, some fat can need to be removed. This can be removed superficially or deep to the platysma muscle or both. The geniohyoid muscle is sutured together using a few interrupted 3 / 0 vicryl sutures, then the mylohyoid muscle is repaired using several 3 / 0 vicryl sutures. The platysma muscle is closed using running 3 / 0 vicryl and the skin is closed using 4 / 0 Monocryl (Ethicon Inc, NJ, USA) subcuticular sutures. Drainage tubes are not necessary and are best avoided to prevent the possibility of infection, unless there has been significant fat removal. In that case, a small suction drain or Penrose drain can be used. A waterproof dressing is applied. A final check of the implant is made with the technician holding the AC / DP and the endoscope is manipulated in an attempt to obtain a view of the airway.

[0066] Subsequently, the patient is extubated and transferred to the recovery room and then the ward.

[0067] Post-operative management

[0068] Pain requirements are minimal, with a pain score of typically 2 / 10. Free oral intake is allowed. The patient is reviewed the following morning and discharged home provided there are no contraindications. They are instructed to keep the waterproof dressing in place for 5 days, then remove it and to have a review 7 days after surgery (see Figure 10 ).

[0069] The patient is scheduled for a one-month appointment to activate the device. Initially, a low stimulation setting is programmed to help the patient acclimatise to the sensation of tongue stimulation. Two weeks later, the first titration sleep study is scheduled, at which time stimulation will be titrated.

[0070] Example

[0071] A 55-year-old female with severe OSA (AHI 73, lowest O2 saturation 79%) was intolerant of nasal CPAP. She could only tolerate 1-2 hours of CPAP use per night, and thus suffered from excessive daytime fatigue. Otherwise, her overall health was excellent.

[0072] Examination revealed that the slim lady had mild recessive upper and lower jaw, and a good nasal airway. She had a Friedman 2 grade tongue position and 2 grade tonsils. Endoscopy revealed AP narrowing of the retropalatal airway, and a slightly lesser degree of narrowing of the retrolingual airway. There was no lingual tonsil hypertrophy. Jaw advancement improved the airway at all levels.

[0073] In 2016, she underwent a modified UPPP, transpalatal advancement pharyngoplasty and radiofrequency tongue channelling.

[0074] She had an uneventful recovery, and her post-operative 3 month PSG showed an AHI of 27 (pre-operatively 73), and a lowest SaO2 of 92%. However, her supine AHI had not changed, at 77.8. Despite a reduction in her Epworth Sleepiness Scale from 18 to 4, she still felt subjectively fatigued, and turning onto the back resulted in severe apnoeas, with frequent arousals.

[0075] Again, she refused to re-try CPAP, and refused to be offered a mandibular advancement splint. She underwent screening for the Nyxoah hypoglossal nerve stimulator, and was successful in the screening.

[0076] Her DISE showed AP retrolingual obstruction, with no significant retropalatal obstruction. She was discharged in the morning after surgery, and had an uneventful recovery.

[0077] Her baseline screening PSG and 2 month titration PSG numbers were as follows:

[0078] Baseline 2-month titration AHI / hour 25.3 3.6 Obstructive apneas / hour 7.3 0 Hypo- and hyperpneas / hour 15.4 3.5 ODI / hr 23.7 1.9

[0079] In the 3 month titration PSG, the device was turned off at 2:48, and turned back on at 3:19, to demonstrate effectiveness of control of OSA. This is highlighted in the PSG in Figure 12 .

[0080] While the embodiments disclosed herein relate to use in humans, it is contemplated that the present application can be used in all mammals, and in all animals having air passages.

[0081] The headings herein are for organizational purposes only and are not intended to be used to interpret, by themselves or with others, the scope or meaning of the specification or claims. As used throughout this application, the word "may" is used in a permissive sense (i.e., meaning having the potential to), rather than the mandatory sense (i.e., meaning must). Similarly, the words "include," "including," and "includes" mean including, but not limited to.

[0082] While the forgoing is directed to embodiments and examples of the present disclosed subject matter, other and further embodiments can be devised without departing from the basic scope thereof.

Claims

1. An implantable system for treating obstructive sleep apnea, comprising: an implant, the implant comprising: a substantially planar central body portion having a top side and a bottom side; at least two adjustable wing portions; and at least two connecting members, each of the at least two connecting members extending from opposite sides of the central body portion, each of the at least two connecting members configured to flexibly connect each of the at least two wing portions to the central body portion on opposite sides; an activation chip; and a disposable patch; a monopolar cautery with a needle or spatula tip for creating a surgical opening to expose the genioglossus muscle; a flexible strut or fish hook for exposing a hypoglossal nerve branch on at least one side of the genioglossus muscle for stimulation by the implant; a tenotomy scissors and bipolar cautery for creating at least one pocket on at least one side of the genioglossus muscle; such that the pocket size is configured to fit at least one of the at least two wing portions of the device. ​

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