Subcutaneous Trigeminal Nerve Stimulation to Relieve Neuropathic Facial Pain

Abstract

Source: Jakobs, M., et al. Subcutaneous Trigeminal Nerve Field Stimulation for Refractory Facial Pain. J. Vis. Exp. (2017)

This procedure demonstrates the implantation of subcutaneous electrodes for trigeminal nerve stimulation to treat neuropathic facial pain. The electrodes are tunneled subcutaneously from the affected facial region to an infraclavicular pocket, where they are connected to an internal pulse generator (IPG). The IPG delivers electrical stimulation, activating mechanoreceptor fibers, which in turn stimulate inhibitory interneurons in the spinal cord, thereby reducing pain transmission to the brain.

Protocol

All procedures involving human participants have been performed in compliance with the institutional, national, and international guidelines for human welfare and have been reviewed by the local institutional review board.

1. Implantation of Permanent Electrodes and internal pulse generator (IPG)

1. Place the patient in a supine position under general anesthesia. Turn the head to the contralateral side of the pain. Place a pillow under the ipsilateral shoulder to expose the clavicle.
2. Administer intravenous single-shot antibiotics (e.g., 2 g cephazoline) 20 min before the start of the procedure.
3. Shave the area around the ear of the painful side of the face. Remove any loose hair. If necessary, tape away the surrounding hair to prevent it from moving into the surgical field.
4. Thoroughly disinfect the surgical field from the facial area, around the ear, down to the clavicular area.
5. Mark the desired position of the permanent electrodes using the x-rays obtained during the outpatient appointment and the marks of the previous skin punctures for guidance.
6. Apply sterile draping around the entire surgical field.
7. Perform the skin puncture with a 14G Tuhoy cannula and implant the permanent electrodes as previously described for the first trial procedure.
   NOTE: Size and length of the electrodes are identical to the trial electrodes (length 60 cm, diameter 1.3 mm, 8 contacts).
8. Make a 1 cm long vertical incision in the supraauricular area and form a small subcutaneous pocket there.
9. Insert the Tuhoy cannula to subcutaneously tunnel from the supraauricular incision to the sites of the skin puncture. Remove the Tuhoy cannula's and the electrode's stylets and insert the distal end of the electrode into the cannula.
   NOTE: The third trigeminal branch requires the length of two Tuhoy cannulas and an additional small skin incision in the preauricular area to fully cover the distance.
   1. Remove the Tuhoy cannula while keeping the electrode in place with forceps.
   2. Use a 3-0 non-absorbable silk suture to suture the electrode to the muscle fascia to prevent electrode dislocation.
   3. In case the patient wears glasses, fix the electrodes at a position that is located above the frame of the glasses to prevent local pain and skin erosion.
10. Perform a 6 cm long infraclavicular incision and manually form a subcutaneous pocket to house the IPG. Use bipolar electrical forceps to coagulate any bleeding vessels.
11. Insert a tunneling spear in the infraclavicular incision and subcutaneously tunnel behind the ear towards the supraauricular incision.
    1. Make a small retroauricular incision for the spear to exit the skin. Then use a second spear to tunnel from the supraauricular to the retroauricular incision.
    2. Remove the spears' stylets and insert the electrodes until they are buried in the subcutaneous tissue without any loops or kinks.
    3. Remove the spear by pulling it out from the infraclavicular incision while keeping the electrodes in place with forceps.
    4. Pay attention to not penetrate the skin with the tunneling spear (especially in patients that have previously undergone surgery for microvascular decompression as they have a retroauricular scar).
12. Connect the electrodes to the IPG and secure them with torque screws.
13. Suture the IPG to the pectoralis muscle fascia with a non-absorbable silk suture (3-0) to prevent IPG dislocation.
    1. Check the system impedance to detect any faulty connections or damaged electrode contacts.
    2. Place the antenna of the Physician Programmer in a sterile drape and position it over the IPG. Connect the programmer with the IPG and go to the "check electrode impedance" section.
       NOTE: Low impedances under 250 Ohms indicate open circuits. High impedances over 500 Ohms indicate insufficient connection of the electrode to the IPG or electrode breakage.
14. Perform skin closure with subcutaneous absorbable 3-0 sutures and non-absorbable 3-0 cutaneous sutures in the facial area and absorbable intracutaneous sutures at the site of the IPG.
15. Disinfect all wounds, clean the surgical field with saline, and apply sterile draping.

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
myStim Patient Programmer	Medtronic	97740	enables the patient to turn off and on stimulation
Prime Advanced	Medtronic	97702	non-rechargeable IPG as powersource for stimulation
Restore Ultra	Medtronic	97712	rechargeable IPG as powersource for stimulation
Charging System	Medtronic	97754	used by the patient to recharge the Restore Ultra IPG
N'Vision Programmer	Medtronic	8840	used by the physician to program the IPG and define stimulation parameters
External Neurostimulator	Medtronic	37022	external IPG as powersource for trial stimulation with externalized electrodes
Advanced Screening Cable	Medtronic	355531	connects externalized electrodes to the external neurostimulator during trial stimulation
Tunnelling Spear 60cm	Medtronic	3655-60	used to subcutaneously tunnel the permanent electrodes to an infraclavicular pocket that houses the IPG
Tunnelling Spear 38cm	Medtronic	3655-38	used to subcutaneously tunnel the permanent electrodes to an infraclavicular pocket that houses the IPG
Tuhoy Cannula	Medtronic	3550-32	14 gauge Epidural Tuhoy cannula (length 9cm) to subcutaneously implant the electrodes
InjexFixation Device	Medtronic	97791 / 97792	used to fixate the electrodes on the skin or on the muscle fascia
Octad Compact	Medtronic	3878-60	permanent electrode (length 60cm) implanted in the subcutaneous tissue with 8 contacts
Vectris Trial Lead	Medtronic	977D260	externalized electrode (length 60cm) used during the stimulation trial
Ethilon*II 3-0	Ethicon	EH7933H	non-absorbable suture for skin closure
Seide 2-0	Resorba	40221	non-absorbable silk suture to fixate electrodes and IPG
Resolon DS21	Resorba	881413	absorbable suture for subcutaneous wound closure
Feather disposable scalpel	Feather	5205052	single use scalpel for skin incision and suture cutting
Scandicain 1%	Astra Zeneca	23186	1% Mepivacain solution for local anesthesia
Cosmopor E steril 10x6	Hartmann	900871	Sterile draping for IPG wound
Cosmopor E steril 7,2x5	Hartmann	900870	Sterile draping for skin punctures and small incisions
Foliodrape Comfort 50x50	Hartmann	252302	Sterile draping for the surgical field
Cephazolin	Fresenius	6062403.00.00	Single shot perioperative antibiotic
Kepinol forte 800mg/160mg	Dr. R. Pfleger Chemische Fabrik	2485177	Postoperative prophylactic oral antibiotic
Poly-Alcohol	Antiseptica	UN1219	Coloured skin disinfectant used during the permanent implantation
Cutasept F	Bode	976800	Un-Coloured skin disinfectant used during the trial implantation