Subcutaneous Trigeminal Nerve Field Stimulation for Refractory Facial Pain
May 10th, 2017
Treating chronic or neuropathic facial pain can be challenging when medical or standard treatment fails. Subcutaneous nerve field stimulation is the least invasive form of neuromodulation and is used for chronic back pain. We applied this technology to treat chronic and neuropathic trigeminal facial pain.
The overall goal of this surgical intervention is to treat patients with chronic therapy-resistant and neuropathic trigeminal pain using minimally invasive subcutaneous nerve field stimulation as a method of neuromodulation. This method can help treat patients with therapy-resistant chronic trigeminal pain such as trigeminal neuralgia or post-therapeutic trigeminal neuropathy who have failed conservative and standard surgical treatment. The main advantage of this technique is that it is minimally invasive, does not destroy any nerve tissue, and its success can be tested in a period of trial stimulation before undergoing permanent implantation.
We offer this treatment as an alternative to destructive techniques such as Radiofrequency Thermocoagulation or Gamma Knife Radiosurgery. After a patient has carried out a 12-day stimulation trial, according to the text protocol, turn the anesthetized patient's head to the side contralateral to the pain. Then, place a pillow under the ipsilateral shoulder to expose the clavicle.
Shave the area around the ear on the painful side of the face. Then remove any loose hair. If necessary, tape away the surrounding hair to prevent it from moving into the surgical field.
Next, thoroughly disinfect the surgical field from the facial area around the ear and down to the clavicle area. From the X-rays of the out-patient appointment, use a sterile surgical pen to mark the desired position of the permanent electrodes in the marks of the previous skin punctures for guidance. For the first trigeminal branch, choose a position on the lateral side of the forehead at which to puncture the skin, roughly 10 centimeters lateral and one centimeter above the medial border of the eyebrow.
For the second trigeminal branch, choose a position that is located roughly one centimeter anterior to the tragus. Do not perform a skin puncture two centimeters or more anterior to the tragus to spare facial nerve fibers from injury. For the third trigeminal branch, choose a position that is located roughly one centimeter anterior and four centimeters below the tragus.
Correct planning of electrode insertion is crucial to the success of this technique as the parasthesia provoked by the stimulation should cover the entire painful area. Use a 14-gauge Tuohy needle to perform a skin puncture at a previously marked position. As the subcutaneous tissue of the facial area is thinner than on other body parts, make sure to stay half a centimeter below the skin surface to prevent skin perforation or direct muscle stimulation.
Make a one centimeter-long vertical incision in the supra-auricular area. And form a small subcutaneous pocket. Take the stylets from the Tuohy cannulas and subcutaneously tunnel them from the site of the skin puncture to the supra-auricular incision.
Insert another Tuohy cannula to subcutaneously tunnel from the supra-auricular incision to the site of the skin puncture. And then insert the electrodes into the Tuohy cannula with the contacts located in the painful area. Remove the Tuohy cannulas and the electrode stylets.
And insert the distal end of the electrode into the cannula. Remove the Tuohy cannula while using forceps to keep the electrode in place. Then use a 3-0 non-absorbable silk suture to fix the electrode to the muscle fascia to prevent electrode dislocation.
Next, perform a six centimeter long infraclavicular incision and manually form a subcutaneous pocket to house the IPG. Use bipolar electrical forceps to coagulate any bleeding vessels. Insert a tunneling spear into the infraclavicular incision and subcutaneously tunnel behind the ear towards the supra-auricular incision.
Make a small retroauricular incision for the spear to exit the skin. Then, tunnel with a second spear from the supra-auricular to the retroauricular incision. Remove the spear stylets.
And insert the electrodes until the electrodes are buried in the subcutaneous tissue without any loops or kinks. After tunneling the electrodes to the retroauricular incision, tunnel them from here to the infraclavicular incision. Then remove the spear by pulling it out of the infraclavicular incision while using forceps to keep the electrodes in place.
Connect the electrodes to the IPG. And use torque screws to secure them. Use a non-absorbable 3-0 silk suture to suture the IPG to the pectoralis muscle fascia to prevent IPG dislocation.
Perform skin closure with absorbable 3-0 subcutaneous sutures and non-absorbable 3-0 cutaneous sutures in the facial area. And absorbable 3-0 intracutaneous sutures at the site of the IPG. Then disinfect all wounds.
Clean the surgical field with saline. And apply sterile draping. Carry out post-operative care according to the text protocol.
In one case series, 10 patients who suffered from pain from the conditions listed in this table underwent test stimulation for subcutaneous trigeminal nerve field stimulation, or sTNFS, and received permanent implantation of electrodes and an IPG. Following an 11-month follow-up, eight of the 10 patients responded to the therapy with pain reduced from 9.3 to 0.75 on the Visual Analog Scale. In another recently published series, eight patients were tested with sTNFS.
After a mean follow-up of 15.2 months, six of the eight patients proceeded to permanent implantation. And according the VAS, pain was reduced from 8.5 to 1.4 points. The series is also the first to describe a 73%reduction in the mean number of painful daily attacks.
The chart shown here was all patients with permanent implantations treated with sTNFS. A mean reduction of 6.8 VAS points and the mean reduction of 12.2 in the number of daily attacks was achieved. Trial electrode placement takes roughly 15 minutes.
The surgery for permanent implantation can be performed within one hour and patients can be discharged on the next day. Subcutaneous trigeminal nerve field stimulation can provide a sustained therapeutic effect on both pain intensity and frequency of painful attacks. The amount of pain medication and its side effects can then be reduced.
After watching this video, you should have a good understanding of how to perform trial electrode placement and permanent implantation surgery for subcutaneous trigeminal nerve field stimulation.
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Overview
This article discusses the use of minimally invasive subcutaneous nerve field stimulation to treat chronic and neuropathic trigeminal facial pain. This method is particularly beneficial for patients who have not responded to standard treatments.
Key Study Components
Area of Science
- Neuromodulation
- Chronic pain management
- Facial pain treatment
Background
- Chronic and neuropathic facial pain can be difficult to treat.
- Standard treatments may fail, necessitating alternative approaches.
- Subcutaneous nerve field stimulation is a less invasive option.
- This technique preserves nerve tissue and allows for trial stimulation.
Purpose of Study
- To evaluate the effectiveness of subcutaneous nerve field stimulation for therapy-resistant trigeminal pain.
- To provide an alternative to more destructive pain management techniques.
- To assess the feasibility of a trial stimulation period before permanent implantation.
Methods Used
- Patients undergo a 12-day stimulation trial.
- Patient positioning is adjusted to facilitate the procedure.
- Monitoring of pain response during the trial period.
- Comparison with traditional treatment methods.
Main Results
- Subcutaneous nerve field stimulation shows promise for chronic trigeminal pain.
- Patients report varying degrees of pain relief during the trial.
- The method is well-tolerated and minimally invasive.
- Success rates may improve with careful patient selection.
Conclusions
- Minimally invasive subcutaneous nerve field stimulation is a viable option for chronic trigeminal pain.
- This approach can be a valuable alternative to more invasive procedures.
- Further studies are needed to establish long-term efficacy and safety.
Frequently Asked Questions
Executive Industry Relevance
Subcutaneous trigeminal nerve field stimulation offers a minimally invasive neuromodulation approach for therapy-resistant facial pain, addressing a critical unmet need in chronic pain management. The technique enables predictive validation through a 12-day trial stimulation period, allowing assessment of pain reduction before committing to permanent implantation. This de-risks therapeutic investment by providing functional evidence of target engagement and symptomatic improvement in a clinically relevant pain model.
Strategic Applications in Biopharma R&D
Early Discovery & Target Validation
- Scientific Value: Enables interrogation of trigeminal nerve pathways as a therapeutic target for neuropathic pain modulation.
- Operational Value: Provides a reversible, tissue-sparing method to validate target engagement through paresthesia mapping and pain symptom reduction.
- Predictive Value: Supports go/no-go decisions based on ≥50% pain intensity or frequency reduction during trial stimulation.
Screening & Assay Development
- Scientific Value: Establishes quantitative pain metrics (VAS, attack frequency) as pharmacodynamic readouts for dose-response assessment.
- Operational Value: Standardizes trial duration and electrode placement criteria for reproducible neuromodulation screening.
- Assay Readiness: Generates continuous, real-time pain intensity and frequency data enabling longitudinal response tracking.
Translational & Preclinical Research
- Scientific Value: Demonstrates disease relevance in refractory trigeminal pain models unresponsive to conventional therapies.
- Operational Value: Bridges acute screening to chronic implantation outcomes, supporting longitudinal therapeutic assessment.
- Translational Continuity: Uses identical stimulation parameters across trial and permanent phases, ensuring mechanistic consistency.
Pipeline & Workflow Integration
The method integrates into pain therapeutic development as a functional validation step following target identification and preceding chronic dosing studies, enabling mechanistic de-risking before resource-intensive programs.
- Discovery Biology: Supports hypothesis testing of neuromodulation targets via reversible peripheral nerve stimulation without tissue destruction.
- Screening: Delivers standardized, quantitative pain intensity and frequency measurements enabling comparator assessment across stimulation parameters.
- Analytics: Provides VAS and daily attack count as longitudinal endpoints for evaluating therapeutic durability and dose titration.
- Translational Research: Connects acute neuromodulation effects to sustained pain relief, supporting predictive modeling of chronic efficacy.
- Enterprise Reuse: Represents a platform neuromodulation approach adaptable to other peripheral neuropathic pain indications.
Operational & Enterprise Impact
- Scientific Value: Reduces mechanistic ambiguity by linking peripheral stimulation to central pain modulation outcomes.
- Operational Value: Enables outpatient trial execution with standardized lead placement and external stimulation control.
- Strategic Value: Improves capital efficiency by reserving permanent implantation for patients demonstrating ≥50% pain reduction.
- Portfolio Impact: Facilitates risk-stratified advancement based on validated pain response thresholds.
Implementation Considerations
- Requires expertise in peripheral nerve anatomy and neuromodulation lead placement techniques.
- Necessitates sterile surgical infrastructure for subcutaneous tunneling and IPG pocket creation.
- Demands cross-functional coordination between neurology, neurosurgery, and pain management teams for patient selection and outcome assessment.
- Involves adaptation considerations for electrode positioning across trigeminal dermatomes to ensure paresthesia coverage.
- Limited by individual pain variability and the need for patient-reported outcomes during trial stimulation.
