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15 Articles in Volume 20, Issue #6
20/20 with Mark Wallace: Where Cannabis Fits into Pain Practice
A Commentary on Opioid Stewardship: Fentanyl, Sufentanil, and Perioperative Pain
Adherence and Relapse – How to Maintain Long-Term Gains in Patients with Chronic Conditions
Advanced Practice Matters with Theresa & Jeremy: COVID, Pain, and Power
Analgesics of the Future: Inside the Potential of Janus Kinase Inhibitors
Application Note: Using Photobiomodulation to Treat Trigeminal Neuralgia
Case Report: Quadratus Lumborum Block for Managing Pathologic Pain to the Hip
Chronic Pain and the Short-term Effects of Medical Cannabis
Differential Diagnosis: Polymyalgia Rheumatica or Rheumatoid Arthritis
Genicular Nerve Blocks: Field Tips on Prognostic Value and Technical Considerations
Guideline Update: ACR Promotes Pharmacologic Treatment for Osteoarthritis
Navigating New York's Medical Marijuana Program: A Patient Handout
Person-Centered Care: Lessons from the VA’s Whole Health Model
Psychedelics for Chronic Pain: Is It Time?
Resident’s Corner: What Pain Medicine Education is Missing in the COVID Era

Application Note: Using Photobiomodulation to Treat Trigeminal Neuralgia

A small case study of an inhibitory dose of light therapy to the sphenopalatine ganglion demonstrates pain relief and a potentially effective approach for long-term pain relief.

Editor’s Note – This article is part of a series on light therapy in pain management, including its use for treatment of fibromyalgia and migraine.

 

Trigeminal neuralgia (TN) is a chronic pain syndrome affecting the fifth cranial nerve. The incidence of TN is approximately 12 per 100,000 people per year or 39,200 Americans annually.1As defined by the International Headache Society, TN is a “unilateral disorder characterized by brief electric shock-like pains, abrupt in onset and termination, and limited to the distribution of one or more divisions of the trigeminal nerve.”2 The disorder can be idiopathic with or without persistent fascial pain or secondary as a result of trauma, multiple sclerosis (MS), herpes zoster, a tumor, or compression of TN ganglion via blood vessels.1

Symptoms vary and may include short sporadic bouts of extreme pain lasting a few seconds or minutes (Type TN1). Additionally, patients may experience a burning feeling. Chronic TN (Type TN2) is characterized as constant pain that is ongoing with no relief. Quality of life is decreased in those with TN, with up to 34% of patients unable to work.1  In the past, TN was referred to as a “suicide disease” due to its high incidence of suicide among sufferers (25%) but this is no longer the case.

Conventional Treatment for Trigeminal Neuralgia

There are three main lines of treatment for trigeminal neuralgia. The first-line approach is pharmacological and consists of antidepressants and anticonvulsants. These medications are mostly effective early on, however, as TN tends to progress, making these medications less effective at time goes on. The second line of treatment is to add medications or switch the medications being used, which may provide relief for a bit longer, however TN1 may continue to progress to TN2.

Surgical interventions are considered the third line of treatment. Surgeries are designed to either destroy the sensory function of the trigeminal nerve or to decompress the trigeminal nerve. These include techniques to damage the Gasserian ganglion with glycerol, radiofrequency thermos-coagulation, and balloon compression. These techniques have varying degrees of success. Pain relief is reported in 90% of patients immediately following these procedures but relief decreases to 68% to 84% after 1 year and 50% at 5 years’ post-surgery. The main side effect is total loss of sensation, which occurs in 50% of the surgeries.1

Another surgical approach uses a focused beam of radiation to sever the trigeminal root in the posterior fossa. The decrease in pain occurs several weeks post treatment, with 63% of patients reporting a decrease in pain after 1 year, which continues to decrease to 52% after 3 years.1

If the cause of TN is vascular related, then microvascular decompression surgery may be the best option. This procedure consists of placing a pad between the vessel causing the compression then the trigeminal nerve.  There is a 90% success rate post treatment and 80% after 1 year, and about 50% of the patients will experience recurrent pain within 15 years.

As a last resort, patients may elect to have a craniotomy on the posterior fossa to reach the trigeminal nerve. However, the morality rate with this procedure is 0.2% to 0.5%. Additionally, 4% of patients have serious adverse effects, including myocardial infarctions, hematomas, and leakage of cerebral spinal fluid.1

Treatment Alternatives for Trigeminal Neuralgia

The second division of the trigeminal nerve passes through the sphenopalatine ganglion (SPG), which is the largest bundle of nerves outside the brain. Blockades of the SPG have been successful for treating cluster and migraine headaches; post-operative head and face pain; post-herpetic neuralgia; musculoskeletal pain; and trigeminal neuralgia.3

One study reported a clinically significant decrease in pain (2 pain points) for TN in 96% of the subjects who treated the SPG with an 8% lidocaine spray.4 Ten percent of the active treatment group had no pain after the treatment.4 However, 60% of the subjects reported side effects from the treatment. All of subjects had their pain return to baseline levels within 1 week post-treatment. A TN case report showed 10 treatments to the SPG using 0.5% bupivacaine resulted in 30 pain-free months.5 Both of these studies suggest that treating the SPG may be effective for TN.

Recently, a clinical case series demonstrated that treating the SPG with photobiomodulation (PBM) was effective for treating migraine.6 Due to the connection of the trigeminal nerve into the SPG, an inhibitory dose of PBM to the SPG may have a similar effect in decreasing trigeminal neuralgia pain. The authors trialed this treatment on three patients and present the outcomes below.

Photobiomodulation: A Quick Background

Adopted by the North American Association of Photobiomodulation Therapy, photobiomodulation refers to light therapy treatments that utilize non-ionizing light sources in the visible and infrared spectrum. PBM is a non-thermal process that involves endogenous chromophores that elicit photo physical and photochemical events, which may lead to beneficial therapeutic outcomes, including the alleviation of pain or inflammation, and immunomodulation, as well as the promotion of wound healing and tissue regeneration.

More specifically, PBM emits photons of light that penetrate the skin and stimulate endogenous light receptors, which result in a physiological response. This response is biphasic in nature and can either stimulate or inhibit biological activities.7 Low doses of PBM have a stimulatory effect that can be used to promote tissue healing and increased blood flow.7

Higher doses of PBM have an inhibitory effect, which is primarily used to promote analgesic effects, for example to treat TN.7 PBM’s effects on inhibiting pain include COX-2 inhibition, therefore decreasing PGE2 formation;8 a decrease in nerve conduction of Aδand C nerve fibers, and decrease in TNFα. Additionally, PBM decreases the release of Substance P and glutamate.9

Case Reports

The authors trialed PBM on three patients (ages 58, 66, and 68) with a history of trigeminal neuralgia. Each patient had a history of chronic trigeminal neuralgia (TN2) from 2 to 24 years (see Table I). Each patient was successfully treated with PBM to the SPG using the same protocol as Doades et al6 (see additional details below).

Initial reported pain levels ranged from 6 to10 out of a 10-point pain scale. All three patients were unable to complete activities of daily living due to severe pain. Patients 2 and 3 had previously attempted pharmacological and surgical treatments with little or no relief. Patient 1 had been unsuccessfully treated with a Class 4 laser with 36 treatments total to her face.

Each PBM treatment consisted of applying a laser puncture utility probe attached to a PBM-transducer (Multi Radiance Medical) that delivered the photons to the SPG. The probe was placed just inside each nostril pointing toward the posterior nasal cavity where the SPG is located (see Figure 1). The treatment frequency and number of overall treatments were tailored to each patient’s responsiveness.

 

Figure 1

Each treatment lasted 180 seconds per nostril (23.9 joules, 0.0382 watts). The device characteristics were as follows: wavelength SPL 905 nm; IR875 nm; Red670 nm; total power, 25W, SPL variable frequency: 1000 Hz and beam spot size 0.4. The patients were evaluated for perceived pain intensity both pre- and post- treatment, and throughout the duration of the treatment.

Patient 1: This 58-year-old female had TN2 affecting all three branches of the trigeminal nerve. Her regimen encompassed three treatments over 1 week. She reported a reduction in constant pain from 6 out of 10 to 2 out of 10 after the first treatment. The patient reported no pain after the full course of treatments,. The patient was equipped with a PBM device to continue treatments PRN.

Patient 2: A 66-year-old female developed TN2 after orthognathic surgery. Her regimen encompassed 15 treatments over 3 weeks. She reported a reduction of pain from a 5 out of 10 to a 2 out of 10 after the first treatment and a 0 out of 10 after the second treatment. However, her pain would slowly increase to ≤ 3 out of 10 between treatments. The pain was reduced to 0 out of 10 after each subsequent treatment. The patient was able to kiss her partner again. She was treated infrequently for flare-ups over the next 3 months.

Patient 3: A 68-year-old female developed TN2 after an orthodontic procedure. She went through a course of one treatment per week for two weeks with moderate success with pain decreasing from a 10 out of 10 to a 3 out of 10 post treatment. However, her pain would return at the level of 8 out of 10 within 48 hours post treatment. The treatment frequency was increased to three treatments per week for 2 weeks (6 total). She reported a similar pain pattern with her pain increasing between treatments, however the peak pain was less than the previous treatment. Additionally, she had a longer duration between flare-ups. Her treatment regimen was reduced to two treatments per week with a final outcome of a 0 out of 10 pain level. She was trained to self-treat at home PRN with good success. The patient reported that she was able to stop several medications and reduce her gabapentin dose.

Discussion and Steps Forward

Trigeminal neuralgia shifts from occasional flare-ups (TN1) to constant pain (TN2) over a period of time. Pharmacological treatments do not always work and are typically unable to prevent the progression to TN2. Even surgical interventions have high failure rates over several years when 50% of patient have a return of symptoms. Additionally, many surgical interventions have severe side effects.  

It appears that the SPG may be an effective treatment site for trigeminal neuralgia. Kanaiet al, reported a 2 out of 10 point decrease in pain in 96% of the patients treated with 8% lidocaine spray to the SPG.4 However, 100% of the patients’ pain returned within 1 week after the treatment.

Overall, PBM treatments described herein were successful for treating TN2 in three patients. All three patients received PBM treatment to the SPG and had a pain reduction of 3 to 7 out of 10 after 1 treatment. Additionally, the patients reported a 0 out of 10 after 3 to 15 treatments. Each patient required a different total number of treatments and course of treatment. None of the patients reported side effects from the treatment. Two of the three patients were equipped with home PBM devices and trained to self-treat for occasional flare-ups. None of the patients reported any side effects and tolerated the treatments well.

Patient 1 had a previous intervention with a Class 4 laser, also described as High Intensity Laser Therapy (HILT). Of note, Class 4 lasers are not considered to be photobiomodulation technologies due to the excess resultant heat from a treatment. The PBM emitter used in the treatment of these patients has a 1M safety classification, which is defined as no known hazards to eye or skin, except when used with optical aids, such as binoculars (American National Standards Institute). Patient 1’s TN pain was reduced to 0 out of 10 in just 3 treatments with the PBM emitter, whereas the Class 4 treatments had no effect on her TN pain, even after 36 treatments.

A range of clinicians have access to treat using PBM, depending on their state’s practice act. These include athletic trainers, chiropractors, dentists, occupational therapists, physical therapists, and physcians. Utilizing trained healthcare clinicians could expand the availability of this safe, non-pharmacological treatment for trigeminal neuralgia. A larger randomized control trial is needed to determine the overall efficacy of the treatment in relieving this painful disorder.

 

 

Continue Reading:
Photobiomodulation for the Treatment of Fibromyalgia
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