Not all facial pain is classical trigeminal neuralgia (TN). This is a common mantra of experienced physicians to their trainees. How to differentiate between TN, especially TN type 2  (atypical TN/ATN) and trigeminal neuropathic pain (TNP), can be quite difficult. TNP is a diagnosis made on the patient’s history. It generally is burning and lacks the jolts of typical TN. Further, people may have had TN in the past, but over time and with treatments may have developed TNP. An extreme case may be anesthesia dolorosa.

TNP can also be caused due to injury to the nerve from TN treatment or from other surgeries or traumas. It may be due to stroke or secondary conditions such as shingles. The diagnosis is difficult and may be made over several visits. Treatments differ based on diagnosis. 

Neuromodulation as a treatment option

For TNP, current treatment includes medications (which may be distinct from those used for TN), botulinum toxin injections, holistic care, and neuromodulation. All are geared at improving pain and quality of life. Less invasive treatments like medications and injections are typically the first recommended. If those techniques are unsuccessful, neuromodulation may then be recommended.

Types of neuromodulation

Typically, the type of neuromodulation offered is based on least to most invasive, starting with peripheral nerve stimulation (PNS), spinal cord stimulation, motor cortex stimulation (MCS), and deep brain stimulation (DBS). PNS is usually the starting point and has been successful in treating TNP. One study showed that TNP patients who received PNS received at least 50% pain reduction even after two years. High cervical spinal cord stimulation is the next option, though there is little reported in the literature for this indication. If those two methods are unsuccessful, MCS or DBS may be offered.

It is essential to note that all the above require off-label use of an FDA-approved device.

MCS involves the placement of electrodes on the primary motor cortex to stimulate pain-controlling regions of the brain. Generally, a good candidate for neuromodulatory treatment is one who has a diagnosis of TNP that cannot be managed using conservative treatments for about 6–12 months. The candidate should be willing to undergo a trial implantation to test the efficacy of the treatment and needs to understand that MCS is not a cure and will not completely abolish the pain.

Once the patient is deemed a good candidate, he or she is evaluated by a pain psychologist. An MRI with special functional MRI images is needed. For MCS to work, it must be placed in the correct area of the motor cortex.

Risks of neuromodulation

The risks are relatively minor. Infection occurs in three to five percent of people. More troublesome side effects like brain bleeds are far less common. The most common complication is lack of meaningful long-lasting pain relief, which may occur in 50% of patients. The next most common complication is seizures, which may occur during programming as the motor cortex is being stimulated. Most adverse effects are related to programming and thus are reversible.

Watch our related webinar, Getting the Brain to Stop the Pain.