Descending Pain: A New Way to Control Severe Chronic Pain

By Dr. Forest Tennant and Ingrid Hollis

The control of severe chronic pain in medical practice today is almost exclusively based on “ascending” or “neuropathic” pain:

Ascending pain occurs when a pain signal is transmitted from the site of injury or disease up the spinal cord to the brain. Neuropathic pain is the pain that results when there is damage or dysfunction of nerve tissue in the brain, spinal cord or peripheral nerves. 

In recent years, researchers discovered that when chronic pain centralizes, it creates a third type of pain called “descending” pain. This is a critical issue for persons with adhesive arachnoiditis and other diseases that cause severe chronic pain, because descending pain requires different medications than those used for ascending and neuropathic pain.

A person with constant pain will produce excess bioelectricity (central sensitization or centralized pain) in the glial cell matrix of the brain. This bioelectricity “descends” or travels down the spinal cord and vagus nerve. It not only produces pain, but over-stimulates the cardiovascular system. 

Descending pain is controlled by the noradrenergic receptor.  The neurotransmitter to this receptor is called noradrenalin or norepinephrine. 

Symptoms of Descending Pain

Descending pain will be present in persons who have constant, unremitting pain. Here are the symptoms:

• Pulse rate elevates

• Periodic hot flashes

• Cold hands/feet

• Excess sweating

• Allodynia (pain upon light touch) 

Over-Reliance on Opioids and Neuropathic Agents

The lack of awareness about descending pain is one reason why high doses of opioids and neuropathic agents (i.e., gabapentin, diazepam) may be over-prescribed. Physicians may simply raise the opioid or gabapentin dosage if they are not aware that the cause is descending pain.  What’s more, the increase in dosage may be ineffective or even harmful.

This also applies to opioids in implanted pumps.  Countless persons have been treated with an implanted device or “pain pump” with the erroneous belief that no medication, except intrathecal opioids, are needed.  Patients with these devices soon learn that their pain is poorly controlled by opioids alone. 

Opioids and neuropathic agents have little effect on descending pain.  It must be treated separately.

Pain treatment and relief are based on a medicinal that activates or stimulates a specific receptor (think “action point”) that is present in nerve cells in the brain, spinal cord or peripheral nervous system. Here is how the three types of pain and their receptors can be treated:

1. Ascending pain needs to be treated with medications that activate the endorphin or opioid receptor. 

2. Neuropathic pain control depends on activation of a receptor called gamma amino butyric acid (GABA). 

3. Descending pain control must activate the norepinephrine (noradrenalin) receptor.

To achieve good control of severe, chronic or intractable pain, all three of these receptors must be simultaneously activated.  Severe chronic pain is commonly undertreated, because all three receptors are not simultaneously activated.

Medication Classes for Descending Pain

Three medication classes are used to treat descending pain.  Medical practitioners and patients have choices, and can experiment to help decide which medications and supplements bring the most comfort.

1. Bioelectric Blockers: Tizanidine, propanolol, clonidine, tapentadol (Nucynta).

2. Receptor Activators: Modafanil (Provigil), methylphenidate (Ritalin), dextroamphetamine, amphetamine salts (Adderall), phentermine, lisdexamfetamine (Vynanse). Non-prescription activators: lion’s mane, mushroom extract, St. John’s wort, rhodiola, mucuna, whole adrenal gland.

3. Precursor (Amino Acids) of Noradrenaline: Phenylalanine at 1,000 to 2,000mg a day. Tyrosine at 1,000 to 2,000mg a day.

When not controlled, chronic pain, inflammation and autoimmunity will deplete a number of neurotransmitters and hormones.  When that happens, noradenaline (norepinephrine) will often be depleted. 

Supplements of either amino acids (phenylalanine or tyrosine) and daily protein intake may help reduce both background and flare pains. Phenylalanine and/or tyrosine need not be taken every day, but they are highly recommended at least two days a week. They can and should be taken with a bioelectric blocker or receptor activator.

Noradrenergic receptor activators do not raise pulse rate or blood pressure in a constant pain patient like they do in a normal person.  They may actually lower blood pressure and pulse rate.  That’s because chronic pain, inflammation and autoimmunity deplete noradrenalin.

One medication, tapentadol (Nucynta), is both an opioid and norandrenergic blocker. It is highly recommended.

Descending pain is a new discovery that must be recognized and controlled to achieve relief from severe chronic pain.  A sole reliance on opioid and neuropathic agents may often provide inadequate pain relief.

To learn more about descending, ascending and neuropathic pain, you can watch a recent episode of DocToks with Dr. Forest Tennant and Friends.

Forest Tennant, MD, DrPH, is retired from clinical practice but continues his research on the treatment of intractable pain and arachnoiditis. Readers interested in learning more about his research should visit the Tennant Foundation’s website, Arachnoiditis Hope. You can subscribe to its bulletins here.

Ingrid Hollis is a person in pain, patient advocate, and advisor to the Tennant Foundation.

The Tennant Foundation gives financial support to Pain News Network and sponsors PNN’s Patient Resources section.   

Brain Receptor May Hold Key to Treating Neuropathic Pain

By Pooja Shree Chettiar and Siddhesh Sabnis  

Pain is easy to understand until it isn’t. A stubbed toe or sprained ankle hurts, but it makes sense because the cause is clear and the pain fades as you heal.

But what if the pain didn’t go away? What if even a breeze felt like fire, or your leg burned for no reason at all? When pain lingers without a clear cause, that’s neuropathic pain.

We are neuroscientists who study how pain circuits in the brain and spinal cord change over time. Our work focuses on the molecules that quietly reshape how pain is felt and remembered.

We didn’t fully grasp how different neuropathic pain was from injury-related pain until we began working in a lab studying it. Patients spoke of a phantom pain that haunted them daily – unseen, unexplained and life-altering.

These conversations shifted our focus from symptoms to mechanisms. What causes this ghost pain to persist, and how can we intervene at the molecular level to change it?

More Than Just Physical Pain

Neuropathic pain stems from damage to or dysfunction in the nervous system itself. The system that was meant to detect pain becomes the source of it, like a fire alarm going off without a fire. Even a soft touch or breeze can feel unbearable.

Neuropathic pain doesn’t just affect the body – it also alters the brain. Chronic pain of this nature often leads to depression, anxiety, social isolation and a deep sense of helplessness. It can make even the most routine tasks feel unbearable.

About 10% of the U.S. population – tens of millions of people – experience neuropathic pain, and cases are rising as the population ages. Complications from diabetes, cancer treatments or spinal cord injuries can lead to this condition. Despite its prevalence, doctors often overlook neuropathic pain because its underlying biology is poorly understood.

There’s also an economic cost to neuropathic pain. This condition contributes to billions of dollars in health care spending, missed workdays and lost productivity. In the search for relief, many turn to opioids, a path that, as seen from the opioid epidemic, can carry its own devastating consequences through addiction.

GluD1: A Quiet But Crucial Player

Finding treatments for neuropathic pain requires answering several questions. Why does the nervous system misfire in this way? What exactly causes it to rewire in ways that increase pain sensitivity or create phantom sensations? And most urgently: Is there a way to reset the system?

This is where our lab’s work and the story of a receptor called GluD1 comes in. Short for glutamate delta-1 receptor, this protein doesn’t usually make headlines. Scientists have long considered GluD1 a biochemical curiosity, part of the glutamate receptor family, but not known to function like its relatives that typically transmit electrical signals in the brain.

Instead, GluD1 plays a different role. It helps organize synapses, the junctions where neurons connect. Think of it as a construction foreman: It doesn’t send messages itself, but directs where connections form and how strong they become.

This organizing role is critical in shaping the way neural circuits develop and adapt, especially in regions involved in pain and emotion. Our lab’s research suggests that GluD1 acts as a molecular architect of pain circuits, particularly in conditions like neuropathic pain where those circuits misfire or rewire abnormally. In parts of the nervous system crucial for pain processing like the spinal cord and amygdala, GluD1 may shape how people experience pain physically and emotionally.

Fixing the Misfire

Across our work, we found that disruptions to GluD1 activity is linked to persistent pain. Restoring GluD1 activity can reduce pain. The question is, how exactly does GluD1 reshape the pain experience?

In our first study, we discovered that GluD1 doesn’t operate solo. It teams up with a protein called cerebellin-1 to form a structure that maintains constant communication between brain cells. This structure, called a trans-synaptic bridge, can be compared to a strong handshake between two neurons. It makes sure that pain signals are appropriately processed and filtered.

But in chronic pain, the bridge between these proteins becomes unstable and starts to fall apart. The result is chaotic. Like a group chat where everyone is talking at once and nobody can be heard clearly, neurons start to misfire and overreact. This synaptic noise turns up the brain’s pain sensitivity, both physically and emotionally. It suggests that GluD1 isn’t just managing pain signals, but also may be shaping how those signals feel.

What if we could restore that broken connection?

In our second study, we injected mice with cerebellin-1 and saw that it reactivated GluD1 activity, easing their chronic pain without producing any side effects. It helped the pain processing system work again without the sedative effects or disruptions to other nerve signals that are common with opioids. Rather than just numbing the body, reactivating GluD1 activity recalibrated how the brain processes pain.

Of course, this research is still in the early stages, far from clinical trials. But the implications are exciting: GluD1 may offer a way to repair the pain processing network itself, with fewer side effects and less risk of addiction than current treatments.

For millions living with chronic pain, this small, peculiar receptor may open the door to a new kind of relief: one that heals the system, not just masks its symptoms.

Pooja Shree Chettiar and Siddhesh Sabnis are neuroscience PhD candidates at Texas A&M University.

This article originally appeared in The Conversation and is republished with permission.

Experimental Implant Uses Coolant to Numb Nerve Pain

By Pat Anson, PNN Editor

Applying ice on inflamed tissues and sore muscles is one of the oldest ways to relieve pain and promote healing.  Researchers at Northwestern University are taking that tried-and-true method a step further, with the development of a small, flexible implant that can alleviate pain by literally cooling nerves.

Researchers believe the experimental implant could be most beneficial to patients who undergo surgeries, nerve grafts or even amputations. Surgeons could implant the device during the procedure to help patients manage post-operative pain on demand without the use of drugs.

“As engineers, we are motivated by the idea of treating pain without drugs — in ways that can be turned on and off instantly, with user control over the intensity of relief,” says John Rogers, PhD, Professor of Materials Science and Engineering at Northwestern and lead author of a study published in the journal Science.

“The technology reported here exploits mechanisms that have some similarities to those that cause your fingers to feel numb when cold. Our implant allows that effect to be produced in a programmable way, directly and locally to targeted nerves, even those deep within surrounding soft tissues.”

In experiments on laboratory rats, Rogers and his colleagues demonstrated that the implants can rapidly cool peripheral nerves to relieve neuropathic pain.

As thick as a sheet of paper, at its widest point the implant is 5 millimeters wide – about the size of the eraser on a pencil. One end is curled into a cuff that can softly wrap around a nerve, without the need for sutures to hold it in place.

“If you think about soft tissues, fragile nerves and a body that’s in constant motion, any interfacing device must have the ability to flex, bend, twist and stretch easily and naturally,” said Rogers.

NORTHWESTERN UNIVERSITY

To induce cooling, the device contains tiny microfluid channels. One channel contains a liquid coolant (perfluoropentane), while a second channel contains dry nitrogen. When the liquid and gas flow into a shared chamber, a reaction occurs that causes the liquid to evaporate and cool. A tiny sensor in the implant monitors the temperature of the nerve to ensure that it’s not getting too cold, which could cause tissue damage.

“As you cool down a nerve, the signals that travel through the nerve become slower and slower — eventually stopping completely,” said coauthor Matthew MacEwan, PhD, from Washington University School of Medicine in St. Louis. “We are specifically targeting peripheral nerves, which connect your brain and your spinal cord to the rest of your body. These are the nerves that communicate sensory stimuli, including pain. By delivering a cooling effect to just one or two targeted nerves, we can effectively modulate pain signals in one specific region of the body.”

An external pump allows patients to remotely activate the implant and increase or decrease its intensity. Because the device is biocompatible and water-soluble, it will naturally dissolve and absorb into the body over the course of days or weeks — bypassing the need for surgical extraction.

Other cooling therapies have been tested experimentally, but have limitations. Instead of targeting specific nerves, they cool large areas of tissue, potentially leading to side effects such as tissue damage and inflammation.

“You don’t want to inadvertently cool other nerves or the tissues that are unrelated to the nerve transmitting the painful stimuli,” MacEwan said. “We want to block the pain signals, not the nerves that control motor function and enables you to use your hand, for example.”

Tiny Experimental Implant Could Treat Neuropathic Pain

By Pat Anson, PNN Editor

A tiny wireless implant that stimulates peripheral nerves from within blood vessels shows potential as a treatment for neuropathic pain, according to a proof-of-concept study by a team of Texas researchers published in the journal Nature Biomedical Engineering.

The implants have only been tested in laboratory animals, but researchers say they could replace larger and more invasive devices currently used to treat Parkinson’s disease, epilepsy, chronic pain, hearing loss and paralysis.

The MagnetoElectric Bio ImplanT -- ME-BIT for short -- is slightly larger than a grain of rice. It’s designed to be placed in a blood vessel near the nerve targeted for stimulation. The implant requires no surgery or batteries, and draws its power and programming from an electromagnetic transmitter worn outside the body.

“Because the devices are so small, we can use blood vessels as a highway system to reach targets that are difficult to get to with traditional surgery,” said lead author Jacob Robinson, PhD, Associate Professor of Electrical and Computer Engineering at Rice University.

RICE UNIVERSITY

“We’re delivering them using the same catheters you would use for an endovascular procedure, but we would leave the device outside the vessel and place a guidewire into the bloodstream as the stimulating electrode, which could be held in place with a stent.”

The ability to power the implant remotely eliminates the need for electrical leads through the skin and other tissues. Leads used for devices like pacemakers can cause inflammation and sometimes need to be replaced. Battery-powered implants may also require additional surgery to replace the batteries.

Researchers say ME-BIT’s wearable charger could even be misaligned by several inches and still provide sufficient power and programming to the implant, without irritating surrounding tissues.

“We’re getting more and more data showing that neuromodulation, or technology that acts directly upon nerves, is effective for a huge range of disorders – depression, migraine, Parkinson’s disease, epilepsy, dementia, etc. – but there’s a barrier to using these techniques because of the risks associated with doing surgery to implant the device, such as the risk of infection,” said co-author Sunil Sheth, MD, Associate Professor of Neurology and director of the Vascular Neurology Program for McGovern Medical School at UTHealth Houston.

“If you can lower that bar and dramatically reduce those risks by using a wireless, endovascular method, there are a lot of people who could benefit from neuromodulation.”

Electrical stimulation can reduce pain when doctors target the spinal cord and dorsal root ganglia (DRG), a bundle of nerves that carry sensory information to the spinal cord. But existing DRG stimulators require invasive surgery to implant a battery pack and pulse generator.

By using blood vessels, researchers say they can place the ME-BIT implant strategically in a minimally invasive way and have more predictable outcomes.

“One of the nice things is that all the nerves in our bodies require oxygen and nutrients, so that means there’s a blood vessel within a few hundred microns of all the nerves,” Robinson explained. “With a combination of imaging and anatomy, we can be pretty confident about where we place the electrodes.

In a previous study, Robinson and his colleagues demonstrated the viability of the implants by placing them beneath the skin of laboratory rodents that were fully awake and free to roam about their enclosures. The rodents preferred to be in parts of the enclosures where a magnetic field activated the implant, which provided a small voltage to the reward center of their brains.

Researchers need to conduct more animal studies and eventually human trials before seeking FDA approval for the implants.

“We’re doing some longer-term studies to ensure this approach is safe and that the device can stay in the body for a long time without causing problems,” said Sheth, who estimates the process will take a few years.

Can a Low-Fat Diet Reverse Neuropathic Pain?

By Pat Anson, PNN Editor

Low fat diets are often recommended for people suffering from obesity and cardiovascular disease, but changes in eating habits are rarely recommended for people who live with chronic pain.

That could be changing thanks to a new study by researchers at the University of Texas Health Science Center, who found that diets high in omega-6 fats are strongly associated with inflammation and neuropathic pain. Omega-6 fats are widely found in typical Western diets of fast food, processed snacks, cakes, and fatty or cured meats.

Conversely, researchers say foods containing healthy omega-3 fatty acids – such as fish, flaxseed and walnuts – could reduce or even reverse neuropathic pain associated with diabetes. Their findings were recently published in the journal Nature Metabolism.

Diabetic neuropathy is a progressive and painful disease that causes burning or stinging sensations in the hands and feet. Many drugs used to treat neuropathic pain, such as gabapentin and pregabalin, often don’t work or have unpleasant side effects.

“This paper is a high-profile contribution for a huge unmet translational need as there are no treatments altering the nature of this neurological disease,” said José Cavazos, MD, director of the South Texas Medical Scientist Training Program at UT Health San Antonio.

In experiments on humans and laboratory animals, UT researchers found that mice fed a diet high in omega-6 polyunsaturated fats became hypersensitive to pain, cold and heat stimulation – signs of peripheral nerve damage. Lowering the amount of omega-6 fats and increasing omega-3 fatty acids reduced pain sensitivity in the mice.

The researchers also found that high levels of omega-6 lipids in the skin of patients with Type 2 diabetes were strongly associated with neuropathic pain and the need for analgesic drugs.

“We believe that these data warrant continued investigation of peripheral fatty acid and metabolite levels as potential pain biomarkers. Such biomarkers could provide clinicians with reliable objective endpoints to guide diagnoses as well as decision making on treatment regimens, including therapeutic diets,” wrote lead author Jacob Boyd, MD, UT Health San Antonio.

About 34 million people in the U.S. have diabetes and about half have some form of neuropathy, according to the American Diabetes Association.

A 2015 study found that a vegetarian diet coupled with vitamin B12 supplements significantly reduced pain and improved the quality of life of people with diabetic neuropathy. Participants also had lower blood pressure and cholesterol levels, and lost an average of 14 pounds.

Is Your Spinal Pain Inflammatory or Neuropathic?

By Forest Tennant, PNN Columnist

Every person with Adhesive Arachnoiditis (AA) or other spinal canal disorder needs to determine if their pain is primarily inflammatory, neuropathic or both. Why? The treatments are different.

AA is fundamentally an inflammatory disease that involves two different intraspinal canal tissues: the cauda equina nerve roots and the arachnoid-dural covering of the spinal canal. The inflammation causes damage to the nerve roots, so electricity either can’t pass or it doesn’t pass in a smooth, natural flow.

Nerve damage that blocks or alters electricity conduction is called “neuropathic” pain. AA usually has both inflammatory and neuropathic pain, but the inflammation may resolve and leave behind damaged nerve roots and neuropathic pain.

The inflammatory and neuropathic pain of AA may also develop into Intractable Pain Syndrome, which is constant, incurable pain with cardiovascular, endocrine (hormonal) and autoimmune complications.

Persons with AA usually need to treat both kinds of pain – inflammatory and neuropathic --   but one type may be predominant. A blood test for inflammatory markers is helpful, but not totally diagnostic.

If your pain improves with a trial of ketorolac (1 or 2 injections) or a corticosteroid (Medrol Dose Pak or dexamethasone), you have active inflammation that must be treated. We also recommend botanical anti-inflammatory agents, such as curcumin/turmeric, Andrographis and serrapeptase.

Prescription medications for neuropathic pain include gabapentin (Neurontin), diazepam, carisoprodol, topiramate, Lyrica and Cymbalta.

Every person with AA of the cervical and/or lumbar spines should experiment with topical medications, such as the Salonpas patch, lidocaine gel or patch, Voltaren gel and diclofenac (prescription needed).

Topical medication that is applied and massaged into the skin may dissolve through the tissues to the inflamed or damaged area. On average, you can expect 10 to 25% additional pain relief, plus the potential to permanently reduce your pain. Sometimes topical  medication will relieve painful areas that other drugs taken orally or by injection cannot reach.

Forest Tennant is retired from clinical practice but continues his research on the treatment of intractable pain and arachnoiditis. This column is adapted from bulletins recently issued by the Arachnoiditis Research and Education Project. Readers interested in subscribing to the bulletins should send an email to tennantfoundation92@gmail.com.

The Tennant Foundation gives financial support to Pain News Network and sponsors PNN’s Patient Resources section.  

Topical Gel Shows Promise as Treatment for Neuropathic Pain

By Pat Anson, PNN Editor

An experimental gel developed to prevent skin damage caused by aging and ultraviolet light is showing promise as a treatment for chronic neuropathic pain, according to research underway in Australia.

The topical gel – known as RM191A – contains a copper-based compound that is absorbed by the skin and prevents the buildup of free radicals that cause skin damage associated with aging and skin cancer.

In a study recently published in the journal Redox Biology, RM191A was found to have potent antioxidant, anti-inflammatory and wound-healing properties in laboratory mice.

The gel is currently being evaluated in 24 patients at a Sydney hospital as a treatment for chronic nerve pain caused by surgery, chemotherapy, trauma and diabetes.  Results are expected later this month.

“Early sample uses of this topical formulation indicated it could be a significant in the management of certain types of chronic nerve pain,” says Llewellyn Casbolt, chief scientist and co-founder of Sydney-based RR MedSciences, which is developing the gel.

“In many ways, scientists see our discovery as a new class of anti-inflammatory that acts by the modulation of free radicals as well as reducing several inflammatory cytokines, providing a drug that can be therapeutically useful where the reduction of inflammation, as well as cellular and tissue healing - indeed pain relief - is also advantageous for a patient.”

The company plans to release an over-the-counter version of its gel in the next 12-18 months as a treatment for skin damage. It will take longer to get regulatory approval for the gel as a treatment for nerve pain and may require a prescription.

RR MedSciences (RRMS) plans to conduct further trials and is seeking additional partners and funding to accelerate the gel’s development.

“The management of pain, often related to conditions of inflammation or trauma that results in nerve or chronic pain is an area of great need.  Advancing the ability for people to modulate their pain, in a safe and effective manner that improves quality of life, is a core objective,” said Helena Libershal Casbolt, CEO and co-founder of RRMS.

A subsidiary of RRMS is currently selling a copper-based body cream called Blue Healer Care as a treatment for damaged skin and for relief from skin irritation and muscle soreness.

Study Finds Most Drugs Ineffective for Neuropathic Pain

By Pat Anson, PNN Editor

A first of its kind study that compared four medications widely used to treat neuropathy found that all four were usually ineffective in treating pain and many patients stopped taking them due to side effects.    

Over 20 million people in the U.S. suffer from neuropathic pain, a tingling, burning or stinging sensation in the hands and feet caused by nerve damage. Neuropathy is often caused by diabetes, chemotherapy or trauma, but in about 25% of cases the cause is unknown and classified as cryptogenic sensory polyneuropathy (CSPN).

There is little guidance for physicians and patients on what drugs to take for CSPN, so researchers at the University of Missouri School of Medicine conducted a “real world” study in which 402 patients with CSPN took one of the four neuropathy medications.

The four drugs studied were nortriptyline (Aventyl), a tricyclic antidepressant; duloxetine (Cymbalta), a serotonin-norepinephrine reuptake inhibitor (SNRI) antidepressant; pregabalin (Lyrica), an anti-seizure drug; and mexiletine (Mexitil), an anti-arrhythmic medication used to treat irregular heartbeats.

Nortriptyline, duloxetine and pregabalin are approved by the FDA for treating neuropathy, while mexiletine is used off-label. None of the drugs were originally developed to treat neuropathic pain.

"As the first study of its kind, we compared these four drugs in a real-life setting to provide physicians with a body of evidence to support the effective management of peripheral neuropathy and to support the need for newer and more effective drugs for neuropathic pain," said lead researcher Richard Barohn, MD, executive vice chancellor for health affairs at the University of Missouri.

After 12 weeks of use, any drug that reduced pain for a patient by at least a 50% was considered effective, a recognized industry standard to define therapy success.. Researchers also kept track of patients who stopped taking a drug and dropped out of the study due to adverse effects.

The study findings, published in JAMA Neurology, can best be described as underwhelming. Patients were far more likely to stop taking a drug than they were to stay on a medication that was helping them.    

Of the four drugs, only nortriptyline was an effective pain reliever for at least 25% of patients. It also had the second-lowest drop-out rate (38%), giving it the highest level of overall utility. Duloxetine had the second-highest efficacy rate (23%) and the lowest drop-out rate (37%).

Pregbalin had the lowest efficacy rate (15%) and the second highest drop-out rate (42%), while mexiletine had the highest drop-out rate (58%) and an efficacy rate of 20 percent.

EFFICACY RATE OF NEUROPATHY DRUGS

SOURCE: JAMA NEUROLOGY

"There was no clearly superior performing drug in the study," Barohn said. "However, of the four medications, nortriptyline and duloxetine performed better when efficacy and dropouts were both considered. Therefore, we recommend that either nortriptyline or duloxetine be considered before the other medications we tested."

While nortriptyline had the highest efficacy rate, it also had the highest rate of adverse events, with over half of patients (56%) reporting side effects such as dry mouth, drowsiness, fatigue and bloating.  

Previous studies have found that duloxetine and pregabalin had higher efficacy rates for neuropathic pain, but Barohn and his colleagues say their research more accurately reflects what patients experience in real life and what physicians encounter in their practice.

“Our findings could affect how these 4 drugs are used by all physicians who treat patients with neuropathy. Findings support duloxetine and nortriptyline as better-performing drug choices in this population with neuropathic pain, suggesting that they should be prescribed before pregabalin or mexiletine are considered. However, this study also supports a finding that all 4 drugs helped improve pain in at least some patients, so each could be tried if others failed,” they concluded.     

There are several other drugs used to treat neuropathy, including gabapentin, venlafaxine and sodium channel inhibitors. Barohn says additional comparative studies should be performed on those drugs. His goal is to build effectiveness data on nearly a dozen drugs for CSPN.

Experimental Treatment Targets Neuropathic Pain

By Pat Anson, PNN Editor

Researchers in Denmark have developed a promising new compound to treat neuropathy that targets the hyper-sensitized nerves that cause chronic pain. The experimental compound – a peptide called Tat-P4-(C5)2 -- has only been tested in mice, but researchers hope to begin clinical trials on humans soon.

"We have developed a new way to treat chronic pain. It is a targeted treatment. That is, it does not affect the general neuronal signaling, but only affects the nerve changes that are caused by the disease," says Kenneth Lindegaard Madsen, PhD, Associate Professor at the University of Copenhagen.

"We have been working on this for more than ten years. We have taken the process all the way from understanding the biology, inventing and designing the compound to describing how it works in animals, affects their behaviour and removes the pain.”

Madsen and his colleagues recently published their findings in the journal EMBO Molecular Medicine .

The image below shows the compound Tat-P4-(C5)2 after it is injected into the spinal cord. The compound (purple) penetrates the nerve cells of the spinal cord (yellow), but not the surrounding cells (the cell nuclei are blue). The compound blocks neuropathic pain signals – the kind associated with diabetic neuropathy, shingles, phantom limb pain and chemotherapy-induced pain — from being sent to the brain.

UNIVERSITY OF COPENHAGEN

In a previous study, the researchers showed in an animal model that use of the compound can also reduce tolerance and the risk of addiction. They believe the compound will be more effective and safer than the anti‐convulsants, antidepressants and opioid medications now used to treat neuropathy.

"The compound works very efficiently, and we do not see any side effects. We can administer this peptide and obtain complete pain relief in the mouse model we have used, without the lethargic effect that characterises existing pain-relieving drugs," said Madsen.

"Now, our next step is to work towards testing the treatment on people. The goal, for us, is to develop a drug, therefore the plan is to establish a biotech company as soon as possible so we can focus on this."

Light Therapy Used to Treat Neuropathic Pain

By Pat Anson, Editor

For someone with peripheral neuropathy, even the slightest touch can cause burning, stinging or shooting pain, usually in the hands or feet.

The pain is caused when the peripheral nervous system is damaged by diabetes, shingles, chemotherapy or some other medical condition. About 8% of adults worldwide suffer from some form of neuropathy. Medications prescribed to dull the pain – such as opioids, anti-depressants or gabapentin (Neurontin) -- often prove to be ineffective, don’t last long or have unwanted side effects.

Scientists in Italy have now discovered an experimental way to treat neuropathy that provides pain relief for weeks at a time without the use of medication. In experiments on laboratory mice, researchers at the European Molecular Biology Laboratory (EMBL) in Rome identified a specific set of nerve cells in mouse skin that play a significant role in neuropathic pain.

NATURE COMMUNICATIONs

When injected with a light-sensitive chemical and then exposed to infrared light, the nerve cells pull away from the skin’s surface and stop sending pain signals. The pain-relieving effects of the light therapy appear to last for weeks.

The accompanying image shows the skin of a mouse, with the nerve cells that are responsible for sensitivity to touch highlighted in green. The neurons are primarily located around hair follicles.

The EMBL's research, first reported in the journal Nature Communications, is still in its early stages. But scientists say human skin tissue is similar to that of mice, indicating that light therapy might be effective in managing neuropathic pain in humans.

"In the end, our aim is to solve the problem of pain in both humans and animals," says Paul Heppenstall, PhD, EMBL group leader. "Of course, a lot of work needs to be done before we can do a similar study in people with neuropathic pain. That's why we're now actively looking for partners and are open for new collaborations to develop this method further, with the hope of one day using it in the clinic."

Heppenstall says light therapy works on the treated nerve cells the same way spicy food or capsaicin patches can cause nerve fibers to retract.  

"It's like eating a strong curry, which burns the nerve endings in your mouth and desensitizes them for some time," says Heppenstall. "The nice thing about our technique is that we can specifically target the small subgroup of neurons causing neuropathic pain."

There are many different types of nerve cells in skin, which respond to different sensations like vibration, cold, heat or normal pain. Researchers say those cells are not affected by the light treatment. The skin is only desensitized to a gentle touch, breeze, or tickling.

Previous attempts to develop drugs to treat neuropathic pain have mostly focused on targeting single molecules.

"We think however, that there's not one single molecule responsible, there are many," Heppenstall explains. "You might be able to succeed in blocking one or a couple, but others would take over the same function eventually. With our new illumination method, we avoid this problem altogether."

The neuropathic pain in mice was assessed with a simple touch. The mice would normally quickly withdraw their paw when it was gently touched, but after light therapy they exhibited normal reflexive response to touch. The effect of the therapy lasted for a few weeks, until the nerve endings grew back and the gentle touch caused pain again.

New Drug Discovered for Neuropathic Pain

By Pat Anson, Editor

Researchers at The University of Texas have discovered a potent non-opioid pain reliever that acts on a previously unknown pain pathway. They say the synthetic compound, known as UKH-1114, is as effective at relieving neuropathic pain in laboratory mice as gabapentin, but lasts much longer.

Now scientists need to find out if drug is safe, effective and nonaddictive in humans -- a process that could take years.

"This opens the door to having a new treatment for neuropathic pain that is not an opioid," said Stephen Martin, a chemistry professor at The University of Texas at Austin. "And that has huge implications."

UKH-1114 binds to a receptor on cells in the central nervous system called the sigma 2 receptor. Although it was discovered 25 years ago, scientists did not know what sigma 2 did until now.

Theodore Price, an associate professor of neuroscience at The University of Texas at Dallas, tested UKH-1114 on mice with nerve damage and found that it alleviated pain as well as gabapentin did, but was effective much longer -- lasting for a couple of days, compared to 4 to 6 hours. Price’s research was the first to demonstrate that the sigma 2 receptor may be a target for treating neuropathic pain.

"We started out just working on fundamental chemistry in the lab," said James Sahn, a research scientist at The University of Texas at Austin. "But now we see the possibility that our discoveries could improve the quality of people's lives. That is very satisfying."

Sahn and his colleagues have filed patent applications on the new compound. Their findings have been published in the journal ACS Chemical Neuroscience. An earlier paper on the sigma 2 receptor was published in the journal Proceedings of the National Academy of Sciences.

Chronic neuropathic pain is caused when nerves in the central nervous system are damaged by chemotherapy, shingles, diabetes or injuries to the brain or spinal cord. About 8% of adults worldwide suffer from some form of neuropathy.

Diabetic peripheral neuropathy causes nerves to send out abnormal signals. Patients can feel stinging or burning pain, as well as loss of feeling, in their toes, feet, legs, hands and arms. Nearly 26 million Americans have diabetes and about half have neuropathy, according to the American Diabetes Association. 

Many patients say drugs commonly used to treat neuropathic pain, such as gabapentin (Neurontin) and pregabalin (Lyrica), either don’t work or have unpleasant side effects such as dizziness, fatigue and diminished cognitive ability. Some doctors also feel the drugs are being overprescribed as alternatives to opioid pain medication.  

Kratom Helps Relieve My Neuropathy Pain

By Robert Dinse, Guest Columnist

I suffer from diabetic peripheral neuropathy.  I can best describe the pain as something akin to being doused in gasoline and then having a match tossed on me.  Pretty much everything from the neck down at times is involved in severe burning pain.

Over time I've been placed on a number of combinations of anti-depressants and anti-seizure medications with various degrees of effectiveness. Presently I am on Lyrica and nortriptyline, an anti-depressant.  So far this seems to be the best compromise between sedation and pain.

I actually got slightly better pain control with amitriptyline, another anti-depressant, but nortriptyline helps my mood more and since Lyrica negatively impacts my mood but greatly reduces my pain, this seems to be the best compromise.

With this combination of drugs, my pain is reasonably controlled about six days of the week, but I have periods, usually lasting 3-6 hours, of breakthrough pain in which I'm on fire again.

Kratom provides relief during those times and it does so without getting me high, or noticeably affecting my mental state in any way.  This leaves me almost pain free and totally functional.

robert dinse

There are two other drugs I've found to be helpful for this breakthrough pain. The first is marijuana, which is legal in Washington State but leaves me pretty much non-functional. I cannot drive, nor effectively do my work on enough marijuana to give pain relief.  Marijuana also stimulates my appetite and as a diabetic I need to lose weight, not gain weight.

The other useful drug is tianeptine sodium, but for it to be effective I need about 140 mg, which is higher than the maximum recommended single dose. At that dosage I also build a rapid tolerance.  Not a problem if the pain flare up is short, but if it lasts more than two days, which on rare occasions it does, then tianeptine sodium becomes ineffective. 

Some people get withdrawal symptoms from tianeptine sodium. I am fortunate that I have not ever experienced that, but it's lack of effectiveness if I get a bad flare-up lasting more than two days is its chief drawback.

I do not seem to rapidly build tolerance to kratom, and I've yet to experience any loss of effectiveness.  It doesn't get me high.  I don't get withdrawal symptoms. For my needs it is ideal, yet the DEA wants to take this away.

I wish that doctors and DEA officials could experience neuropathic pain firsthand so they could understand the hell their fouled up policies are putting people through. We have tens of thousands of deaths every year due to alcohol and tobacco, and the 16 alleged kratom deaths in the last five years all involved a mixture of other drugs that were most likely responsible for those deaths.

It is very hard to overdose on kratom because you take too much and you puke it up.  I have experimentally determined the puke up threshold for me is about 12 capsules, and 10 capsules totally relieve my pain with no sense of intoxication or impairment.

I don't know how you could ask a pain reliever to be simultaneously anywhere near as effective or safe as kratom.  Too much aspirin and you bleed to death internally, too much Tylenol and you toast your liver, many other NSAIDS readily available over the counter are bad for your heart.

Problem is, as a natural product, it's not patentable and thus competes with other patentable but much more dangerous and less effective drugs.

Robert Dinse lives in Washington State with his family.

Pain News Network invites other readers to share their stories with us.  Send them to:  editor@PainNewsNetwork.org. 

The information in this column should not be considered as professional medical advice, diagnosis or treatment. It is for informational purposes only and represents the author’s opinions alone. It does not inherently express or reflect the views, opinions and/or positions of Pain News Network.

‘Wakeup Call’ for Neurontin Abuse

By Pat Anson, Editor

A drug that is often prescribed as an alternative to opioid pain medication is increasingly being abused by patients, according to a small study that found one out of five patients taking the drug illicitly.

Gabapentin – which is sold by Pfizer under the brand name Neurontin -- is approved by the Food and Drug Administration to treat epilepsy and neuropathic pain caused by shingles.

It is also prescribed “off-label” for a variety of other conditions, including depression, migraine, fibromyalgia and bipolar disorder.

In a study of urine samples from 323 patients being treated at pain clinics and addiction treatment centers, 70 patients were found to be taking gabapentin without a prescription.

“The high rate of misuse of this medication is surprising and it is also a wakeup call for prescribers. Doctors don’t usually screen for gabapentin abuse when making sure patients are taking medications, such as opioids, as prescribed. These findings reveal that there is a growing risk of abuse and a need for more robust testing,” said Poluru Reddy, PhD, medical director of ARIA Diagnostics in Indianapolis, IN. Reddy presented his study at the annual meeting of the American Association for Clinical Chemistry in Philadelphia.

Researchers found that of those patients taking gabapentin illicitly, over half (56%) were taking it with an opioid, about a quarter (27%) with an opioid and muscle relaxant or anxiety medication, and the rest with other substances. The urine samples came primarily from pain clinics in Indiana, Arizona, and Massachusetts.

“Little information exists regarding the significance of Gabapentin abuse among clinical patients. Until recently, it was considered to have little potential for abuse however this review has shown that a significant amount of patients are taking Gabapentin without physician consent. This could be due to the fact that recent studies have revealed that Gabapentin may potentiate the ‘high’ obtained from other central nervous system acting drugs,” wrote Reddy.

"Patient safety is Pfizer’s utmost priority.  We strongly support and recommend the need for appropriate prescribing and use of all our medicines," a spokesperson for Pfizer said in an email to Pain News Network.

Gabapentin is not scheduled as a controlled substance and when taken alone there is little potential for abuse. But when taken with other drugs, such as opioids, muscle relaxants, and anxiety medications like Valium and Xanax, researchers say gabapentin can have a euphoric effect.

Between 2008 and 2011 the number of emergency room visits for misuse or abuse of gabapentin increased by nearly five times, according to the Drug Abuse Warning Network. Side effects from gabapentin include weight gain, dizziness, ataxia, somnolence, nervousness and fatigue.

Increased Prescribing of Gabapentin

A report by IMS Health found that 57 million prescriptions for gabapentin were written in the U.S. in 2015, a 42% increase since 2011.

Gabapentin is one of several medications being promoted by the Centers for Disease Control and Prevention as a "safer"  alternative to opioids.  The American Pain Society recently recommended that gabapentin be considered for post-operative pain relief.

But the growth in gabapentin prescribing is drawing scrutiny in the UK, where the Advisory Council on the Misuse of Drugs (ACMD) recommended earlier this year that gabapentin and pregabalin (Lyrica) be reclassified as Class C controlled substances, which would make them harder to obtain.

“Both pregabalin and gabapentin are increasingly being reported as possessing a potential for misuse. When used in combination with other depressants, they can cause drowsiness, sedation, respiratory failure and death,” said Professor Les Iverson, ACMD chairman, in a letter to Home Office ministers.

“Pregabalin causes a ‘high’ or elevated mood in users; the side effects may include chest pain, wheezing, vision changes and less commonly, hallucinations. Gabapentin can produce feelings of relaxation, calmness and euphoria. Some users have reported that the ‘high’ from snorted gabapentin can be similar to taking a stimulant.”

Gabapentin is "one of the most abused and diverted drugs” in the U.S. prison system, according to Jeffrey Keller, MD,  the chief medical officer of Centurian, a private company that provides prison healthcare services.

“Inmates show up at my jails all the time with gabapentin on their current medication list,” Keller wrote in Corrections.com. “It produces euphoria, a marijuana-like high, sedation, and, at high enough doses, dissociative/psychedelic effects. It works so well that it is used in the drug community to mellow out methamphetamine tweaking and to cut heroin. Since drug abusers know about these illicit uses of gabapentin on the streets, once they get to jail they often view gabapentin as an obtainable ‘jail substitute’ for their preferred drugs.

“Unfortunately, the abuse potential of gabapentin is not recognized much outside of jails and prisons. Community prescribers are generally unaware that gabapentin can be misused and (in my experience) are often incredulous and even disbelieving when told about ‘the dark side’ of gabapentin.”

Gabapentin (Neurontin) has a checkered history. Originally developed as a nerve drug, Pfizer agreed to pay $430 million in fines to resolve criminal and civil charges for illegally marketing Neurontin to treat conditions it was not approved for. According to some estimates, over 90% of Neurontin sales are for off-label uses.

In 1999, a Pfizer executive was so mystified by Neurontin’s popularity he called it the “snake oil of the twentieth century.”  

An Opportunity to Make Ourselves Heard

By Richard “Red” Lawhern, Guest Columnist

Many kinds of chronic pain are represented by the readers of Pain News Network -- among them, several forms of peripheral neuropathic pain.  PNN readers might not be aware that a public meeting was recently held by the U.S. Food and Drug Administration on “Patient-Focused Drug Development for Neuropathic Pain Associated with Peripheral Neuropathy.” 

You can watch and listen to the June 10th meeting by clicking here.

The FDA maintains a public gateway for comments on the meeting and its goals.  I urge anyone who wishes to influence this issue to submit their comments. The public comment period ends August 10th. 

As of July 2nd, only 27 comments have been received! 

To get any notice at all, we need 2,700 -- or better yet, 27,000 comments -- not 27.  Silence will almost certainly be maliciously interpreted by the FDA to mean that pain patients are doing okay with presently available remedies, which all of us realize we most decidedly are not.

To make a comment, the FDA gateway may be reached by clicking here.

The following was the questionnaire filled out by meeting attendees.  Follow-up comments may be more effective if focused on these areas:

          Topic 1: Disease symptoms and daily impacts that matter most to patients.

1)  How would you describe your pain associated with peripheral neuropathy? What terms would
you use to describe the most bothersome aspects of pain? (Examples may include stabbing
sensations, electric shocks, burning or tingling, etc.)

2)  Are there specific activities that are important to you but that you cannot do at all or as fully as
you would like because of your neuropathic pain? (Examples may include sleeping
through the night, daily hygiene, participation in sports or social activities, intimacy with a
spouse or partner, etc.)

3)  How does your neuropathic pain affect your daily life on the best days? On the worst days?

4)  How has your neuropathic pain changed over time?

5)  What worries you most about your condition?

Topic 2: Patients’ perspectives on current approaches to treatment

1)  What are you currently doing to help treat your neuropathic pain associated with peripheral neuropathy? (Examples may include prescription medicines, over-the-counter products, and other therapies including non-drug therapies such as physical therapy). How has your treatment regimen changed over time, and why?

2)  How well does your current treatment regimen control your neuropathic pain? How well have these treatments worked for you as your condition has changed over time? Would you define your condition today as being well managed?

3)  What are the most significant downsides to your current treatments, and how do they affect your daily life? (Examples of downsides may include bothersome side effects, going to the hospital or clinic for treatment, time devoted to treatment, restrictions on driving, etc.)

4)  Assuming there is no complete cure for your neuropathic pain, what specific things would you look for in an ideal treatment for your neuropathic pain?  What would you consider to be a meaningful improvement in your condition (for example specific symptom improvements or functional improvements) that a treatment could provide?

5)  If you had the opportunity to consider participating in a clinical trial studying experimental treatments for neuropathic pain, what things would you consider when deciding whether or not to participate? (Examples may include how severe your neuropathic pain is, how well current treatments are working for you, your concern about risks, etc.)

Mine was one of the first comments submitted.  After summarizing my background as a chronic pain patient advocate, I offered several inputs.  Two seem particularly aligned with the concerns of PNN readers:

1)  Despite the legal restrictions still placed on medical marijuana, there is ample evidence in patient reports that several strains of this natural plant can be used effectively in pain management for a wide variety of chronic pain conditions, including peripheral neuropathy. Federal funding is needed to bring marijuana research out of the shadows and integrate it into mainstream medicine. If legislative changes are needed, then seek them soon.

2)  The most important near term outcome that this public meeting can reinforce is recognition that legally prescribed opioid medications play an indispensable role in present treatment of chronic neuropathic pain which is refractory to other therapies. In this context, the recently published CDC “voluntary” guidelines on prescription of opioids in adult chronic non-cancer pain need to be withdrawn immediately and rewritten to make this role clear -- for both peripheral neuropathic pain and many other chronic pain conditions.

In their present form, the CDC guidelines have become a de facto restrictive practice standard that is driving doctors out of pain management and thousands of patients into unmitigated agony. The basis for the guidelines is also scientifically weak and may have reflected professional or financial self-interest bias on the part of some participants in the “Core Expert Group” that supported the guidelines.

Insofar as I can determine, the working group did not include a SINGLE practicing board certified pain management specialist who is actively treating patients. Revisions of the guidelines need to reflect a much more patient-centered frame of reference, with explicit recognition that dose levels must be tailored to the individual patient and that effectiveness is highly variable between patients due to genetic factors which make some people poor metabolizers of this class of medication.

Richard “Red” Lawhern, PhD, became a patient advocate 20 years ago after his wife developed trigeminal neuralgia, a chronic facial pain disorder. He presently supports 20 groups on Facebook with a membership of over 15,000 patients and family members.

Pain News Network invites other readers to share their stories with us.  Send them to:  editor@PainNewsNetwork.org. 

The information in this column should not be considered as professional medical advice, diagnosis or treatment. It is for informational purposes only and represents the author’s opinions alone. It does not inherently express or reflect the views, opinions and/or positions of Pain News Network.

Cellphone Towers Amplify Pain in Amputees

By Pat Anson, Editor

For many years there has been a debate about the possible health effects of cell phone towers, power lines and other transmission devices that create electromagnetic fields (EMFs). These magnetic and electromagnetic frequency waves pass right through us, raising concern that they might cause cancer and other adverse health effects.

A new study by researchers at The University of Texas at Dallas suggests that cellphone towers may trigger neuropathic pain, especially in amputees that suffer from phantom limb pain.

"Our study provides evidence, for the first time, that subjects exposed to cellphone towers at low, regular levels can actually perceive pain," said Dr. Mario Romero-Ortega, senior author of the study and an associate professor of bioengineering in the University's Erik Jonsson School of Engineering and Computer Science. "Our study also points to a specific nerve pathway that may contribute to our main finding."

Most of the previous research into the possible health effects of cellphone towers has been conducted on individuals with no diagnosed, pre-existing conditions. This is one of the first studies to look at the effects of EMFs on amputees.

For years, retired Maj. David Underwood noticed that whenever he drove under power lines or near other electromagnetic fields, he would feel a buzz in what remained of his left arm. When traveling by car through Texas' open spaces, the buzz often became more powerful.

"When roaming on a cellphone in the car kicked in, the pain almost felt like having my arm blown off again," said Underwood, an Iraq War veteran who was injured by an improvised explosive device (IED). His injuries resulted in 35 surgeries and the amputation of his left arm.

"I didn't notice the power lines, cellphones on roam or other electromagnetic fields until I first felt them in my arm," says Underwood.

After learning about Underwood’s experiences, Romero-Ortega decided to study the phenomena.

He and his colleagues thought that neuromas -- inflamed peripheral nerve bundles that often form due to injury – could be more sensitive to EMFs. To test their theory in a laboratory, they assigned 20 rats into two groups -- one receiving a nerve injury that simulated amputation, and the other group receiving a sham treatment.

Researchers then exposed the rats to a radiofrequency electromagnetic antenna for 10 minutes, once per week for eight weeks. The antenna delivered a power density similar to what a human would be exposed to 125 feet away from a cellphone tower.

By the fourth week, 88 percent of the rats in the nerve-injured group demonstrated a behavioral pain response, while only one rat in the sham group exhibited pain. After growth of neuroma and resection -- the typical treatment in humans with neuromas who are experiencing pain -- the pain responses persisted.

"Many believe that a neuroma has to be present in order to evoke pain. Our model found that electromagnetic fields evoked pain that is perceived before neuroma formation; subjects felt pain almost immediately," Romero-Ortega said. "My hope is that this study will highlight the importance of developing clinical options to prevent neuromas, instead of the current partially effective surgery alternatives for neuroma resection to treat pain."

Romero-Ortega says since the research produced pain responses in rats similar to those in anecdotal reports from humans such as Major Underwood, the results "are very likely" generalizable to humans.

"There are people who live in caves because they report to be hypersensitive to radiomagnetism, yet the rest of the world uses cellphones and does not have a problem. The polarization may allow people to disregard the complaints of the few as psychosomatic," he said. "In our study, the subjects with nerve injury were not capable of complex psychosomatic behavior. Their pain was a direct response to man-made radiofrequency electromagnetic energy."

At one point in the study, members of the research group showed Underwood video of subjects in the experiment and their response to radiofrequency electromagnetic fields.

"It was exactly the same type of movements I would have around cellphones on roam, power lines and other electromagnetic fields," said Underwood.

Until the study was published online in PLOS ONE, there was no scientific evidence to back up the anecdotal stories of people like Underwood, who reported neuropathic pain around cellphone towers and other technology that produce EMFs. .

Phantom limb pain is a common and painful disorder that many amputees feel after their limbs are removed. The origin of the pain and sensations from the missing limb are not well understood. There are nearly 2 million amputees in the United States, according to the Centers for Disease Control and Prevention.