Central sensitization is one explanation

The etiology of fibromyalgia is still largely unknown, but it isn’t as controversial as it used to be.

A decade ago, the chronic rheumatic disease was most often attributed to muscle and ligament problems. Some declared it a psychogenic disorder. (Some still do.) More recently, however, studies have linked fibromyalgia with malfunctioning neurotransmitters, neurochemical imbalances and other neuropathic conditions.

“Today, it’s more widely accepted that fibromyalgia is primarily a neurogenic disease,” says Philippe Berenger, MD, a pain management specialist at Cleveland Clinic. “It still doesn’t explain the disease, but it’s a step forward.”

Dr. Berenger bolstered this belief in a presentation at Cleveland Clinic’s 18th Annual Pain Management Symposium in San Diego in March.

Definitions we can agree on

In 1994, the International Association for the Study of Pain (IASP) defined neuropathic pain as “initiated or caused by a primary lesion or dysfunction of the nervous system.” In 2008, the IASP’s Neuropathic Pain Special Interest Group tweaked the definition to include “disease of the somatosensory nervous system.”

“Fibromyalgia fits these definitions,” says Dr. Berenger. “Although the condition has no anatomically definable lesions, it is marked by altered neurological function in the spinal cord and brain. It can, therefore, be considered a dysfunction of the central inhibitory process of pain control.”

Fibromyalgia’s link to central sensitization

It’s clear that fibromyalgia has mechanisms and pathways associated with central sensitization, he notes. The condition follows similar pathways as other neuropathic pain syndromes, such as complex regional pain syndrome, interstitial cystitis and irritable bowel syndrome.

“All nerves in fibromyalgia patients are more sensitive than they should be — including the brain and spinal cord,” says Dr. Berenger. “Many patients have difficulty with concentration or have hypersensitivity to light, odors or sounds. Some have additional neuropathic pain syndromes or struggle with autonomic dysfunction, such as vasovagal symptoms.”

Central sensitization has been demonstrated in animals and humans by using various triggers (e.g., mustard oil, heat, hypertonic saline injection) to activate nociceptors in skin, viscera or muscle. Sensitization presents as:

1. Tactile allodynia

2. Hyperalgesia

3. Enhanced pressure and thermal sensitivity

4. Spreading to neighboring nonstimulated sites and remote regions

Increased excitability of spinal cord neurons can cause a series of events:

1. Increased duration (spontaneous firing) and a growing area of response

2. Abnormal neuro-anatomical reorganization (new connections between A-beta, A-delta and C fibers, which spread and involve multiple dermatomes)

3. Diffuse symptoms — which can outlast the stimuli (long-term potentiation)

Newer evidence supports neurogenic claim

In 2014, researchers discovered through skin biopsy that patients with fibromyalgia had lower epidermal nerve fiber density than patients without fibromyalgia. Small fiber neuropathy, therefore, is likely another contributing factor in fibromyalgia pain — and yet more evidence that the condition has neurogenic roots, notes Dr. Berenger.

What this means for treatment

“Most of the drugs used today to treat fibromyalgia — like antidepressants and antiepileptics — are already focused on neurological targets,” says Dr. Berenger.

However, considering fibromyalgia as a central sensitization disorder opens up a larger array of treatment options, he says. Agents active on the central nervous system include:

–> Sodium channel blockers

–> Calcium channel blockers

–> Serotonin-norepinephrine reuptake inhibitors (SNRI)

–> NMDA receptor antagonists

–> Nerve growth factor (NGF) inhibitors

Low-dose naltrexone is another treatment option on the horizon. One 2013 study found that the drug significantly reduced pain and improved mood and general satisfaction in people with fibromyalgia. Other studies have reported similar positive responses to the drug.

It’s all in your head!

When I was first diagnosed with fibromyalgia in 2001, it was not a popular diagnosis. I did not fit the criteria. I was 21 years old and it took 50 doctors and 2 years of visits to get down to why I wasn’t getting better after a broken pelvis. I am forever thankful for a friendly chiropractor who sent me to the Mayo clinic. The day I was diagnosed I remember thinking, terrified, that I had spent my last penny getting there. This was my last hope. I was so nervous. This rheumatologist walks in, does a physical exam for all of 3 minutes which has me in hysterics, and reads over this 20 page questionnaire he had me fill out prior to coming. He looks up, says, “yep you have fibromyalgia, you need to sleep better. Here’s 50mg of Amitriptyline, I’ll see you in 6 months.” And promptly leaves the room. I had just traveled to see this guy. I was in agony. And I need to SLEEP?! It would be many more years before I slept properly again.

A month later, I bought every book I could find on fibromyalgia. I made my family read them. I’ll never forget the night I had dinner at my brother’s house. He had just finished Fibromyalgia For Dummies. He said, “so it’s all in your head?!” I didn’t talk to him for 6 months. He left messages…“it’s your central nervous system sister… It’s in your head. That’s all I meant!” I was too mad. Already too many people had dismissed me. My mother and I have had years of distance due to this disease and her judgements on my choices. I will admit to choosing myself. I will admit to choosing my bed. Because I have to.

I say all this because the medical community has done is a great disservice here. It’s too easy to use Fibromyalgia as a diagnosis of exclusion versus actually following the protocol. Do not ever fall for that. If you do not fit the criteria, keep pushing. The last thing you want is this label, believe me. For those of us who do fit it to a T, you must be your best advocate. You must read every book, article, publication… You can get your hands on. Rest assured your doctor isn’t. Know your body, know your symptoms, know your Illness and most of all, be strong in what you will and won’t settle for. You have that right. Fibromyalgia does not make you less. Nothing can. Each and every one of us beautiful creatures was put here for something.

Too many of us have to rely on our own bodies, minds, families, and fragile social structures to help us to feel better on a daily basis. Often, we are so weakened by external forces like work, friends, family and chores that we don’t trust our own bodies anymore. We wake in the mornings and do our system checks. I find myself listing the few parts that do not hurt before I get out of bed. I get up, do my housework and crash less than an hour later. It is the strength of my fellow Fibromytes that gets me through many of my worst days. The emotional pushes I get when I log into my Facebook and see that I am not alone, I am not the only one that lives like this. Those are the things I know I need to have a smile on my face in the evenings when my man comes home from work. When we have doctors, family and friends that doubt us we are forced to fight. After years of fighting, I know I for one am very tired of it. I will not allow more negativity to bring me down, especially not coming from those people meant to help me.

Tell me one last thing,” said Harry. “Is this real? Or has this been happening inside my head?”

“Of course it is happening inside your head, Harry, but why on earth should that mean that it is not real?

-J.K. Rowling, Harry Potter and the Deathly Hallows (Harry Potter, #7)

It is our responsibility to ensure that our world is only filled with those people who will support us. I know that sounds much easier said than done, but it truly isn’t. Ridding yourself of people who don’t support you is a blessing and not a hardship. Those people are not happy in your life either. They are speaking to you out of their own frustration with you or your illness. I’ve made it very clear to everyone who stays in my life that I will get worse, not better. I will suffer every day. I will whine like a baby and cry out for my mommy sometimes and you will either get with the program and deal with it or get the heck out of my life! I don’t have time or energy to stroke anyone’s ego. It truly is all about me, and guess what? I am ok with that. So is anyone who stays. It has to be.

It is our right to refuse a treatment and refuse care from rude, unsympathetic, or uncooperative doctors as well. I’m not telling you to go in and demand pain pills and keep doctor shopping until you get them. Don’t hear that, but if your doctor is flat not helping, but rather hurting… Don’t let him/her be your doctor. I just fired mine.

“It’s all in the mind”

Saying that fibromyalgia is “all in the mind” isn’t entirely wrong, concludes Dr. Berenger.

“Pain pathways and centers are in the brain. And we can employ techniques like mindfulness and biofeedback to control pain,” he says. “However, it’s more helpful — and accurate — to consider it a neurogenic disorder.”

Join the fibromyalgia support group for FAQs, Discussions and Support ” Living with Fibromyalgia and Chronic Illness”