No one wants a debilitating illness. Now, imagine a debilitating illness with neither a confirmed cause nor an effective treatment protocol. If you can envision that, then you have a tiny bit of insight into the ramifications of a diagnosis of Functional Neurological disorder. An FND diagnosis means a sentence to life with a serious disability that the medical establishment does not understand.

According the fndhope.org, which is considered an authoritative site on all things FND, “Functional Neurological Disorder provides an umbrella term for a variety of symptoms of apparent neurological origin but which current models struggle to explain psychologically or organically.” Symptoms of FND can include: bladder and bowel changes, chronic pain, cognitive changes, gait and balance problems, headache and migraine, involuntary movements, paralysis and weakness, seizures, sensory changes, sleep disturbances, speech problems, and visual changes.

The site goes on to note that “Very few effective treatment plans exist. Physical Therapy is the most effective form of treatment with a goal of re-introducing proper movement and motor control. The most common treatment plan is Cognitive Behavior Therapy (CBT), which yields a 13% success rate. CBT is most effective for patients who have a known psychological connection to their symptoms. Lack of understanding the condition has negatively influenced treatment and care. Researchers, money, and volunteers are greatly needed.”

As a person once misdiagnosed with FND, I spent a lot of time reading up on the disease. Imagine my surprise when I finally got an accurate, laboratory confirmed diagnosis of Mast Cell Activation syndrome, and realized that almost every single one of the symptoms associated with FND can be attributed to MCAS. Some people think of MCAS as a disease that only manifests in ways traditionally associated with allergies; like rashes, hives, and anaphylaxis. But MCAS can also cause symptoms that currently fall under the umbrella of neurology, such as slurred speech, insomnia, muscle weakness, and paralysis and seizure like events. [1]

People with MCAS often have paresthesia, which is tingling or numbness, usually in the extremities. Other symptoms of MCAS that present neurologically include weakness, tics, migraines, difficulty focusing one’s vision, and brain fog. Dysfunction of the autonomic system isn’t uncommon either, blood pressure and heart rate can rise and fall, and sleep attacks can occur. [2]

Inappropriate mast cell activation can cause severe pain, as well as a wide range of gastrointestinal issues. Diarrhea, constipation, or alternating diarrhea and constipation are among known presentations of this mast cell disease. MCAS can cause also nausea and vomiting. And it doesn’t stop there. MCAS can cause issues in the genitourinary tract as well. Painful urination and UTI symptoms without evidence of infection sometimes develop in people with MCAS. [3]

Most patients with FND have been told by one or more of their doctors that stress, either recognized or unrecognized, was and continues to be a trigger for their illness. That truth becomes easier to swallow when we learn how stress affects mast cell activation. According to mastcellresearch.com, “Stress can be a trigger for mast cell activation. Stress also causes the biggest variance in the presentation of symptoms in almost all of the conditions mentioned above. Stress can be an insult to the body, such as trauma – both emotional and physical – lifestyle choices, and environmental factors that are both in our control and not in our control. Some examples of stress are serious illnesses, alcoholism, toxicity from heavy metals or chemicals, surgery, reaction to medications, anaphylaxis, abuse, and accidents.”

Let’s look back to the quote from fndhope.org, “Functional Neurological Disorder provides an umbrella term for a variety of symptoms of apparent neurological origin but which current models struggle to explain psychologically or organically.”

There’s a huge problem with that line of thinking. In the current age of investigation into the gut-brain connection and neuroimmunology, there’s isn’t a good reason to conclude that something that presents neurologically is of “apparent” neurological origin.

I think the key to accurately diagnosing and treating people who have symptoms associated with Functional Neurological disorder lies with looking outside the narrow lens of neurology and into the intersection of the central nervous system and other systems in the body. I’d like to see neurologists trained to order 24 hour urine prostaglandins and n methylhistamine labs on their FND patients as a starting point. I’d also like for more gastroenterologists to learn how to stain reportedly “normal” biopsies for elevated concentrations of mast cells.

Is there an upside to substituting an accurate immune diagnosis for an inaccurate neurological diagnosis? Yes! There are many treatment options for Mast Cell Activation syndrome, and some people with it eventually find a great deal of relief.

With all that being said, do I think it’s possible that some people diagnosed with FND have symptoms that are purely psychogenic? Absolutely. But I think they are a small minority of FND patients, and I also think that an initial stress trigger can set in motion a series of physical changes in the body that perpetuate the symptoms even when a person becomes less stressed or learns better strategies for stress management. There’s more to FND than meets the eye, brain, or immune system.

Am I saying everyone with FND actually has a mast cell disease? No, I’m not. There may be other causes for FND symptoms beyond the scope of what I’m discussing here. I’m not a doctor, so I can’t diagnose or treat anyone. I’m just a thinking patient who has high hopes that other patients may some day find healing.

Addendum Sept 26, 2017– This post isn’t meant to be critical of the people behind fndhope.org. They’re awesome folks who are pushing for more research into FND. They want people with this diagnosis to find ways to heal. We’re allies in that goal.


2. Afrin M.D., Lawrence B., Never Bet Against Occam: Mast Cell Activation Disease and the Modern Epidemics of Chronic Illness and Medical Complexity (Sisters Media LLC, 2016), 162.

3. Afrin M.D., 134, 146-156

Are you curious about part one of this series? Find it here.

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Twilah H is a recovering patient. She studied Philosophy with a concentration in ethics at the University of Kansas. Through writing, meditation, relationship building, and quilt creation she has found a place of peace.

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