The Three (Misunderstood) Hallmarks of Motor FND

How the same features that once shamed me, later saved me.

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Contrary to the belief that Functional Neurological Disorder (FND) is a “wastebasket diagnosis” when all else has been ruled out, there are three defining features of motor-based FND. As neurologist Jon Stone and colleagues emphasize, these are positive diagnostic signs (Stone et al., 2020).

• Hoover’s sign. A leg that appears weak or paralyzed will generate normal reflexive force when the opposite leg is pressed in a specific way. This isn’t fakery—it’s evidence that the motor pathways are intact but not being accessed automatically. Hoover’s sign is one of the most validated positive signs of functional leg weakness (Stone et al., 2010).

• Distractibility. Symptoms diminish when attention shifts elsewhere. While historically this was framed as “proof” of deception, it instead reflects the brain’s ability to reengage automatic movement patterns when conscious monitoring gets out of the way. This is a core feature of functional movement disorders (Espay et al., 2018).

• Entrainment. If one body part has a tremor, and the patient rhythmically moves another body part, the tremor will temporarily disappear. Entrainment is considered the single most reliable sign of functional tremor (Edwards & Bhatia, 2012).

Misinterpreted Meanings

Unfortunately, for over a century these three features have been misinterpreted to prove that patients were faking their symptoms, and doing an infantile job of it. Why else would someone be so easily distracted out of their symptoms? Conversely, symptoms worsen when one pays excess attention them—wasn’t this proof of hypochondriacal self-absorption?

This was exactly how this was explained to me as a graduate student in psychology in the 1990s, and I had no reason to question it at the time.

I had reason to question my own sanity once I experienced the symptoms myself in 1998. Especially after doctors had pointed them out with a triumphant “gotcha, you’re faking” smirk.

I couldn’t explain why my symptoms temporarily disappeared while I was engaged in writing my dissertation or working out at the gym, but came back when I lost focus. Since my job consisted of tedious data entry while isolated inside a gray burlap cubicle, I was bored—and highly symptomatic—most of the time at work. Perhaps the psychiatrist was right—I was an emotional toddler acting out when bored. But the harder I tried to fight the embarrassing symptoms, the worse they got.

The “Tricks” I Thought Proved I Was Broken

Eventually I discovered some tricks in managing my symptoms. Rhythmically tapping my foot could stop abnormal movements in my hands and arms. Even tapping one finger could sometimes control symptoms elsewhere. Staring at one point in the distance as I walked forward, instead of wondering why my legs were refusing to move normally, could snap me back into a more normal gait.

Somehow these strategies worked better than fighting against the symptoms, which always seemed to fight back and win.

At the time I had no idea why these tricks worked. Perhaps it was proof I was crazy, but at least I was learning to hide it. The more I practiced these tricks, the better I could manage my symptoms and my life. But as the symptoms improved, the shame grew worse. It seemed the doctors were right; my symptoms were never real and I was profoundly, incurably neurotic.

The “Aha!” Moment

By 2022—after COVID flared my symptoms to levels I hadn’t experienced since 1998—I had stopped searching for answers. Then I stumbled across a video of a woman discussing her FND symptoms with a neurological physical therapist. This explanation changed everything:

An FND patient can limp into the room, hear her phone ring in the other room, then run effortlessly to get it. It looks like faking. What’s actually happening is that automatic movement patterns return when the person is distracted.

Suddenly the podiatrist’s comment from decades earlier—your automatic walking patterns seem disrupted—made even more sense. See "Unexpected lessons..."

I began reading about predictive motor control and how FND disrupts automatic movement programs. How aggressively fighting against abnormal movements often backfires. This is exactly what the predictive‑processing model describes: attention interfering with automatic motor execution (Edwards et al., 2012).

I at last understood why walking sometimes felt natural, and sometimes felt like tightrope-walking. Why picking up a pencil was sometimes effortless, and sometimes felt like a losing battle against my own hand. Why the most embarrassing symptoms escalated to seizure-like intensity when I desperately tried to stop them. Yet rhythmically moving a different part of my body could bring them under control.

And I finally understood:

I wasn’t faking. I wasn’t attention‑seeking. I wasn’t crazy.

The very signs neurologists had used as “gotchas” were not just positive diagnostic features, but potential management tools.

What Clinicians Need to Know

These three signs are not evidence of deception or even neuroses, but disrupted automaticity. This concept has been central to modern rehabilitation models for over a decade (Nielsen et al., 2015).

Here’s a quick demonstration: pick up a pencil without thinking about it. Now try it again while closely monitoring every movement of your hand and fingers. The second attempt is slower and more awkward because conscious attention disrupts automatic motor programs.

In FND, this disruption is a core problem. The brain amplifies internal monitoring and diminishes automatic motor predictions, so movements that should run on autopilot become unstable, effortful, or break down entirely. However, distraction or entrainment can pull the automatic processes back “online.”

When clinicians frame distractibility or entrainment as “proof” of deliberate or subconscious faking, they don’t just misunderstand the concepts. They shame the very mechanisms that could help patients recover.

Instead of smirking with derision, imagine if a healthcare provider explained:

• “This shows that your movement pathways are intact; you’re just not able to access them consistently.”

• “Here’s how we can use this to help you regain automatic movement.”

• “This is why fighting the symptoms backfires, but focusing elsewhere works.”

That shift alone could profoundly improve the patient-provider relationship, the patient’s understanding of their movement disorder, and even their patient’s self-concept.

It certainly did for me.

References

• Edwards, M. J., & Bhatia, K. P. (2012). Functional (psychogenic) movement disorders: Merging mind and brain. The Lancet Neurology, 11(3), 250–260.

• Espay, A. J., Aybek, S., Carson, A., et al. (2018). Current concepts in diagnosis and treatment of functional neurological disorders. JAMA Neurology, 75(9), 1132–1141.

• Nielsen, G., Stone, J., & Edwards, M. J. (2015). Physiotherapy for functional motor disorders: A consensus recommendation. Journal of Neurology, Neurosurgery & Psychiatry, 86(10), 1113–1119.

• Stone, J., Carson, A., Duncan, R., et al. (2010). Who is referred to neurology clinics?—The diagnoses made in 3781 new patients. Clinical Neurology and Neurosurgery, 112(9), 747–751.

• Stone, J., LaFrance, W. C., Brown, R., et al. (2020). Functional neurological disorder: The bare essentials. Practical Neurology, 20(1), 14–25.