Sleep that will not come easily. Body aches with no clear source. Brain fog that shows up out of nowhere. Sudden weakness in an arm or leg. Seizure-like episodes that are not, technically, seizures. Parents describe a child or teenager going through a rotation of these symptoms, missing school and social events, while every scan and lab test comes back clean. That combination, real symptoms with no disease found to explain them, is often what leads to a diagnosis of Functional Neurological Disorder. For a lot of families, hearing that phrase for the first time raises more questions than it answers, since it sounds vague next to a diagnosis with a clear scan or a clear lab value behind it.
What Functional Neurological Disorder Actually Is
Functional Neurological Disorder, or FND, is fundamentally different from conditions like a stroke, multiple sclerosis, or a brain injury. Those conditions involve physical damage to brain tissue that shows up on imaging. FND does not come from that kind of damage. It comes from a problem in how the brain and nervous system are functioning, in how signals are being sent and received.
A useful way to picture it: every action your body takes, lifting a finger, digesting a meal, regulating emotion, depends on a signal traveling correctly through the nervous system. In FND, some of those signal pathways are not transmitting the way they should, even though the wiring itself is intact. The symptoms that result are completely real. They are not something a person can simply choose to stop.
The Two Main Categories of Symptoms
FND symptoms generally fall into two groups, and a person can experience one or both.
- Psychogenic nonepileptic seizures (PNES): seizure-like episodes that are not caused by the abnormal electrical activity seen in epilepsy. These can include a brief loss of focus or memory, a state of confusion, blacking out, or a sense of being disconnected from what is happening around them.
- Functional movement disorder (FMD): symptoms affecting the body without seizures, including limb weakness or paralysis, tremors, twitching, muscle spasms or stiffness, balance and walking problems, numbness or tingling, vision changes, and slurred or otherwise altered speech.
Someone with FND does not need every symptom on this list, and severity varies a great deal from one person to the next. Even one symptom, present consistently enough to disrupt daily life, can be enough to warrant a closer look. Symptoms can also come and go, be present for a short stretch and then fade for months, or persist steadily, and that variability is itself a recognized part of the condition rather than a sign it is being misunderstood or exaggerated.
What Contributes to FND
There is no single known cause of Functional Neurological Disorder. A mix of physical, structural, biological, and psychological factors tends to be involved, and high stress or a traumatic experience can make someone more likely to develop it, without being the sole cause on its own. Not everyone under high stress develops FND, and not everyone with FND has a history of major stress. Four things show up often in the history of children and teens dealing with FND: real distress during the prenatal period, physical stress or intervention during labor and delivery, stress in the earliest years alongside motor or developmental delays, and a heavy load of mental and emotional stress overall. We refer to this build-up as the Perfect Storm, and you can read more about how we understand it on our Perfect Storm page.
How FND Is Different From Other Diagnoses
Because FND symptoms overlap with so many other conditions, it is typically diagnosed by ruling other things out first, ordering the imaging and lab work that would catch a structural or disease-based cause, and arriving at FND once those come back clear. That process can take time, sometimes months of appointments and testing, and it can feel discouraging when nothing on paper explains what your child is actually going through day to day. Functional Neurological Disorder is a genuine diagnosis in its own right, not a placeholder for "we could not find anything." It comes with its own recognized symptom patterns and its own reasoning, even without a scan that lights up to confirm it.
Who FND Shows Up In
Functional Neurological Disorder can affect children, teens, and adults, and it does not follow one predictable path. Some children who develop seizure-like PNES episodes recover from them over time and go on without lasting symptoms, which is part of why catching what is driving it early matters. Because FND still gets misunderstood even inside medicine, some families spend a long stretch feeling unheard before anyone puts a name to what their child is going through.
How Our Doctors Think About FND
Rather than starting from the label, our doctors look at what may be interfering with the nervous system's signaling itself, sometimes called subluxation, using a gentle exam and case history to understand your child's early story alongside their current pattern of symptoms. Light, nervous system focused adjustments are aimed at easing tension and interference built up from pregnancy, birth, or accumulated stress since, supporting clearer communication between the brain and body. This kind of care can work alongside physical therapy, speech therapy, or counseling your child's care team already has in place, adding a nervous system focused piece to whatever else is already part of your child's plan.
What Parents Often Notice
Families frequently describe deeper sleep, steadier energy through the day, a calmer overall mood, better emotional regulation, and more settled digestion. Because FND symptoms are so varied, the specific changes families notice tend to reflect whichever symptoms were most prominent for their own child.
Where to Go From Here
If your child's symptoms keep shifting and nothing on a scan explains them, understanding what is actually happening in the nervous system is a reasonable next step. Learn more about our approach to nervous system care, call our Royal Oak office at (248) 616-0900, or book online to talk through your child's story.
