ⓘ Context

For a full introduction to what FND is and how symptoms are diagnosed, read What Is FND? — the comprehensive guide. This page is a detailed reference for each symptom type.

Motor Symptoms in FND

Motor symptoms affect the body's ability to move. They range from mild weakness to full paralysis, and include involuntary movements that can look like tremor, dystonia, or gait problems.

Functional Weakness

Loss of strength in an arm, leg, or one side of the body. Power may vary significantly from one moment to the next — 2/5 on one test, 4/5 on the next. Often described as "heavy" or "not responding."

Functional Tremor

Shaking, usually in a hand or limb. Key feature: the tremor changes or lessens when the person is distracted (e.g., tapping the opposite hand). May also change frequency unpredictably.

Functional Dystonia

Sustained muscle tightening causing abnormal posture — a clenched fist, twisted neck (cervical dystonia), or a foot turned inwards. Positions can be painful and may persist during sleep.

Functional Gait Disorder

Walking difficulties that do not match any neurological lesion pattern. Knees may buckle, feet may drag, or the person may walk with an unusual pattern (the "drag-toe" gait is characteristic of FND).

Functional Myoclonus

Sudden, brief jerks in a limb, the torso, or the whole body — similar to the "hypnic jerk" that happens when falling asleep, but occurring at other times without warning.

Functional Facial Symptoms

Weakness on one side of the face, drooping eyelid, or difficulty opening the mouth — mimicking a stroke, but internally inconsistent.

Sensory Symptoms in FND

Sensory symptoms affect how the body feels touch, temperature, pain, and spatial position. Unlike sensory loss from nerve or spinal cord damage, FND sensory symptoms often follow non-anatomical patterns.

Numbness and Tingling

Reduced sensation or pins-and-needles in a limb, half the body, or other areas. In FND, the pattern does not follow dermatomes (the map of nerve supply) — a key diagnostic clue.

Visual Disturbance

Blurred vision, tunnel vision, double vision, or a sense that vision has changed — without any eye disease. Can come and go and may worsen with attention or stress.

Hearing Disturbance

Partial or complete hearing loss, tinnitus (ringing), or muffled sound perception — without inner ear damage. Usually intermittent.

Spatial Disorientation

A sense that your body is in a different position than it actually is — or that the world is moving when it is not. Affects balance and navigation.

Cognitive and Speech Symptoms in FND

FND frequently affects thinking, concentration, and speech — sometimes referred to as "functional cognitive disorder" when concentration and memory problems are the primary presentation.

  • Brain fog — slowed thinking, difficulty following conversations, losing track mid-sentence. Often worsens under stress or when fatigued.
  • Memory problems — difficulty forming new memories or recalling recent events. Often described as "everything goes in one ear and out the other."
  • Concentration difficulty — inability to sustain focus on a task that previously came easily. Often described as thoughts being "scrambled."
  • Functional dysphonia — loss of voice (whispered or absent) or a changed voice quality, with no structural problem in the vocal cords.
  • Functional dysarthria — slurred or distorted speech, difficulty coordinating the muscles used for speaking.
  • Stuttering — new-onset stammering that varies in severity and may temporarily improve during certain activities.
  • Word-finding difficulty — searching for the right word, or substituting a related but incorrect word.
  • Severe fatigue — overwhelming tiredness that does not improve with rest and is not explained by other medical conditions.

Dissociative Seizures (PNES)

Dissociative seizures — also called Psychogenic Non-Epileptic Seizures (PNES) or Functional Seizures — are the most widely recognised FND symptom. They resemble epileptic seizures but arise from a different mechanism: the brain's normal protective responses become activated in a way that produces episodic, involuntary events.

Hyperkinetic PNES

Convulsive shaking, jerking movements, thrashing, or whole-body rigidity. The person may cry out, drool, or bite their tongue. Often misidentified as epilepsy.

Diminished-awareness PNES

Staring, unresponsiveness, confusion — appearing "switched off." The person does not respond to their name or environment. May include subtle repetitive movements (automatisms) like lip-smacking, hand rubbing, or picking at clothes.

Mixed PNES

Seizures that begin with one presentation and transition to another — e.g., staring, then escalating into convulsive shaking.

PNES with autonomic features

Episodes dominated by racing heart, hyperventilation, flushing, or a feeling of impending doom — may be mistaken for panic attacks or vice versa.

ⓘ Key distinguishing feature

In PNES, eyes are typically closed during the event. In epileptic seizures, eyes are usually open. PNES episodes often last longer than epileptic seizures and may involve resistance to being held or turned. Up to 1 in 5 people with epilepsy also have PNES — the two can coexist. A video EEG telemetry recording during an event is the definitive test.

Autonomic Symptoms in FND

The autonomic nervous system — which controls heart rate, breathing, digestion, and other involuntary functions — can also be affected by FND.

  • Functional palpitations — awareness of a racing or irregular heartbeat, often triggered by hyperventilation or anxiety. Can be very frightening and may lead to emergency room visits.
  • Shortness of breath — feeling unable to get enough air, often accompanying hyperventilation. Can closely resemble asthma or a pulmonary embolism.
  • Functional abdominal symptoms — nausea, bloating, pain, and altered bowel habits with no structural GI disease.
  • Temperature dysregulation — feeling excessively hot or cold without a fever or infection.
  • Sweating abnormalities — excessive sweating or an absence of sweating in certain body areas.

Symptom Type Summary

FND symptoms can be grouped into categories. Many people experience symptoms from more than one category simultaneously.

Category Common symptoms Key features
Motor Weakness, tremor, dystonia, gait disorder, myoclonus Inconsistent; distractible; non-anatomical pattern
Sensory Numbness, tingling, vision changes, hearing loss Pattern ignores dermatomes; can fluctuate rapidly
Cognitive / Speech Brain fog, memory problems, functional speech problems Highly variable; worsened by stress and fatigue
Dissociative seizures (PNES) Convulsions, staring, automatisms Eyes usually closed; variable duration; can coexist with epilepsy
Autonomic Palpitations, breathlessness, abdominal symptoms Often triggered by anxiety or hyperventilation
← Continue reading

New to FND? Start with the full explainer: What Is FND? (The Complete Guide) — covers what FND is, how it is diagnosed, and what treatment options exist.

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Medical disclaimer

This article is for informational purposes only and does not constitute medical advice. Always consult a qualified neurologist or healthcare provider for diagnosis and treatment.