Functional Neurologic Disorder (FND)

Authors

Affiliations

Nate Yomogida, B.S., SPT

Doctor of Physical Therapy

B.S. in Kinesiology

Chloë Kerstein, B.S., SPT

Doctor of Physical Therapy

B.A. in Neuroscience

History of FND

Conversion Disorder

These disorders were traditionally termed “Conversion disorder” by Freud and his followers to describe the conversion of “psychic energy” into physical symptoms¹

Psychogenic Neurologic Disorder

2 types of clinical psychogenic neurologic disorders:

Note

Both of these disorders are considered to have no physical explanation of symptoms¹

Chronic illness + Classical Hysteria

A chronic illness marked by multiple and often dramatically presented symptoms and somatic abnormalities of “classic hysteria,”
Predominantly in women (there is potential sexism and acquisition bias in this categorization but we report our and our colleagues contemporary experience) and

Compensation Neurosis

Inexplicable disability or symptomology
Individual is obtaining compensation, influencing litigation, avoiding military duty or imprisonment, or for the manipulation of some other interpersonal or societal situation.
- This latter state has been called compensation neurosis, compensation hysteria, or hysteria with sociopathy, in other words, malingering.
Predominantly of men but also of women who

Pathophysiology Framework of FND

Note

Through studies, it has been shown that functioning of brain is different than feigning².

FND has been described as dysfunction across brain circuits³. Of these brain circuits, 5 constructs have been created³.

Emotion processing (salience)

Dysfunction in the emotional processing construct manifests as emotional reactivity, deficits in emotional awareness (ie physiological arousal in absence of emotional arousal), amplification of FND symptoms in some mood states (ie panic, shame), aberrant salience processing, etc³.

Agency

Dysfunction in Agency manifests as impairment in belief/circuit around: Pt is agent of action/Free will → produces voluntary movement³. Movement lacking self agency is experienced as involuntary³. These involuntary movements are clinically deemed functional tremors or functional seizures, but the brain areas generating these movements are the same ones involved in the production of voluntary movements³.

Attention

Attentional perseveration is defined as the “tendency to focus on a physiological system to the neglect of other systems, and an impaired ability to adaptively, volitionally shift attention³.” This concept is analogous to hemineglect syndrome wher patients can attend to his/her unaffected body parts but this focus is considerably difficult and requires conscious effort³. Likewise, patients wtiAllocate attentional resources to threat stimuli (ie angry faces) (especially those with functional seizures)

Interoception

Interoception refers to a process by which the nervous system senses/interprets/integrades internal body signals into conscious and unsconscious perceptions of sensation³. In FND, the percetion produced through interoception can be abnormally enhanced or diminished³. Abnormal interoception sensations can materialize as attenuated visual, auditory, or skin sensitivity³. Abnormal interoception can impact movements and result in tremors, dystonia, seizures, and weakness³.

Predictive processing/inference

Predictive processing/inference refers to the process by which a person generates beliefs about cause/effects of events within/outside body³. Environmental conditions can rapidly alter this process³. FND patients with this dysfunction can demonstrate erroneous perceptual inference (about sensorimotor or emotionally valenced phenomena), and their beliefs become reality³.

items that need to be cleaned up and added to the paragraph

Deficits in decision making and sensory processing³. Prior history dominates ongoing perspectives³.

Examples

Someone who expects weather to be cold will wear a winter jacket even on a sunny day in summer³.
Functional leg weakness → pt does not sense that limb IS there, opposite of phantom limb syndrome³.

Abnormal sensory input

updated by sensory input that indicates it IS there

Subjective

History

Note

Due to the importance of MOI and risk factors, the subjective should Focus on predisposing, precipitating and perpetuating factors!²

Adverse experience in childhood/recently? (very common)
- Attachment theory (life growing up)
Consider: Social/cultural norms, life experiences, religion, language, stress
Psychological comorbidities
Comorbidities

Other medical evaluation

Beliefs about the medical system
Low rate of misdiagnosis → did a doctor diagnose?²
- IBS? Chronic pain syndromes? CRPS?²
Imaging

Mechanism of onset

What did you notice when it first started (emotions? Events? Drug side effects? Dissociation? infection?)²
What are your triggers now? (if any)²

Functional limb Weakness

Functional limb weakness
- Does it feel like the body does not belong to them?²
- Any sensory disturbances associated with it?²
- Collapsing weakness?²
- Any falls?
Expect: voluntary movements are hard while automatic ones are preserved. Also expect that there is a global pattern- affects flexors/extensors equally²

Involuntary movements

Functional tremor?
- aggs/eases?
Functional seizure:²
- any urinary incontinence/physical injury? Seizure plan?
- Any precursors like autonomic arousal? → note:

Note

functional seizures can be seen as an involuntary, learned brain “reflex” that gets rid of unpleasant sensations. Can explain to patients this way.

Note

Side note: No medications (seizure meds) should be used as it can exacerbate events → as much as 40% of pts with functional seizures can improve with meds (however, likely placebo effect)²

Functional dystonia

Presence
Aggravating factors
Easing factors

Urinary retention/scan negative cauda equina

CBT usual tx²

Functional cognitive symptoms

Memory problems?²

Note

Memory problems in FND are likely d/t attentional deficits (lapses in concentration)²

Metacognitive error is prominent in the form of catastrophic negative self evaluation of one’s own cognitive performance (up to 24% of pts attending memory clinics may have functional cognitive disorder)²
Examination of behavior and language during consultation discriminates functional from degenerative cognitive symptoms – those with functional cognitive disorder are likely to attend meetings alone, be distressed, give rich/specific accounts of memory failures compared to those with neurodegenerative disease²
CBT helpful, contextualizing memory lapses that fall within normal, tackle unhelpful avoidance, and excessive/counterproductive use of memory aids/strategies (think post its etc). Also treat comorbid anxiety/depression as common².

Other symptoms

Fatigue? Sleep disturbance? Concentration symptoms?²
Speech problems (dysarthria, mutism, foreign accent syndrome), sensory problems (numbness/positive sensory symptoms, especially with motor symptoms) , hearing loss/sensitivity, visual loss/diplopia, globus, PPPD (chronic dizziness)²

APTA Recommendations

Per APTA may be beneficial to ask:

Does the disorder produce more attention from a spouse?
Does the disorder mean that the patient does not have to return to a job that she/he did not like?
Is the amount of money received with disability insurance more, or more secure, than what the patient might get by working?
Does the patient know how to get a job or what job she/he has sufficient expertise to do?

APTA’s red flags

Per APTA- Red Flags suggesting FMD

Adult age of onset
Paroxysmal tremor as predominant clinical feature
High phenomenological variability between episodes
Rapid and maximal severity
Precipitation of attack or increase in symptom severity during examination
Atypical and variable duration of attacks
Presence of multiple atypical triggers
Altered level of responsiveness
Presence of odd precipitating factors
Presence of unusual relieving maneuvers
Additional functional physical signs or medically unexplained somatic symptoms
Atypical response to medication
Presence of somatization

Objective

Functional limb weakness

Note

Note/Pt edu: Functional leg weakness → pt does not sense that limb IS there, opposite of phantom limb syndrome. Abnormal brain prediction that leg is not there, which overrides/fails to be updated by sensory input that indicates it IS there²

Hoover’s sign

A clinician can check for Hoover’s sign in order to differentaite between general hip extension weakness and functional hip extension weakness.

Technique (assuming the L hip is demonstrating weakness):

Patient goes into hip extension against resistance with L leg
Test patient’s ability to perform resisted hip flexion on the right leg which indirectly tests hip extension on the left leg.
If the patient has L hip extension weakness against direct resistance, but has sufficient strength against resistance with R hip flexion, this is considered positive

Hip Abductor Sign

Weakness of hip abduction that returns to normal with contralateral hip abduction against resistance

Arm Drop Test

^APTA?

Patient is positioned in the supine. Ensure the patient’s face is shielded (in case of an organic etiology). Lift the patient’s plegic arm, suspending it over the patient’s face, then suddenly dropping the arm. If the patient has FMD, the patient will deflect the arm from hitting the face in the case of FMD.

Functional limb weakness should be treated with patient education

Functional Tremor

In the arms, ask the patient to copy a rhythmical movement made between finger/thumb using their better hand². In the legs, ask the patient to copy foot tapping². And in the neck, have the patient follow movements of your hand with their tongue².

In a functional tremor, one should expect to see variable frequency (not amp) tremor that changes dramatically during externally cued rhythmic movements². If the tremor on the other hand stops, entrains to the same rhythm, or pt has difficulty copying movement → consider functional tremor².

Other distraction maneuvers via APTA

Finger tapping movements at different speeds
Side-to-side tongue movements
Counting-serial 7 backward
Contralateral rhythmic ballistic movements

Note

While a functional tremor will entrain with distraction, an organic tremor will typically increase in amplitude with distraction. Entrainment can result in remission in FMD during distraction maneuvers with uninvolved limbs

Other presentations of functional tremors
Item	Phenotype
Optional Features
Ballistic suppression	Brief arrest of tremor with performance of a ballistic movement in the opposite limb
Dual task interference	Disruption in tremor frequency and amplitude when simultaneously executing a competing task
Increase amplitude with weight loading	Tremor amplitude increases with increasing weight applied to limbs
"Whack-a-mole" sign	Spread of tremor to another body part when restrained by the examiner’s hand
Other functional signs or phenotypes	Give-away weakness, non-dermatomal hypoesthesia, associated functional gait disorder, functional dystonia, etc
Universal features
Frequency variability	Tremor frequency changes throughout examination
Entrainment or full suppressability	Tremor either disappears (suppressability) or adopts the frequency of a repetitive task elsewhere (entrainment)
Distractibility	Tremor amplitude attenuates when attention is driven away from affected body part
Tonic coactivation	Co-contraction of antagonistic muscles immediately prior to reemergence of tremor
Source:⁵

Note

Many movement disorders worsen with stress/disappear with sleep → do not rely on these sx for a diagnosis

Functional Dystonia

Functional dystonia can presenta s fixed abnormal posture, but other forms are usually mobile²

Can present as:

Inverted/PF ankle
Flexion of fingers
Face dystonia (jaw deviation to one side + contraction of platysma + lip curl down/upward + facial weakness + contraction of orbicularis oculi can be present + eyebrow lowered on affected side²)

Functional dystonia commonly results in secondary symptoms of pain which can severely impede with ADLs².

Functional Seizures

Signs of functional/dissociative seizures:

Longer duration >90 seconds².
Fluctuating course².
Asynchronous movements².
Side to side head or body movement².
Closed eyes².
Memory of the event².

Signs for epileptic seizures

Post ictal confusion².
Stertorous breathing².

Functional Sensory symptoms

Yes/No Test

In the yes/no test, the patient is asked to say “yes” when they detect a stimulus and “no” when they do not detect a stimulus. A response of “no” immediately after a stimulus may indicate a nonorganic sensory loss. A response of “no” would suggest that a functional disorder is not present, as a truly anesthetic patient would not feel anything and therefore would not respond.

Forced choice test

In the Forced-Choice test, the patient is asked to distinguish between a sharp or dull stimulus, and an upward or downward movement of a toe or finger. A percentage of correct responses in a series of trials that is less than that observed by chance may indicate nonorganic sensory loss.

Interventions

Note

Note: many have negative experiences with healthcare → education is key about their brain/NS functioning. Never use a “nothing wrong” accusation. Finding a root cause is uncommon, as it is multifactorial

Patient Education

Communication of diagnosis/understanding

Example

“FND is a problem with the functioning of the NS, a problem with the software, not the hardware”²

Limb weakness

Example

After Hoover’s sign

”Did you see how your leg returned briefly to normal when I did that test (Hoover’s sign). That shows us that there is a problem with the way your brain is sending the signal to your leg (voluntary movement), but the automatic movements are still okay”².

Limb blindness

Example

“Have you heard of phantom limb syndrome? That’s when someone has an amputation, but their brain still thinks the limb is there. FND is a bit like the opposite, the leg/vision/sensation is there but the brain thinks it isn’t anymore. The map of that part of the body in the brain has gone wrong”².

Weakness/movements

Example

“Functional brain scans have shown that the brain is working too hard in FND. Normally we shouldn’t have to think about how to move our arms our legs. As soon as our brains start to work on this too hard it goes wrong. It’s similar to thinking about your feet when you are climbing upstairs, or trying too hard to fall asleep at night”².

Seizures

Example

“Functional seizures are when the brain goes into a trance-like state called “dissociation” suddenly, all by itself. This is the medical word for being cut off or distant from your surroundings. That’s a bit like the feeling you have just before your seizures sometimes. We think it does this as a “reflex” response – sometimes to get rid of a horrible feeling that many people report just before. After a while, it will often happen for no reason and when people are most relaxed”².

Dystonia

Example

“Your brain thinks that the foot is straight even though it’s turned inwards. That’s why it’s hard for you to keep it in a straight position”².

Note

Cervical dystonia clinical pearl from ReActive PT instagram page:

Skipping with scarves
Scarves are a great external focus for eyes/head movement (great for automatic head movements)
Postural responses : bouncing, skipping, dancing, moving on a tilt board/bosu can all help with automatic responses
Postural righting responses = automatic head movement

Associated pain

Example

“Chronic pain is usually due to an ‘increased volume knob’ in the pain pathways throughout the nervous system, but especially the brain. This is called ‘central sensitisation’ and, like FND, is also a problem with abnormal nervous system functioning”².

Prognosis

Note

“It is not an easy problem to put right, many factors affect it, but there is a potential to improve and many do make a full recovery”².

How physical therapy can help

Example

“Physiotherapy can help ‘retrain’ the brain in FND. It works best when we can use those principles of distraction that I showed you. A physiotherapist may ask you to try to speed up the movement or do it in an unusual way, to music or in a mirror. Somewhere in your brain we think the automatic movements are in there, and we need to coax them out”².

Psychologists

Note

“It is common in FND for people to have problems like anxiety and depression. This can be a consequence of having the symptoms but, in many, it is already there for other reasons. FND symptoms make people fearful of falling and being injured and of being embarrassed. For some, there are things that have happened which may explain why your brain is vulnerable to going wrong in this way and could be worth exploring. I think a psychiatric/psychological assessment could be helpful. What do you think?”²

Patient Resources

Neurosymptoms.org

FND Hope

FND Action

Functional MOTOR disorder (FMD) (what PT treats!)

Note

based on⁶

Consensus recommendations

Education (normalize illness beliefs, reduce abnormal self directed attention, break down learned patterns of abnormal movement)⁶.
Demonstrate normal movement can occur (through automatic pathways)⁶.
Retrain movement with diverted attention⁶.
Change maladaptive behaviors related to symptoms⁶.

General Treatment Principles

Build trust before challenging the patient⁶.
Limit hands on treatment, facilitate- do not support⁶.
Encourage early WB (bed strength does not correlate with ability to walk/stand)⁶.
Foster independence/self management with goals⁶.
Goal directed rehab - focus on functional/automatic movements (ie walking) rather than impairments (weakness) and controlled (requiring lots of attention) movement (like strength/non automatic movements)⁶.
Minimize use of maladaptive patterns/positions (retrain with correct biomechanics)⁶.
Avoid adaptive equipment/aids unless absolutely necessary (never recommend splints)⁶.
Challenge / recognize unhelpful thought patterns⁶.
Develop a relapse prevention plan⁶.
NEVER say psychogenic/conversion disorder, use functional movement disorder or weakness/paralysis/tremor/dystonia etc⁶.
Acknowledge that their symptoms are real, and not imagined⁶.
Acknowledge that these symptoms are common and you FREQUENTLY see patients with these symptoms (trust is huge, they need to buy in completely)⁶.
Explain that their symptoms can get better : the problem is with NS functioning and not actual physical damage to the NS⁶.
Explain that FMD is diagnosed with clinical signs which demonstrate normal movement is possible, and physical therapy can help coax out the automatic movements that were once within your brain. (through distraction, music, etc)⁶.
- Clinical signs: hoovers, hip abductor sign, abolishing tremor with rhythmical movements⁶.
Explain a wide variety of factors can cause symptoms → physical illness, injury, psych factors like anxiety/depression/trauma⁶.
- PT can retrain the NS to regain control over movement⁶.

Language

Correctly remove blame/fault/voluntariness⁶.
- “Brain is attending to your body in an abnormal way, your tests show that your muscles are capable of movement, but we have to retrain your nervous system to allow that movement to happen”⁶.
To cue “ALLOW your leg to come forward”, do not say: “step your leg forward”⁶.

Treatment ideas

Retrain movement through diverted attention⁶.
- Minimize self focused attention by distracting/preventing the patient from cognitively controlling movement and to stimulate automatically generated movement⁶.
- Can be achieved by altering focus of motor attention, such as thinking about a different part of the movement or trying FAST, RHYTHMICAL, UNFAMILIAR, OR UNPREDICTABLE MOVEMENT⁶.
- Distraction
  - Conversation, music, mental tasks (like math)⁶.
  - Task oriented exercises are preferred (effective, translate directly into improved function, encourage implicit motor control)⁶.
  - WB/automatic postural responses like sitting on an unstable surface- like a therapy ball⁶.
- OTHER ideas to normalize movement:⁶.

Treatment Plan

Mechanism

Symptoms

Note

functional seizures can be seen as an involuntary, learned brain “reflex” that gets rid of unpleasant sensations. Can explain to patients this way.

References

Ropper AH, Samuels MA, Klein J, Prasad S. Adams and Victor’s Principles of Neurology. 12th ed. McGraw Hill; 2023.

Bennett K, Diamond C, Hoeritzauer I, et al. A practical review of functional neurological disorder (FND) for the general physician. Clinical Medicine (London, England). 2021;21(1):28-36. doi:10.7861/clinmed.2020-0987

Drane DL, Fani N, Hallett M, Khalsa SS, Perez DL, Roberts NA. A framework for understanding the pathophysiology of functional neurological disorder. CNS spectrums. Published online September 2020:1-7. doi:10.1017/S1092852920001789

Sonoo M. Abductor sign: A reliable new sign to detect unilateral non-organic paresis of the lower limb. Journal of Neurology, Neurosurgery, and Psychiatry. 2004;75(1):121-125.

Schwingenschuh P, Espay AJ. Functional tremor. Journal of the Neurological Sciences. 2022;435:120208. doi:10.1016/j.jns.2022.120208

Nielsen G, Stone J, Matthews A, et al. Physiotherapy for functional motor disorders: A consensus recommendation. Journal of Neurology, Neurosurgery, and Psychiatry. 2015;86(10):1113-1119. doi:10.1136/jnnp-2014-309255

Citation

For attribution, please cite this work as:

Yomogida N, Kerstein C. Functional Neurologic Disorder (FND). https://yomokerst.com/The Archive/Neuroscience/Neuropathology/Functional Neurologic Disorder/functional_neurologic_disorder_FND.html