FND

Question 1

Define FND

Answer 1

FND is a neurological disorder that are altered by attention and occur in a dysfunctional neurobiological system, but people can still function normally.

So for example, you have a person with a gait problem, but when we distract the person, they are able to walk normally and function normally

Question 2

what are some features seen in FND

Answer 2

-functional weakness
-functional dystonia
-functional gait disorder
-functional jerks
-functional tic like behaviours
-paroxysmal non-epileptic seizures

Question 3

what are some risk factors for FND

Answer 3

This is a multifactorial disorder with many risk factors.

Physical – i.e., minor trauma, a fall and hit the knee and can trigger FND

Epigenetic factors – unknown, currently being researched

Other neurological disease- epilepsy, Parkinson, headache

Social- higher educational level is associated with FND

Psychological life stressors but usually hard to demonstrate upon first examination

Therefore, the way the diagnosis is done is by examining for positive signs

psychiatric diseases

Question 4

what is the age of onset

Answer 4

37-50 years
affects females more than males

Question 5

what are the functional motor disorders of FND?

Answer 5

-FMD with excess movement like dystonia, tremor, jerks, tic-like

-FMD with lack of movement (weakness, slowness)

-Functional gait and balance disorders

-paroxysmal FMD- non-epileptic seizure

-functional cognitive disorder

-functional sensory disorder

Question 6

what is the most common FND and what/where does it affect?

Answer 6

The most common FND is functional weakness, usually affects lower limb and usually occurs on left side (Non dominant side)

Question 7

what is the second most common FND and the others following this?

Answer 7

Then the second most common is functional tremor, following that is functional dystonia, the gait disorders.
There’re often localised in hands, legs, but then you can also see it in eyes and tongue.

Question 8

what non-motor symptoms can those with FND present with?

Answer 8

Individuals with FND also have lots of non-motor symptoms such as anxiety, fatigue, pain (which complicated management), headache, insomnia, panic attacks

Question 9

what does the diagnosis of FND entail?

Answer 9

-clinical history
-clinical examinsation
-electrophysiology
-Inconsistency is variability over time
-Incongruency is not fitting well with something else
-Now we look for positive signs

Question 10

what is an example of an incongruent phenotype (seziure)?

Answer 10

Immediate recovery after a seizure attack with eyes open is a positive sign for FND, as people with epilepsy have their eyes closed during seizure as usually in epilepsy they need some time to recover.

Question 11

what is an example of inconsistency?

Answer 11

This patient has paroxysmal motor disorder characterised by episodic involuntary movements (dystonia-involuntary muscle contraction/spasms, dyskinesia-involuntary erratic movement in trunk, arm, leg, face, ataxia-lose muscle control in arms and legs

Question 12

what are positive signs?

Answer 12

Positive signs are specific clinical manifestations that we see in people with FND and support their diagnosis

Question 13

what are the positive signs in functional weakness?

Answer 13

2 important positive signs for functional weakness

-drift without pronation (people with stroke, have drift with pronation(flexing) whereas FND patients don’t

Hoover’s Sign: If a person is lying down and is asked to lift one leg, they may say they can’t lift it because of weakness. However, when they are asked to lift the other leg, the doctor places their hand under the “weak” leg. Without realizing it, the person will push down with the “weak” leg while trying to lift the other. This involuntary action suggests that there is strength in the “weak” leg, indicating the weakness might be functional (related to how the brain is controlling the leg) rather than due to damage in the leg’s muscles or nerve

Question 14

electrophysiological diagnosis for functional weakness?

Answer 14

It’s a technique, obtaining electrophysiological response, recording from arm or leg, etc. we stimulate motor cortex with machine called transcranial magnetic stimulation, and you induce a contraction in one body part and record response. In stroke patients, we stimulated left hemisphere and record response, such that if the stroke is on the right side when stimulating left hemisphere, the response is delayed. In people with FND, this test is normal as stimulation of motor cortex

Question 15

what are positive signs for functional tremor?

Answer 15

variability of frequency or severity over time

(amplitude, frequency, direction)

clear resolution or reduction upon distraction

clear worsening when attention is focused on symptoms

clear entrainment (They usually ask to perform a finger tapping movement at lower frequency, so their tremor synchronised to the repetitive movement.)

So, when they do slow repetitive movement with their other limb you can see suppression/reduction in frequency of tremor.

This is something you don’t see in Parkinson’s so that’s one way of distinguishing

Question 16

what are some of the main distraction manouvres for functional tremor

Answer 16

side to side tongue movement

finger tapping movements with the contralateral limb

arithmetic calculation

Question 17

what is a way to distinguish between functional tremor and PD?

Answer 17

Typically, functional tremor in lower limbs disappear when their foot is unsupported i.e., in mid-air.
But this is opposite for Parkinson’s disease so when you relax your foot/ leg you will see tremor remaining

Question 18

how can positive signs of functional tremor be identified with electrophysiology?

Answer 18

When we are uncertain, we can electrophysiology, neurophysiology, EMG is a technique used to record activity of muscle and its velocity.
The tremor is a oscillation.

You can see once ballistic movement occurred; tremor stopped

The patient is in lab, connect electrode in different muscles in upper/lower limb. We ask patient to perform takes to see if tremor disappears whilst doing the task or if the tremor amplitude/ frequency changes

Question 19

what is functional dystonia?

Answer 19

Frequent manifestation of FND, characterised by abnormal movement with involuntary fast muscle spasms/ contractions leading to painful abnormal posturing

Cervical dystonia is painful and disabling and is commonest.
Treatment is Botox.
People with functional dystonia don’t respond to Botox so it can be identifiable

Question 20

what are the 3 different types of functional dystonia?

Answer 20

-Functional dystonia can manifest in three ways, as a paroxysmal episode, persistent (a lot of fast movement which is hard to identify compared to organic functional dystonia) -fixed dystonia (fixed posture to one body part which is extremely painful, and can occur in face, and
-mobile functional dystonia.

Question 21

what is one key difference between idiopathic dystonia and functional dystonia?

Answer 21

Idiopathic dystonia, typically when they move other body parts, their dystonia worsens, this called overflow. People with functional dystonia lack overflow

Question 22

what is functional facial spasm?

Answer 22

Hemifacial spasm when they have spasm attacks on one part of their face. This occurs as usually there is a vein in the brain that is pressing against the cranial seventh nerve.

In hemifacial spasm the contraction occurs on ipsilateral side but functional facial spasm occurs contraletally

Question 23

what are the 3 neural mechanisms for FMD?

Answer 23

-First one is disorder of attention (attention is impaired such that this disorder increases when their attention is focussed on the affected body part)

-second mechanism is they have a mismatch between sensory data and their belief expectation (they expect something, but their sensory data produces a different sensory prediction) -Mismatch Between Sensory Data and Expectation: Think of this like going to eat your favorite cookie, expecting that sweet taste, but you bite into it and it’s salty. Your brain expected one thing based on past cookies (sweetness), but your senses just told you something else (salty). Similarly, in functional motor disorders, your brain might expect your leg to move a certain way, but your leg seems to have a mind of its own and moves differently, which can be confusing and distressing.

-third one is mis attribution (abnormal sense) of agency which means the capacity to be in control of our movements. Agency is like the feeling that you’re the boss of your movements—you decide to move, and your body listens. In functional motor disorders, there’s a mix-up with that feeling. It’s like if you wrote a note and later found out it was in someone else’s handwriting. You’d be sure you wrote it, but the evidence says otherwise. With this disorder, you might move your hand, but it feels like you aren’t the one doing it, or it doesn’t feel like it’s your hand acting.

Question 24

why is there a disorder of sensory decoding in FMD?

Answer 24

They have abnormality in decoding sensory info, there’s an alteration in temporal parietal junction (which is an important area to elaborate sensory data and provide sensory prediction

So here we analyse the sensory processing, delivering electrical stimuli to index finger. We deliver a pair of stimuli in intervals like 10 ms, 30 ms going up to 400 ms.in normal subject can discriminate between the two electrical stimuli as separate around 60 ms. Whereas in functional dystonia, they discriminate these as separate stimuli at 100-150 ms. We see this in people with organic dystonia, so this isn’t a test for diagnosis. Its relevant that there is abnormality in sensory processing in FND.

So, people with FND have abnormal discriminatory ability and they cannot produce a sensory predication

Question 25

explain how the pain threshold is altered in those with functional fixed dystonia and why this is?

Answer 25

Pain tolerance in fixed dystonia is higher due to a disconnection between sensory input and mental experience in functional dystonia

Question 26

what are some of the treatments for FND?

Answer 26

-Physical or occupational therapy. Working with a physical or occupational therapist may improve movement symptoms and prevent complications. …
-Speech therapy. …
-Stress reduction or distraction techniques.