Functional Disorders in Neurology

Question 1

What is a functional disorder in neurology?

Answer 1

FND describes a disorder of the voluntary motor or sensory system with genuine symptoms including paralysis, tremor, dystonia, sensory disturbance (including visual loss), speech symptoms, and seizures.

The hallmark is that such symptoms can be positively identified as internally inconsistent or incongruent with recognised pathophysiological disease.

Question 2

Describe the parts of the Gordian Knot (worries and confusion)

Answer 2

• ‘Missed’ neurological or medical disease (5%)
• As yet undefined neurological or medical disease
• Factitious Disorder or Malingering, rare and requires definitive evidence
• Neurological vs Psychology vs Psychiatric

Question 3

How to take a history of functional neurological disorders

Answer 3

Look for other functional symptoms / syndromes in the GP letter
Make a list of all physical symptoms at the beginning
Framing: What do they think is wrong, do they want explanation, treatment or just a consultation?

Think about the MECHANISM of the symptoms
Consider other physiological/disease triggers – e.g. pain, injury, disease
Look for dissociative and panic symptoms

Question 4

What should you not do?

Answer 4

Don’t believe all the physical diagnoses in notes
Don’t wade in with blunt questions about ‘Depression’ or ‘Anxiety’
Don’t make a diagnosis of functional symptoms because someone is ‘nuts’
Don’t avoid a diagnosis of a functional problem because someone is ‘normal’

Question 5

How to examine patients with functional neurological disorder

Answer 5

Make a diagnosis of a functional disorder on the basis of positive physical signs (e.g. Tremor distractibility, Hoover’s sign) and a familiar history
-Pathways of NS are intact, activated through examination
Not because the scan is normal
Not because the symptoms are unfamiliar / weird

Question 6

What are dissociative disorders?

Answer 6

• Change in conscious perception of self
• mild dissociation associated with FND is not necessarily ‘caused’ by early childhood trauma. That evidence is largely from personality disorder research (e.g. DID). Great care is needed when exploring this area in clinical practice.

Question 7

What may cause them?

Answer 7

A disorder of PFC modelling for self? (i.e. wrong Bayesian priors)

Dissociation – can be viewed as a disorder of the self to be modelled accurately (or at all)

Tremor & Dissociative seizures more complex but potentially amenable to such an interpretation

Question 8

What are potential triggers/ sustaining factors of dissociative disorders?

Answer 8

1) Pain
Enormous attentional salience:
Consequences for cognitive capacity & sensory processing accuracy (generally)
Impact on motor activation (guarding)

2) Disability/Disease
Models are plastic – if a leg is immobilized for a period, the brain learns to expect that it won’t move when standard voluntary pathways are activated. That model can persist after the immobilization is removed.

3) Mood disorders
Anxiety increases arousal and amplifies sensory perception (hypervigilance)
Depression reduces arousal and de-amplifies sensory perception + motor activation

Question 9

What are the treatments for this condition?

Answer 9

Underling disease and disability (if possible)
Pain
Mood disorders
Deconditioning
Positive reinforcement factors (family, money, doctors)

Question 10

How would you explain the condition?

Answer 10

Tell them what it is….
Explain why you are making the diagnosis
Typical features on examination
Describe something about WHAT’S gone wrong (eg. brain software not working)
Don’t spend too long on WHY its happened because its complicated and we often aren’t sure