Positive Neurological Signs of FND

Question 1

What are negative diagnostic features of FND?

Answer 1

No disease found that can explain the symptoms

Question 2

What are positive diagnostic features of FND?

Answer 2

Symptoms that are not explainable by physical disease

Question 3

What are the main positive neurological features of FND?

Answer 3

▪️ Impaired conscious function but normal unconscious function
▪️ Incongruence with anatomy and physiology
▪️ Other non-specific signs (e.g., collapsing weakness)

Question 4

What are levels of diagnostic certainty of FND?

Answer 4

1. Documented - remittance with suggestion, physio, psychotherapy, placebo etc
2. a) clinically established features inconsistent over time/incongruent with condition
   b) clinically established features incompatible with organic disease
3. Laboratory (supportive) evidence (e.g., EEG)

Question 5

What levels of certainty are necessary for a clinically definite diagnosis of FND?

Answer 5

1, 2a, and 2b

(3 = supportive

Question 6

What clues may suggest at a functional gait disorders?

Answer 6

▪️ Monoplegic ‘dragging’ gait - imitating what would be expected from leg weakness
▪️ Fluctuations
▪️ Excessive slowness
▪️ “walking on ice”
▪️ Uneconomic postures
▪️ Sudden knee buckling
▪️ improvement with distraction (e.g., when turning)

Question 7

What tests can you use to detect functional gait disorder?

Answer 7

Pull person back to see how they adjust their posture -
▪️ Normal people will adjust movement prediction to stop them falling
▪️ In FND, prediction error so strong they will fall

Question 8

What factors might suggest someone has a functional motor disorder?

Answer 8

▪️ Psychiatric comorbidities and psychological stressors
▪️ Risk factors
▪️ Secondary gain?
▪️ Multiple undiagnosed conditions
▪️ Incongruent with organic movement disorders
▪️ Suggestibility

Question 9

How do functional motor symptoms typically present?

Answer 9

▪️ Abrupt onset - paroxysmal
▪️ Static course
▪️ Spontaneous remission

Question 10

What movement inconsistencies may be indicative of FMD?

Answer 10

▪️ Variability over time in frequency, amplitude, direction, or distribution of movement
▪️ Distractibility reduces/resolves
▪️ Attention increases
▪️ Selective disability
▪️ Entrainment

Question 11

How might a functional tremor present?

Answer 11

▪️ Severe postural tremor with no effect on function
▪️ Mild tremor that greatly affects function

Incongruent!

Question 12

How can you test for a functional tremor?

Answer 12

▪️ Often stops when distracted
▪️ Entrain it to take on a rhythm

Question 13

How does functional fixed dystonia typically start?

Answer 13

With complex regional pain syndrome

Question 14

How can you distinguish functional fixed dystonia from organic?

Answer 14

Will often go away with therapeutic sedation

Question 15

What are the main positive tests for FND?

Answer 15

▪️ Hoover’s sign
▪️ Tremor entrainment
▪️ Tuning fork test
▪️ Monitor gait

Question 16

How can Hoover’s sign be used to test for FMD?

Answer 16

Presence of weakness of hip extension that returns to normal with contralateral hip flexion against resistance

Question 17

How can a tuning fork be used to test for FND?

Answer 17

▪️ Vibrating tuning fork placed on each side of forehead
▪️ Asymmetry in feeling = function because frontal bone is single bone so should vibrate as one