Functional Neurology

By Rebecca Young (4th year, Newcastle University Medical School)

plus a few added videos that I have "borrowed" from youtube. Hopefully the owners won't mind as I think they illustrate the breadth of the disorder and how difficult it can be to diagnose and treat.

The videos are often American, so the terminology is a little different - Ed

What are they?

Functional neurological symptoms are caused by an issue with the functioning of the nervous system, rather than a disease of the nervous system itself. It can be described as being an issue with the “software” rather than the “hardware” of the nervous system.

It is important to recognise that these symptoms are real, not necessarily related to mental health and can seriously affect patient’s day to day functioning and quality of life.

Why do I need to know about them?

Functional neurological symptoms are really common; in fact they are the second largest cause of presentation to neurology outpatients, after migraines. They make up 10-30% of presentations to secondary care neurology and affect about 1/200 of the general population.

They can be severely disabling and are often misdiagnosed, so it’s important to be able to recognise and properly manage these patients.

How do they present?

Patients often suffer from more than one symptom at once. There is an extensive list of symptoms which patients may suffer from.

Patients have often had their symptoms for many years, have seen lots of healthcare professionals about them and have undergone lots of investigations.

Here are some of the more common presentations discussed in greater detail:

Motor symptoms

Dystonia

Commonly presents with curled fingers/clenched hand or the patient’s ankle turning in, although it can affect any area of the body

Can be intermittent dystonia (spasms) or chronic
May begin suddenly or come on gradually
Pain is common in patients with dystonia and there is often an overlap with complex regional pain syndrome
Differentials include primary dystonia or secondary dystonia due to medication, head trauma, Wilson’s disease, neuronal brain iron accumulation and Parkinson’s disease.

Tremor

The tremor often has a variable frequency and fluctuates in severity.
It can occur after injury, as a part of chronic regional pain syndrome, after getting a tremor from a medical problem e.g. as a medication side effect, after a panic attack, with dissociation. Equally, there may be no trigger.
The patient may have a new tremor or a pre-existing essential tremor may be amplified
If the tremor is functional the patient is likely to display these positive signs:
Entrainment – ask the patient to tap on their knee with one hand, the tremor in the contralateral hand will take on the rhythm of the tapping
The tremor should reduce when the patient is distracted. This can be elicited by getting the patient to work out a mathematical sequence.
The tremor will often get worse when the limb is held still

Differentials include essential tremor, Parkinson’s disease and associated syndromes, medication induced tremor, metabolic issues such as hyperthyroidism and B12 deficiency, cerebellar disorders and rubral tremor.

Weakness

The patient may experience a feeling of “heaviness” down one side, drop things or say that the limb doesn’t feel like a part of them
On examination there is often weakness but no other neurological signs e.g. normal reflexes and tone.
Some positive signs which may suggest a functional diagnosis:
Collapsing weakness – the limb “collapses” when being tested. Often, the limb gets weaker the more the patient tries.
Hoover’s sign – weakness of hip extension which resolves on hip flexion

A dragging walk, as opposed to leg swinging as in stroke or MS
Differentials include stroke, multiple sclerosis, myopathy, brain tumours, myasthenia gravis and polymyalgia rheumatic.

Non-epileptic attack disorder (NEAD)

Non-epileptic attach disorder can present as an attack with or without movement
Attacks with movement typically involve thrashing movements which can look like a generalised seizure. Attacks without movement commonly involve patients collapsing and lying unresponsive and motionless for several minutes.
75% of patients are female with a high incidence of personality traits/disorder.
Seizures can occur randomly, at rest and not distracted (e.g. in bed), with hyperventilation and with depersonalisation or derealisation.
50% of the time patients have “warning” panic symptoms.

Cognitive problems

Cognitive symptoms such as memory loss and poor concentration are especially common where there is also poor sleep, low mood or anxiety.

Organic	Functional
Patient brought in by relative or friend	Patient attends alone
Someone else has noticed the symptoms	Patient has noticed the symptoms themselves
Older age group	Younger age group
More likely to be constant and progressive	More likely to fluctuate and be circumstantial

Figure 4: features which can help differentiate organic and functional cognitive problems

Visual problems

Patients can experience a range of symptoms:
Visual blurring due to convergence spasm – mimics a 6^th nerve palsy causing miosis, convergence and accommodation. Vision often improves with distraction.

Photophobia – patients commonly on the same side as any functional weakness. The patient may start wearing dark sunglasses but it is important to encourage gentle light exposure so that the eyes don’t become too sensitised.
Blindness – patients may report loss of vision in one or both eyes, but often their light and accommodation reflexes are still intact. The “moving stripe” test can be carried out (getting patients to watch a screen of moving stripes) – even though the patient cannot see the screen, the eyes move as if they were watching the stripes.

“Tubular fields” – the patient experiences a visual field defect where they can only see in the centre of their vision. Unlike an organic visual field defect, if you move further backwards to test the patients visual field, they will not be able to accommodate and therefore see more of the field. The condition is likened to “looking down a cardboard tube”.

It’s important to carry out a full eye examination in patients presenting with these symptoms. In functional conditions, the examination is generally normal.

How do we diagnose them?

The diagnosis of a functional neurological condition should be based on the presence of positive signs and symptoms e.g. Hoover’s sign, entrainment.

Certain tests are useful to rule out organic diagnoses e.g. CT head for a subarachnoid or stroke but a diagnosis of a functional condition should not be made on the basis of a normal test result.

How do we manage them?

A multi-disciplinary approach is really important in managing functional problems, and often the best approach is to present all the options to the patient and allow them to guide their own care by choosing which method they think would work best for them.

Medication	Antidepressants can be helpful although it is important to explain to the patient that they are not necessarily being used because in a mental health capacity. Neuropathic painkillers (e.g. gabapentin, amitryptiline) can be useful for pain. Sleeping tablets (e.g. zopiclone) are useful where there is poor sleep. Anti-epileptic medication is of no use in managing NEAD
Physiotherapy	Gradually increasing the level of activity and keeping it constant using a graded exercise programme can help patients return to normal levels of functioning. To begin with it may make the symptoms worse so it is important to support patients well through this process.
Psychology	Talking to a psychologist or psychiatrist allows patients to explore the symptoms and the behaviours surrounding these symptoms. This may give them the opportunity to discuss behaviours and thoughts which may be standing in the way of recovery.
Strategies	For patients who suffer from NEAD and have a prodrome, being able to recognise an oncoming seizure and learning calming techniques can be used to avert episodes.

Figure 7: management strategies for functional neurological problems

References

Jon Stone, Functional and dissociative neurological symptoms: a patient’s guide, available from: neurosymptoms.org
The Dystonia Society, About Dystonia, available from: www.dystonia.org.uk
Abhishek Ghosh et al., Functional Convergence Spasm, Indian Journal of Psychological Medicine (Online), 2014, 36(3) p. 332-334. Link