For some unknown and poorly misunderstood reasons patients can develop impairment of physical function that can mimic neurological disorders including strokes, cord compressions, seizures etc. By functional we mean that the disorder is not volitional and that the patient is not deliberately feigning injury for some secondary gain. Neurological tests are normal and there is felt to be a disorder of function rather than an underlying pathology.
The clues to establishing a functional disorder as the diagnosis is really based on the collection of findings from the history, examination and imaging and other diagnostic tests. The functional diagnosis should really only be made after a through history, examination and testing which may include imaging. One should objectively assess all findings before making the diagnosis.
Warning bells may begin to ring if there have been a complex past history of similar functional issues such as atypical chest pain, irritable bowel syndrome, various pain syndromes, panic attacks and 'difficult' home environment set ups though in many cases none of these features is present. The GP notes should be obtained and may show a litany of previous attendance at specialists out of keeping with the patient's age. Most functional patients are younger though functional disorders can certainly be seen later in life. If possible get a copy of the full hospital notes being aware that patients often move and local notes may not reflect life long issues.
'La belle indifference' has been used to describe the patient with a functional disorder in that grief at disability seems to be absent. However with right cortical strokes and anosognosia their can be massive impairment with no insight and an indifference. In stroke this could easily be accused with anosognosia seen in right sided strokes and one must make sure that it is not due to this or a global cognitive deficit. The deficit or disability may have direct followed a less severe physical injury. The functional patient history is often convoluted and confused and difficult to establish the chronology easily whereas the stroke patient has a very clear and simple story. The stroke patient has a single symptoms - weakness or speech though the functional patient has a more complex story. Panic and shaking are uncommon in stroke. Functional patients despite obvious signs of distress or fears usually do not discuss or refer to their feelings during the assessment. Painful paraesthesia is commonly a complaint though the aetiology is unclear. There may be a mild hyperventilation syndrome due to abnormal breathing. Many of the functional patients in my experience tend to come from difficult environments and smoke and drink more than their peers. It becomes more difficult when there have been diagnoses of TIA made in the past or even stroke which may or may not be the case.
The more bizarre the presentation and the greater the major improvements with gentle therapy the less likely is the diagnosis to be organic. Indeed if a patient gets up and when walking has extremes of gait with their centre of gravity going way beyond their foot base and then compensating and bringing it back and remaining upright they can only do this if their nervous system is working absolutely normally. Those with organic disease walk with feet apart and do all they can to make sure their centre of gravity always remains as close as possible to their footbase usually with a broad and very careful and cautious gait.
- Behaviour: The affect is often altered. More hyperalert looking at all at what is going on and then drowsy and sleepy. Weakness is usually one sided and often involves arm and leg and even face usually through overstimulation of facial muscles using platysma to pull the lip down and other muscles to partially close the eye. Stroke patients however can behave strangely too.
- Collapsing weakness: this is a tendency for an arm or leg to 'collapse' when being tested. This may be interpreted by a doctor as 'not trying'. In fact, patients with functional weakness typically find that the limb gets weaker the more they try
- Hoover's sign: in this test, your affected leg may be weak when you try to push your foot down into the bed. However, when the doctor asks you to push up with your other leg the strength in your affected leg returns. Some patients with functional weakness use this sign as a form of physiotherapy to encourage normal movement in their affected leg (and to help demonstrate to themselves that the diagnosis is correct)
- Altered gait: Limb weakness is often give way and there is much overuse and grunting and excessive effort associated with simple movements with breath holding. With leg weakness the leg often drags behind the patient externally rotated and actually does some of the pushing. Other gait abnormalities include astasia-abasia patterns with bizarre uneconomical gaits and near falls. Patient often falls onto a safe surface such as bed.
- Hoover's sign: is often positive. When asked to stand and walk a hand on the weak side muscles will demonstrate muscle activity as unconsciousness balance reflexes kick in. It almost goes without saying that tone, reflexes and plantars are normal. Sitting alignment is often normal despite significant unilateral signs and symptoms.
Despite all that is said if I have any doubt then I rely on MRI. Some true stroke patients behave bizarrely and have very odd presentations and I associate this sometimes with thalamic infarcts and deep infarct involving the basal ganglia.
A positive attitude is given by the complete stroke team. It is important unless there is strong evidence to the contrary to treat the patient with time and empathy aiming for a positive outcome and using goal directed therapies. Very few of these patients are being manipulative and deliberate in manifesting an illness. Genuine patients with functional disorders or with structural lesions desire to get better. Without appropriate management patients can settle into a cycle of disability and this can lead to secondary complications. Early appropriate management is key.
I talk about a "functional block" and the aim of therapy and the doctor can play a key role here as inexperienced therapists may be reluctant to mobilise patients who appear unsteady. "We are going to unblock your block with gentle exercise". Again I emphasise these patients are not malingerers and are as equally perplexed at their loss of function and want to get better. Treating them negatively is unfair and does not foster a good patient doctor relationship.
If you perceive that there are stresses or a difficult lifestyle you could suggest that this is a manifestation of stress. Some patients however are unstressed and then simply explaining that the wrong signals are getting through is given. Reassurance that no structural abnormality such as tumour, stroke or MS needs reiterated and that the hardware works fine its just that the programming or software needs work. Therapy needs to follow a few golden tips. Firstly all contact and weight talking should be by fingertips so that the patient takes their own weight. Distraction techniques are useful to distract from the task in hand. Early standing should be achieved and attempts at walking tried. gait often improves with speed or distraction. Walking aids must be avoided. If they have been given by others then try and withdraw them. Set some real goals and make definite plans to achieve them quickly. Assessment should start with simple lying to standing. Do not rush to assist but watch the patients attempts which may be incongruous. Again any help should be minimal or fingertip. Make sure patient takes all weight. Patients whose functional weakness are best managed on the stroke unit and those with delayed recovery should be considered for community stroke rehabilitation as this is where the skills lie to enable recovery.
- Explain absence of serious pathology - Good news
- Problem is abnormal function which needs retrained
- Explain benefits of therapy
- Early standing
- Fingertip approach with therapy avoiding taking any significant weight
- Avoid in bed exercises - early mobilisation
- Avoid provision of aids
- Positive reinforcement and encouragement
- Build rapport and self esteem
- Avoid Over realistic goals but set targets
- Allow patient to have some control
- Involve the family
- Provide written information
- Build up trust
If available it may be reasonable to offer referral to clinical psychology especially for difficult cases.
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