How is the diagnosis of a functional neurological disorder made?

Like any other diagnostic process the first step is the history and physical examination that will be carried out by your neurologist.

• Key features of the history will be:
• What symptoms are you experiencing?
• How long are the symptoms present?
• What was the nature of symptom onset (gradual or sudden)?
• Do the symptoms vary day-to-day?
• Is there anything in particular that makes them worse?
• Was there any trigger before they started- this could range from no trigger, to an accident or to a stressful time period?
• Can you sleep through your symptoms?
• Is there ever a time that you feel they are completely resolved?

A functional neurological disorder can present with several different symptoms- you may have weakness in a leg, numbness or tingling in an arm, double vision or blurred vision, speech issues, bladder issues, tremor or seizures. It is the job of your neurologist to decipher which symptoms are due to a breakdown of function rather than structure.

Your neurologist will go on to perform a physical examination to complement the findings from the history.

• The neurological examination will be carried out and if your neurologist feels the problem may be in the functioning of your nervous system there are a few extra physical examination tests that he or she will perform:
• When testing the strength in a functionally weak muscle it is possible to demonstrate that the weak muscle actually has the ability to correct itself- this is called the Hoover sign;
• When testing a functional tremor it is possible to demonstrate that the tremor will change in character along with the other hand in doing a simple “drawing of a spiral” test;
• Some people are unable to move their foot up or down at the ankle when asked to do so in a lying down position but then they are able to stand on their heels and toes;
• Some people have a functional weakness of one side of their face but it is possible to demonstrate that there is actually over-activity rather than underactivity of the facial muscles;
• Some people have seizures during which they are unconscious without moving for prolonged periods of time. Rather than this being due to epilepsy it is more likely a dissociation between consciousness and unconsciousness and these are referred to as dissociative seizures. This is something that is established through the history (rather than physical examination).

All of these signs will help your neurologist make a diagnosis of a functional neurological disorder. Because it is a disorder that is still in the early stages of being fully understood you may not receive the diagnosis without having some tests which usually do not show up any abnormality. In an ideal world the functional neurological disorder would be diagnosed on clinical findings alone however this is not likely to happen until there is a greater understanding of these disorders by the medical profession.

My practice is to explain this diagnosis based on my clinical findings and clinical impression. I will often proceed to an MRI scan or some test where, if there was a structural issue, this is where I would find it. For example, if a patient has weakness down one side and I feel it is a functional problem I will tell them this and I may still go on to do an MRI scan to give both me and the patient reassurance that the structure is normal. And once that test is normal the diagnosis is made- I do not continue doing test after test as I think it is pointless and unhelpful for the patient.