- Definitions/ Essential features (ICD11 criteria)
- Symptoms of FND
- Potential history features
- Examination findings of motor or sensory FND
- Functional seizures
- Making and communicating the diagnosis
- Treatment of functional neurological disorders
- Take-home messages
- Examples of media related to this area of interest
Functional neurological disorders are some of the most common neurological problems and are conceptualised as disorders of the functioning of the nervous system (rather than the structure). They can cause a wide array of symptoms, such as seizures, weakness and dizziness, and typically there are clinical features that actively support the diagnosis of FND. Previously deemed untreatable and labelled as ‘medically unexplained symptoms’, there are now therapeutic options available with neurological mechanisms being recognised as underpinning these disorders.
Definitions/ Essential features (ICD11 criteria)
-It is no longer a diagnosis of exclusion, owing to examination and history findings possessing high sensitivity for these disorders.
-‘Involuntary disruption or discontinuity in the normal integration of motor, sensory or cognitive function, lasting at least several hours’
-‘Clinical findings not consistent with disease of the nervous system or another medical condition’
-Symptoms not due to a recreational drug, medication or alcohol use/withdrawal, or sleep-wake disorders.
-‘Not accounted for by another mental disorder’, for example, post-traumatic stress disorder (PTSD) or schizophrenia.
-These symptoms lead to an impairment in functioning, such as social, occupational, and relationships.
Symptoms of FND
-Functional seizures (also can be termed dissociative)
-Motor symptoms (e.g. weakness, tremor)
-Sensory symptoms (numbness, pins and needles)
-Mixed motor/ sensory
-Cognitive symptoms (e.g. poor memory and attention)
The diagram below gives examples of the variety of possible symptoms at presentation:
In addition, there are other symptoms that are commonly associated with FND, such as fatigue, headache, anxiety, pain and poor sleep.
Potential history features
The challenge in these cases is the diversity and often multiple co-existing symptoms and clinical signs present. For a non-specialist junior, it is recognising that the presentation in front of you does not reflect alternative pathologies, whilst also not experiencing diagnostic overshadowing in a patient with a history of functional neurological disorder.
The following outline the common characteristics of the presenting population, however, patients can fall outside of these:
-Typical age range is between puberty to young adults (35 years of age)
-Female: Male 2-3:1
-Previous history of trauma e.g. physical trauma, childhood abuse, parental neglect
-Previous history of mental health or physical health condition e.g. schizophrenia, epilepsy, multiple sclerosis
-Experience symptoms similar to that of a relative with a condition e.g. functional seizures in a relative of an epileptic.
Examination findings of motor or sensory FND
The table below outlines some of the presenting features that can be elicited on examination. Some have high specificity (positive Hoover’s sign) but low sensitivity. Therefore, their presence is highly specific for FND, but often they are not present.
Table outlining the potential findings from limb and truncal neurological examination.
Table outlining the potential findings from cranial nerves examination.
This is the most common subtype of functional neurological disorder. The previous names for this condition include non-epileptic seizures and pseudoseizures. This diagnosis makes up as much as a quarter of all cases presenting to epilepsy clinics, with 80% of these patients being female and 90% having a history of other psychiatric comorbidities and/or previous adverse life events.
Making and communicating the diagnosis
These conditions are typically made by a senior, most commonly in the specialties of neurology, psychiatry and paediatrics. However, as the junior, you may meet those with a suspected or a known diagnosis, where you are the clinician listening and answering their questions and concerns. For some patients, a functional diagnosis is accepted and is reassuring, but stigma remains. A thoughtfully delivered diagnosis with signposting to support services and extra information can be a way to show the patient that there are therapies available.
Treatment of functional neurological disorders
It should be first noted that the treatment of these disorders can be first hampered by strain on services, with long waiting times being commonplace for these conditions. This should be explained to the patient early on to manage expectations.
The mainstay of treatment is non-pharmacological and is instead through psychotherapy and cognitive behavioural therapy (CBT). There are a small number of specialist functional neurological disease centres that can provide inpatient therapies for these patients, but there are issues with high demand and long waiting times. First-line therapies for motor FND includes physiotherapy. There is also occupational therapy and speech and language therapy (SLT) inclusion in the multidisciplinary team, particularly for motor type with dysarthria.
Another important treatment a specialist will do is weaning patients off medications that have been prescribed for an organic disease that they do not have, such as anti-epileptic medications in a patient with functional seizures. This should be done thoughtfully, with the involvement of the patient and their family. The role of SSRIs and SNRIs is if comorbid mental health disorders co-exist, not directly for FND.
-FND is common and usually presents as a recognisable syndrome.
-Referral to a neurologist for diagnosis enables patient access to treatment, with prevention of potentially further unnecessary investigation or treatment (e.g. antiepileptic medications).
-FND can co-exist with other neurological and physical health conditions therefore, avoid diagnostic overshadowing in this cohort.
Diagnosis and management of functional neurological disorder, Selma Aybek and David L Perez, BMJ 2022.
Functional Seizures, Evie Marcolini and Benjamin Tolchin, Emergency Medicine clinics of North America, 2021.
Functional neurological disorder: new subtypes and shared mechanisms, Mark Hallett et al, Lancet 2022.
Braincast- a Maudsley Learning podcast hosted by Dr Sotiris Posporelis, a very charismatic host with a variety of guests in the field of Functional Neurological disorders and the broader field of Psychiatry.
This Article was written by Dr Isobel Platt (FY2 Neurology) and was edited by Dr Jacob Day (Neurology Specialty Registrar)
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