December 2, 2023

Takeaways highlights

  1. Establishing causation in functional neurological disorder (FND) cases is a complex process that involves a thorough medical history and examination, evaluation of the temporal relationship between the incident and the onset of symptoms, and the use of diagnostic tests to rule out other conditions.
  2. The variability and inconsistency of FND symptoms can be challenging, but identifying a pattern or certain triggers can support causation.
  3. A psychiatric evaluation can be instrumental due to the strong association between FND and psychiatric conditions such as anxiety, depression, and PTSD.
  4. The claimant’s response to treatment, such as physiotherapy or cognitive-behavioral therapy, can further support the diagnosis of FND.
  5. An expert neurologist witness plays a crucial role in integrating all these pieces of evidence and providing an expert opinion on whether it’s more likely than not that the incident caused the claimant’s FND.
  6. Understanding the legal principles of causation is essential for the neurologist serving as an expert witness, as the court ultimately decides causation based on the balance of probabilities.


The field of neurology is complex and constantly evolving, with a broad spectrum of disorders that can have profound implications on a person’s life. One of these conditions, functional neurological disorders (FND), is particularly challenging, both in terms of diagnosis and legal proceedings. In this context, the role of a neurologist serving as an expert witness is pivotal. This article aims to explore this role in detail.

Understanding Functional Neurological Disorders:

FND, also known as conversion disorder, presents with neurological symptoms, including movement and speech disorders, seizures, and sensory loss, without an identifiable structural neurological disease. The exact cause of FND is still unknown, but it is believed to be a complex interplay of psychological and biological factors.

The Neurologist as an Expert Witness:

In legal cases involving FND, a neurologist expert witness plays an instrumental role. The neurologist’s primary responsibility is to provide an unbiased, accurate, and comprehensive opinion on the claimant’s condition, its cause, prognosis, and impact on the claimant’s life.

  1. Evaluation: The neurologist expert witness conducts a thorough medical evaluation of the claimant, including a review of medical records, a physical examination, and analysis of diagnostic tests. The expert might also need to assess the claimant’s psychological state, given the nature of FND.
  2. Causation: One of the most challenging aspects in FND cases is determining causation. The neurologist expert witness needs to evaluate whether the claimant’s symptoms are genuinely attributable to FND, or if they could be related to malingering, factitious disorder, or another neurological or psychiatric condition.
  3. Prognosis and Impact: The neurologist expert witness assesses the prognosis of the claimant and the impact of the FND on their ability to perform daily activities and work-related tasks. This assessment is critical in determining the level of compensation.
  4. Expert Testimony: The neurologist expert witness presents these findings in a clear, concise, and scientifically grounded manner, both in written reports and when called to testify in court.

Establishing causation

Establishing causation in cases involving functional neurological disorder (FND) can be complex due to the multifaceted nature of the disorder. Here are some key factors a neurologist expert witness may consider in the process:

  1. Thorough Medical History and Examination: The first step to establishing causation is to conduct an in-depth review of the claimant’s medical history, including past and present illnesses, treatments, and other psychological and environmental factors that may influence health. A comprehensive neurological examination can help identify any neurological signs that align with FND. It’s essential to note that FND is not a diagnosis of exclusion but requires positive clinical features.
  2. Temporal Relationship: It’s crucial to examine the temporal relationship between the alleged incident (such as an accident or traumatic event) and the onset of symptoms. If symptoms of FND appeared shortly after the incident and no other possible causes are evident, this may support causation.
  3. Diagnostic Tests and Investigations: Diagnostic tests (like EEG, MRI, etc.) and investigations can help rule out other neurological conditions that might present similarly to FND. These tests might not confirm FND per se but are essential in excluding other organic causes.
  4. Consistency of Symptoms: FND symptoms can be inconsistent and variable over time. Still, if there’s a pattern where symptoms worsen or reoccur during periods of stress or following certain triggers, this could potentially indicate FND.
  5. Psychiatric Evaluation: Given the strong association between FND and psychiatric conditions (like anxiety, depression, PTSD), a psychiatric evaluation can be useful. If a clear link can be established between the claimant’s mental health and the onset of neurological symptoms, this may support causation.
  6. Response to Treatment: Often, people with FND will show significant improvement with appropriate treatment such as physiotherapy, cognitive-behavioral therapy (CBT), or other forms of psychotherapy. If this is the case, it may further support the diagnosis of FND.
  7. Expert Opinion: The neurologist expert witness will use their expertise to integrate all these pieces of evidence. Their role isn’t to prove causation, but to state whether it is more likely than not that the incident caused the claimant’s FND, based on the balance of probabilities.

Causation in FND cases, as in any legal case, is ultimately determined by the legal standard, not the medical standard. The court decides on the balance of probabilities (i.e., more likely than not), while medicine often works to higher levels of certainty. Therefore, an understanding of the legal principles of causation is crucial for the neurologist serving as an expert witness.


The role of a neurologist expert witness in FND medico-legal cases is crucial to ensure justice is served. Their expertise helps demystify the complexities of FND, provides insights into the claimant’s condition, and aids the court in making informed decisions. Therefore, it’s essential to engage a neurologist expert witness who is not only clinically competent but also has a deep understanding of the legal framework.

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