Expert Reasoning Errors in Epilepsy Claims: A Review of Records and Diagnostic Stability

In clinical negligence and personal injury litigation, the threshold for establishing a diagnosis of epilepsy is frequently a point of contention. Misidentification of non-epileptic events—or, conversely, the failure to recognise ictal phenomena—can lead to profound implications regarding causation, prognosis, and the apportionment of damages. Experts must distinguish between clinical observation, objective investigation, and historical reporting to avoid reasoning errors that misrepresent a claimant’s neurological status.

Clinical Concepts and Diagnostic Stability

The diagnosis of epilepsy is primarily clinical, supported by ancillary investigations such as EEG and neuroimaging. A risk in medico-legal assessment is the over-reliance on a single ‘abnormal’ EEG reading, which may reflect a non-specific finding rather than diagnostic evidence of an epileptic syndrome. Establishing whether a patient meets the operational definition of epilepsy requires a clear history of recurrent, unprovoked seizures. Errors often arise when an expert adopts an earlier clinical label without scrutinising the longitudinal stability of that diagnosis.

When an expert performs a detailed analysis of the medical chronology, they should assess whether the initial presentation met the diagnostic criteria at the time or if alternative differentials, such as syncope or Functional Neurological Disorder (FND), were prematurely excluded. In cases of traumatic brain injury (TBI), the distinction between acute symptomatic seizures—which may be a direct consequence of brain trauma—and the subsequent development of unprovoked chronic epilepsy is critical for quantifying the extent of a neurological injury.

Common Pitfalls in Causation and Apportionment

Expert reasoning frequently falters when failing to separate pre-existing vulnerability from trauma-induced pathology. Under the ‘eggshell skull’ principle, as established in Smith v Leech Brain & Co, the defendant takes the claimant as they find them. However, if a claimant had a latent predisposition to seizures prior to an index incident, the expert must articulate whether the event merely precipitated a pre-existing condition or whether it constituted a distinct causative factor.

• Confirmation Bias: Accepting a historical diagnosis without evaluating the evolution of the symptom profile over time.
• Ignoring Differential Diagnoses: Failing to adequately address FND, where clinical indicators such as distractibility or variable semiology during episodes may be overlooked.
• Misapplication of Regulatory Thresholds: Conflating DVLA driving standards—which focus on public safety and seizure freedom—with clinical evidence of permanent neurological impairment or prognosis.
• Speculative Prognosis: Predicting future seizure frequency or remission rates without reference to documented patterns for the specific seizure type identified.

The Role of the Expert in Civil Litigation

Under CPR Part 35, the expert’s overriding duty is to the court, not to the instructing party. In claims involving alleged failure to diagnose or negligent management of epilepsy, the court assesses evidence through the lens of the Bolam test, as refined by Bolitho. An expert must demonstrate that their opinion is based on a responsible body of medical opinion. If an expert relies upon a flawed interpretation of clinical records, their opinion risks failing the Bolitho requirement, particularly if that opinion cannot be logically supported by the underlying neurological facts.

When experts from different parties reach divergent conclusions, they may be directed to engage in an expert discussion under CPR 35.12. The resulting joint statement must clarify which issues are agreed and which remain in dispute. This process is distinct from the appointment of a single joint expert under CPR 35.7, where the court directs the appointment of a single expert, with instructions governed by CPR 35.8, to provide an impartial report.

Practical Considerations for Instructing Professionals

Solicitors should focus on the quality and temporal breadth of the provided clinical records. An expert is better placed to provide a reliable opinion on prognosis when they have access to primary care notes, secondary care seizure diaries, and original imaging studies rather than summarised reports. When formulating instructions, ensure the expert is specifically asked to address the robustness of the original diagnosis rather than assuming its accuracy. By ensuring that the expert has access to all pertinent primary documentation and by framing instructions that require an evaluation of diagnostic stability rather than mere confirmation of a label, instructing parties can significantly enhance the reliability of the expert report.