Multiple Sclerosis Misdiagnosis: When a Diagnostic Delay Becomes a Negligence Claim

Multiple Sclerosis (MS) is a complex, chronic autoimmune demyelinating disease affecting the central nervous system. Its varied presentation, often mimicking other neurological conditions, makes diagnosis challenging and sometimes protracted. For individuals experiencing delayed or incorrect diagnosis, the consequences can be profound, potentially altering disease progression and treatment opportunities. In UK medico-legal practice, such diagnostic delays frequently form the basis of clinical negligence claims, requiring meticulous examination of clinical facts against established standards of care.

The Clinical Landscape of Multiple Sclerosis Diagnosis

MS typically manifests with diverse neurological symptoms, including sensory disturbances, motor weakness, visual impairment (optic neuritis), balance issues, fatigue, and cognitive difficulties. The relapsing-remitting form, characterised by symptom exacerbation followed by partial or full recovery, is most common. Over time, many individuals transition to a secondary progressive phase, where disability accrues independently of relapses.

Diagnosis relies primarily on clinical presentation, supported by imaging and other investigations. The 2017 McDonald criteria are the established international diagnostic standard, requiring evidence of dissemination in space (DIS) and dissemination in time (DIT). DIS involves identifying lesions in at least two characteristic CNS regions (periventricular, juxtacortical, infratentorial, spinal cord) on MRI. DIT is demonstrated by simultaneous gadolinium-enhancing and non-enhancing lesions, new lesions on follow-up MRI, or a second clinical attack.

Diagnostic challenges often arise from:

• Non-specific symptoms: Early symptoms can be subtle and overlap with conditions like migraine, vitamin B12 deficiency, or Functional Neurological Disorder (FND). Differentiating FND from organic neurological disease requires careful clinical assessment.
• Mimics: Conditions such as Neuromyelitis Optica Spectrum Disorder (NMOSD), MOG antibody disease, vasculitis, or sarcoidosis can present with similar demyelinating features, necessitating careful differential diagnosis.
• Atypical presentations: Some individuals present with monosymptomatic or atypical features, making early recognition difficult.

A timely and accurate diagnosis is critical, as disease-modifying therapies (DMTs) are most effective when initiated early. DMTs can slow disease progression, reduce relapse frequency, and preserve neurological function. The range of available DMTs has expanded significantly, with options including interferons, glatiramer acetate, natalizumab, and newer oral agents like dimethyl fumarate and teriflunomide. Early intervention with these therapies can significantly impact long-term outcomes.

Legal Ramifications: Breach, Causation, and Standard of Care

In clinical negligence claims arising from MS misdiagnosis, establishing breach of duty and causation is essential. The standard of care is assessed using the principles from Bolam v Friern Hospital Management Committee [1957] and refined in Bolitho v City and Hackney Health Authority [1998]. These cases require that a medical professional’s conduct be judged against what a responsible body of practitioners would have done, with the practice needing to be logical and defensible.

Potential breaches of duty in MS diagnostic pathways include:

• Failure to take a comprehensive history of neurological symptoms
• Inadequate neurological examination, missing objective signs
• Failure to consider MS in the differential diagnosis when red flag symptoms are present
• Delayed or inappropriate referral to a consultant neurologist
• Failure to order relevant investigations, such as MRI or lumbar puncture, in a timely manner contrary to NICE guidance
• Misinterpretation of investigation results

Establishing causation requires demonstrating that the negligent delay materially worsened the claimant’s prognosis. This involves quantifying the impact of delayed DMT initiation on disease progression, relapse rate, and accumulated disability. Legal authorities such as Bailey v Ministry of Defence [2008] and Williams v Bermuda Hospitals Board [2016] address material contribution to injury, while Khan v Meadows [2021] clarified the scope of duty and harm for which a defendant is responsible.

Informed consent issues, as articulated in Montgomery v Lanarkshire Health Board [2015], may also arise if a practitioner failed to explain reasonable alternative diagnoses or the importance of certain investigations.

The Pivotal Role of the Neurological Expert Witness

In MS misdiagnosis cases, the instruction of a consultant neurologist expert witness is indispensable. Operating under CPR Part 35, the expert provides impartial specialist opinion on breach of duty and causation.

A neurologist expert will review all relevant medical records, including clinical notes, imaging, neurophysiology reports, and laboratory results. Their analysis focuses on:

• Assessing the standard of care against the Bolam/Bolitho test
• Identifying omissions or delays in reasonable steps, such as prompt referral or specific investigations
• Determining the likely date when MS could and should have been diagnosed
• Evaluating the impact of diagnostic delay on the claimant’s condition and prognosis
• Comparing the claimant’s actual disease course with the hypothetical course had diagnosis and treatment been timely
• Addressing the extent to which earlier DMT initiation would have altered disease trajectory, considering relapse frequency and disability accumulation
• Providing opinion on life expectancy where relevant

The expert may prepare various reports, including Screening & Merits reports, Breach of Duty reports, or Combined Breach & Causation reports. They may also act as a Single Joint Expert (SJE) or participate in joint discussions under CPR 35.12 and 35.14.

Practical Guidance for Legal Professionals

For solicitors and barristers handling MS misdiagnosis claims, several considerations are paramount:

1. Early Expert Instruction: Obtain a screening report from a consultant neurologist early to determine claim merits and identify potential breaches.
2. Comprehensive Records: Ensure all medical records, including imaging reports and raw images, are obtained. Gaps in records can hinder expert analysis.
3. Focus on Causation: While breach may seem evident, establishing causation with the required certainty is often the greatest challenge. The neurologist expert’s ability to articulate how the delay materially worsened the outcome is critical.
4. Understanding DMTs: Familiarise yourselves with the range of DMTs available during the relevant period and their known efficacy to better assess the impact of delayed treatment.
5. Collaborative Approach: Work closely with the neurological expert to ensure all relevant aspects of the case are thoroughly examined and clearly presented.