How is Multiple Sclerosis (MS) diagnosed?

From the Guidelines

Multiple Sclerosis (MS) diagnosis is primarily based on the demonstration of disease dissemination in space (DIS) and time (DIT) through Magnetic Resonance Imaging (MRI) and exclusion of other conditions that can mimic MS.

Key Diagnostic Criteria

• The diagnosis requires the presence of focal lesions in the white matter of the central nervous system (CNS) that are typical for MS in terms of distribution, morphology, evolution, and signal abnormalities on conventional MRI sequences 1.
• The 2010 McDonald criteria, which include MRI criteria for MS, are widely used for diagnosis and require the demonstration of DIS and DIT, as well as the exclusion of alternative diagnoses 1.
• MRI findings can support and substitute clinical information for MS diagnosis, allowing for earlier and more accurate diagnosis and treatment 1.

MRI Criteria

• The presence of at least one typical MS lesion in at least two characteristic regions (periventricular, juxtacortical, infratentorial, and spinal cord) is required for diagnosis 1.
• Key MRI sequences include T2-weighted and T1 post-gadolinium images of the brain and spinal cord 1.
• Lesions should be confirmed on multiple planes to avoid false positive findings due to artifacts and false negative results 1.

Clinical Considerations

• The clinical syndrome should be typical of demyelination, and the criteria should be applied to adult patients (between 18 and 50 years) 1.
• In patients older than 50 years or with vascular risk factors, more stringent criteria should be considered 1.
• Interpretation of MRI scans should be performed by trained (neuro)radiologists or clinicians deeply familiar with the features of MS and disorders considered in the differential diagnosis 1.

Additional Considerations

• Serial imaging can support the diagnosis of MS, given that MS is characterized by the accrual of lesions over time and in new areas of the CNS 1.
• The pattern of gadolinium-enhancement in MS lesions is variable but almost always transient (2-8 weeks) 1.
• CSF testing to support the diagnosis of relapsing MS is no longer required by the 2010 criteria, but CSF findings might be relevant in certain patients, particularly those for whom MRI is not entirely diagnostic or reveals features that are unusual in MS 1.

From the Research

Diagnostic Criteria for Multiple Sclerosis

The diagnosis of Multiple Sclerosis (MS) is based on demonstrating evidence of inflammatory-demyelinating injury within the central nervous system that is disseminated in both time and space 2. The diagnostic criteria for MS have evolved over time, with the latest version facilitating earlier diagnosis of MS in those presenting with typical clinical syndromes 3.

Clinical Assessment and Paraclinical Features

The diagnosis of MS can be made based on clinical symptoms and signs alone or a combination of clinical and paraclinical features 3. Clinical assessment includes a patient's symptoms, medical history, and physical examination. Paraclinical features, such as magnetic resonance imaging (MRI), cerebrospinal fluid examination, and evoked potentials, can support the diagnosis but are not definitive on their own 4, 2.

Role of MRI in Diagnosis

MRI is a crucial tool in the diagnosis of MS, allowing for the detection of asymptomatic dissemination of lesions in space and time 4. Characteristic lesions that favor MS include Dawson Fingers, ovoid lesions, corpus callosum lesions, and asymptomatic spinal cord lesions. However, other white matter diseases can have similar appearances on MRI, and a standardized MRI protocol is essential for comparing across studies or between centers 4.

Key Points in MS Diagnosis

• The diagnosis of MS is based on clinical symptoms and signs, as well as paraclinical features such as MRI and cerebrospinal fluid examination 3, 2.
• The diagnostic criteria for MS have evolved over time, with the latest version facilitating earlier diagnosis of MS in those presenting with typical clinical syndromes 3.
• MRI is a crucial tool in the diagnosis of MS, but it is not definitive on its own and should be used in conjunction with clinical assessment and other paraclinical features 4.
• A positive test for a putative MS "mimic" does not exclude the diagnosis of MS, and differential diagnosis must be guided by clinical presentation and neurologic localization 2.

Typical Symptoms and Presentation of MS

Typical symptoms of MS include:

• Discrete episodes ("attacks" or "relapses") of numbness, tingling, weakness, vision loss, gait impairment, incoordination, imbalance, and bladder dysfunction 2.
• Fatigue and heat sensitivity between attacks 2.
• Insidious worsening of neurologic function and accumulation of disability ("progression") that is not associated with discrete relapse activity 2.