Diagnosing Multiple Sclerosis: 5 Things to Know

In the United States, nearly 1 million people are living with multiple sclerosis (MS), an immune-mediated inflammatory disease that causes demyelination and axonal transection, with resulting regional and whole-brain atrophy in the central nervous system. The hallmark of relapsing MS are symptomatic episodes that occur months or years apart as the disease progresses. Classic symptoms include sensory loss; spasticity; bladder, bowel, and sexual dysfunction; fatigue; and muscle weakness. However, the presenting symptoms of MS are highly variable among patients.

Here are five things to know about the diagnosis of MS.

1. MS is one of the most common neurologic causes of disability in young adults.

Relapsing MS is most often diagnosed in people between 20 and 40 years of age, in the prime of patients' lives when they are developing their careers and starting families. Long believed to be a condition of young White people, the incidence rate of MS in Black people is higher than previously thought. The female-to-male ratio in MS is approximately 3:1, a phenomenon seen in other autoimmune diseases as well. People living with MS have decreased  health-related quality-of-life measures, most commonly driven by physical disability, depression, anxiety, and fatigue. Therapeutic strategies to help mitigate these symptoms require close partnership with a multidisciplinary team of MS specialists and primary care providers.

2. MS is a clinical diagnosis.

According to the McDonald Criteria used for the diagnosis of relapsing MS, patients must have a clinical event consistent with a demyelinating disorder such as unilateral or bilateral optic neuritis (manifesting as central vision loss, pain with eye movements, and color desaturation) brainstem syndrome (manifesting as diplopia or vertigo) or incomplete transverse myelitis (manifesting as numbness, tingling, weakness, or bowel/bladder dysfunction). In patients with relapsing-remitting MS (85% of people at the time of diagnosis; the other 15% have primary-progressive MS clinically manifesting as at least 1 year of continuous progressive neurological symptoms not accounted for by a different neurological disorder), any demyelinating attack or relapse must include symptoms related to one of the aforementioned syndromes that last for at least 24 hours and are constant. Many patients will also have objective signs on a neurologic exam, localizable to the central nervous system, that include but are not limited to ataxia, proprioception deficits, decreased fine motor coordination, and extremity weakness. It is reassuring to some patients when they are educated on the fact that brief or transient neurologic symptoms, such as numbness or tingling for less than 24 hours, are unrelated to an MS relapse.

3. MRI imaging studies should be reviewed by MS care experts for differential diagnoses.

As previously mentioned, MS is a clinical diagnosis. Paraclinical studies, such as MRI of the brain, cervical, and thoracic cord, cerebrospinal fluid testing, and serum lab tests (eg, antinuclear antibody, erythrocyte sedimentation rate, antibody titer for Lyme disease, vitamin B12 levels, thyroid-stimulating hormone, angiotensin-converting enzyme, HIV, human T-lymphotropic virus 1) to help exclude conditions that have symptoms similar to MS can help rule in or rule out the diagnosis. Many patients will have MRI of the brain ordered in primary care for various reasons unrelated to MS, and the radiology results be interpreted as showing "multiple areas of increased white-matter signal hyperintensities seen in the deep white matter." This finding does not necessarily confirm a diagnosis of MS because these lesions can be a result of other conditions, such as small-vessel ischemic changes, migraine, vasculitis, or Lyme disease, among others. Therefore, although generating a differential diagnosis is logical from a radiologist's perspective, these MRI scans should ideally be reviewed by an MS expert, such as a neurologist, who can attempt to assess the full clinical picture and paraclinical results to arrive at the correct diagnosis. Confusion around the radiologic interpretation of MRI scans has contributed to the misdiagnosis rate of MS, which is nearly 20% in the United States according to a recent study.

4. MS causes both physical and cognitive symptoms

For decades, MS researchers neglected to understand the important role that cognitive impairment plays in the lives of people living with this disorder. Cognitive dysfunction affects 40%-65% of patients and commonly manifests as impaired short-term memory and deficits in processing speed, difficulty with concentration and multitasking. Importantly, cognitive dysfunction in MS can occur early in the disease process. Cognitive dysfunction in MS is commonly multifactorial and is related to comorbidities and other factors, including but not limited to thyroid disease, vitamin B12 deficiency, sleep disruption, anxiety, depression, side effects of medication used to treat MS symptoms for spasticity, bladder dysfunction, and fatigue, the latter of which is described as one of the most bothersome symptoms by patients. Depression and anxiety are also among the symptoms that most affect quality of life. Educating patients to recognize that these symptoms are part of the chain of potential MS symptoms is important so that they can be managed appropriately by their clinicians. There are no drugs approved by the US Food and Drug Administration (FDA) to treat cognitive dysfunction in MS. However, appropriate treatment of comorbid conditions; following a healthy diet, such as the Mediterranean diet; learning new skills or hobbies; and exercising regularly can help improve cognitive dysfunction. Patients with significant cognitive dysfunction leading to social or occupational impairment may need a detailed neuropsychological evaluation to further delineate their cognitive deficits.

5. The future of MS treatment looks promising.

Before the advent of immunotherapies for MS, about 30 years ago, there were no FDA-approved drugs to treat patients living with the disease. The early treatments, including various forms of interferon beta therapy and glatiramer acetate, were injectable medications with marginal efficacy, and they commonly caused side effects that could lead to drug discontinuation. Today, there are over 20 MS immunotherapies with various routes of administration, including injections, pills, and infusions.

MS was long thought of as a disease mediated by T cells, but the introduction of B cell–depleting therapies in 2017 brought about a paradigm shift in our understanding of MS. These agents, are highly effective at reducing the risk for relapses and new lesion formation on MRI of the brain, but they have been shown to increase the risk for infection in some patients, with upper respiratory infections being the most common according to the OPERA I and OPERA II clinical trials. Moreover, new therapeutic drugs are under investigation: for example, tolebrutinib, which inhibits Bruton tyrosine kinase, an enzyme expressed in B lymphocytes and myeloid cells including microglia.

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Cite this: Diagnosing Multiple Sclerosis: 5 Things to Know - Medscape - May 09, 2024.