Neurologist Sonia Singh, M.D., specializes in caring for people with multiple sclerosis at MUSC Health, which has the state’s only comprehensive MS center. Since the actress Christina Applegate revealed that her MS diagnosis turned out to be inaccurate, some patients have contacted Singh with questions about their own cases.
They are aware that Applegate's neurological symptoms remain disabling as her medical team continues to investigate the cause. It is a reminder, Singh said, that multiple sclerosis requires a careful initial diagnosis and ongoing consideration of whether the diagnosis continues to fit over time. "What's most important in my field is being very humble."
With that in mind, Singh explores key questions in this Q&A.
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What is multiple sclerosis?
Multiple sclerosis is an immune-mediated disease of the central nervous system - the brain, spinal cord and optic nerves. In MS, the immune system mistakenly attacks myelin, the protective insulation around nerve fibers that helps electrical signals travel efficiently. This damage creates areas of injury, called lesions, that can disrupt communication within the nervous system and cause different symptoms, depending on their location.
The name means "multiple scars," referring to areas of damage in the central nervous system. MS is a chronic disease. New lesions can develop over time, and damage to nerve fibers can contribute to lasting disability including difficulty moving about, trouble controlling urination and cognitive difficulties.
Medications called disease-modifying therapies can reduce relapses, or episodes of new or worsening symptoms, and decrease new lesions. Depending on the treatment and type of MS, they can also slow disability progression.
How do you diagnose MS?
MS is a clinical diagnosis. There is no single blood test or single spinal fluid test that makes the diagnosis. You must fulfill specific diagnostic criteria called the McDonald Criteria.
MS experts around the world periodically revise those criteria as our understanding of the disease and our diagnostic tools improve. We have come a long way with imaging over the past 20 years. Our MRI technology is better, and we are able to identify characteristics of lesions that can help distinguish MS from other conditions.
The most recent iteration of the McDonald criteria for MS relies heavily on clinical history and imaging. You must establish that lesions occur in characteristic locations and have features consistent with MS. In some circumstances, the clinical presentation and imaging may be sufficient to establish the diagnosis. In others, patients undergo a lumbar puncture so we can analyze the spinal fluid for evidence of immune activity within the central nervous system.
