American Board of Internal Medicine (ABIM) Certification Practice Exam

What is the next best step to confirm the diagnosis of multiple sclerosis in a patient with a single ring-enhancing lesion on brain MRI?

1. Cerebral angiography

2. Spinal cord imaging

3. Further brain imaging

4. Lab tests for CSF analysis

The correct answer is: Spinal cord imaging

To confirm the diagnosis of multiple sclerosis (MS) in a patient presenting with a single ring-enhancing lesion on brain MRI, the next best step involves identifying additional evidence that aligns with the criteria for MS. Spinal cord imaging is critical in this context because MS frequently involves not only the brain but also the spinal cord. By performing spinal cord imaging, clinicians can assess for lesions in the spinal region, which complement brain findings and fulfill the dissemination in space criterion necessary for MS diagnosis. Presence of lesions in both the brain and spinal cord, along with the patient's clinical manifestations, would support the diagnosis of MS. This approach utilizes the understanding that MS is a demyelinating disease characterized by lesions in multiple, distinct areas of the central nervous system (CNS) over time. Other methods, such as lab tests for CSF analysis or further brain imaging, may provide some information but are not as definitive for confirming MS on their own as spinal cord imaging is in the context of a patient with a suspected MS diagnosis.