A 35-year-old woman comes to the office due to a 2-day history of weakness in her right hand. She has no other symptoms but reports a transient episode of lower extremity numbness that resolved spontaneously. The patient has a history of herpes labialis and she takes valacyclovir as needed. She recently began taking a vitamin D supplement after she was found to have low serum vitamin D levels. Other medications include oral contraceptive pills; she has also received annual influenza vaccines. The patient does not use tobacco, alcohol, or illicit drugs. Family history is significant for type 2 diabetes mellitus in her mother and hypertension in her father. BMI is 28 kg/m². Examination shows mild spasticity in her right hand. MRI of the brain shows the findings seen below. Which of the following is most strongly associated with this patient's current condition?

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11ec25c8_d55f_b9b8_bc81_4b27471372e2_MD0003_00 This patient with hand weakness, a prior episode of lower extremity numbness, and white matter lesions on MRI likely has multiple sclerosis (MS), an immune-mediated demyelinating disease of the central nervous system. Diagnosis is largely clinical but supported by neuroimaging demonstrating well-demarcated plaques of demyelination in the periventricular white matter and cerebrospinal fluid analysis showing oligoclonal immunoglobulin bands. plaques of demyelination MS is most common in younger (age <50) Caucasian women. It has a genetic predisposition and is seen more frequently in patients with affected family members and in those with certain major histocompatibility complexes (eg, HLA-DRB1). In addition, patients with vitamin D deficiency are at increased risk of MS development; other risk factors (eg, geographic location, colder climates, reduced sunlight exposure) are likely related to this. Epstein-Barr virus infection and smoking are also associated. (Choice A) Vaccines can rarely provoke Guillain-Barré syndrome (GBS), a demyelinating disorder of the peripheral nervous system. Patients with GBS develop an ascending symmetric paralysis; GBS does not involve the central nervous system and would not cause abnormal MRI findings in the brain. (Choices B and C) Herpes simplex infection can cause encephalitis and Bell palsy, but there is little evidence that it is associated with MS. Although barrier protection can reduce transmission rates of herpes simplex virus, contraceptive practices are not associated with risk of MS. (Choice D) Valacyclovir is not associated with the development of MS. Unlike acyclovir, which commonly causes crystal-induced kidney injury, crystalline nephropathy is rare and typically occurs only in patients with chronic kidney disease. Educational objective: Multiple sclerosis is an immune-mediated demyelinating disease of the central nervous system. The disease is most common in Caucasian women age <50. Risk factors include vitamin D deficiency, geographic location, genetic predispositions (HLA-DRB1), and smoking.

A 35-Year-Old Woman Comes to the Office Due to a 2-Day