Differential Diagnosis
The patient presents with a 36-hour history of double vision, fatigue, difficulty speaking, numbness in the right leg, and difficulty maintaining balance. The neurologic examination and MRI findings suggest a central nervous system (CNS) disorder. Here is the differential diagnosis:
- Single most likely diagnosis
- Multiple Sclerosis (MS): The presence of multiple periventricular white matter lesions on MRI, decreased sensation to light touch over the right lower extremity, and the patient's symptoms (double vision, difficulty speaking, and balance issues) are consistent with a relapsing-remitting course of MS. The presence of oligoclonal bands in cerebrospinal fluid (option E) is a common finding in MS.
- Other Likely diagnoses
- Neuromyelitis Optica (NMO): Although less likely than MS, NMO can present with similar symptoms, including optic neuritis and transverse myelitis. However, the absence of optic neuritis and the presence of multiple periventricular lesions make MS more likely.
- Acute Disseminated Encephalomyelitis (ADEM): ADEM is a monophasic illness that can present with similar symptoms, but it is often preceded by a viral infection or vaccination, which is not mentioned in the case.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Stroke: Although the patient's symptoms have been present for 36 hours, and the MRI shows white matter lesions, it is essential to rule out a stroke, particularly a brainstem stroke, which can present with similar symptoms.
- CNS Vasculitis: This condition can present with similar symptoms, including stroke-like episodes, and can be fatal if not treated promptly.
- CNS Infections (e.g., abscess, encephalitis): These conditions can present with similar symptoms and can be life-threatening if not treated promptly.
- Rare diagnoses
- Vitamin B12 deficiency: Although option A mentions decreased serum vitamin B1 (thiamine) concentration, a deficiency in vitamin B12 can cause similar neurologic symptoms, including numbness and weakness in the legs.
- Syphilis: Option D mentions a positive rapid plasma reagin (RPR), which is a test for syphilis. Although neurosyphilis can cause similar symptoms, it is less likely given the patient's presentation and the absence of other symptoms suggestive of syphilis.
- Myasthenia Gravis: Option C mentions positive acetylcholine receptor antibodies, which are found in myasthenia gravis. However, the patient's symptoms and MRI findings are not consistent with this diagnosis.
- Systemic Lupus Erythematosus (SLE): Option B mentions elevated serum double-stranded DNA antibodies, which are found in SLE. Although SLE can cause neurologic symptoms, it is less likely given the patient's presentation and the absence of other symptoms suggestive of SLE.