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NEUROSAE 2018 ANNUAL MEETING EDITION (VOLUME 10, ISSUE 3)
QUESTION 79 OF 100
A 32-year-old woman who presents to the emergency department with an acute onset of bilateral lower extremity weakness undergoes lumbar puncture and MRI of the spine. A diagnosis of multiple sclerosis is made. Three weeks later at follow up with a neurologist, she reports no improvement in symptoms and that she now requires assistance ambulating. She also had blurred vision in the right eye 6 months ago, but it resolved spontaneously. Which of the following laboratory tests should be ordered?
A. Rapid plasma reagin (RPR) test
B. Antinuclear antibody (ANA)
C. Anti-aquaporin 4 antibody **
D. Angiotensin-converting enzyme (ACE)
E. Human immunodeficiency virus (HIV) antibody
** = Your answer
Based on the imaging studies and history, the patient most likely has neuromyelitis optica (NMO), a demyelinating disease characterized by bilateral optic neuritis and severe myelitis that typically occur in quick succession. Also known as Devic’s disease, NMO is less common in the Caucasian population (approximately 1% to 2% of demyelinating disease) than in Asian, African American, and Native American populations (approximately 30% of demyelinating disease).
NMO typically can be differentiated from multiple sclerosis with MRI of the brain. Findings may be normal or appear as nonspecific white matter changes that are not in the typical pattern for multiple sclerosis. Characteristic findings on an MRI scan of the spine include robust enhancement of a longitudinally extensive span (>3 levels). Anti-aquaporin 4 antibody is useful in providing a more concrete diagnosis, with a sensitivity of around 70% and a specificity of >90%. A positive result should obviate the need for more invasive diagnostic methods, such as spinal cord biopsy.
* Wingerchuk DM, Weinshenker BG. Acute disseminated encephalomyelitis, transverse myelitis, and neuromyelitis optica. Continuum Lifelong Learning Neurol. 2013;19(4):944-967.