What Is Your Diagnosis?
NeuroQuiz Section Editor: Lawrence S. Honig, MD, PhD, Columbia University, New York, New York.
A 53-year-old man with diabetes mellitus, hypertension, coronary artery disease, prior myocardial infarction, and alcohol use presented with vertigo, ataxia, headaches, and panic attacks. Magnetic resonance imaging revealed T2-weighted fluid-attenuated inversion recovery (FLAIR) hyperintensities in the medulla, pons, and cerebral peduncles (Figure 1A and B). Contrast-enhanced images showed no brainstem parenchymal contrast enhancement but some unusual vascularity (Figure 1C). Susceptibility-weighted images (Figure 1D) showed evidence of hypointensities consistent with hemosiderin deposits. The next month he had right facial droop, diagnosed as a facial nerve palsy. He was treated with valacyclovir hydrochloride and prednisone, with limited recovery. However, he again presented 2 months later with a 3-week history of nausea and vomiting. Magnetic resonance imaging revealed increased intensity and extension of the brainstem T2-weighted FLAIR hyperintensities (Figure 2A and B ), now with contrast enhancement (Figure 2C and D). Cerebrospinal fluid was noncontributory, without cells, and with a protein level of 0.102 g/dL (to convert to grams per liter, multiply by 10.0) and a glucose level of 190 mg/dL (to convert to millimoles per liter, multiply by 0.0555), both consistent with his long-standing diabetes. Findings on other laboratory tests, including human immunodeficiency virus antibody, angiotensin-converting enzyme level, and paraneoplastic panel, were negative. He was treated with steroids for possible inflammatory vs lymphomatous disease, with recrudescent symptoms of dizziness and headaches upon each taper of steroids. Positron emission tomography was also performed, and findings were negative for abnormal fluorodeoxyglucose avidity in the brainstem (not shown). Due to recurrent symptoms and concern over the underlying diagnosis, brain biopsy was performed.
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Correct Answer: Dural arteriovenous malformation.
What is your diagnosis?
The syndrome is of recurrent and progressive posterior fossa symptoms, including dizziness, vertigo, ataxia, and headaches, with some steroid-responsiveness. The MRI is most remarkable for FLAIR hyperintensities and GRE hypointensities in the medulla, pons, and cerebellum. Because of the expansile nature of the lesions, and steroid-responsiveness, diagnoses of demyelinating disease such as multiple sclerosis, as well as sarcoidosis and lymphoma were strongly considered. However, the lack of diagnostic CSF findings and lack of any fluorodeoxyglucose avidity on PET scan make these diagnoses less likely. Central nervous system vasculitis is a possibility in a steroid-responsive disorder, but the restricted location, extensive blood products, and overall course make this much less likely. Because of the blood products, initial scan without evidence of blood-brain barrier disruption, and punctate course, the possibility of a dural-based arteriovenous malformation was considered. Indeed angiography showed extensive vascularity consistent with such a diagnosis. But because of concern that the vessels might be secondary to some other primary process, a brain biopsy was performed. There was no evidence for malignancy. Arteriovenous malformations can mimic other mass lesions. Recurrent symptoms, and evidence of blood products, should always prompt retention of this disorder within the differential diagnosis.