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H ashimoto encephalopathy (HE)-also known as steroid-responsive encephalopathy associated with autoimmune thyroiditis-is a rare syndrome loosely associated with Hashimoto thyroiditis. HE mostly affects middle-aged women; is characterized by delirium, seizures, and myoclonus; and is thought to be an immune-mediated disorder. The pathophysiology of HE is not entirely understood. Most cases appear to be due to autoimmune vasculitis or an immune complex deposition that disrupts the cerebral microvasculature. This immunologic phenomenon has been observed on brain biopsy with a lymphocytic infiltration around small arterioles and venules. 1,2 Patients with HE appear to respond to corticosteroid therapy or other forms of immunosuppression. The presence of elevated antithyroid antibodies, which is consistent with an active autoimmune process, is essential for a diagnosis of HE.We report a case of HE with diffuse vasculitis on cerebral angiography with multiple anterior and posterior circulation strokes. The combination of HE and stroke with angiographically proven vasculitis is rare and its management has not been well-described. Case reportA 53-year-old woman with a history of hypertension presented with sudden-onset slurred speech and unsteady gait. NIH Stroke Scale score at presentation was 3. Initial CT of the head demonstrated multiple old infarcts and a meningioma in the left frontal convexity. CT angiography (CTA) showed a high-grade stenosis in the V4 segments of both vertebral arteries. Shortly after admission, the patient became less responsive. EEG demonstrated diffuse slowing consistent with a global encephalopathy. Brain MRI demonstrated multiple infarcts of the anterior and posterior circulation. The patient was transferred to our stroke center for a higher level of care.Cardiac workup failed to identify a source of embolus. MRI with gadolinium was done and did not show any enhancing lesions but did show an increased number of areas of diffusion restriction (figure 1). Repeat EEG was without discreet seizures or epileptiform activity that would explain Practical ImplicationsDiagnostic markers for Hashimoto encephalopathy include patient response to high-dose steroid treatment and angiographic vasculitis.Neurology.org/cp 519 the patient's persistent encephalopathy, which appeared out of proportion to her infarct burden and did not correlate neuroanatomically with the location of acute infarctions. The patient was noted to have thyroid-stimulating hormone of 9 mIU/mL, free T4 was normal, and free T3 was slightly low at 2 pg/mL. Serum antimicrosomal antibodies (4,500 U/mL) and antithyroglobulin (250 U/mL) were substantially elevated. Other antibody and inflammatory tests were found to be either normal or unrevealing. CSF protein was mildly elevated at 56 mg/dL with normal glucose and opening pressure. There were no erythrocytes without pleocytosis. CSF cultures and blood culture were negative. A diagnostic cerebral angiogram revealed vasculitis (figure 2).Treatment was initiated with IV methylprednisolone (IVM...

Background: In the setting of acute stroke, the decision to treat a patient with IV tPA is typically based on a brief pertinent history, neurological examination, urgent labs and head CT. Because “time is brain,” the evaluation is rushed and the diagnosis is occasionally erroneous. In this study we investigated the characteristics of patients who received IV tPA when the final diagnosis was not ischemic stroke. Methods: We conducted a retrospective study of 113 patients who presented from January 2009 to January 2011with acute stroke symptoms and received IV tPA either in our primary stroke center or one of the three satellite hospitals in our stroke network. Results: Of 113 patients, 23 had post-tPA negative diffusion weighted images (DWI) on MRI and a discharge diagnosis other than ischemic stroke. Other discharge diagnoses included: TIA (10 cases), complicated migraine (4 cases), post-ictal Todd’s paralysis (3 cases), conversion disorder (3 cases), and toxic/metabolic encephalopathy (3 cases). The misdiagnosis rate of stroke was higher in the satellite hospitals compared to our primary stroke center (39% vs. 11%; P<.0.001). The diagnosis of acute stroke in our satellite hospitals was made by an emergency department (ED) physician after a phone consultation with one of our stroke neurologists. Other differences between patients with and without final diagnosis of stroke included: mean age (61 vs. 52 years; P<0.02), median admission NIHSS score (11 vs. 6 points; P<0.001), psychiatric co-morbidities (3% vs. 17%; P<0.05), history of hypertension (84% vs. 56%; P<0.01), and mean length of hospitalization (11 vs. 6 days; P<0.001). There were two cases of uncomplicated gingival and nose bleeding at the time of tPA infusion among patients who did not have stroke. Conclusion: This study suggests that ED physicians working outside of the major stroke centers have difficulty distinguishing between stroke and its mimics. In the future, telemedicine may improve stroke diagnosis in satellite and rural hospitals. The results are also consistent with other studies that IV tPA causes relatively little harm in stroke mimics. Further study is warranted.

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