© 2010 Mayo Foundation for Medical Education and Research A 28-year-old female nurse at a skilled nursing facility with a medical history remarkable only for depression presented to an outside emergency department (ED) in October 2007 with maxillary sinus tenderness, tinnitus, and otalgia of 3 weeks' duration. She had been married for 5 years and had no history of foreign travel. Her family history was only remarkable for a maternal uncle with sarcoidosis. At the time of her evaluation, a physician noted that the patient had cervical lymphadenopathy and made a diagnosis of acute sinusitis and otitis media. The patient was prescribed amoxicillin-clavulanate and discharged home. After 1 week of antibiotic therapy, all of the symptoms had improved. In the following month, she developed intermittent flulike symptoms of cough, sore throat, fatigue, and night sweats. During the following 2 months, she unintentionally lost more than 30 lbs (13.6 kg). For these reasons, she was admitted to her local hospital. On admission, she was afebrile with marked cervical, supraclavicular, and axillary lymphadenopathy. Laboratory testing disclosed marked peripheral eosinophilia of 2300/ μL, which was 15% of the white blood cell differential. Computed tomography (CT) of the chest showed normal lung parenchyma but demonstrated substantial bilateral hilar adenopathy. A cervical lymph node biopsy revealed reactive hyperplasia but was negative for malignancy and granulomas. A week after hospitalization and supportive therapy, the patient was discharged without a diagnosis; her fever and sore throat spontaneously resolved. Two months after her hospitalization, the patient began experiencing a painful, asymmetrical, multifocal weakness that was worse in the lower extremities and more prominent on the right. According to the patient, her weakness was persistent and neither worsened with exercise nor improved with rest. Her initial neurologic examination was remarkable for a right foot drop and considerable right lower extremity weakness, but after 2 weeks she developed bilateral foot drop and symmetrical bilateral lower extremities weakness. In the next 2 months, she experienced symmetrical weakness in her lower extremities and became wheelchairbound. She was readmitted to the hospital. Findings on CT of the head were negative. Electromyography (EMG) and nerve conduction studies (NCSs) showed reductions in both conduction velocity and the amplitude of sensory and motor action potentials. Additional laboratory tests showed a fasting serum glucose level of 90 mg/dL (reference ranges provided parenthetically) (70-100 mg/dL) and were negative for Epstein-Barr virus IgM and IgG; cytomegalovirus IgG and IgM; extractable nuclear antigen panel (Sjogren syndrome antigen A, Sjogren syndrome antigen B, scleroderma-70 antigen, antihistidyl–transfer RNA synthetase, Smith antibodies, ribonucleoprotein); Lyme IgM and IgG; human immunodeficiency virus; hepatitis A, B, and C; perinuclear antineutrophil cytoplasmic antibody (ANCA); and cytoplasmic ANCA. However, she continued to have elevated levels of peripheral eosinophils (15%) and a mildly elevated antinuclear antibody level (5.1 U [≥3 U is positive]). A muscle biopsy was unremarkable for myositis. A lumbar puncture with cerebrospinal fluid (CSF) studies yielded the following results: erythrocyte count, 1/mm (0/mm); leukocyte count, 1/mm (0-3/ mm); glucose, 48 mg/dL (40-85 mg/dL); total protein, 95 mg/dL (15-50 mg/dL); and a normal level of angiotensinconverting enzyme.