Angiostrongylus Pachymeningitis and Encephalitis With Extensive Parenchymal Involvement and Lack of CSF Eosinophilia

A 71-year-old man who resides in Hawaii presented with 2 weeks of worsening headaches and confusion without fevers.Neurologic examination was notable for right gaze preference, left hemineglect and hemiparesis, and obtundation.MRI demonstrated extensive right temporoparietal subependymal enhancement, vasogenic edema, and impending uncal herniation (Figure).Lumbar puncture was performed after improvement of mass effect after 72 hours of dexamethasone, with opening pressure of >50 cm H 2 O. CSF demonstrated 15 nucleated cells (95% lymphocytes, 5% macrophages), protein 106 mg/dL, and normal glucose; PCR detected Angiostrongylus cantonensis DNA.Albendazole was added; he was discharged home with improving examination.Previous reports of Angiostrongylus meningitis mostly describe nonfocal symptoms and small foci of subcortical enhancement and leptomeningeal involvement, 1,2 compared with extensive parenchymal involvement with mass effect in this case.The lack of CSF eosinophilia (reported in 95% of cases) 2 may be explained by initiation of dexamethasone before lumbar puncture.