Chronic and subacute meningitis.

PURPOSE OF REVIEW This article describes the background, clinical presentation, diagnosis, and treatment of selected etiologies of subacute and chronic meningitis. Key diagnostic considerations when evaluating a patient presenting with chronic inflammation of the CNS are discussed, and several specific infectious, neoplastic, and autoimmune etiologies are reviewed in detail. RECENT FINDINGS With recent advancement in serologic and CSF diagnostic testing, specific infectious, neoplastic, or autoimmune etiologies of chronic meningitis can be identified. Eliminating previous diagnostic uncertainty of chronic inflammation in the CNS has led to rapid and specific treatment regimens that ultimately improve patient outcomes. Recent advances in imaging have also aided clinicians in both their diagnostic approach and the detection of inflammatory complications such as hydrocephalus, hemorrhage, and ischemic stroke. SUMMARY Meningitis is defined as inflammation involving the meninges of the brain and spinal cord. Meningitis can be categorized as acute, subacute, or chronic based on duration of inflammation. This article focuses on the most common causes of subacute and chronic meningitis. Chronic meningitis is commonly defined as inflammation evolving during weeks to months without resolution of CSF abnormalities. Determining the time course of meningitis is important for creating a differential diagnosis. Most organisms causing acute meningitis rarely persist more than a few weeks. Although numerous etiologies of subacute and chronic meningitis have been identified, this article focuses on the most common etiologies: (1) infectious, (2) autoimmune, and (3) neoplastic.