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INTRODUCTION

Chronic inflammation of the meninges (pia, arachnoid, and dura) can produce profound neurologic disability and may be fatal if not successfully treated. Chronic meningitis is diagnosed when a characteristic neurologic syndrome exists for >4 weeks and is associated with a persistent inflammatory response in the cerebrospinal fluid (CSF) (white cell count >5/μL). The causes are varied, and appropriate treatment depends on identification of the etiology. Five categories of disease account for most cases of chronic meningitis: (1) meningeal infections, (2) malignancy, (3) autoimmune inflammatory disorders, (4) chemical meningitis, and (5) parameningeal infections. In addition, there is increasing recognition that some patients with recurrent meningitis may have monogenic autoinflammatory disorders.

CLINICAL PATHOPHYSIOLOGY

Neurologic manifestations of chronic meningitis (Table 139-1) are determined by the anatomic location of the inflammation and its consequences. Persistent headache, clinical signs of hydrocephalus, meningeal signs, cranial neuropathies, radiculopathies, and cognitive or personality changes are the cardinal features. These can occur alone or in combination. When they appear in combination, it may be indicative of widespread dissemination of the inflammatory process along CSF pathways. In some cases, the presence of an underlying systemic illness points to the probable cause of the meningitis (Fig. 139-1). The diagnosis of chronic meningitis is usually made when the clinical presentation prompts the physician to examine the CSF for signs of inflammation. CSF is produced by the choroid plexus of the cerebral ventricles, exits through narrow foramina in the fourth ventricle into the subarachnoid space surrounding the brain and spinal cord, circulates around the base of the brain and over the cerebral hemispheres, and is resorbed by arachnoid villi projecting into the superior sagittal sinus where it mixes with blood in the venous sinuses. Recently, a cerebral lymphatic system has been identified that drains the dura mater (Chap. 424); however, its role in chronic meningitis has not been studied. CSF flow provides a pathway for rapid spread of infectious and other infiltrative processes over the brain, spinal cord, cranial, and spinal nerve roots. Spread from the subarachnoid space into brain parenchyma may occur via the arachnoid cuffs that surround blood vessels that penetrate brain tissue (Virchow-Robin spaces).

TABLE 139-1Symptoms and Signs of Chronic Meningitis
FIGURE 139-1

Systemic manifestations that may ...

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