Clinical Pearls & Morning Reports
Published September 1, 2021
Chronic meningitis is a challenging diagnostic entity that differs from acute meningitis with respect to causes and diagnostic process and is associated with many potential underlying infectious and noninfectious inflammatory disorders. As new-generation sequencing and other techniques are applied judiciously, higher rates of diagnosis may be attained. Read the NEJM Review Article here.
Q: How is chronic meningitis defined?
A: The generally accepted definition of chronic meningitis is inflammation of the meninges, with signs and symptoms persisting for at least 4 weeks without alleviation.
Q: What is currently the most common cause of chronic meningitis in immunocompromised persons?
A: Cryptococcal meningitis is currently the most common cause of chronic meningitis in immunocompromised persons and persons with human immunodeficiency virus infection.
A: Symptoms of chronic meningitis include headache, lethargy, mental status changes, and fever. The headache is typically constant but nonspecific in location, quality, and temporal pattern. Progressively worsening headache, especially with mental clouding, and fever should prompt consideration of lumbar puncture to detect the inflammatory formula in cerebrospinal fluid (CSF) that characterizes chronic meningitis. Cranial-nerve dysfunction such as hearing loss or diplopia can also point to chronic meningitis, since these nerves are affected in their course through the subarachnoid space. Cognitive changes occur in approximately 40% of patients with chronic meningitis, with the incidence varying according to the cause. In some cases, cognitive change is the sole presenting feature, which makes chronic meningitis part of the differential diagnosis in patients with rapidly progressive dementia, particularly those with a history of immunosuppression. Nuchal rigidity occurs less commonly in chronic meningitis than in acute or subacute meningitis and occurs even less commonly with noninfectious causes than with infectious causes.
A: The CSF cell count is elevated, almost by definition, in chronic meningitis, but there are exceptions in persons with severe immunosuppression or in some forms of neoplastic meningitis. There is generally a lymphocyte-predominant pleocytosis because of the chronic nature of the disorder. However, tuberculous meningitis and some other infections, including nocardia, brucella, and fungal infections, may be characterized by persistent neutrophilic meningitis, and that CSF pattern is a hint to their presence. Chronic neutrophilic meningitis has also been described in autoimmune disorders such as Still’s disease and in cases without an identified cause. Eosinophils may indicate parasitic or coccidioidal meningitis. The CSF protein concentration is nearly always elevated, but this finding is nonspecific. Hypoglycorrhachia commonly accompanies infectious (and some noninfectious) causes of chronic meningitis, including sarcoidosis and meningeal metastases, but the CSF glucose concentration may be normal with other causes.