In the latest Case Record of the Massachusetts General Hospital, a 29-year-old man was admitted to the hospital because of headache, vomiting, photophobia, diplopia, and stiff neck. He was born in Southeast Asia. Brain imaging showed diffuse leptomeningeal enhancement. Cultures were sterile. A diagnostic procedure was performed.
Chronic meningitis differs in important ways from acute meningitis. The symptoms of chronic meningitis are typically milder, and patients less often present with a complete meningitis syndrome. Over time, however, focal and diffuse neurologic deficits can accrue. Cases that involve prominent basal inflammation can be particularly severe, with cranial-nerve palsies, vasculopathy in the circle of Willis, and obstruction of CSF outflow leading to hydrocephalus.
• What are the most common infectious causes of chronic meningitis?
Historically, the most common infectious cause of chronic meningitis in case series has been Mycobacterium tuberculosis. Other organisms that cause chronic meningitis are Borrelia burgdorferi, Treponema pallidum, and Ehrlichia chaffeensis. Pyogenic bacteria rarely cause chronic meningitis but can do so in persons with a parameningeal focus, endocarditis, or partially treated acute bacterial meningitis. HIV is the most common viral cause of chronic meningitis, but HIV-related meningitis is rarely symptomatic. Fungal organisms are a typical cause of chronic meningitis in persons with immunocompromise. However, several fungi, especially cryptococcus, can cause meningitis in apparently normal hosts.
• What are the noninfectious causes of chronic meningitis?
There is an extensive list of noninfectious causes of chronic meningitis. Several forms of vasculitis are associated with chronic meningitis, including primary central nervous system vasculitis, the Churg-Strauss syndrome, granulomatosis with polyangiitis (formerly known as Wegener’s granulomatosis), and Cogan’s syndrome. Connective-tissue diseases associated with meningitis include systemic lupus erythematosus, rheumatoid arthritis, and Sjogren’s syndrome. Several other systemic inflammatory processes have been associated with chronic meningitis, the most important of which is neurosarcoidosis. Chemical irritation can cause chronic meningitis in persons who have a dermoid cyst with intermittent release of cholesterol crystals, in those who have undergone a craniotomy, and in those who have received treatment with intravenous immunoglobulin or trimethoprim-sulfamethoxazole. Finally, neoplasms, most commonly breast carcinoma, lung carcinoma, melanoma, and leukemia, are relatively frequent causes of chronic meningitis.
Morning Report Questions
Q: What is the differential diagnosis for a low glucose level in the cerebrospinal fluid (CSF)?
A: Although there is an extensive differential diagnosis for causes of hypoglycorrhachia (a low CSF glucose level), the most prominent infectious causes are pyogenic bacteria, tuberculosis, and fungi, and the most important noninfectious causes are neoplasms, sarcoidosis, and subarachnoid blood; pyogenic bacteria and neoplasms tend to cause the lowest glucose levels.
Q: What are the characteristics of primary diffuse leptomeningeal gliomatosis?
A: Primary diffuse leptomeningeal gliomatosis is a distinct glioma syndrome, which is defined by diffuse infiltration of neoplastic glial cells in the leptomeninges without evidence of a primary intraparenchymal tumor. This is a rare diagnosis; there are approximately 50 autopsy-confirmed cases reported in the literature. This disease tends to affect relatively young people, and the prognosis is generally extremely poor, with a median survival time from diagnosis of 4 months in one review.