Specific fungi associated with CNS infections
Increased use of immunosuppressive drugs, increasingly potent broad-spectrum antibiotics, and the spread of AIDS have made fungal infections of the CNS much less rare than they once were. They may even be predicted from the clinical context.141
Most patients with a fungal infection of the central nervous system (CNS) have some predisposing flaw in their immune response that allows invasion by relatively nonvirulent fungi:
| Immune risk/deficit | Representative fungi |
| Prematurity | Candida albicans |
| Inherited immune defects (e.g., chronic granulomatous disease, severe combined immunodeficiency) |
Candida, Cryptococcus, Aspergillus |
| Acquired immune defects | |
| Steroids | Cryptococcus, Candida |
| Cytotoxic agents | Aspergillus, Candida |
| HIV infection | Cryptococcus, Histoplasma |
| Alcoholism | Sporothrix |
| Iron chelator therapy | Zygomycetes |
| Intravenous drug abuse | Candida, Zygomycetes |
| Ketoacidosis | Zygomycetes |
| Trauma, foreign body | Candida |
Different clinical syndromes are more commonly associated with various specific fungi:
| Species | Relative incidence | Clinical syndrome | ||
| Meningitis | Abscess | Infarct | ||
| Cryptococcus | Common | Common | Infrequent | Infrequent |
| Coccidioides | Common | Common | Infrequent | Infrequent |
| Candida | Common | Occasional | Occasional | Rare |
| Molds (e.g., Aspergillus) | Occasional | Infrequent | Occasional | Common |
| Zygomycetes | Occasional | Infrequent | Occasional | Common |
| Histoplasma | Occasional | Infrequent | Infrequent | Infrequent |
| Blastomyces | Occasional | Infrequent | Infrequent | Rare |
| Sporothrix | Occasional | Infrequent | Rare | Rare |
Information on the epidemiology, diagnosis, and treatment of CNS fungal infections that can be complicated by seizures is listed in Table: Epidemiologic, diagnostic, and therapeutic aspects of CNS fungal infections
Fungal meningitis
Clinical manifestations of fungal meningitis are less stereotyped than the manifestations of bacterial meningitis. Patients often present with a chronic meningitis syndrome (defined as meningitis that persists for at least 1 month). In fact, fungal meningitis is always a consideration in the differential diagnosis of any patient with a chronic meningitis syndrome.
CSF cultures are frequently negative. Because fungal meningitis often involves the base of the brain more prominently than the spinal cord, cisternal CSF may yield organisms when lumbar CSF is negative. Repeated examinations of lumbar CSF or aspirates of cisternal or ventricular fluid may be needed before a diagnosis is made.139,140 Cryptococcal meningitis is the easiest fungal CNS infection to diagnose via CSF analysis.
Seizures with CNS fungal infections
The full range of seizure symptomatology can occur secondary to CNS fungal infections. There are many reports of patients presenting with new-onset seizures who deteriorated or died before a fungal cause was diagnosed,142 underscoring the importance of liberal inclusion of fungal infection in the differential diagnosis of new-onset seizure, especially when any predisposing clinical context exists.143
Anticonvulsant therapy follows routine guidelines. The clinician must be aware of frequent antifungal-anticonvulsant interactions. Maintenance anticonvulsant therapy is usually required, even after definitive antifungal treatment.
Immune Response Table adapted from JR Perfect, DT Durack. Fungal Meningitis. In WM Scheld, RJ Whitley, DT Durack (eds), Infections of the Central Nervous System. Philadelphia: Lippincott–Raven, 1997;721–739.
Different clinical syndromes Table adapted from JR Perfect, DT Durack. Fungal Meningitis. In WM Scheld, RJ Whitley, DT Durack (eds), Infections of the Central Nervous System. Philadelphia: Lippincott–Raven, 1997;721–739.
Adapted from: Goldstein MA and Harden CL. Infectious states. In: Ettinger AB and Devinsky O, eds. Managing epilepsy and co-existing disorders. Boston: Butterworth-Heinemann; 2002;83-133.
With permission from Elsevier (www.elsevier.com).
