From WikiCNS
- i. Usually present as basal meningitis or intraparenchymal abscesses; hyphal forms obstruct large and medium-sized arteries and cause extensive infarcts (aspergillosis and phycomycosis do this); pseudohyphae (such as Candida) occlude small parenchymal blood vessels producing adjacent small infarcts that evolve into microabscesses
- ii. Most common fungal infections in the CNS:
- 1. candidiasis, cryptococcosis, aspergillosis, mucormycosis
- iii. aspergillosis
- 1. branching, septate hyphae 4-12 micrometers in width
- 2. airborn spores derived from soil, water, or decaying vegetation usually gaining access through the lungs
- 3. typically involve the anterior and middle cerebral artery distributions in the cerebral cortex
- 4. typically present with headache, focal deficits or seizures
- 5. microscopically see infiltration of blood vessels by fungal hyphae and vascular thrombosis, hemorrhage, and infarction
- iv. mucormycosis
- 1. typically seen in poorly controlled diabetics
- 2. usually spreads from skin of face or nasal or nasopharyngeal mucose through the cribiform plate into the brain; may cause thrombosis in the cavernous sinus or carotid arteries
- 3. illness is usually acute and fulminating leading to death in a few days
- 4. microscopically see broad non-septate hyphae in wall of blood vessels and meninges
- 5. treatment: aggressive surgical clearance and antifungal therapy
- v. yeast infections (single cell)
- 1. cryptococcosis
- a. seen in soil and bird excrement
- b. typically causes meningitis or abscesses with primary infection usually pulmonary with hematogenous spread to the CNS
- i. cryptococcal infection is the most common cause of fungal meningitis
- c. symptoms of meningitis are usually not fulminant; mild headache, irritability, insomnia, and mild cognitive impairment are common
- d. often see intraparenchymal cysts that resemble soap bubbles
- e. staining with PAS shows a halo around the organism
- 2. candidiasis
- a. found in normal intestinal and skin flora
- b. budding round or oval yeasts 2-3 micrometers in length
- c. cerebral lesions are late manifestations of systemic candidiasis and are usually associated with cardiac and renal lesions
- d. usually associated with oral thrush and acute lesions in the vagina, skin, nails and lungs
- e. symptoms: low grade meningitis
- vi. dimorphic fungi
- 1. coccidioidomycosis
- a. large spherical 20-35 micrometers in diameter; within the spherules are endospores which are 2-5 micrometers in diameter
- b. usually from pulmonary source after exposure to large amounts of dust in the Southwestern U.S.
- c. involvement of the CNS is a very late event
