Definition A neurodegenerative disorder; most frequent cause of dementia in adults—pathologically characterized by variable cerebral atrophy with neuritic (“senile”) plaques and neurofibrillary tangles Clinical Features Epidemiology Majority of Alzheimer's disease (AD) cases are sporadic, affecting adults usually older than 60…
Prion-Related Diseases (Overview) Definition Transmissible spongiform encephalopathies caused by misfolded prion proteins Clinical Features Epidemiology Prion disease: first identified in sheep (scrapie) Later identified in elk, deer, mink, large felines Cellular PrP glycoprotein (PrPc—normal protein of unknown function) PRNP gene:…
Primary Central Nervous System HIV Infection Definition Neurologic complications directly attributable to primary infection of the CNS by human immunodeficiency virus-1 (HIV-1) Clinical Features Epidemiology Virus enters CNS early, may remain subclinical Neurologic complications develop in up to 50% of…
General Viral Effects on the Central Nervous System Definition CNS viral infection associated with clinical or laboratory evidence of neurologic dysfunction based on viral tropism Clinical Features Epidemiology Viruses: number one cause of encephalitis and meningitis Most cases: acute, self-limited…
Cerebral Toxoplasmosis Definition CNS infection with Toxoplasma gondii , a ubiquitous obligate intracellular protozoan that parasitizes humans and animals Clinical Features Epidemiology Worldwide distribution with increased incidence in France, Central and South America Definitive hosts: cats 225,000 cases/year in United…
Cerebral Cryptococcosis Definition Severe CNS fungal infections caused by the genus Cryptococcus ; includes meningitis and focal “cryptococcomas” Clinical Features Epidemiology C. neoformans : ubiquitous in soil, bird excrement, compost C. gattii : tropical/subtropical climates, North American western coast Eucalyptus…
Acute Purulent Meningitis Definition An acute inflammatory process involving leptomeninges and cerebrospinal fluid Clinical Features Epidemiology Approximately 2.5/100,000 (United States) each year Hematogenous spread most common Pneumonia with bacteremia Other routes Direct inoculation (trauma, procedures) Invasion (sinusitis, mastoiditis, oral infections)…
Chordoma of Skull Base Definition Slow-growing, locally aggressive bone tumor; believed to originate from embryonic notochord rests (“ecchordosis physaliphora”), found incidentally in 1% to 2% of autopsies Clinical Features Epidemiology Rare tumor: 0.2% of all intracranial tumors; 3% to 4%…
Definition Hematogenous spread of a primary tumor originating outside the CNS to the brain or its coverings Clinical Features Epidemiology Most common brain tumors in adults Incidence of about 10 to 30 per 100,000 per year CNS metastases found in…
Definition Benign developmental thin-walled cysts defined by type of epithelium and location Examples: epidermoid, dermoid, colloid, arachnoid, endodermal, and ependymal Clinical Features Epidemiology Constitute about 1% of intracranial masses Affect all ages No gender predominance Believed to result from developmental…