Download Focal CNS Infections

Focal CNS Infections
Anatomic Relationships of the
Meninges
• Bone
– Epidural Abscess
• Dura Mater
– Subdural Empyema
• Arachnoid
– Meningitis
• Pia Mater
• Brain
Anatomic relationships of the Brain
• Frontal Lobe
– Frontal and Ethmoidal Sinuses
• Sella Turcica
– Sphenoidal sinuses
• Temporal Lobe
– Middle Ear, Mastoid, Maxillary Sinuses
• Cerebellum, Brain Stem
– Middle Ear, Mastoid
Brain Abscess
• 50% - Local Source
– otitis media, sinusitis, dental infection
• 25% Hematogenous spread
–
–
–
–
adults - lung abscess, bronchiectasis and empyema
children - cyanotic congenital heart disease (4-7%)
pulmonary AVM - Osler-Weber-Rendu syndrome (5%)
rarely bacterial endocarditis
• 10% trauma / surgery
Brain Abscess - pathology
• Location
– temporal > frontal > other lobes
• >10% are multiple
• Stages - based on histologic findings
– 1. Early cerebritis - poorly demarcated from surrounding
brain
– 2. Late cerebritis - reticular marix (collagen precursor) and
developing necrotic center
– 3. Early capsule formation - neovascularity, necrotic center,
developing capsule
– 4. Late capsule formation - collagen capsule, necrotic center,
gliosis surrounding capsule
Subdural Empyema
• Located in the potential space between the dura and the
arachnoid.
• May spread rapidly due to lack of anatomical boundaries.
• Less mass effect than brain abscess
• Surgical Emergency
• Usually from a local source of infection
– >50% stem from a paranasal sinusitis (fronto-ethmoidal)
– trauma or surgery
– progression of an epidural abscess, ostermyelitis
Etiologies of SDE
•
•
•
•
•
•
•
paranasal sinusitis - 67-75%
otitis-14%
post neurosurgical - 4%
trauma -3%
meningitis (mainly peds) - 2%
congenital heart disease - 2%
other 7%
Intracranial Epidural Abscess
• Localized between dura and bone
• sharply defined - mainly be dural adherence to
bone at suture lines
• focal osteomyelitis
• associated with subdural empyema
• Management and etiology same as subdural
empyema
Spinal Epidural Abscess -source
• Hematogenous spread
– Skin infections
– Parenteral infections (IVDA)
– Bacterial endocarditis
– UTI
– Respiratory infection
– Dental abscess
Spinal Epidural Abscess -source
• direct
– decubitus ulcer
– psoas abscess
– trauma
– pharyngeal infection
– mediastinitis
– pyelonephritis
Spinal Epidural Abscess -source
• Following spinal procedures
– open procedure
• for example disectomy
– closed procedure
• LP
• Epidural catheter
• No source in 50% of patients in some series
Spinal Epidural Abscess - location
• Cervical – 15%
• Thoracic - 50%
• Lumbar - 35%
• Posterior to the Cord - 82%
Parasitic Infections - Cysticercosis
• Most common parasitic infection in CNS
– Caused by larval stage of Taenia solium- pork
tapeworm
– Incubation period from months to decades
• 83% of cases show symptoms within 7 years of
exposure
Parasitic Infections - Cysticercosis
• Common routes of infection
– Food (usually vegetables) or water containing eggs
from human feces
– Fecal - Oral autoinfection (poor sanitation habits)
– Autoinfection from reverse peristalsis - (theory
possibly offered by patients who autoinfected
themselves)
Parasitic Infections - Cysticercosis
• cystercercus cellulosae - (3-20 mm)
– regular round thin walled cyst,
– produces only mild inflammation
– larva in cyst
• cystercercus racemosus - (4-12 cm)
– active growing
– grape like clusters
– intense inflammation
– no larva in cyst
Parasitic Infections - Cysticercosis
• Location:
– meningeal 27-56%
– parenchymal 30-63%
– ventricular 12-18% (may cause hydrocephalus)
– mixed - 23%
• Clinical
– symptoms of increased intracranial pressure
Parasitic Infections - Cysticercosis
• serology
– antibody titers significant if 1:64 in the serum and
1:8 in the CSF
• CT scan
– ring enhancing / calcified lesions, multiple
Fungal Infections
• Cryptococcosis - most common fungal infection in
CNS diagnosed in live patients
– Cryptococcoma (mucinous pseudocyst) - occurs
almost entirely in the HIV population
– 3-10mm, most commonly in the basal ganglia
• Candidiasis - most common fungal infection in
CNS diagnosed in dead patients
– rare in healthy individuals
• Aspergillosis
• Coccidiomycosis - normally causes meningitis