1、Anatomic Relationships of the MeningesBoneEpidural AbscessDura MaterSubdural EmpyemaArachnoidMeningitisPia MaterBrainAnatomic relationships of the BrainFrontal LobeFrontal and Ethmoidal SinusesSella TurcicaSphenoidal sinusesTemporal LobeMiddle Ear, Mastoid, Maxillary SinusesCerebellum, Brain StemMid

2、dle Ear, MastoidBrain Abscess50% - Local Sourceotitis media, sinusitis, dental infection25% Hematogenous spreadadults - lung abscess, bronchiectasis and empyemachildren - cyanotic congenital heart disease (4-7%)pulmonary AVM - Osler-Weber-Rendu syndrome (5%)rarely bacterial endocarditis10% trauma /

3、surgeryBrain Abscess - pathologyLocationtemporal frontal other lobes10% are multipleStages - based on histologic findings1. Early cerebritis - poorly demarcated from surrounding brain2. Late cerebritis - reticular marix (collagen precursor) and developing necrotic center3. Early capsule formation -

4、neovascularity, necrotic center, developing capsule4. Late capsule formation - collagen capsule, necrotic center, gliosis surrounding capsuleLater Cerebritic / Early Abscess Stage increasing necrosis of center with beginnings of capsule formationMature abscess (Late Stage) - dense fibro-gliotic caps

5、ular wall and purulent centerBrain Abscess - microbiologyStreptococcus most frequent (33-50%), Multiple organisms(80-90%) of cases, May also include anaerobes (Bacteroides sp.)When secondary to frontal-ethmoidal sinusitis:Strep. Milleri, Strep. AnginosusWhen from otitis media, mastoiditis, or lungmu

6、ltiple organisms including anaerobic strep., bacteroides, enterobacter (proteus)Post Traumatic Abscess include:Staph. aureus and Enterobacteriaceae:Abscess wall inner portion formed by a layer of neutrophils and fibrin, middle layer with mainly fibrin (Blue on trichrome stain) and the outer portion

7、with reactive glia. Pyogenic meningitis note the neutrophils are collected in the subarachnoid space.Brain Abscess - Clinical PresentationSymptoms are non-specific for abscess and are normally due to increased intracranial pressure / mass effect: Headache, Nausea/Vomiting, or Lethargy. Occasionally

8、Seizures.Abscess CT presentationCT appeareance dependent on stageCerebritic stage thick diffuse ring of enhancement, further diffusion on contrast into central lumen or lack of decay of contrast on delayed scan 30-60 minutes later.Capsular stage faint rim present on pre contrast CT. (Necrotic center

9、 with edematous surrounding brain makes the collagen capsule easier to see.). Thin ring on enhancement and there is decay of enhancement on delayed scans.Abscess MRI presentationMRI presentation also varies with capsule formationEarly Cerebritic stage hyperintense in T2 with poor contrast enhancemen

10、t on T1. Later Cerebritic Stage central region of necrosis is hyperintense to brain on T2, rim is isointense to mildly hyperintense on T1. The capsule enhances with contrast.Early and Late Capsule Stages Capsule is easily visible on unenhanced scans as a well deliniated isointense to slightly hyperi

11、ntence ring with becomes hyperintense with contrast on T1. Capsule is hypointense on T2Intraparenchymal abscessInitial management of Brain AbscessBlood Cultures (rarely helpful)LP role is dubious because of risk of transtentorial herniation. CSF is typically abnormal but cultures are usually negativ

12、e.initiate antibiotic therapy (preferably after biopsy specimen is obtained), regardless of which management mode is chosen.Brain Abscess AntibioticsIf pathogen is unknown or S aureus is suspected:Vancomycin - Adult 1 gm q 12 hoursPLUS3rd generation cephalosporin (e.g Claforan)PLUSMetronidazole Adul

13、t (30mg/kg/d) divided q12 or q6 hoursORChloramphenicol Adult 1 gm IV q 12 hoursORfor post traumatic abscess use po rifampin 9mg/kg/d qdBrain Abscess - medical treatmentMedical therapy alone is more successful if:The treatment is begun before complete encapsulationThe lesion is 0.8-2.5cm in diameter

14、or less(3.0 cm is the typical cutoff)The duration of symptoms is 50% stem from a paranasal sinusitis (fronto-ethmoidal)trauma or surgeryprogression of an epidural abscess, ostermyelitisEtiologies of SDEparanasal sinusitis - 67-75%otitis-14%post neurosurgical - 4%trauma -3%meningitis (mainly peds) -

15、2%congenital heart disease - 2%other 7%Subdural Empyema - clinicalfever -95%focal neurological deficit (mainly hemiparesis) - 80-90%nuchal rigidity - 80%headache 77%Seizures - 50-60%Forehead or eye swelling from emissary vein thrombosis - 30%Vomiting - 20%Male to female ratio - 3:1Subdural Empyema -

16、 evaluationCT of head both with and without contrastLP - hazardous - risk of transtentorial herniationLocation - convexity 70-80%falcine 10-20%32/10,000 autopsiesSubdural empyema - BacteriologyAerobic Streptococcus - 30-50%Staphylococcus - 15-20%Microaerophilic and anaerobic strep - 15-25%Anaerobic

17、Gm negative rods- 5-10%other 5-10%Management of Subdural empyemaCraniotomy - relatively emergency to debride and drainwide craniotomy is used because of septations / loculationsAntibiotics - initiallyVancomycin and chloramphemicol OR Cefotaxime and flagyl Modify based on culture resultsMeningitis pr

18、ogression to subdural empyemaSubdural EmpyemaIntracranial Epidural AbscessLocalized between dura and bonesharply defined - mainly be dural adherence to bone at suture linesfocal osteomyelitisassociated with subdural empyemaManagement and etiology same as subdural empyemaMixed Abscess LocationSpinal

19、Epidural Abscessclinical presentationback painfever spine tendernessmajor risk factorsdiabetesIV drug abusechronic renal failurealcoholismSpinal Epidural Abscess - Exammyelopathic distal to lesiondeterioration of exam with timeclassic presentation of a “skin boil” in 15% of patientsPatients complain

20、 of excruciating pain localized to the spineAlso may note bowel/bladder disturbancesSpinal Epidural AbscessAverage time courseBack pain to root problems - 3 daysRoot problems to weakness - 4.5 daysWeakness to paraplegia - 24 hoursSpinal Epidural AbscessEpidemeology.2-1.2 / 10,000 hospital admissions

21、40-60 years oldincidence increasingSpinal Epidural Abscess -sourceHematogenous spreadSkin infectionsParenteral infections (IVDA)Bacterial endocarditisUTIRespiratory infectionDental abscessSpinal Epidural Abscess -sourcedirectdecubitus ulcerpsoas abscesstraumapharyngeal infectionmediastinitispyelonep

22、hritisSpinal Epidural Abscess -sourceFollowing spinal proceduresopen procedurefor example disectomyclosed procedureLPEpidural catheterNo source in 50% of patients in some seriesSpinal Epidural Abscess - locationCervical 15%Thoracic - 50%Lumbar - 35%Posterior to the Cord - 82%Spinal Epidural Abscess

23、- treatmentSurgery goal is to determine causative organism and debridement is necessaryimmobilization - infected segments may become unstableNon-surgical management indications:patients with prohibitive operative risk factorsinvolvement of an extensive length of the spinal canalcomplete paralysis fo

24、r 3 daysabsence of neurological deficit (controversial)Spinal Epidural Abscess - treatmentAntibiotics3rd generation cephalosporinPLUSVancomycin - until MRSA is ruled outPLUSRifampin poDuration of treatment3-4 weeks IV followed by 4 weeks of pomortality 18-23%Discitis with local osteomyelitis and epi

25、dural empyemaParasitic Infections - CysticercosisMost common parasitic infection in CNSCaused by larval stage of Taenia solium- pork tapewormIncubation period from months to decades 83% of cases show symptoms within 7 years of exposureInfection with the adult form - tapeworm in gut man is the only k

26、now permanent host for the worm eggs are excreted in the feces - does not cause neurocysticercosisParasitic Infections - CysticercosisInfection with the larvaanimals (pigs) serve as an intermediate hostlarva burrow through the small bowel to gain access to the systemic circulationmainly infect the f

27、ollowing sites:Brain (60-92% of cases)Skeletal muscleEyeSubcutaneous TissueParasitic Infections - CysticercosisCommon routes of infectionFood (usually vegetables) or water containing eggs from human fecesFecal - Oral autoinfection (poor sanitation habits)Autoinfection from reverse peristalsis - (the

28、ory possibly offered by patients who autoinfected themselves)Parasitic Infections - Cysticercosiscystercercus cellulosae - (3-20 mm)regular round thin walled cyst, produces only mild inflammationlarva in cystcystercercus racemosus - (4-12 cm)active growinggrape like clustersintense inflammationno la

29、rva in cystParasitic Infections - CysticercosisLocation:meningeal 27-56%parenchymal 30-63%ventricular 12-18% (may cause hydrocephalus)mixed - 23%Clinical symptoms of increased intracranial pressureParasitic Infections - Cysticercosisserologyantibody titers significant if 1:64 in the serum and 1:8 in

30、 the CSFCT scanring enhancing / calcified lesions, multipleParasitic Infections - CysticercosisTreatmentSteroids - symptomatic reliefAntihelmintic drugsPraziquantal - (DOC for intestinal infestation) - 50mg/kg divided tid for 15 daysAlbendazole -15mg/kg divided bid po tid for 3 monthsNiclosamide - m

31、ay be given orally for GI infestationCystercercus cellulosae - (3-20 mm)regular round thin walled cyst, produces only mild inflammationlarva in cystParasitic Infections - Echinococcosis“Hydatid Cyst” - caused by ingestion of the dog tapeworm(Uruguay, Australia, New Zealand)Treatment - Surgical excis

32、ion without cyst ruptureCyst is full of worms Adjunctive treatmentAlbendazole - 400mg po BID for 28 daysEchinococcus Cyst intraoperativeFungal InfectionsCryptococcosis - most common fungal infection in CNS diagnosed in live patientsCryptococcoma (mucinous pseudocyst) - occurs almost entirely in the

33、HIV population3-10mm, most commonly in the basal gangliaCandidiasis - most common fungal infection in CNS diagnosed in dead patientsrare in healthy individualsAspergillosisCoccidiomycosis - normally causes meningitisCryptococcosis Aspergillosis Abscess in the centrum ovale. (Also may cause diffuse c

34、erebritic infections) Note many satellite lesions common among fungal infections. (Patient was on steroid therapy for leukemia.)Mucor aggressive and locally destructive infection.ToxoplasmosisCNS manifestationsMass lesion (most common)MeningoencephalitisEncephalopathyToxoplasmosis CT findingsMass lesion - compr