Focal CNS Infections

1
Focal CNS Infections

• Donnie Tyler MD
• Department of Neurosurgery
• University of Mississippi Medical Center

2
Anatomic Relationships of the Meninges

• Bone
• Epidural Abscess
• Dura Mater
• Subdural Empyema
• Arachnoid
• Meningitis
• Pia Mater
• Brain

3
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

4
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

5
Brain Abscess - pathology

• Location
• temporal gt frontal gt other lobes
• gt10 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

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Early Abscess (Cerebritis) Poorly localized
area of discoloration and softening.
7
Later Cerebritic / Early Abscess Stage
increasing necrosis of center with beginnings of
capsule formation
8
Mature abscess (Late Stage) - dense fibro-gliotic
capsular wall and purulent center
9
Brain Abscess - microbiology

• Streptococcus 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. Anginosus
• When from otitis media, mastoiditis, or lung
• multiple organisms including anaerobic strep.,
  bacteroides, enterobacter (proteus)
• Post Traumatic Abscess include
• Staph. aureus and Enterobacteriaceae

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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 with reactive glia.
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Pyogenic meningitis note the neutrophils are
collected in the subarachnoid space.
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Brain Abscess - Clinical Presentation

• Symptoms are non-specific for abscess and are
  normally due to increased intracranial pressure /
  mass effect Headache, Nausea/Vomiting, or
  Lethargy. Occasionally Seizures.

13
Abscess CT presentation

• CT appeareance dependent on stage
• Cerebritic 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 with edematous
  surrounding brain makes the collagen capsule
  easier to see.). Thin ring on enhancement and
  there is decay of enhancement on delayed scans.

14
Abscess MRI presentation

• MRI presentation also varies with capsule
  formation
• Early Cerebritic stage hyperintense in T2 with
  poor contrast enhancement 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 hyperintence ring with
  becomes hyperintense with contrast on T1.
  Capsule is hypointense on T2

15
Intraparenchymal abscess
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Initial management of Brain Abscess

• Blood Cultures (rarely helpful)
• LP role is dubious because of risk of
  transtentorial herniation. CSF is typically
  abnormal but cultures are usually negative.
• initiate antibiotic therapy (preferably after
  biopsy specimen is obtained), regardless of which
  management mode is chosen.

17
Brain Abscess Antibiotics

• If pathogen is unknown or S aureus is suspected
• Vancomycin - Adult 1 gm q 12 hours
• PLUS
• 3rd generation cephalosporin (e.g Claforan)
• PLUS
• Metronidazole Adult (30mg/kg/d) divided q12 or q6
  hours
• OR
• Chloramphenicol Adult 1 gm IV q 12 hours
• OR
• for post traumatic abscess use po rifampin
  9mg/kg/d qd

18
Brain Abscess - medical treatment

• Medical therapy alone is more successful if
• The treatment is begun before complete
  encapsulation
• The lesion is 0.8-2.5cm in diameter or less
• (3.0 cm is the typical cutoff)
• The duration of symptoms is lt 2 weeks
• The patients should show improvement in the first
  2 weeks of treatment

19
Brain Abscess - surgical treatment, indications

• significant mass effect exerted by lesion
• proximity to ventricle
• poor neurological condition
• Inability to obtain weekly CT scans
• In patient undergoing medical treatment
• Intervention, if neurological deterioration
  occurs, anatomic progression of abscess towards
  ventricles, or after 2 weeks of therapy if
  abscess is enlarged. Also consider if there is
  no decrease in abscess size by 4 weeks of
  treatment.

20
Brain Abscess - surgical treatment

• modern methods
• Needle aspiration - recommended for thin walled
  (immature) or multiple lesions
• Surgical excision - only can be performed on
  mature abscess
• Historical methods
• Tube drainage - 34 morality
• marsupialiaztion - remove overlying cortex and
  pack - 23 mortality
• Decompressive craniectomy with spontaneous
  migration of abscess

21
Treatment of Brain Abscess in 1895

• If symptoms of abscess exist trephine the skill
  at once.
• If there are localizing symptoms open over that
  region.
• If pus is not found in the epi/sub dural spaces
  and the brain bulges very much and is not seen to
  pulsate then instert a grooved director to 2.5
  inches, if no pus the redirect and reinsert.

22
1895 medicine continued

• When pus is found, incise the brain overlying he
  cavity. Scrape out the granulation tissue in the
  abscess cavity.
• Irrigate with hot salt solution.
• Place a rubber drainage tube to externally drain.
  Close dura and skin.
• Slowly remove the rubber tube over the next 4-7
  days.
• (Pennicillin 1943)

23
Mortality / Morbidity

• pre-CT era - 40-60 morality
• post CT era - 0-10
• (Improvement due to better antibiotics, surgical
  methods and ability to diagnose earlier)
• neurologic disability 45
• late focal or generalized seizures - 27
• hemiparesis - 29

24
Multiple abscesses in a 6 year old
25
Presumed source of polymicrobial abscesses.
26
Cerebellar Abscess from open skull fracture.
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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
• gt50 stem from a paranasal sinusitis
  (fronto-ethmoidal)
• trauma or surgery
• progression of an epidural abscess, ostermyelitis

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Etiologies of SDE

• paranasal sinusitis - 67-75
• otitis-14
• post neurosurgical - 4
• trauma -3
• meningitis (mainly peds) - 2
• congenital heart disease - 2
• other 7

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Subdural Empyema - clinical

• fever -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 - 31

30
Subdural Empyema - evaluation

• CT of head both with and without contrast
• LP - hazardous - risk of transtentorial
  herniation
• Location -
• convexity 70-80
• falcine 10-20
• 32/10,000 autopsies

31
Subdural empyema - Bacteriology

• Aerobic Streptococcus - 30-50
• Staphylococcus - 15-20
• Microaerophilic and anaerobic strep - 15-25
• Anaerobic Gm negative rods- 5-10
• other 5-10

32
Management of Subdural empyema

• Craniotomy - relatively emergency to debride and
  drain
• wide craniotomy is used because of septations /
  loculations
• Antibiotics - initially
• Vancomycin and chloramphemicol OR Cefotaxime and
  flagyl
• Modify based on culture results

33

• Meningitis progression to subdural empyema

34
Subdural Empyema
35
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

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Mixed Abscess Location
37
Spinal Epidural Abscess

• clinical presentation
• back pain
• fever
• spine tenderness
• major risk factors
• diabetes
• IV drug abuse
• chronic renal failure
• alcoholism

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Spinal Epidural Abscess - Exam

• myelopathic distal to lesion
• deterioration of exam with time
• classic presentation of a skin boil in 15 of
  patients
• Patients complain of excruciating pain localized
  to the spine
• Also may note bowel/bladder disturbances

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Spinal Epidural Abscess

• Average time course
• Back pain to root problems - 3 days
• Root problems to weakness - 4.5 days
• Weakness to paraplegia - 24 hours

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Spinal Epidural Abscess

• Epidemeology
• .2-1.2 / 10,000 hospital admissions
• 40-60 years old
• incidence increasing

41
Spinal Epidural Abscess -source

• Hematogenous spread
• Skin infections
• Parenteral infections (IVDA)
• Bacterial endocarditis
• UTI
• Respiratory infection
• Dental abscess

42
Spinal Epidural Abscess -source

• direct
• decubitus ulcer
• psoas abscess
• trauma
• pharyngeal infection
• mediastinitis
• pyelonephritis

43
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

44
Spinal Epidural Abscess - location

• Cervical 15
• Thoracic - 50
• Lumbar - 35
• Posterior to the Cord - 82

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Spinal Epidural Abscess - treatment

• Surgery
• goal is to determine causative organism and
  debridement is necessary
• immobilization - infected segments may become
  unstable
• Non-surgical management indications
• patients with prohibitive operative risk factors
• involvement of an extensive length of the spinal
  canal
• complete paralysis for gt3 days
• absence of neurological deficit (controversial)

46
Spinal Epidural Abscess - treatment

• Antibiotics
• 3rd generation cephalosporin
• PLUS
• Vancomycin - until MRSA is ruled out
• PLUS
• Rifampin po
• Duration of treatment
• 3-4 weeks IV followed by 4 weeks of po
• mortality 18-23

47
Discitis with local osteomyelitis and epidural
empyema
48
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
• Infection with the adult form - tapeworm in gut
• man is the only know permanent host for the worm
• eggs are excreted in the feces - does not cause
  neurocysticercosis

49
Parasitic Infections - Cysticercosis

• Infection with the larva
• animals (pigs) serve as an intermediate host
• larva burrow through the small bowel to gain
  access to the systemic circulation
• mainly infect the following sites
• Brain (60-92 of cases)
• Skeletal muscle
• Eye
• Subcutaneous Tissue

50
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)

51
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

52
Parasitic Infections - Cysticercosis

• Location
• meningeal 27-56
• parenchymal 30-63
• ventricular 12-18 (may cause hydrocephalus)
• mixed - 23
• Clinical
• symptoms of increased intracranial pressure

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Parasitic Infections - Cysticercosis

• serology
• antibody titers significant if 164 in the serum
  and 18 in the CSF
• CT scan
• ring enhancing / calcified lesions, multiple

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Parasitic Infections - Cysticercosis

• Treatment
• Steroids - symptomatic relief
• Antihelmintic drugs
• Praziquantal - (DOC for intestinal infestation) -
  
• 50mg/kg divided tid for 15 days
• Albendazole -15mg/kg divided bid po tid for 3
  months
• Niclosamide - may be given orally for GI
  infestation

55
Cystercercus cellulosae - (3-20 mm)regular round
thin walled cyst, produces only mild
inflammationlarva in cyst

56
Parasitic Infections - Echinococcosis

• Hydatid Cyst - caused by ingestion of the dog
  tapeworm
• (Uruguay, Australia, New Zealand)
• Treatment - Surgical excision without cyst
  rupture
• Cyst is full of worms
• Adjunctive treatment
• Albendazole - 400mg po BID for 28 days

57
Echinococcus Cyst intraoperative
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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

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Cryptococcosis
60
Aspergillosis Abscess in the centrum ovale.
(Also may cause diffuse cerebritic infections)
Note many satellite lesions common among fungal
infections. (Patient was on steroid therapy for
leukemia.)
61
Mucor aggressive and locally destructive
infection.
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Toxoplasmosis

• CNS manifestations
• Mass lesion (most common)
• Meningoencephalitis
• Encephalopathy

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Toxoplasmosis

• CT findings
• Mass lesion - comprises 70-80 of cerebral masses
  in AIDS patients
• large low density area with mild to moderate
  edema
• Ring enhancement with contrast
• most commonly in the basal ganglia
• Often multiple
• Most patients with CT diagnosed toxoplasmosis
  also have evidence of cerebral atrophy

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Toxoplasmosis

• Treatment
• Pyrimethamine 200mg loading dose then 75-100mg/d
• PLUS
• Sulfadiazine 75mg/kg po loading dose then
  25mg/kg/q6 hours
• PLUS
• Folic Acid 5-40mg/d (usually 10mg with each dose
  of Pyrimethamine)
• Should show radiologic response in 3 weeks. If
  response is good then continue dose for 6-12
  weeks then reduce by 50 and continue for life

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Toxoplasmosis

• Biopsy in following settings
• negative toxo titers
• (keep in mind the patient may be anergic)
• accessible lesions atypical for toxo
  (non-enhancing, not in basal ganglia, etc)
• in patients with extraneural infections or
  malignancies that may involve CNS
• Single lesion
• The role of biopsy for non-enhancing lesions is
  less well defined as the diagnosis normally does
  not influence therapy (most are PML or the
  biopsies are non-diagnostic), it may, however, be
  useful for prognostic purposes.

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Toxoplasmosis
67
Toxoplasmosis
68
Texas Tapeworm
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END