Meningitis and Brain abscess

7/30/2019 Meningitis and Brain abscess

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Meningitis and Brain abscess


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CSF FLOW AND SPREAD OF

INFECTION

Produced by the Choroid plexus of the cerebralventricles

Exits through narrow foramina into thesubarachnoid space

Circulates around the base of the brain and over thecerebral hemispheres

Resorbed by arachnoid villi projecting into the

superior sagittal sinus.


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CSF FLOW AND SPREAD OF

INFECTION

CSF flow provides a pathway for rapid spread ofinfectious and malignant processes over the brain,spinal cord, and cranial and spinal nerve roots.

Spread from the subarachnoid space into brainparenchyma may occur via the arachnoid cuffs thatsurround blood vessels that penetrate brain tissue(Virchow-Robin spaces).

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Acute infections of the nervous

system

Acute bacterial meningitis

Viral meningitis

Encephalitis Focal infection: brain abscess, subdural

empyema, infectious thrombophlebitis

Fever & Headache


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Meningitis

Acute infection of meningitis, important medical problem

Causes:

Infective: Bacterial

Viral: Enterovirus; mumps

Fungal: cryptococcus; candida

Protozoa: amoeba; toxoplasma; cysticercus

Non infective: Malignant disease: breast CA; leukemia; lymphoma; Bronchial CA

Inflammatory: Behcets disease; SLE; sarcoidosis


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Acute bacterial meningitis

Acute purulent infection of the sub-arachnoid

space

Epidemiology:

Annual incidence: >2.5/100,000 population

Common organisms (community acquired):

Strep. pneumoniae: 50%

N. meningitidis: 25% adults (50% in >2 and 50yrs with underlying dis.) Listeria monocytogens: 10%

H influenza: < 10%

Staph aureus: neurosurgical procedure


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Causative organisms

Age of onset Common Less common

Neonate Gramve bacil

Gr. B Strep.

Listeria

Pre school H. Influenza

N meningitidis

St. Pneumoniae

Older childrenand adult

N meningitidis

St. Pneumoniae

Listeria

H influenza

Staph aureus


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Etiology

Strep Pneumoniae: most common in > 20yrs

Predisposing condn.

- pneumonia, sinusitis, otitis media,

- alcoholism, diabetes,

- splenectomy,

- hypogamma.,complement defn. Mortality: 20%

Neisseria meningitidis 25% Children and young adults: 60%

Petechial rash

Disease can be fulminant

Listeria monocytogens: < 1 month & >60 yrs; pregnancy, immunocompromised (all ages)

Ingestion contaminated food : milk products, meat products


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Pathophysiology

Colonize nasopharynx

Intravascular space

Choroid plexus

CSF

Proliferation of bact.

Avoids phagocytosis

Absence effective host

defense mech


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Pathophysiology

Most neuro. Manifest & complications: immune response to invadingpathogen and not direct bact. Induced injury

Injury can progress even after CSF sterilized

Lyse bacteriarelease of cell wall components (LPS, teicholic &peptidoglycan) in SA space cytokines (IL 1 & TNF)

WCC & CSF protein

Production of excitatory amino acids, reactive O2, nitrogen species

permeability of BB barrier: vasogenic oedema; protein in SA space

Sub arachnoid space exudates Obstruction of flow of CSF

Decrease resorptive capacity

Increase ICP


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Clinical manifestations

Onset: rapid (few hours) or subacute (worsens overdays)

Classic clinical triad : Fever, headache, nuchual rigidity(Kernigs sign; Brudzinski sign)

level of consciousness 75% (lethargy to coma) Nausea and vomiting

Photophobia

Seizure (20-40%)

Focal: focal ischemia or infarction; cv thrombosis; focal edema Generalized: hyponatremia; cerebral anoxia; toxic effect of Penn.

Rash: meningococcemia


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Clinical manifestations

ICP 90%

Signs: level of consiousness

PapilloedemaDilated and partly reacting pupils

VI th nerve palsy

Decerebrate posture

Cushingss reflex: pulse rate, HTN, irreg. resp


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Diagnosis

Suspected blood culture empiricalAntibiotics

Diagnosis by CSF examination

LP safely done in: Immunocompetent person

normal level of consiousnessNo PapilloedemaNo focal neurological signs


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Cond. Cell Count Glucos Protein

mg/dL

Gram

Normal Lymph 0-4 >60% bl 0 to 45 _

Viral Lymph 10-2000 N N _

Bact. Polym. 1000-5000

N/ +

TB Lymp/mixed

50-5000 Often-

Fungal Lymph 50-500 +/-

Malig Lymph 0-100 N/ -


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Diagnosis

CSF in pyogenic meningitis PMN leucocytes (>100/microL) 90%

glucose (< 40 mg/dL) 60%

protein ( > 45 mg/dL) 90%

pressure (> 180 mm H2O) 90%

Gram stain: 60% Culture: >80%

Causes of low CSF glucose Fungal

TB

CA

Imaging : CT or MRI, latter preferred

Biopsy of petechial lesions: Meningococcemia


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Differential Diagnosis

Viral meningo encephalitis: HS virus CSF: normal glucose and lymphocytosis

MRI : high intensity signal lesions

EEG

Rickettsial disease fever, headache, myalgia and nausea and vomiting

Rash in 96 hrs

Focal suppurative CNS infection subdural and epidural empyema

Brain abscess

Non infectious diseases SAH

Inflammatory


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Treatment

Start Antimicrobial: Goal, < 60 mins arrival to ER

Empirical before CSF results Patients with typical meningococcal rash

- Benzylpenicillin 4 megaunits 6 hrly

Adults : 18 -50 without typical meningococcal rash- 3rd gen. Cephalosporin ( ceftriaxone 2 g 12 hrly)

Penn resistant pneumocci suspected

- 3rd gen. Cephalosporin + Vancomycin 1 g 12 hrly

Listeria suspected ( < 3/12 and > 55 yrs)

- 3rd gen. Cephalosporin + Ampicillin 2 g, 4 hrly H/O anaphylaxix to B lactam

- Chloramphenicol 25mg/kg, 6 hr + Vancomycin 1 g 12 hrly


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Adjunctive Treatment

Dexamethasone: 20 minutes before antibiotic therapy.(Before the macrophages and

microglia are activated by endotoxin)

No benefit if started > 6 hrs after Ab therapy

Dose: 10 mg, 6 hrly for 4 days

Benefits synthesis of IL1 and TNF

CSF outflow resistance

stabilizing the BB barrier

Reduce the number of unfavorable outcomes- unfavourable outcome 15% vs 25%

- death: 7% vs 15%


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Adjunctive Treatment

Treatment of raised ICP

Elevation of patients head 30-45 degrees

Intubation and hyperventilation (PaCo2 25-30

mmhg)

Mannitol


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Prognosis

.

Poor prognostic markers

decrease level of cons.

seizure in 24 hrs Sign of increase ICP

Young age & >50 yrs

Co morbid condn.

Delay in starting treatment

decrease CSF glucose (3 g/l)


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Prevention of meningococcal

infection

Indication

HH and other close contacts of pt. with

meningococcal infections

Drug:

Rifampicin : 10 mg/kg, 12 hrly for 2 days

Ciprofloxacin: 500 mg single dose

Vaccines: available for prevention of

Group A and C.


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Course and prognosis

Mortality: 3 to 20%

Poor prognostic factors: level of consciousness

Increase ICP Onset of seizure within 24 hrs

Extremes of age

Delay in treatment

low CSF glucose (< 40 mg/dl)

Sequele intellectual fxn

memory impairment

seizure Extremes of age

Difficulty in gait


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Viral meningitis

Most common cause Usually benign and self limiting illness requiring notherapy

Common organisms: echo & mumps

C/F:

Children or young adults affected Headache, irritability, fever and meningnism

Focal neurological signs: rare

Investigation; CSF: (verify that pt. has not received

antibiotics lymphocytes

Glucose normal

Protein: normal or raised

Treatment: No specific treatment. Recovery in few days


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Brain abscess

Pathogenesis & Etiology

Penetrating injury, direct spread from paranasal

sinus or middle ear

Hematogenous spread: septicaemia

Initial infection suppuration loculation of pus

surrounding wall of gliosis

Etiology

StreptococciAnaerobes

Staphylococci


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Brain abscess

Investigations LP hazardous

CT: single or multiple low density areas with ring enhancement andsurrounding oedema

DD: cerebral toxoplasmosis and tuberculoma

Management Medical treatment: small abscess (

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Meningitis and Brain abscess