CNS%20Infections

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CNS Infections
RASHMI KUMAR
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Importance

• Invasion of brain parenchyma by infectious agent
• High mortality
• Permanent disability
• Features of both meningeal and brain involvement
  to various degrees
• Common features in presentation and sequelae
• Bacterial meningitis
• Tuberculous meningitis
• Viral meningoencephalitis
• Brain abscess
• Fungal
• polio

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Differential Diagnosis

• Infectious encephalopathies
• Cerebral malaria
• Enteric encephalopathy
• Shigella encephalopathy
• Sepsis
• Structural lesions with fever eg stroke/ tumour
• Non infectious encephalopathy with fever eg
  Reyes, electrolyte encephalopathy, diabetic
• Febrile seizures esp in 1 mth 3 year age group
• WHO 2006 Acute encephalitis syndrome

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Acute bacterial Meningitis (ABM)

• Very common serious
• Medical emergency
• 100 curable if treated adequately or 100 fatal
• High index of suspicion important
• Dx by CSF examination

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ABM Etiology

• First 2 months gram ves, gp b strep, Listeria
• 2 m 2 yrs H inf B, Pneumo, meningo
• gt 2-3 yrs Pneumo, meningo
• Anatomic defects ( base of skull, pilonidal
  sinus), immunodeficiency ? others

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ABM Epidemiology

• Max in 1st 5 yrs
• Risk Factors
• Colonization
• Crowding person to person droplet infection
• Poverty
• Male
• Absence of breast feeding

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ABM Pathology

• Bacterial colonization of nasopharynx ?
  bacteremia ? choroid plexus ? meninges
• Meningeal exudates, ventricultis, perivascular
  inflammatory exudates, venous occlusion,
  infarction, necrosis, ?ICT
• Role of cytokines

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ABM Clinical Features

• Sudden onset
• Older child high fever, headache, anorexia,
  myalgia, photophobia, meningeal signs,
  convulsions, stupor, coma
• Infant fever, poor feeding, tense bulging
  anterior fontanelle, irritability, photophobia,
  meningeal signs /-
• Newborn lethargy, not feeding, hypoalert, ill
  looking, shrill cry, seizures

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ABM Clinical Features

• s/o ?ICT hypertension, bradycardia, bulging AF,
  3rd/6th cranial nerve palsy, posturing, breathing
  abnormalities. Papilledema unusual
• Purpuric rash s/o meningococcus
• Septic foci
• CF in partially treated cases

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ABM

• DDx
• TBM
• Viral meningoencephalitis
• Aseptic meningitis
• Other

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ABM

• Diagnosis
• High index of suspicion very important
• Confirm by CSF examination
• LP deferred if features of ?ICT or PVF
• Start imperical antibiotics on suspicion
• CSF ?Pressure, turbid, ?cells (mostly polys),
  ?protein, ?sugar to lt 40 of blood sugar
• Gram stain, culture
• CIE
• Latex
• Imaging

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ABM

• Complications
• Subdural effusion
• Subdural empyema
• Ventricultis
• Abscess
• SIADH
• Hydrocephalus
• Infarcts
• Sequelae
• Neurological deficits
• Deafness
• MR
• Epilepsy
• hydrocephalus

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ABM Treatment

• Antibiotics early, heavy, prolonged
• 3rd generation cephalosporin
• Ceftriaxone 100 mg/kg/d in 2 doses
• Cefotaxime 200 mg/kg/d in 4 doses
• Subsequent therapy according to sensitivity
• Treat for 10-14 days 3 weeks in newborn
• Repeat LP/ imaging indicated if poor response
• Supportive Rx
• IV Fluids ? Restrict
• Management of ?ICT mannitol, glycerine,
  acetazolamide
• Tt of Seizures, pyrexia
• Dexamethasone
• Treat shock, DIC if present
• Nutrition
• Nursing

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ABM Prevention

• Vaccines
• Hib
• Pneumococcal vaccine 23 valent in high risk
  groups or 7 valent
• Meningococcal vaccine during outbreaks
• Chemoprophylaxis for contacts rifampicin 10
  mg/kg/d every 12 hrs x 2 days

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Tuberculous meningitis (TBM)

• Most dreaded and dangerous form of TB
• Esp common in children lt 3 yrs
• Risk Factors
• Young age
• Household contact
• Recent infection
• Measles
• PEM
• Pathophysiology
• Primary infection ? bacillemia ? hematogenous
  seeding of meninges (Richs foci) ? rupture
• Thick exudates in basal cisterns
• Arteritis

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TBM Clinical Features

• 3 stages
• Stage 1 prodromal stage with nonspecific
  symptoms 1-4 weeks
• Stage 2 neurological manifestations seizures,
  deficits, meningeal signs
• Stage 3 coma
• Decerebrate posturing, cranial nerve palsies,
  optic atrophy, extrapyramidal signs,
  hydrocephalus (communicating or obstructive) more
  common

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TBM

• DDx
• Partially treated bacterial meningitis
• Other CNS infections
• Dx
• CSF examination - ?pressure, cells upto 500 /cu
  mm, mostly lymphos, ?protein, sugar ?upto ½ of
  concommitant blood sugar
• AFB
• Culture
• CXR
• Skin test
• Newer Tests
• Tuberculostearic acid
• Adenosine deaminase test
• Bromide partition test
• NBT
• ELISA for antibody/antigen
• PCR
• Intrerferon gamma release assays

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TBM

• Complications sequelae
• Hydrocephalus
• Optic neuritis
• Focal deficits
• Epilepsy
• MR
• Spinal block/ arachnoiditis
• Endocrine
• Treatment
• 4 drugs for initial 2 months 3 drugs for 6-7
  months
• DOTS ??
• Steroids initially for 6 weeks
• Shunt surgery for hydrocephalus

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VIRAL MENINGOENCEPHALITIS

• Encephalitis and meningitis are 2 ends of the
  spectrum
• Neurotropic non neurotropic viruses can cause
  VME
• Arbo JE/ west nile/ dengue
• Entero
• HerpesHSV1, EBV, CMV, HHV-6, Varicella zoster
• Myxo
• Paramyxo
• Adeno
• Rhabdo

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VME Clinical features

• 3 stages
• Prodromal fever, vomiting, diarrhea, anorexia,
  malaise
• Acute encephalitic stage convulsion. Coma,
  neurodeficits, raised ICT, death
• Convalescent stage improving coma,
  extrapyramidal

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VME

• Neutrophilia /-
• CSF clear, pleocytosis /-. ?protein, normal
  sugar
• Specific Dx by PCR
• Imaging normal/ edema/ patchy hypodensity/
  specific changes
• EEG nonspecific diffuse slowing

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VME

• DDx very wide
• Other CNS infections
• Enteric encephalopathy
• Reyes
• Cerebral malaria
• Vascular
• Abscess
• Metabolic

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VME treatment

• Specific Tt only for HSE
• Supportive
• Treat pyrexia
• Treat seizures
• Treat ?ICT
• Raise head end
• Mannitol
• Diuretics
• Diamox
• Glycerine
• Ventilation
• Fluids electrolytes
• Nutrition
• Nursing
• Treatment of movement disorder
• Physiotherapy rehabilitation

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Japanese encephalitis

• Neurotropic RNA virus (Flavivirus sub gp of
  arboviruses)
• Largest number of VE cases worldwide
• Epidemics in south east India Public health
  problem
• Zoonotic disease Cycle between pig and mosquito
  (Culex tritaeniorrhynchus breeds in rice
  fields).
• Man an incidental dead end host
• Extrapyramidal features common
• CT/ MRI changes in thalamus/ BG
• Mortality in 1/3rd
• Preventable by vaccines
• Killed mouse brain vaccine
• Live attenuated SA-14-14-2 strain
• Killed IC51(Ixiaro) purified, formalin-inactivate
  d whole virus JE vaccine, based on the strain
  SA14-14-2 and cultivated in Vero cells
• Indian strain vaccine launched 2013

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Herpes encephalitis

• Commonest sporadic encephalitis in west
• Severe, fulminant course
• Focal deficits
• Focal features on EEG
• Imaging temporal hypodensities
• Specific antiviral Treatment available acyclovir
  10 mg/kg/d x 14-21 days

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Viral (aseptic) meningitis

• Mild, self limited
• Etiology
• Mumps
• Entero
• EBV
• Arbo
• M pneumoniae
• Clinical features
• Fever
• Headache
• Irritability
• Vomiting
• Convulsion (rare)
• Meningeal signs
• Lab CSF clear, pleocytosis, ?protein, normal
  sugar
• Tt supportive only

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Brain Abscess

• Predisposing features
• Congenital cyanotic heart disease
• Meningitis
• Penetrating head injury
• Local extension from mastod, otitis, sinusitis,
  soft tissues of face and scalp
• Etiology
• S aureus
• Micro aerophilic strep
• Other aerobic anaerobics
• Mixed infections in 35
• Clinical Features
• Fever
• Headache
• Vomiting
• Focal deficits
• ?ICT
• Lab
• Blood counts non specific
• CSF normal/ slight pleocytosis

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