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Acute Meningoencephalitis

Intern. Sunder Chapagain

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Acute Meningoencephalitis

• meningoencephalitis is an acute inflammatory process involving the meninges and, to a variable degree, brain tissue.

• Acute Bacterial Meningitis• Acute Viral Meningoencephalitis

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Acute bacterial meningitis

• Etiology

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Aseptic meningitis

• Viral– Enterovirus (Echovirus, Coxsackie virus, Polio)– Herpes Simplex Virus-2– Mumps: The commonest complication– Lymphocytic choriomeningitis virus

• Fungal (in imuunocompromised)– Cryptococcus neoformans– Histoplasmosis, Candidiasis, Blastomyces

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• Parasitic– Toxoplasmosis– Cysticercosis– Amoebiasis

• Miscellaneous– SLE– Leukemia– Lymphoma

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Risk Factors• Age• Low socioeconomic status• Head trauma• Splenectomy• Chronic diseases• Children with facial cellulitis, periorbital cellulitis, sinusitis and septic

arthritis• Maternal infection and pyrexia at the time of delivery.

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Clinical featuresNewborn & Infants: non-specific• Fever • Irritability• Lethargy• Vacant stare• Poor tone• Poor feeding• High pitched cry• Bulging anterior fontanelle• Convulsions• Opisthotonus

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Older children

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• Seizures• Alteration in mental status• Hypotension, fever or Hypothermia,

Tachycardia (Septic shock)• Bleeding, Renal dysfunction (DIC)

Increased intracranial pressure (ICP)• Papilledema• Cushing’s triad

– Bradycardia– Hypertension– Cheyne-Stokes Breathing

• Projectile vomiting• Headache

Physical examination•Neck rigidity•Focal neurological signs•Ptosis•Cranial nerve palsies•Bulging fontanel

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TB meningitis• Children 6 months – 5 years• Local microscopic granulomas on meninges• Meningitis may present weeks to months after

primary pulmonary process• CSF:

– Profoundly low glucose– High protein– Acid-fast bacteria (AFB stain)– PCR

• Steroids + antitubercular agents– (2HRZE+ 10 HR) WITH steroid for 4-6 weeks

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Stages

• Stage 1: stage of invasion– Low grade fever, loss of appetite, vomiting,

headache, photophobia, irritable, restless• Stage 2: Stage of meningitis

– Neck rigidity, focal neurological deficits, isolated cranial nerve palsies, loss of sphincter control

• Stage 3: Stage of coma– Loss of consciousness, altered respiratory pattern,

dilated pupils, ptosis, ophthalmoplegia, coma

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Neisseria meningitis(Meningococcemia)

• Neisseria meningitidis: serotype Grp B commonest

• Endotoxin causes vascular damage vasodilatation, third spacing, severe shock

• Severe complication:Waterhouse-Friderichsen syndrome: massive haemorrhage of adrenal glands secondary to sepsis: adrenal crisis-low B.P, shock, DIC, purpura, adreno-cortical insufficiency

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Morbiliform, non blanching petechiae to purpura involving mostly extensor surfaces Tumbler test

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Investigations• Complete blood count• C- Reactive Protein• Renal function test• Serum glucose• Blood culture and

sensitivity• If tubercular suspected

– PCR – Chest X-ray– Mantoux test

• Arterial blood gas• Fundoscopy• CT scan

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CSF analysis

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Management

Medical emergency• Early diagnosis essential• Immediate optimum treatment• Intensive supportive therapy• Rehabilitation• Prophylaxis to family• Notification to Public Health

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Treatment

• Managed in Intensive Care Unit• Manage airway, breathing and circulation first• Management of raised ICP• Fluid management• Dexamethasone: only in Pneumococcal and H.

Influenzae B, given 1-2 hours before antibiotics• Antibiotics• Inotropes: increasing aortic diastolic pressure

and improving myocardial contractility

ICP treatment• 3% NaCl, 5 cc/kg over ~20

minutes• May utilize osmotherapy

(Mannitol) - if serum osmolarity <320 mOsm/L

• Mild hyperventilation– PaCO2 <28 may cause regional

ischemia– Typically keep PaCO2 32-38

mm Hg• Elevate head end of bed by

30o

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Fluid management• Restore intravascular volume & perfusion• Monitor serum Na+ (osmolality, urine Na+):

– If serum Na+ <135 mEq/L then fluid restrict (~2/3x), liberalize as Na+ improves

– If severely hyponatremic, give 3% NaCl • SIADH

– 4 - 88% in bacterial meningitis– 9 - 64% in viral meningitis

• Diabetes insipidus• Cerebral salt wasting

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Antibiotics

• Best started within 60 min• Empirical therapy• Meningococcal meningitis

– Benzyl penicillin 400-500,000 units/kg/day q 4 hour• Pneumococcus/ H. influenza

– Ampicillin (if penicillin susceptible) 300 mg/kg/day IV q6 hour

– Ceftriaxone (if penicillin resistant) 100-150 mg/kg/day q12 hour

– Cefotaxime 150-200 mg/kg/day q8 hour– Vancomycin 60 mg/kg/day

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Meningitis - Treatment duration• Gram negative organisms: 21 days• Pneumococcal (ampiclox/ceftriaxone): 10-14 days• H influenza: 7-10 days• Meningococcal: 7 days• No growth: 7-10 days

• The CSF should be sterile within 24–48 hr of initiation of appropriate antibiotic therapy.

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Dexamethasone use in meningitis• Consider if

– H. influenza & Streptococcus pneumoniae – > 6 wks old

• Dose: 0.6 mg/kg/day in 4 divided doses for 2 days• MOA:

– local synthesis of TNF-, IL-1, PAF & prostaglandins resulting in BBB permeability, meningeal irritation

• incidence of hearing loss• May adversely affect the penetration of antibiotics into CSF• May decrease fever, giving false impression of improvement

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Prophylaxis

• Rifampicin: – Children 5mg/kg bd x 2 days– Adults: 600 mg bd x 2 days

• Pregnant contact:– Cefuroxime IM x 1 dose

Meningitis – Early complications• Encephalitis• Septic shock• DIC• Abscess• SIADH• Subdural effusion or

empyema ~30%• Dural sinus

thrombophlebitis• Stroke

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Intermediate• Hydrocephalus • Cranial nerve palsy

Late• Cerebral palsy• Hearing loss• Learning disability

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Acute Encephalitis• Encephalitis is an acute inflammatory process

affecting the brain• Viral infection is the most common and important

cause, with over 100 viruses implicated worldwide• Symptoms

– Fever– Headache– Behavioral changes– Altered level of consciousness– Focal neurologic deficits– Seizures

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Etiology

Non-Arbo viral• Herpes viruses (sporadic)

– HSV-1, HSV-2– varicella zoster virus– cytomegalovirus– Epstein-Barr virus– human herpes virus 6

• Adenoviruses• Influenza A• Enteroviruses, poliovirus• Mumps• Rabies

Arbo-Viral (epidemic)• Flaviviridae

– Japanese encephalitis– St. Louis encephalitis– West Nile

• Togaviridae– Eastern equine encephalitis– Western equine encephalitis

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– Herpes simplex virus (HSV) • the most common etiology of acute sporadic

encephalitis– Arboviruses – arthropod-borne virus

• outbreaks in summer time…mosquitos and ticks– Varicella zoster virus (VZV)

• immunosuppressed patients

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Japanese encephalitis

• Most important cause of arboviral encephalitis worldwide

• Transmitted by culex mosquito, which breeds in rice fields

• Commonly involve Basal ganglia: Extra pyradimal symptoms

• Post-immunization: Measles, Mumps

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Herpes Simplex Encephalitis

• Primary infection: On the mucosa of oropharynx, mostly asymptomatic

• Following primary infection, a latent infection in trigeminal ganglion

• Inflammation and necrotizing lesions in – Inferior and medial temporal lobe– Orbito-frontal lobe– Limbic structures

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• Evolve over several days or acutely• Fever, headache, confusion, stupor, coma,

seizures, status epilepticus• Personality changes, irritability, delirium• Temporal lobe seizures: Gustatory or olfactory

hallucinations, anosmia

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CSF Analysis• Increases CSF pressure• Cell count: 10-500 cells/mm3

• Lymphocyte predominance • Erythrocytes (in 80% of the cases) • Normal CSF findings in 10%

• Xanthochromia: Due to lysis of RBC• Glucose (mg/dl): normal or low • Protein (mg/dl): >50 mg/dl• HSV PCR: For the first 24-48 hours, detecting HSV DNA

by PCR in CSF: – specific (100%) and – sensitive (75-98%)

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Neuroimaging

• Contrast Enhanced MRI• Sensitive for early period HSV encephalitis• Edema in orbitofrontal and temporal regions

• CT Scan– Less sensitive than MRI

• EEG– If seizures are the features

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Treatment

• If shock/hypotension exists, crystalloid infusion

• If unconscious, provide airway/breathing• Seizure, lorazepam 0.1 mg/kg, IV• Acyclovir IV, 14 – 21 days

– Neonates and infant: 60 mg/kg/day in 3 divided doses

– Children: 30 mg/kg in 3 divided doses• Reduce ICP: restrict fluid, hyperventilation• Acute psychosis: Haloperidol

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References

• Nelson Textbook of Pediatrics 20th edition• Essential Pediatrics, OP Ghai, 8th Edition• Harrisons textbook of Internal Medicine• AAP Guidelines 2016

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Thank You