COMMON INFECTIONS OF THE CNS IN CHILDREN ACUTE BACTERIAL MENINGITIS VIRAL ENCEPHALITIS CEREBRAL MALARIA INTRACRANIAL ABSCESS

MENINGITIS IN CHILDREN Acute bacterial meningitis Partially treated meningitis Viral meningitis Tuberculous meningitis - The most common type is Acute bacterial Meningitis Age influences i) Aetiological agents ii) clinical features iii) outcome of the disease

ACUTE BACTERIAL MENINGITIS It occurs in all age groups 3 major groups - Neonatal period ( 0-28days) -Pre-school age (<5yrs) -Older child (> 5years) The period after 28days to 3months is important because there is often an overlap in aetiological agents

COMMON AETIOLOGICAL AGENTS IN CHILDHOOD MENINGITIS These agents include the Gram negative organisms - E.coli, Klebsiella, Pseudomonas and Proteus: Mostly seen in the neonatal period. Rarely seen in any other age group except in debilitated patients. Other common organisms in the neonatal period include Staph.aureus, GBS, N. meningitidis *N.meningitidis cuts across all age groups and most often seasonal H. influenza is seen commonly in the pre-school period. S.pneumonia is commoner in the older child

PATHOGENESIS. Most cases of meningitis result from hematogenous dissemination. Less often, it results from contiguous spread as a result of - direct trauma to the skull - contamination of neural tube defects - congenital sinus tracts etc. PATHOLOGY Cerebritis and septic infarcts are common in bacterial meningitis. Abscess formation, ventriculitis, hydrocephalus, and subdural effusions occur more often in newborn infants than in older children.

NEONATAL MENINGITIS Any newborn with bacterial sepsis is at risk for meningitis. The incidence is low in infants with early- onset sepsis but much higher in infants with late-onset infection.

Late-onset bacterial infection (at more than 5 days of age) presents in a more subtle manner, with poor feeding, lethargy, hypotonia, temperature instability, altered perfusion, new or increased oxygen requirement, and apnea.

The initial signs and symptoms may however be indistinguishable from those of other infectious and noninfectious diseases of the newborn infant. Neurologic signs may or may not be present. Neurologic manifestations include lethargy (50–90%); bulging or full fontanel (20 –30%); focal, generalized, or subtle seizures (30–50%); nuchal rigidity (10–20%); and, rarely at initial presentation, signs of increased intracranial pressure.

DIAGNOSIS. The diagnosis is confirmed by examination of the cerebrospinal fluid (CSF) and identification of an organism by culture or antigen detection. Blood culture and complete blood count are part of the initial evaluation because 70–85% of neonates with meningitis have a positive blood culture. The incidence of positive blood cultures is highest with early-onset sepsis and meningitis Lumber Puncture is mandatory in mgt of meningitis in any age group. Lumbar puncture may however be deferred in a severely ill infant if the lumbar puncture would further compromise respiratory status.

Normal, uninfected neonates frequently have elevated CSF protein levels (term 90 mg/dL [range 20–170], preterm 115 mg/dL [range 65–150]) CSF is xanthochromic in colour because of inc. protein Reduced glucose (term 52 mg/dL [range 34–119], preterm 50 mg/dL [range 24–63]) Reduced CSF-to-blood glucose ratios (51% term, 75% preterm) and slightly elevated CSF leukocyte counts 57–61% neutrophils. In addition, preterm infants may develop elevated CSF protein levels and leukocytes and hypoglycorrhachia following intraventricular hemorrhage. Many nonpyogenic congenital infections also can produce asymptomatic alterations of CSF protein and leukocytes (toxoplasmosis, CMV, syphilis, HIV).

The Gram stain of CSF is positive in as many as 85% of patients with GBS meningitis and 61% of those with gram-negative meningitis. The leukocyte count is often elevated with a predominance of neutrophils (>70}–90%); the number is often greater than 1,000 in patients with gram-negative meningitis but may be less than 100 in those with GBS disease. Microorganisms are recovered from most patients who have not been pretreated with antibiotics. Bacteria have also been isolated from CSF that did not have an abnormal number of cells (<25) or an abnormal protein level (<200 mg/dL).

This is more typical of GBS meningitis but emphasizes the importance of performing a culture and Gram stain on all CSF specimens. Head ultrasonography or computed tomographic (CT) scan with contrast enhancement may be helpful in diagnosing ventriculitis and brain abscess.

Cephalosporins, gentamicin, anti-staph are used in neonatal meningitis Meningitis should be treated for 21 days. The mortality rate of neonatal meningitis is approximately 25%, with significant neurologic morbidity present in one third of the survivors. Use of dexamethasone has not been studied in neonates. Anticonvulsants for seizures- Carbamazepine is preferred Management of cerebral edema, inappropriate antidiuretic hormone secretion, and hydrocephalus. COMPLICATIONS include subdural effusion, hydrocephalus, cranial nerve deficits, seizures, cerebral palsy and mental subnormality

Acute Bacterial Meningitis Beyond the Neonatal Period Organisms as outlined above. Clinical features are more definite Fever occurs in 90-95% of patients and is usually high grade with headache which is often diffuse in nature. Fever usually resolve early in children with pneumococcal or meningococcal infections compared with H.influenza. Prolonged fever (>10days) is noted more with H.influenza

SECONDARY FEVER: This refers to a relapse of elevated temperature after an afebrile interval. Usually caused by an intercurrent infection eg malaria, nosocomial infections, thrombophlebitis or drug fever. Coma-there is initial alteration of mental status, Irritability, lethargy and loss of consciousness. Occurs in over 50% of children. Can be as a result of cerebritis or inappropriate ADH secretion. Anorexia and poor feeding; vomiting. Symptoms of upper respiratory tract infection such as cough and catarrh; myalgias, arthralgias, inc. pulse rate

Seizures (focal or generalized) due to cerebritis, infarction, or electrolyte disturbances are noted in 20– 30% of patients with meningitis. About 10–20% of children with bacterial meningitis have focal neurologic signs They are more frequently noted in patients with H. influenzae and pneumococcal meningitis than in those with meningococcal infection.

Seizure can start before treatment, during or months to years after treatment Seizures occurring in the first 3-4 days of onset of illness has no prognostic importance. Seizures that persist after the 4th day of illness and those that are difficult to treat are associated with a poor prognosis. Post-meningitic seizures are more often partial in nature Carbamazepine has been found very useful

Focal neurologic signs usually are due to vascular occlusion. Overall, about 10–20% of children with bacterial meningitis have focal neurologic signs. This frequency increases to >30% with pneumococcal meningitis, as this bacteria tends to stimulate the most vigorous inflammatory response.

Cranial palsies Cortical blindness most common for all organisms. > 90% resolution after discharge. Auditory nerves palsy (sensorineural deafness) seen more frequently in H. influenza infection. oculomotor, abducens, and facial nerve palsies may be due to focal inflammation.

Signs of meningeal irritation manifest as nuchal rigidity, Kernig sign and Brudzinski sign (involuntary flexion of the knees and hips following flexion of the neck while supine).SLRR (Lassig sign) In some children, particularly in those less than 2years of age, signs of meningeal irritation are difficult to demonstrate. Most evident from 3years of age.

Hypotension, and various cutaneous signs, such as petechiae, purpura, or an erythematous macular rash esp. in meningococcal infection Increased intracranial pressure is suggested by headache, emesis Bulging fontanel or diastasis (widening) of the sutures (in those less than 18months of age), oculomotor or abducens nerve paralysis

Hypertension with bradycardia especially with raised intracranial pressure Decorticate or decerebrate posturing, stupor or signs of herniation.

MANAGEMENT LP after funduscopy Note the following: CSF appearance Pressure Sugar Protein Gram stain Culture  FBC:

Treatment Antibiotic Either of the 3rd generation cephalosporins: ceftriaxone or cefotaxime, represents current standard therapy for bacterial meningitis. Both drugs achieve high bactericidal levels in the CSF; virtually all patients have sterilization of CSF within 24 hr The dose of ceftriaxone is 50 mg/kg/dose, given every 12 hr. Cefotaxime can be as high as 200 mg/kg/24 hr given every 8hr. Cephalosporins highly broad spectrum.

Chloramphenicol also covers H.influenza and N.meningitidis. Given mg/kg/24hrs every 6hrs Crystalline penicillin still very useful in meningococcal and pneumococcal infections. Given at the dose of iu/kg/24hr every 6hrs

DECONGESTANT I/V mannitol (10%) 1-2GM/kg over 30mins given 8hrly in 24hrs. I/V Dexamethasone ( 0.15mg/kg/dose) useful if given before commencement of antibiotics. Have been found useful in H.influenza. Reduction in rate of sensorineural deafness which is commoner in H. influenza.

ANTICONVULSANT Immediate therapy for seizures includes intravenous diazepam (0.3mg/kg/dose) Pay careful attention to the risk of respiratory suppression. After immediate management of seizures, the patient should receive carbamazepine (10-20mg/kg/24hrs) in 2- 3 divided doses. This is preferred to phenobarbitone because it produces less CNS depression and permits assessment of the patient's level of consciousness.

NURSE AS AN UNCONSCIOUS CHILD MAINTAIN CALORIES-N/G Tube feeding Monitor fluid administration: 2/3 of maintenance fluid as a result of ISADH COMPLICATIONS These include cortical blindness with up to 90% recovery within 6 months Other cranial nerve palsies ( deafness) Motor deficits, seizures, hydrocephalus etc