CNS INFECTION

Definitions:Definitions: Meningitis : infection predominantly involved subarachniod space.Meningitis : infection predominantly involved subarachniod space. Encephalitis : infection predominately involved brain tissues.Encephalitis : infection predominately involved brain tissues. Brain abscess : is afocal suppurative infection within the brain parenchyma typically surrounded by a vascularized capsule.Brain abscess : is afocal suppurative infection within the brain parenchyma typically surrounded by a vascularized capsule.

Acute bacterial meningitis :Acute bacterial meningitis : -Definition. -Epidemiology: -it is the most common form of suppurative CNS infection. -annual incidence in the united states of >2.5 cases /100,000 population. -dramatic decline in the incidence of meningitis due to H. inf. & smaller decline due to N. men. -community acquired bacterial meningitis. -strep. Pnue. -N. men. -group B S. -L. mono. -strep. Pnue. -N. men. -group B S. -L. mono. -H. inf. -H. inf.

-S. pneumonia : is the most common cause of meningitis in adults >20 years. -N. men. 60 % of cases in children & young adults bet years. -group B strp. & S. agalactiae are mostly in neonates. -L. mono. Mostly in pregnant neonates & >60 years. -Staphylococcus predominantly in neurosurgical head trauma. Risk factors: -pneumococcal pneumonia. -acute & chronic sinusitis. -alcoholism. -otitis media. -D.M. -splenectomy. -hypogamaglobulinemia. -complement deficiency. -head trauma. -cirrhosis. -Chronic UTI. -immunecompromise def.

Clinical presentation:Clinical presentation: -present either acute or subacute onset. -the classic clinical triad >90%. -alteration in mental state vary from lethargy to coma. -seizures. -nausea, vomiting, photophobia are common. -sings of increase ICP. -petechial or purpuric skin lesions. -cranial N. palsy.

Diagnosis:Diagnosis: -1- History & exa. : - neck stiffness -kernigs sing. -Brudziaski sing. - neck stiffness -kernigs sing. -Brudziaski sing. -2- Blood culture. -3- neuroimaging : all patient should undergo to CT or MRI prior to LP. -4- CSF exa: classic finding. -pressure. -pressure. -WBC. -WBC. -RBC. -RBC. -Glucose. -Glucose. -Protein. -Protein. - Gram stian. - Gram stian. -Culture. -Culture. -5- PCR : -5- PCR :

DDx:DDx: 1- viral meningoencephalitis &HSV encephalitis. 2-Rickteshial disease. 3-focal suppurative CNs infection. 4-chemical meningitis. 5-drug induced meningitis. 6-carcinomatous & lymphomatous M. 7-inflammatory disorders. 8-subacute meningitis.

Treatment:Treatment: -the goal to start Abs. therapy within 60 min. of arrival emergency room. -empirical therapy is initiated before CSF result. -empirical therapy in children & adults should include. -antibiotic used in empirical meningitis. 1- preterm infants to infants < 1 month. 1- preterm infants to infants < 1 month. 2- infants 1-3 months. 2- infants 1-3 months. 3-immunocompetent children > 3mon & adults 3mon & adults <55. 4-adults >55 & adults of any age with deblitating illness 4-adults >55 & adults of any age with deblitating illness 5- hospital acquired meningitis. 5- hospital acquired meningitis. -prophylaxis.

-Adjuctive therapy: 1- dexamethasone. 2-treat raised ICP. Prognosis: -mortality rate is 20% for S. pneu. 15% for L. mono. 15% for L. mono. 3-7% for H.inf., N.men., or group B strep. 3-7% for H.inf., N.men., or group B strep. -Poor prognostic factors: -decrease level of consciousness on admission. -Seizures within 24 h. -sings of increase ICP. -extreme age. -comorbid condition. -delay in the initiated of treatment. -decrease CSF glucose 3g.

Complication :Complication : - moderate or severe occurs in 25% of patient. -decrease intellectual function. -memory disorders. -seizure. -cranial N. palsy. -hemiparesis & hemisonsory loss. -dizziness & vertigo. -hydrocephalus. -cerebellar ataxia. Urine disorders.

Acute viral meningitis:Acute viral meningitis: -it is aseptic meningitis present as fever, headache, malaise, myalgia, anorexia, vomiting. -focal neurological deficits, seizures &disturbance level of consciousness are generally absent. -meningeal irritation are usually absent. Etiology: -Enterovirus account for 75-90% of aseptic M., that represent the commonest one,typically occurs in summer monthe in children < 15 years. -Arbovirus, typically occurs in summer months in endemic & epidemic form. -HSV2, occurs in 25% of women & 11% of men as episode of genital herpes. - mumps, present in late winter early spring.

Diagnosis:Diagnosis: 1- CSF examination : typical profile is. 2-PCR. 3-Serological studies: -4-Other sources for viral isolation: Treatment: -usual case of aseptic M., treatment is symptomatic & hospitalization is not required. -indication for admission : -symptomatic T. -oral or I.V. acyclovir.

Viral Encephalitis:Viral Encephalitis: -there are approximately 20,000 cases of encephalitis per year. -the most important viruses causing sporadic cases in immunocompetent adults are. -less commonly enterovirus & others include. Clinical manifestation: - in addition to acute febrile illness with meningitis, patient commonly has confusion, behavioral abnormalities. -altered level of consciousness. -seizures. -focal neurological deficits. -cranial N. palsy. -focal neurological deficits. -cranial N. palsy. -involuntary movement. -psychological disorders. -hypothalamus-pituitary lesion.

Laboratory diagnosis:Laboratory diagnosis: 1- CSF examination: csf finding is indistinguishable from viral M. 2-CSF PCR: 3-CSF culture: 4-serological studies: 5- CT & MRI: 6- EEG : 7-Brian biopsy:

DDx:DDx: -1- Meningitis. -2-Meningoencephalitis. -3-Brian abscess. -4Empyema.-5-Tumors. -6-Subdural hematoma. -7-Vasculitis. -8-Toxic encephalopathy. -9-Limbic encephalitis. -10-ADEM. -11-Prion disease.

Treatment:Treatment: -specific antiviral therapy should be initiated when appropriate. -monitoring of vital functions. -treat raise ICP. -treat seizure. -prevent & treat of complication. -antiviral therapy. -acyclovir. -acyclovir. -ganciclovir & foscarnet. -ganciclovir & foscarnet.

Subacute meningitis:Subacute meningitis: -typically have unreleating headache, stiff neck, low grade fever, & lethrgy for days. -cranial N. palsy. -night sweats may be present. -unsteadiness & ataxia. -memory impairment. -mylopathy, radiculopathy & neuropathy. -common organisms include.

TB. Meningitis :TB. Meningitis : -M. tuberculosis is acquired by inhalation of aerosolized droplet nuclei. -it is does not develop acutely from hematogenous spread of bacilli to the meninges. -Miliary tubercles form in the parenchyma of the brain during dissemination of tubercle bacilli in the course of primary infection. -The propensity for a caseous lesion to produce meningitis is determined by its proximity to the SAS.

Diagnosis :Diagnosis : 1- History & examination : 2- Classic CSF exa.: 3-PCR: 4-Chest x-ray: 5-ESR.

Treatment:Treatment: 1- combination of antibiotics. 2-steriod.