Introduction Infection predominantly involves the subarachnoid space---MENINGITIS. Brain tissue directly involved is called as ENCEPHALITIS. Focal bacterial,fungal,parasitic infection involving brain tissue – CEREBRITIS –absence of capsule,ABSCESS presence of capsule. Nuchal rigidity (STIFF NECK ) – pathognomonic sign of meningeal irritation-resistance to passive flexion. Classical signs of meningeal irritation –KERNIG’S,BRUDZINSKI’S sign.
What is ? MENINGISM :the symptoms and signs of meningeal irritation assosciated with acute febrile illness or dehydration without actual infection of the meninges…also called meningismus…PSEUDOMENINGITIS.
KERNIG’S SIGN Patient to be in supine position. Thigh flexed on abdomen. Knee flexed. Attempt to passively extend knee elicit pain when irritation is present.
BRUDZINSKI’S sign Supine position. Passive flexion of neck –spontaneous flexion of hips and knees. Specificity and sensitivity of these tests –UNCERTAIN.
Where they could be absent are? Immunocompromised Very young or elderly. Severely depressed mental state. False positive – cervical spine disease..
IMPORTANT POINTS.. It is an emergency. Empirical antibiotics to be started. Do CT scan/MRI in case of immunocompromised,recent head trauma,focal neurological deficits ---LP – but AB not to be delayed. No depressed level of consciousness –think of viral meningitis. Immunocompetent ,consciousness good –can be treated on OP basis. Failure of a patient to improve < 48 hrs – reevaluate the patient,repeat LP ,lab studies and neurological examination.
Much of the pathophysiology is due to direct consequence of chemokines,cytokines.
Clinical features Decreased level of consciousness >75% Nausea,vomiting,photphobia common Classical triad –less sensitivity Only two may be present nearly in all cases. Seizure –initial presentation in 20-40% cases Focal –focal arterial ischemia,cortical venous thrombosis,focal edema GTCS– hyponatremia,anoxia,high dose penicillin. RAISED ICP- >90 % have CSF pressure – 180mmH20 20% -- 400mm H20 Rash of meningococcemia – diffuse,petechial;
DIAGNOSIS CSF analysis Blood cultures CT scan/MRI --- LP Latex agglutination – S.pneumoniae,N.meningitidis Lumuluslysate –gram negative In case of immunocompetent,no h/o head trauma,no evidence of papilledema –LP without CT scan AB therapy to be started hrs before LP –no change in analysis,or visualization of organisms
CSF glucose may be zero – CSF/serum glucose corrects for hyperglycemia CSF/s.glucose < 0.6 CSF/s.glucose < 0.4 – bacterial,fungal,tuberculosis,carcinomatosis 30 min to several hours to reach equilbrium with blood glucose levels –so can start 50 ml of 50 % D. PCR –useful in pretreated pts,gram stain negative MRI >CT for cerebral edema Diffuse meningeal enhancement --gadolinium –increased permeability of BBB.
Treatment BEGIN AB < 60 min Empirical treatment –dexamethasone,cefotaxime or ceftriaxone,vancomycin,azithromycin,acyclovir,doxycycline. Post op cases –ceftazidime,cefepime,meropenem,vancomycin Then change according to culture reports
Meningococcal PENICILLIN G is DOC In case of resistance – Ceftriaxone,cefotaxime Uncomplicated course--7 day course. All close contacts should receive chemoprophylaxis – 2 day regimen of rifampicin 600 mg every 12 hrs * 2days/ciprofloxacin 750 mg od/azithromyxin 500 mg OD/ceftriaxone 250 mg OD Who are close contacts --- nasopharyngeal secretions,kissing,toys,beverages use.
pneumococcal Cephalosporin plus vancomycin If resistance – vancomycin Rifampin can be added synergistic action 2 week course Repeat LP after 24-36 hrs –sterilization of CSF –if not introventricularvancomycin
Listeria and others Ampicillin for 3 weeks Gentamicin 2mg/kg/d loading – 7.5 mg/kg/d every 8hrs TMP SMX –every 6hrs STAPHYLOCOCCAL –vancomycin Gram negative – 3 weeks of third generation cephalosporin.
Adjunctive therapy Dexamethasone – decreases synthesis of IL1,TNF,stabilises BBB 20 min before AB Rx Inhibits TNF production by macrophages only before activated by endotoxin. Decreases penetration of vancomycin into CSF. 10 mg IV 30 min before AB every 6hrs -4 days.
Raised ICP Elevate head end of bed 30-45 Intubation Hyperventilation PaCo2 – 25-30 mm Hg mannitol
Who are at risk of poor prognosis Decreased level of consciousness at admission Seziures < 24 hrs of onset Raised ICP Young age,>50 yrs Mechanical ventilation Delay in treatment <40 mg /dl -glucose >300 mg/dl -protein
sequelae Decreased intellectual function Memory impairement Seizures Hearing loss Gait disturbances
SUMMARY Acute bacterial meningitis is an emergency Triad is seen less commonly Pathognomonic feature is neck rigidity Altered level of consciousness and seziures can be the presenting features. S pneumoniae is the most common organism overall Other organisms based on the age ,and clinical background CSF analysis after CT scan is the rule… PMNs,hypoglycoracchchia,raised proteins and pressure is the hallmark PCR to be done only in negative cases MRI for cerebral edema
Antibiotics for a week in case of uncomplicated meninogcocci,2 weeks in s pneumoniae,3 weeks listeria. All close contacts to be given chemoprophylaxis in case of meningococci with rifampicin 600 mg bid for 2 days. Triad of meningitis is fever,headache,neckstiffness Postoperative cases think of s aurues,gram negative. Ampicillin to be given in case of suspicion of listeria for 3 weeks S. pneumoniae has high mortality of 20%
Antibiotic treatment not to be delayed for the results of investigations Third generation cephalosporins,vancomycin,ampicillindurgs empirically will cover all organisms. Dexamethasone for stabilisingBBB,to be given beofre AB. HSV encephalitis is closest DD 1 week therapy in case of meningococci,2 weeks pneumoniae,3 weeks –listeria Raised ICP –hyperventilate,raise head end,mannitol Sequelae decrease on early management 20% mortality in case of s.pneumoniae Thank you