ACUTE PYOGENIC MENINGITIS

ACUTE PYOGENIC MENINGITIS

AETIOLOGY

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Causative organisms

Meningococci-commonest (above 4 years), pneumococci (above 45 years), streptococci, Haemophylus influenza (within 4 years) and others.

Source of infection

Middle ear infection (commonest), droplet infection from nasopharynx, sinuses, mastoid, infection from the danger area of the face, cerebral abscess, embolism, head injury, infection from scalp etc. Other predisposing causes are chronic malnutrition, poverty, overcrowding, immunosuppression from AIDS, carcinomatosis, splenectomy, asplenia, diabetes, chronic alcoholism, pneumonia, CSF shunts.

 CLASSIFICATION OF MENINGITIS

A, B, C, Y, W-135 and other groups of N. meningitis are commonly involved in meningococcal cases. The clinical picture may take the form of meningococcemia, chronic form may also exist manifested with fever, rash and arthritis particularly in persons with terminal complement deficiencies (C7-Co) or low properdin level.

CLINICAL FEATURES

Clinically in average cases of meningitis the following three stages are seen though there may be considerable overlapping.

Stąge of Meningeal irritation

Temperature is raised 102°F to 104° F (39°C to 40°C), which may come with slight chill. It occurs within 2 days of infection.

2.Headache is tremendous, bursting or splitting in type localised in the occipital or at times in the frontal region. It may radiate upwards and downwards in the neck. This is a characteristic symptom of meningitis.

3. Restlessness and irritability are present, patient does not like to be examined.

4. Photophobia: Patient lies keeping his back side towards Light or keep the eyes closed in presence of light.

5. Delirium, convulsion, meningeal cry may occur.

6. Generalised flexed attitude: Huddled up position may be seen. It is thought that in this attitude meninges are less stretched and CSF pressure is less felt.

7. Neck or cervical rigidity and back rigidity. These are important signs and are due to spasm of the neck muscles and back muscels.

Neck cannot be flexed so chin will not touch the chest. In an attempt to flex the neck the whole body may be raised up as there is back rigidity also.

Sometimes the neck may remain in the extended or retracted position. This is called gun hummer position. This is best seen in post-meningeal adhesion. Headache, fever, and stiff neck are present in more than 85 % of cases.

8. Kernig’s sign is positive. After flexing the hip joints at right angle if the leg is tried to be extended at the knee, spasm of the hamstring muscles will prevent it and patient complains of pain when conscious.

9. Brudzinski’s sign:

a) Neck sign-during flexing the neck both the lower limbs are flexed.

(b) Leg sign-during testing for Kernig’s sign in one leg, opposite leg will be flexed.

10. Pulse shows tachycardia.

11.  Respiration rate is normal or hurried.

12. Pupils are irregular and irregularly react to light.

13. In about 40% of patients a rose rash may develop in lower limbs, petechial and purpuric in nature particularly in cases of meningococcal meningitis. So the disease is called spotted fever. Sometimes there may be eccymoses and ganorene.

14. Reflexes: Planter reflex is flexor in type, jerks are brisk, sphincteric reflexes are normal.

15. Cranial nerves are normal.

16. Ophthalmoscopic examination reveals no abnormality.

Stage of Meningeal Compression

1. Headache becomes more intense. Convulsion continues. Vomiting starts; it is projectile in nature and it is not preceded by nausea (cerebral vomiting).

2. Temperature continues. Patient gradually becomes drowsy, delirious and confused.

3.  Pulse rate is slow and it becomes bounding.

4. Respiration may show Cheyne-Stoke’s or Biot’s type of breathing.

5. Anterior fontanelle is bulged in children.

6. Neck rigidity and Kernig’s sign are present as before. Convulsion starts. Sometimes it may be so severe that patient becomes ophistonic.

7. Pupils are slightly dilated but sill react to light.

8. Oculomotor palsy particularly bilateral 6th nerve palsy may develop.

9. Reflex: Plantar reflex may become extensor, jerks are still brisk and sphincteric retention develops.

10. Ophthalmoscopic examination may reveal papilloedema.

Stage of Coma or Paralysis

1. Patient becomes deeply comatose.

2. Temperature is high, pulse shows tachycardia, respiration rate may be high

3. Neck rigidity and Kernig’s sign may disappear.

4. Pupils are widely dialated, fixed and do not react to light.

5. Limbs are flaccid, plantar reflex is extensor, jerks are lost.

6. Involuntary evacuation of urine, faeces may develop

7. Papilloedema becomes prominent.

8. Bedsores and gangrene may develop.

Cranial nerve palsy, lateralising signs, papilloedema, drowsiness or coma usually indicate complications, e.g. cerebral oedema, venous sinus thrombosis, hydrocephalus, etc. It is to be remembered that these stages described above are not always well marked and in many cases are overlapped to each other.

INVESTIGATIONS

1. Blood examination shows leucocytosis with increased polymorphs.

2. CSF examination shows increased pressure, colour is turbid, cells are 1000-3000/cmm mainly pus cells, protein is increased, sugar and chloride are diminished (sugar is markedly diminished). CSF smear shows the causative organisms. Absence of organism does not rule out the diagnosis. Culture is positive. Polymerase chain reaction (PCR) is also helpful for identification of bacteria. Smear and staining from the centrifuged deposit of CSF and culture of blood aspirated from the rash, oropharyngeal swab may show the causative organisms. Bacterial antigen and endotoxin assay can also be done.

3. The capsular polysaccharide or N. meningitides can be demonstrated in CSF or urine in 60% to 80% of cases.

4. CT scan of brain is required sometimes to exclude mass lesion.

COMPLICATIONS

1. Hydrocephalus.

2. Permanent blindness due to optic Atrophy or by iridochoroiditis.

3. Permanent deafness due to 8th nerve paralysis.

4. Other cranial nerve palsies.

5. Insanity.

6. Hemiplegia or paraplegia.

7. Septicaemia.

8. Hyperpyrexia.

9. Acute adrenal failure.

10. Purulent pericarditis, bacterial endocarditis.

11. Arthritis.

12. Nephritis and renal failure.

13. Pneumonia, bronchopneumonia.

14. Disseminated intravascular coagulation.

15. Prothrombin time, PTT are prolonged, fibrinogen level is low, fibrin dimers are elevated, platelet count is low.

16. Hyponatraemia due to inappropriate secretion of ADH

17. Subdural effusion.

18. Epilepsy

19. Peripheral gangrene.

TREATMENT

1. Rest in bed in a railed cot and isolation should be done.

2. If the patient is in coma all measures for coma are to be taken.

3. Chemotherapy: The choice of chemotherapeutic agents depends on sensitivity test. However, until report of sensitivtity test is available for practical purpose Ampicillin in the IV route 150 mg to 250 mg/Kg of body weight daily is the best form of treatment. Alternatively, Crystalline Penicillin may also be given 2 mega units (40,000 gm/kg) IV every 2 hourly. In penicillin sensitive case Chloramphenicol 1 gm IV (75-100 mg/kg) 6 hourly may be given. Ceftriaxone 4 gm IV once daily or Cefotaxime 50 mg/kg IV are also useful. These are best indicated for Haemophilus infection. In neonates Cefotaxime or Gentamicin and Ampicillin are useful. The drug is to be continued till clinical improvement occurs and then at a lower dose the drug is be continued till CSF sugar and cells come to a normal level. On an average 7-10 days course is required.

4. LP Should be done to decrease intracranial tension and may be repeated. To reduce intracranial tension intravenous Mannitol 2 gm per kg may sometimes be used. Steroids are also helpful. These are specially indicated for cerebral oedema.

5. If there is circulatory collapse then 5% Dextrose in normal saline in IV drip to be started with steroids e.g. Injection Dexamethasone 2 mg 8 hourly with other circulatory stimulants.

6. Fluid and electrolyte imbalance is to be corrected.

7. Symptomatic treatment of headache with Aspirin or of convulsion with Paraldehyde 6-8 cc IM or Diazepam 5-10 mg IV may be given. If there is evidence of DIC, heparin 50 units per kg IV is to be given so as to keep the clotting time in the range of 15-25 minutes.

8. Polyvitamins are to be given.

Prevention: Effective polysaccharide vaccines are now available for A, C, Y and W 135, These are used in epidemic. Single dose of polyvalent vaccine is helpful to give protection against above strains. Nasopharyngeal carriers are best given Rifampin 600 mgm twice daily for 2 days or a single dose of Ciprofloxacin 500 mg or a single injection of ceftriaxone 250 mgm IM.