04/01/2026
MENINGITIS
The inflammation of the pia and arachnoid membrane. (The two layers of meninges) Classification
• Commonest cause: Pneumococcus in adults. H. influenza in children.
• Predisposed: Alcoholic, sickle cell disease, Hodgkin’s lymphoma, splenectomy.
Type of inflammation
• Sterile
– Subarachnoid hemorrhage.
– Poliomyelitis.
– Carcinomatosis.
• Infective
– Purulent.
– Meningococcal.
– Pneumococcal.
– Strepto and staphylococcal etc. • Non-purulent
– Viral.
– Tubercular.
– Fungal etc.
• Chronic meningitis by typical mycobacteria, spirochetes
Acute pyogenic meningitis
Etiology -
Pneumococci, Streptococci, Staphylococci, etc.
Source of infection
• Middle ear infections - commonest.
• Droplet infection from naso-pharynx.
• Cerebral abscess.
• Embolism.
• Head injury etc.
Symptoms/ signs
• Signs/ symptoms of meningitis present.
• Signs/ symptoms of local septic focus.
Investigations
• CSF examination.
• Sugar decreased below 40 mg/dl.
• Proteins raised.
• Pressure raised.
• WBC increased, neutrophils about 200-20,000.
• Gram’s stain may show pathogenic organisms.
Meningococcal meningitis (Cerebrospinal fever)
Etiology -It is the most common type of pyogenic meningitis. It spreads by droplet infection and enters the body through nasopharynx and subsequently carried to the blood stream via choroid plexus. Onset: Sudden, may occur in epidemics.
Symptoms
• Onset is acute with headache, pyrexia and rigors.
• Pain in back with headache involving neck also.
• Projectile vomiting.
• Generalised flexed attitude.
• Convulsions at the onset esp. in children.
• Photophobia.
• Irritability, confusion and drowsiness.
Signs of meningeal irritation
• Neck rigidity: Passive flexion is difficult so chin will not touch the chest
• Kernig’s sign: If thigh is flexed at 90° from abdomen it is impossible to straighten the knee passively due to spasm of hamstring muscles.
• Brudzinski’s sign: Passive flexion of a thigh causes spontaneous flexion of opposite thigh and flexion of neck causes flexion of hips and knee on both sides.
Signs of septicemia
• Petechial rashes before the third day of the ailment.
• Hypertension.
• Conjunctivitis.
• Adrenal failure due to hemorrhage into adrenal cortex.
• Pulse: Tachycardia.
• Pupils irregularly react to light.
• Anterior fontanelle may bulge.
Investigations
• Blood polymorphonuclear leucocytosis. Entirely polymorphs.
• CSF: increased pressure.
• Turbid and contains more than thousand cells predominantly polymorphs/ cmm.
• Gram negative diplococci (Culture Positive).
• Protein contents raised.
• Glucose content is lowered.
• CT, MRI might be needed in case of mass lesions.
Differential diagnosis
• Other meningitis.
• Meningism.
• Sub-arachnoid hemorrhage.
Complications
• Hydrocephalus.
• Permanent blindness due to optic atrophy.
• Insanity.
• Septicemia.
• Hyperpyrexia.
• Acute adrenal failure.
• Hemiplegia or paraplegia.
• Cranial nerve palsies (10-20%) commonly III, IV, VII, VIII.
• Aseptic meningitis.
Treatment
• Rush to hospital.
• Control of fever
• Hydration to be maintained.
• Blood pressure and adrenal function needs monitoring