=inflammation of the meninges. Clinically neck stiffness/pain, headache, photophobia. Almost always vomiting. Usually infective, so usually fever too. Can be viral, bacterial or tuberculosis.
This clinical picture gets confused with the diagnosis of meningococcal disease. Meningococcus (gram negative diplococcus, very distinctive under the microscope) commonly causes meningitis but tends to cause a relatively mild disease with good outcome. It can also cause sepsis that is rapid onset and often fatal, meningitis is rarely a feature of this disease (indeed, having meningitis at the same time is a good prognostic feature).
Diagnosis is by lumbar puncture. Bugs often seen under microscope, which will usually give organism too, else rapid antigen tests available. White cells will be high (often in thousands if bacterial), protein high (can be over 2 if bacterial). Neutrophil predominance suggests bacterial but this is not v reliable esp in babies. Low glucose v suggestive of bacterial.
Can be complicated by raised intracranial pressure and seizures.
In neonates, mostly Group B streptococcus, else gram negative bacilli. Listeria can present with sepsis or meningitis in young infants (90% under 30 days).
In older infants and children, mostly meningococcal disease, else pneumococcal or haemophilus. All declining rapidly as a result of immunisation, currently conjugate Hib, PCV-13 and MenACWY plus 4CMenB.
Antibiotics to kill bugs. Steroids to reduce damage.
Ceftriaxone is ideal, broad spectrum, good CSF penetration, once daily. But listeria resistant, and gets chelated by calcium so contraindicated if likely HDU/ICU care where calcium infusions often necessary. Also contraindicated in preterm infants under 41/40 corrected, and in neonates esp jaundice, acidosis, hypoalbuminaemia.
For listeria, amoxicillin or ampicillin for 21 days in total, plus gentamicin for at least the first 7 days.
Dexamethasone has been shown to reduce complications eg deafness. Regimen is 0.15 mg/kg (max 10 mg) qds x 4 days. Only given to children ≥ 3 months old. Ideally given before or with first dose antibiotics – NICE says within 12 hours, assuming positive LP viz frankly purulent CSF, or CSF WCC > 1000/μl, or raised CSF WCC and protein > 1 g/L, or bacteria on Gram stain. Steroids should not be used in developing countries.
For unconfirmed bacterial, NICE says minimum 10/7 for over 3/12, 14/7 (with amoxicillin) for under 3/12 – but depending on signs, symptoms and clinical course. Discuss with expert if complicated clinical course.
TB meningitis is a whole different ball game. See NICE NG33 before administering steroids.
Hydrocephalus, epilepsy, deafness. Particularly seen with Pneumococcal disease.
Recent evidence highlights that meningitis in early childhood is associated with higher depressive and anxiety symptoms, psychological and behavioural problems, and increased risk of psychotic experiences. Not just that, higher risk of ADHD, and lower IQ on average. Follow up therefore very important for young babies, and probably appropriate to warn families.