Neurological Disorders: Meningitis

Introduction

Meningitis is a common type of neurological disease and is associated with inflammation of the coverings of brain and spinal cord. A Neurologist is frequently involved in the care of this condition.

Many types of this condition are generally serious and life threatening in nature if not promptly treated (example – caused by bacteria or TB etc). Early institution of antibiotics generally results in favorable out come; however it is not a guarantee. Certain types, like viral one are generally not serious and self limiting!

The term is usually used to indicate involvement of brain coverings. But not to forget that the spinal cord is covered by this structure as well. When the inflammation occurs only around the spinal cord then it is preferably called as spinal-meningitis, and if there is involvement of coverings of both brain & spinal cord then it is called as cranio-spinal-meningitis.

Who are the culprits?

Meningitis causes usually include;

• Bacteria
• Viruses
• Tubercular bacteria (TB)
• Fungus
• Parasites (e.g. amoebic)
• Carcinomatous meningitis
• Chemicals
• Drugs (example – ibuprofen)

Majority of this condition is caused by microorganisms like viruses, bacteria, TB & fungi.

Bacterial:

The type of bacteria causing this depends upon the age & immunity status of the patient.

Age < 6 months (including new born);

  • Streptococci (group B)

  • E. Coli
  • Listeria monocytogens

Younger children;

  • Meningococcal

  • H influenza

Older children/adolescent/adults;
  • Pneumococcal

  • Meningococcal
Older people & immuno-compromised;
  • Pneumoccoal
  • Listeria monocytogens
  • Meningococcal
  • H influenza
TBM (Tubercular):

This is produced by TB (tuberculosis bacilli) and incidence is high in developing countries especially during childhood.

Fungal:

It is caused by various fungi, and Cryptococcus neoformans is the commonest cause and called as cryptococcal meningitis. Immuno-compromised people (example - AIDS patients, patients on steroid etc) are especially susceptible for this type of meningeal involvement.

Viral:

This is caused by myriad viruses and many of these viruses are frequently encountered by human beings in the form of gastroenteritis, respiratory tract infections etc.

Carcinomatous type

There are several tumors in the body that can spread to the meninges like the lung & breast cancers.

How do the microorganisms reach the brain/meninges?

They gain access to the brain coverings through the blood or from contiguous structures like sinuses, nose, middle ear etc. Head injuries & open skull surgeries facilitate direct entry of these microorganisms in to the meninges.

How does the patient present?

The common manifestations include;

  • High grade fever
  • Severe headache
  • Vomiting
  • Intolerant to light (photophobia)
  • Intolerant to sounds (phonophobia)
  • Poor feeding, Irritability, in infants & young kids etc.

Not always patients present with these classical above mentioned symptoms, sometime one or more of these symptoms may be absent or mild which confuses the picture. For example in young children the neck stiffness may not be prominent. Fever may not be conspicuous in immuno-suppressed and older people.

Meningeal inflammation can be classified as acute, sub-acute/chronic based on the rapidity of onset & build up of the symptoms. With the acute type the onset and evolution of the symptoms are rapid and usually just a few days, e.g. bacterial ones. With the sub acute & chronic types the disease process builds up gradually over weeks to months e.g. fungal, TB types.

On examination the following findings are usually seen;

  • Neck stiffness
  • Kerning’s sign
  • Brudzinski’s sign
  • Papilloedema (swelling of optic nerve or “nerve of vision”
    inside the eye)
The above findings are detected by doctors during their examination of the patient.

Diagnosis

Spinal tap and CSF (cerebrospinal fluid) analysis is the single most important diagnostic test for this condition. It not only confirms this condition also guides us regarding the antibiotics to be chosen. A CT or MRI of the brain may also be necessary in certain situations.

A typical case will show increased cell count & protein. Glucose is either normal or decreased. The decreased glucose is seen with bacterial, TB (tuberculous), fungal & carcinomatous type of meningeal infections. In viral type it is generally normal.

Gram stain is done to identify the bacteria. A bacterial culture is done to isolate he organism. Some bacterial antigens may be detected too in the CSF.

For tuberculous type acid fast staining, TB bacilli culture, PCR test are usually done.

For fungal type; fungal staining, culture, antigen tests are usually done.

In viral-meningitis there will be just increased cells (mononuclear) and protein, rest of the tests for bacteria, fungus, TB etc all are expected to come normal. Of course in typical viral type cases you need not send CSF for all these additional tests as clinical picture + the routine CSF report it self is sufficient to make the diagnosis.

Treatment

For viral type treatment is supportive & symptomatic. The prognosis is excellent with almost full recovery in almost all cases (of course we are talking about the non specific routine viruses, if virus like HIV or AIDS virus caused it then prognosis is decided by the underlying HIV infection).

For bacterial, TB and fungal aggressive antibiotic treatment is mandatory for survival. A course of steroid may be given especially with TB and certain types of bacterial meningitis.

For carcinomatous type the treatment usually consists of chemotherapy, radiotherapy and treatment for the primary tumor.

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