INFECTIONS OF CENTRAL NERVOUS SYSTEM
Introduction central nervous system infection:
Nervous system —
- Central Nervous System
- Peripheral Nervous System
Central Nervous system –
- Brain — Cerebrum, Brain stem & cerebellum
- Spinal cord
Coverings of brain – Meninges
- Dura mater
- Arachnoid mater
- Pia mater
Definition of central nervous system infection:
Infection occurring in relation to the central nervous system.
Two types —
- Generalized –Meningitis, Encephalitis & Myelitis
- Localized — Abscesses – Brain & S. Cord
Infections again are of two types—
Infection may be –
- Viral—Herpes simplex, Herpes zoster, Jakob-Creutzfeldt disease (Mad Cow Disease)
- Fungal –
- Protozoal—Malaria, Trypanosoma, Toxoplasma, E.histolytica
Inflammation of leptomeninges.
Bacterial, Viral, Fungal.
- Spontaneous -Bacteriology— Strep., Enterobactericae, Listeria
Pneumo, Meningococci, H.Influ,
Antibiotics of choice – Ampicillin, Gentamicin,
- Post-traumatic or Post-surgical (Surgical Meningitis)-
Bacteriology— Staph. aureas, Pseudomonas, Enterobactericae
Antibiotics of choice – Flucoxacilline, Vancomycin, Ceftazidime
Route of entry—
- Direct—CSOM, Air sinus infection, Post-traumatic CSF leak, Penetrating injury,
- Clinical parameters
- Laboratory and imaging data
Length of treatment — Antibiotics should be continued for at least 5 days after symptoms resolve.
Not less than 14 days according to some author.
Brain abscess, Empyema, Cord abscess.
- Pulmonary abnormalities ( Infection, A-V fistulas)
- Congenital cyanotic heart disease
- Bacterial endocarditis
- Penetrating head injury
Source of infection:
- Contiguous spread – CSOM, Sinusitis, Odontogenic infection.
- Hematogenous spread – Pulmonary, Cardiac, Dental infection, GI infection, Systemic infection.
In adult- Lung abscess(most common), Bronchiectasis and Empyema.
In children- Cong. Cyanotic heart disease esp. TOF.
- Following penetrating trauma or Neurosurgical procedures.
Site of Abscesses:
For hematogenous spread-
- Mostly MCA territory and on the Lt. side.
- Pulmonary origin- usually multiple, Cardiac origin- usually solitary.
- In patients with septic embolization, risk of cerebral abscess is elevated in areas of previous infarction or ischemia.
For contagious spread-
- CSOM and mastoid air cells- Temporal lobe and cerebellar abscess.
- Nasal Sinusitis- Frontal lobe abscess.
- Sphenoid sinusitis- Least common but high incidence of intracranial complication due to venous extension to cavernous sinus.
- Odontogenic- Rare
- Strptococcus– most frequent, 33-50% anaerobic and microaerophilic.
- Fungal – Common in transplant patients Aspergillus fumigatus
- Toxoplasma, Nocardia – common in immunocompromised patients.
- Features of raised ICP
- Focal neurological sign
- Features of cause of the lesion
- Gen. features of infection.
- CT scan- Depends upon the stage of the disease.
Usually Iso to hypodense lesion, with contrast ring enhancement.
- MRI – Iso to hypointense in TIWI, hyperintense on T2WI, ring enhancement in gadolinium enhancement.
- If treatment can be started in cerebritic stage
- Very small lesion < 3cm
- Poor surgical candidate
- Multiple small abscesses
- Critical location- Dominant hemisphere, Brain stem
- Concomitant Meningitis
- get blood culture
- antibiotics (3rd generation cephalosporin+ metronidazole+ vancomycin) or according to blood culture
- anti conversant
- significant mass effect exerted by the lesion
- proximity to ventricles
- raised ICP
- traumatic abscess with foreign body
- multiloculated abscess
Dr. Zahed, MS, FCPS
Asst. Professor, Neurology