Infectious diseases of the CNS and PNS occupy one of the leading places among neurological diseases due to their prevalence. The severity of the infectious process, serious complications resulting in a deep neurological deficit require a good knowledge of this pathology for timely diagnosis and proper treatment.
There are various classifications of infectious diseases of the nervous system.
By type of infectious agent, the following forms are distinguished:
- bacterial;
- viral;
- fungal;
- protozoal.
By the method of penetration of the infectious agent (site of entry), there are the following pathways:
- airborne;
- contact (for injuries, diseases of ENT organs);
- hematogenic;
- lymphogenic;
- perineural (along the peripheral nerves).
Infectious agents can primarily affect the nervous system (so-called neurotropic pathogenic agents), or the disease can occur secondarily as a complication of the infectious process in other organs and systems.
By the localization of the pathological process in the brain membranes, meningitis can be:
- pachymeningitis ― involvement of the dura mater;
- leptomeningitis ― involvement of the pia mater.
Previously, the classification included an isolated involvement of the vascular (arachnoid) membrane, i.e., arachnoiditis; currently, this condition is included in the group of leptomeningitis.
The following structures may be involved:
- brain — encephalitis;
- spinal cord — myelitis.