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Meningeal syndrome - Causes and pathogenesis
Last reviewed: 06.07.2025

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Causes and pathogenesis of meningeal syndrome
Meningitis. Depending on the etiology, meningitis is divided as follows.
- Bacterial (meningococcus, pneumococcus, Haemophilus influenzae and tuberculosis bacilli, etc.).
- Viral (Coxsackie, ECHO, mumps viruses, etc.).
- Fungal (cryptococcosis, aspergillosis, candidiasis, etc.).
- Parasitic infections (cysticercosis, toxoplasmosis, amoebiasis, etc.).
Meningitis is divided into primary meningitis, which develops without previous signs of a pathological process, caused by a corresponding pathogen (for example, meningococcal), and secondary meningitis, in which damage to the membranes of the brain is preceded by other manifestations of a generalized or local infection (for example, meningitis in epidemic mumps, otogenic pneumococcal meningitis).
The causative agent of meningitis can enter the meninges hematogenously (with meningococcal infection, sepsis, leptospirosis, etc.), lymphogenously, and by direct spread from purulent foci located on the head (otitis, mastoiditis, osteomyelitis, etc.).
In addition to inflammatory changes in the tissue of the meninges, meningitis is accompanied by excessive formation of cerebrospinal fluid (leading to the development of intracranial hypertension) and increased permeability of the blood-brain barrier. The spread of the inflammatory process to the walls of the ventricles leads to the development of ventriculitis, and directly to the brain substance - to purulent meningoencephalitis.
The toxic effects of the waste products of meningitis pathogens are accompanied by microcirculation disorders, cerebrospinal fluid dynamics disorders, which result in the development of cerebral edema, its dislocation, the development of secondary brainstem syndrome and disruption of vital functions.
Subarachnoid hemorrhage. Spontaneous subarachnoid hemorrhage is most often caused by a ruptured saccular aneurysm of the arteries of the base of the brain. Much less frequently, it is caused by arteriovenous malformations, mycotic aneurysms that arise as a result of an infectious lesion of the vascular wall, or a dissecting aneurysm of the vertebral or internal carotid artery.