Generally, complications of meningitis include: Complications due to spread of infection Complications due to healing
(I)Complications due to spread of infection to: 1 - Ependymal surface of brain ventricles leading to ependymitis and ventriculitis. 2- Sub and extradural spaces leading to sub and extradural effusion. 3- Leptomeningeal veins and sinuses leading to thrombophlebitis with vascular occlusion and haemorrhagic brain infarcts. 4- Blood stream leading to metastatic complications as arthritis, pericarditis, empyema, etc..
( II)Complications due to healing : 1-Arachnoid fibrosis leading to hydrocephalus. 2-Compression of cranial nerves leading to cranial nerve palsies, e.g.: deafness, blindness or squint.
3-Obliterative endarteritis causing brain ischaemia or infarcts resulting in variable neurological sequelae as seizures, paralysis, ataxia, cerebral palsy and mental retardation.
In viral meningitis: Complications are rare as it is usually a benign illness, but if associated with encephalitis seizures and neurological deficits are more likely to occur. While in bacterial meningitis: Complications are more common especially with H.influenzae and pneumococcal meningitis which may be complicated by subdural effusion. Complications are also common with meningeococcal meningitis where infection may spread to blood stream leading to either localization of meningeococci in different tissues resulting in arthritis, pericarditis, or less commonly septicemia with extensive haemorrhage due to suprarenal failure which is known as “ Waterhouse-Friedrichsen syndrome”.
Also in bacterial meningitis neurological sequelae are common such as deafness (severe to profound hearing loss), seizures, blindness, abnormal deep tendon reflexes and mental retardation. As for tuberculous meningitis: It is a potentially fatal condition and is the principal cause of death from TB in young age and survivors are likely to suffer complications as hydrocephalus, seizures, cognitive impairment and focal neurological sequelae as motor deficits and optic atrophy .