This is a really serious illness and a dangerous diagnosis, most of us first hear about meningitis in childhood, from parents or caregivers, and this word carries not just a negative, but frankly frightening meaning: if you don’t put on a warm hat, you will get meningitis. But even in adulthood, no, no, but you have to hear this diagnosis, usually pronounced in an undertone and explaining a case of severe disability that turned a flourishing and successful person into a shadow hiding behind heavy curtains.
This is indeed a serious illness and a dangerous diagnosis. Like other diagnoses of this kind, this term is surrounded by a halo of myths, horror stories, prejudices and other irrational layers. The best way to dispel this fog is knowledge and understanding. Meningitis is a disease, not a doom or a heavenly punishment; like any other disease, it has its own causes and risk factors, its own pitfalls and ways to overcome it. This disease is now treated and in most cases cured. In addition, it can be prevented if you know and understand how.
The most important, in every sense, part of the nervous system, that is, the brain together with the spinal cord, we call the central nervous system (CNS). It is quite natural that nature has provided this functional block with the most powerful bone protection. However, the organs of the central nervous system are surrounded not only by the bones of the skull and spinal column. There are three additional meninges: two-lobed hard, arachnoid (arachnoid) and soft. Each of them differs in structure and performs its own functions, but under adverse conditions, an inflammatory process can begin in this three-layer brain protection, which is called meningitis.
Isolated inflammation of any one membrane is considered impossible today, therefore the diagnosis of arachnoiditis (inflammation of the arachnoid membrane of the brain) familiar to many is outdated. In special sources, however, the terms “pachymeningitis” (inflammation of the hard shell) and “leptomeningitis” (inflammation of the arachnoid and soft membranes) are used. If the inflammation spreads to the underlying structures of the brain, they speak of meningoencephalitis.
To give the absolute frequency of occurrence of meningitis on the globe is hardly legitimate; however, such estimates are almost never published. There are several reasons for this. Firstly, meningitis is not one, but actually a group of diseases that are very heterogeneous in etiopathogenetic and clinical aspects (some authors even suggest considering meningitis not a disease, but a syndrome or symptom complex). Secondly, with the accumulation of systematic medical statistics, rises and falls in the incidence are constantly recorded. Thirdly, there is a regional dependence (endemicity) of meningitis: for example, in the poorest African countries, the incidence, according to various estimates, is from 30 to 60 or more times higher than in developed countries with a temperate climate. Persons of both sexes, all races and nationalities, at any age are at risk; at the same time, among the diseased, a certain predominance of men, children, persons over 55 years of age is revealed (meningitis is most dangerous in the first months of life). In general, an estimate of the incidence among pre-pubertal children living in a temperate climate zone can be considered acceptable-accurate: one case in about ten thousand in the general population. Again, at the maximum allowable approximation and averaging, various sources report a trend towards a steady increase in incidence.
Before the advent of etiotropic treatments, mortality in meningitis approached one hundred percent. In the 20th century, the situation changed dramatically, however, even today the average mortality rate remains very high (primarily due to untreated and fulminant forms); estimates vary within 10-20%.
The reasons
The vast majority of inflammatory processes in the meninges are infectious in nature, that is, they are caused by pathogens. This predominance is so great that in some sources meningitis is treated as a disease of exclusively infectious origin. Strictly speaking, this is not true, since there are meningeal inflammations caused by autoimmune disorders, tumors, injuries, and taking hormone-containing drugs. However, their share, we repeat, is small, and below we will talk about meningitis as an infectious and inflammatory process.
All known types of pathogenic microorganisms are capable of causing inflammation of the meninges: bacteria, viruses, fungi and protozoa. At the same time, fungal and protozoal, in particular, amoebic, meningitis are very rare, acquire the character of meningoencephalitis with rapid destruction of the brain substance, proceed severely and, as a rule, end in death.
In most cases, a bacterial pathogen is found in patients with meningitis, most often meningococcus (70%), as well as pneumococcus, Haemophilus influenzae, streptococcus, chlamydia, staphylococcus, etc.
Viral meningitis is usually milder than bacterial ones and, with proper medical support, is completely reduced within a few days. They are most often caused by enteroviruses (in particular, the aggressive species ECHO30, brought to Russia from China and therefore not met with a proper immune counterattack in the Russian population), as well as mumps, measles, influenza, herpes, etc. viruses.
Accordingly, with such a variety of possible pathogens, the route of infection can also be practically any: airborne, fecal-oral, contact, transplacental, through insect bites, contaminated water, etc.
However, not always and not necessarily the presence of a pathogen in the body leads to infection of the meninges. For example, the introduction of meningococcus into the mucous membranes of the nasopharynx creates a risk of onset of meningitis only at a level of about 5% – in other cases, the person remains a passive asymptomatic carrier.
The main risk factor is a weakened, for one reason or another, immunity. There is a very high risk of infection with an open craniocerebral or spinal cord injury, followed by transport of the pathogen with a current of CSF. It is also possible to carry the pathogen with blood or lymph (through the channels of the nerves), which makes one of the risk factors the presence of chronic foci of infection, especially in close proximity to the brain or spinal cord (sick teeth, otitis media, osteomyelitis, inflammation in the organs of vision, epidural abscesses, etc.).
Symptoms
The clinical picture and type of meningitis can vary widely. Primary meningitis is distinguished, when the meninges become the focus of the inflammatory process, and secondary, which develops against the background and as a result of another infectious and inflammatory process (for example, SARS, tuberculosis, candidiasis, or “normal” mumps). The nature of the inflammation is classified as serous or purulent. Variants of the course vary from asymptomatic chronic to fulminant (fulminant and extremely severe), but most often the manifestation of meningitis is acute, that is, with a rapid increase and significant severity of symptoms.
With meningitis, the secretion of cerebrospinal fluid increases and intracranial pressure increases sharply. With the development of the process, cerebral intoxication, disturbances of the main and microcirculatory blood circulation, and oxygen starvation of the brain increase. In the absence of an adequate therapeutic response, the substance of the brain is involved in the process, edema occurs with gross, often fatal violations of vital functions (most often the cause of death is respiratory depression), and in some cases sepsis develops.
Despite the diversity of etiology and clinical picture, the most typical, almost universal symptoms are distinguished, one or another combination of which always allows a doctor (and of any profile) to suspect meningitis. These symptoms include a very intense, often unbearable headache, a sharp increase in temperature with a feverish state, photophobia, stiffness (persistent involuntary tension) of the occipital muscles, nausea, and often uncontrollable vomiting; a meningococcal generalized infection is characterized by a rash in the form of small “asterisks” (subcutaneous hemorrhages). Neurological and, in some cases, psychiatric symptoms are rapidly growing (delirium, then progressive depression of consciousness up to cerebral coma).
Diagnostics
Diagnosis is made on the basis of an available history, the presence of the aforementioned or similar symptom complex, and other meningeal signs (a number of pathologically altered reflexes serve as diagnostic criteria). If meningitis is suspected, a lumbar puncture is mandatory; signs of inflammation in the cerebrospinal fluid confirm the diagnosis; the absence of such signs rules it out. The causative agent is identified by a laboratory study of cerebrospinal fluid (bakposev, serological analysis, PCR, etc.). Material is selected for general clinical and biochemical analyzes, CT, MRI and other instrumental studies are prescribed, depending on the situation.
Some atypical or “erased” cases (for example, the onset of meningitis against the background of unauthorized and inadequate use of antibiotics), as well as symptomatically similar conditions (in particular, subarachnoid hemorrhages, intoxications or infections with the “meningism syndrome”), require especially careful differential diagnosis.
Treatment
The basis of the therapeutic strategy is the suppression of the activity of the identified infectious agent (with the help of adequately selected and dosed antibiotics, antimycotics, antiviral drugs, immunomodulators, etc.). Another important task is the prevention or relief of clinical manifestations of cerebral edema. Measures are taken for detoxification and dehydration, other procedures are prescribed, which are necessary in this particular case.
The main dangers of meningitis are the transience of development, the addition of cerebral symptoms, the risk of severe, disabling complications (epileptic syndrome, outcome in organic dementia in adults or developmental deficiency in meningitis in early childhood, strabismus, hydrocephalus, deafness, etc.). Accordingly, it is of utmost importance to immediately seek help at the first characteristic symptoms (it is better to be safe a hundred times than to wait and “observe” once), the fastest and most accurate diagnosis, and the urgent start of therapeutic and preventive measures. In this case, meningitis can be cured completely and without any serious consequences.
Prevention measures are also very important: a number of vaccines exist and are effectively used to prevent both primary and secondary forms of meningitis. From the foregoing, it clearly follows that it is extremely unreasonable to refuse such vaccination. Non-specific preventive measures include personal hygiene, elimination of the above risk factors, and maximum caution when in contact with a sick person or while staying in endemic areas.
