Central Nervous System Infections

The general name for a group of infectious diseases with the localization of the pathogen in various departments of the Central Nervous System of neuroinfection. Viruses, bacteria, fungi, protozoa, and prions can cause neuroinfection. Allocate inflammation of the membranes of the brain and spinal cord (meningitis), damage to the substance of the brain (encephalitis), and spinal cord (myelitis). Meningoencephalitis is diagnosed if there are signs of meningitis and encephalitis.

These Central Nervous System Infections are polyetiological in nature, accompanied by general intoxication of the body and inflammatory changes, differing in clinical manifestations depending on the type of pathogen, localization of the process, and the scale of infection.

Depending on the characteristics of the cellular composition of the patient, neutrophilic or lymphomonocytic pleocytosis, neuroinfections are divided into purulent or serous meningitis (encephalitis), respectively. The approximately equal ratio of neutrophilic leukocytes and lymphocytes indicates a mixed nature of pleocytosis, which can be determined in the early stages of the disease in bacterial meningitis of any etiology. Purulent CSF most often implies the bacterial nature of the infection; the predominance of lymphocytes in the CSF indicates a predominantly viral etiology. Therefore, obtaining puncture results in a patient in the first hours of admission to the hospital allows one to determine the range of possible causative agents of the disease (bacteria or viruses) and prescribe adequate treatment. At the same time, we must remember that several bacterial meningitis (tuberculous, syphilitic, yersiniosis, etc.) can be both purulent and serious in nature.

The most common cause of purulent bacterial meningitis (encephalitis) is Neisseria meningitidis, Streptococcus pneumoniae, Haemophilus influenzae b, Staphylococcus aureus; other pathogens are much less common. According to the primary lesion of the membranes and brain matter, these diseases are divided into primary, characterized by the development of the disease without a previous focal or septic lesion of the body by a microbial agent, and secondary, complicating localized acute or chronic infection as a result of generalization of the process or trauma.

In addition to the already mentioned meningitis with mixed pleocytosis, serous bacterial meningitis includes diseases of mycoplasma, Leptospira, and Borrelia etiology. Serous protozoal meningitis is most commonly caused by Toxoplasma gondii.

Inflammatory diseases of the central nervous system occupy an essential place in modern neurology. Their development can be triggered by bacteria, fungi, protozoa, and viruses. Also, such autoimmune processes as multiple sclerosis or vasculitis are often found in this case; the body cannot recognize individual structures as its own, which, in turn, can cause inflammation of the nervous system. The immune system, which must suppress pathogenic influences (for example, the activity of pathogenic bacteria), in these cases, produces antibodies against the structures of its own body, for example, certain parts of the nervous system. The main diseases resulting from the activity of infectious agents include inflammation of the meninges (encephalitis), infections of the spinal cord (myelitis), and, in rare cases, infections of nerves and muscles.

Neuroborreliosis and shingles are common clinical symptoms of pathogen-induced brain infection. Against the background of immunosuppressive and immunomodulatory therapy, Central Nervous System infections in debilitated patients often manifest as progressive multifocal leukoencephalopathy in multiple sclerosis. Travel, food imports, climate change, and migration are gradually leading to the emergence of rare inflammatory diseases in our latitudes, caused, for example, by the Zika, Chikungunya, or Dengue viruses.

Symptoms of Central Nervous System Infections

• A person has such alarming symptoms as sudden onset of fever, headache, photophobia, vomiting, epileptic seizures, and, especially if the day before they have had a severe acute respiratory viral infection or other infection, an urgent need to consult a doctor.

In a hospital, a patient with Central Nervous System Infections usually undergoes a lumbar puncture to examine the cerebrospinal fluid (CSF) for inflammation and identify bacterial and viral agents, as well as an MRI of the brain. The tactics of treatment depend on the results of the study.

• Chronic indolent neuroinfections occur most often in arachnoiditis or arachnoencephalitis, and often have a viral etiology. They are manifested by persistent headache, low-grade fever, severe general weakness and sweating, chronic fatigue, double vision, unsteadiness when walking, nausea, and vomiting in the morning (often at the height of the headache).

Central Nervous System Infections are necessarily confirmed by MRI detection of inflammatory changes in the brain or membranes, signs of intracranial hypertension in the fundus, as well as specific immunological blood parameters.

• Identification of the causative agent of infectious brain disease is essential. For this, a study of the content of antibodies (immunoglobulins) in the blood to the main causative agents of neuroinfections is used:

1. cytomegalovirus
2. herpes simplex viruses type I and II
3. Epstein-Barr virus
4. varicella zoster
5. toxoplasma, etc.

Due to the development and use in clinical practice of strong antibacterial and antiviral drugs, immunoglobulins, there is a significant improvement in the quality of therapy for patients with inflammatory diseases of the central nervous system.

The presence of prolonged low-grade fever in combination with persistent headaches and nausea, epileptic seizures of unknown origin is a reason to consult a neurologist and be examined for neuroinfection and neurol neurosurg psychiatry.

Diseases Caused by Central Nervous System Infections

Herpetic encephalitis. The most common sporadic encephalitis is herpetic encephalitis. The main symptoms of this deadly disease include headaches, fever, and various quantitative and qualitative disturbances of consciousness. If a patient is suspected of having herpetic encephalitis, antiviral therapy should be carried out. Without treatment, the disease can be fatal, and any delay in starting antiviral therapy could cost the patient their life.

Meningitis. The most common causes of bacterial meningitis are streptococci, listeria, and meningococci. The disease symptoms are headaches, fever, nausea, vomiting, and the so-called meningism or stiffness of the neck muscles. In very young as well as in older patients, the symptom of meningism may be absent. Similar to viral diseases, bacterial meningitis requires immediate therapy, rapid diagnosis, and qualified patient care in an intensive care unit.

Multiple sclerosis. The most famous autoimmune disease of Central Nervous System Infections is multiple sclerosis. It is a chronic inflammatory demyelinating disease with axonal damage to the central nervous system. The cause of multiple sclerosis is unknown, but the success of immunosuppressive treatment with disease-modifying drugs suggests autoimmune pathogenesis.

Common symptoms of multiple sclerosis are visual disturbances, numbness, concentration disturbances, fatigue, speech disturbances, coordination disturbances, spasticity, urinary disturbances, sexual disturbances, swallowing disturbances, and double vision. However, today, modern drugs for the treatment of multiple sclerosis make it possible to control the course of the disease well. Moreover, the earlier the diagnosis is made and the therapy is selected, the more successful the treatment is. On average, 80 out of 100 patients, ten years after the onset of the disease, remain functional.

Myelitis. Another example of inflammatory disease of the central nervous system is myelitis, an inflammation of the spinal cord. It can diffusely affect an entire spinal cord area (transverse myelitis) or be focal (disseminated myelitis). The main symptoms of the disease are:

• muscle weakness
• paresis, including spastic
• sensitivity disorders
• gait disturbances
• pain in the whole body
• depression
• emaciation
• as well as bowel and/or bladder dysfunction.

Both the transverse and disseminated course of myelitis can also be accompanied by transverse paralysis with sensory or motor disorders, depending on the region of the lesion.

The prevalence of Central Nervous System Infections is very high. Early diagnosis, neurol neurosurg psychiatry, and highly differentiated therapy are essential for further prognosis. As in the case of a stroke, in inflammatory diseases of the central nervous system, the rule is that the sooner you start treatment, the more chances you will not develop severe consequences; this means that the loss of time is tantamount to the loss of the human brain. Prompt and correct treatment can be life-saving.