What causes meningeal syndrome?

Meningeal syndrome may be caused by an inflammatory process caused by various microbial flora (meningitis, meningoencephalitis) or non-inflammatory lesions of the meninges. In these cases, the term "meningism" is used. In the case of inflammation, the etiologic factor may be bacteria (bacterial meningitis), viruses (viral meningitis), fungi (fungal meningitis), protozoa (toxoplasma, amoeba).

The main causes of meningeal syndrome:

I. Meningitis (meningeal + cerebrospinal fluid syndromes).

II. Meningism (pseudomeningitis):

A) Caused by physical causes:

• Insolation.
• Water intoxication.
• Post puncture syndrome.

B) Caused by somatic reasons:

• Intoxication (uremia, alcohol).
• Infectious diseases
• (flu, salmonellosis, dysentery and others).
• "Hypertensive crisis" (transient ischemic attacks in arterial hypertension) and acute hypertensive encephalopathy.
• Hypoparathyroidism.

C) Caused by neurological diseases (swelling and irritation of the membranes):

• Subarachnoid hemorrhage.
• Hypertensive-occlusive syndrome in volumetric processes, vascular accidents, brain injuries, carcinomatosis and sarcoidosis of the membranes.
• Pseudotumor (Pseudotumor cerebri).
• Radiation damage.

D) Caused by other (rare) reasons: severe allergies, etc.

III. Pseudomeningeal syndrome (pseudo-Kernig syndrome in processes in the frontal lobe of various origins, increased tone of the extensor muscles of the neck in some neurological, vertebrogenic and even mental illnesses).

I. Meningeal syndrome

Meningeal syndrome (irritation syndrome of the meninges) is most often caused by an inflammatory process in the meninges during bacterial or viral infections (bacterial or viral meningitis). But it can also develop as a reaction to a foreign substance in the subarachnoid space (subarachnoid hemorrhage, administration of drugs, contrast material, spinal anesthetics). It is also characteristic of aseptic meningitis (meningeal syndrome pleocytosis without bacterial or fungal infection) and meningism (irritation syndrome of the meninges without pleocytosis).

Meningeal irritation syndrome includes the following symptoms: headaches with stiffness and pain in the neck; irritability; hyperesthesia of the skin; photophobia; phonophobia; fever and other manifestations of infection; nausea and vomiting, confusion, delirium, epileptic seizures, coma. Complete meningeal syndrome also includes characteristic changes in the cerebrospinal fluid (CSF syndrome) and the following signs of meningeal irritation: stiffness of the neck muscles; resistance to passive extension of the legs; Kernig's sign (the leg does not extend at the knee joint more than 135 °); Bickel's sign - an analogue of Kernig's sign on the arms; upper Brudzinski's sign; lower Brudzinski's sign; reciprocal contralateral Brudzinski's sign on the legs; buccal Brudzinski's sign; Brudzinski's symphyseal sign; Guillain's sign; Edelman's thumb phenomenon.

Two-thirds of patients with bacterial meningitis have a triad of symptoms: fever, neck stiffness, and altered consciousness. It is useful to remember that neck stiffness is often absent in children under 6 months of age. Cervical spondylosis in the elderly makes neck stiffness difficult to assess.

Cerebrospinal fluid examination is the only way to confirm the diagnosis of meningitis and identify the pathogen. CT or MRI are used for differential diagnostic purposes (to exclude abscess, tumor, etc.). The cerebrospinal fluid is examined for cytosis, protein and sugar content, and bacteriological (and virological) and serological studies are performed. Microscopic examination of the cerebrospinal fluid is mandatory. Edema of the optic nerve is observed in only 4% of cases of bacterial meningitis in adults. Somatic examination often provides the key to understanding the nature of meningitis. Diagnosis and treatment of meningitis do not tolerate delay.

The differential diagnosis of bacterial meningitis should include viral infections of the central nervous system, traumatic brain injury, subdural hematoma, brain abscess, febrile seizures in children, sepsis, Reye's syndrome, metabolic encephalopathy, acute hypertensive encephalopathy, intoxication, subarachnoid hemorrhage, carcinomatous meningitis.

II. Meningism

Meningism is a syndrome of irritation of the meninges, in which no changes in the cerebrospinal fluid are observed (pseudomeningitis).

Excessive insolation can lead to heat stroke, which is characterized by hyperemia and edema of the membranes and brain tissue. Severe forms of heat stroke begin suddenly, sometimes apoplectiformly. Consciousness can be impaired from mild degrees to coma; psychomotor agitation or psychotic disorders, epileptic seizures; meningeal syndrome are possible. Body temperature rises to 41-42° and higher. Heat stroke usually occurs during the period of maximum heat exposure and only in rare cases during the period after overheating.

Water intoxication occurs when there is excessive intake of water (with a relative deficiency of electrolytes), especially against the background of insufficient fluid excretion (oliguria in adrenal insufficiency; kidney disease; use of vasopressin or its hypersecretion after injury or surgery). The water content in the blood plasma increases; hyponatremia and hypokalemia occur; hypoosmolarity of the blood is characteristic. Apathy, confusion, headache, cramps, and meningeal syndrome develop. Nausea, which intensifies after drinking fresh water, and vomiting that does not bring relief are characteristic. In severe cases, pulmonary edema, ascites, and hydrothorax develop.

Post-dural puncture syndrome sometimes manifests itself as symptoms of mild meningism, which usually resolves on its own within a few days.

Somatic causes of meningismus are most often associated with endogenous (uremia) or exogenous intoxication (alcohol or its surrogates), intoxication in infectious diseases (flu, salmonellosis, dysentery, etc.). Transient ischemic attack in patients with hypertension is rarely accompanied by symptoms of irritation of the meninges. Acute hypertensive encephalopathy develops over several hours and is manifested by headache, nausea, vomiting, meningismus, impaired consciousness against the background of high blood pressure (diastolic pressure 120-150 mm Hg and above) and symptoms of cerebral edema (CT, MRI, edema of the optic nerve). Focal neurological symptoms are not typical. Impaired consciousness varies from mild confusion to coma. Differential diagnosis is carried out with subarachnoid hemorrhage, acute alcohol intoxication and other conditions.

Hypoparathyroidism reflects the insufficiency of the parathyroid glands and is characterized by a decrease in the calcium content in the blood. Causes: surgical intervention on the thyroid gland (secondary hypoparathyroidism), autoimmune thyroiditis Hashimoto and Addison's pernicious anemia. Among the various neurological manifestations of hypocalcemia in hypoparathyroidism (tetany with muscle spasms and laryngospasms, myopathy, impaired consciousness, psychotic disorders, hemichorea, intracranial calcification and even epileptic seizures) an increase in intracranial pressure with edema of the optic nerve discs has been described. Pseudotumor cerebri may develop. Clinical manifestations of the latest complications of hypoparathyroidism may sometimes include mild symptoms of irritation of the meninges.

Neurological diseases such as subarachnoid hemorrhage, as well as hypertension-occlusion syndrome in volumetric processes, vascular accidents, brain injuries, carcinomatosis and sarcoidosis of the membranes are accompanied by a clearly expressed meningeal syndrome. These diseases are usually recognized clinically or by neuroimaging and general somatic examination.

Radiation damage to the brain most often develops in connection with the treatment of brain tumors and is manifested by a transient worsening of the symptoms of the underlying disease (tumor), epileptic seizures and signs of increased intracranial pressure, which is presumably associated with cerebral edema (although the latter is not confirmed by MRI data). Symptoms of meningism (an early complication of therapy) may sometimes be present here. Increased intracranial pressure is sometimes observed against the background of late (progressive dementia, ataxia, urinary incontinence, panhypopituitarism) complications (3 months to 3 years after therapy) of radiation therapy. Late complications are associated mainly with the development of multifocal necrosis zones in the brain tissue.

III. Pseudomeningeal syndrome

Pseudomeningeal syndrome is most often discussed in connection with increased tone in the posterior cervical muscles in the absence of true symptoms of irritation of the meninges (meningism). Such a symptom may be a manifestation of paratonia (gegenhalten, counter-continence) in frontal lesions of various origins (metabolic encephalopathy, diffuse cerebral atrophy, vascular encephalopathy in arterial hypertension), plastic increase in muscle tone (parkinsonism, progressive supranuclear palsy, other dystonic syndromes, stiffness), catalepsy in schizophrenia, diseases of the cervical spine or vertebrogenic muscular-tonic syndromes. Difficulty in extension of the head in these conditions is observed in the context of other pronounced neurological, somatic and mental disorders, which must be taken into account when interpreting this symptom.

For differential diagnosis between inflammatory lesions of the meninges and meningism, it is necessary to examine the cerebrospinal fluid obtained by spinal puncture.

Additional methods include examination of the fundus, skull radiography, echoencephalography (sonography for children under one year), EEG, CT and MRI of the brain. If the patient has meningeal syndrome, the following algorithm of actions is advisable.

Pathogenesis of meningeal syndrome

Meningeal syndrome can be caused by an inflammatory process and vascular disorders in the membranes of the brain, cerebrospinal fluid hypertension.