Acute suppurative meningitis

Introduction to acute suppurative meningitis Acute suppurative meningitis, also known as meningitis, is an acute inflammatory reaction of the pia mater, arachnoid, cerebrospinal fluid and ventricle caused by purulent bacteria. The brain and spinal cord surface may be slightly affected, often with purulent encephalitis or brain abscess. presence. Suppurative meningitis is a serious intracranial infection. Although the development of antibiotics has made great progress, the mortality and morbidity rate of acute suppurative meningitis is still high. basic knowledge The proportion of the disease: the disease is an infectious disease, the incidence rate is also a relatively high disease in a specific population, 1% -2% Susceptible people: no special people Mode of infection: non-infectious Complications: sinusitis, hydrocephalus, brain abscess, thrombosis, cerebral infarction, pneumonia, septic arthritis

Causes of acute suppurative meningitis

Bacterial infection (80%):

The most common pathogens of purulent meningitis are meningococcus, pneumococci and Haemophilus influenzae type B, followed by Staphylococcus aureus, streptococcus, Escherichia coli, Proteus, anaerobic bacteria, and Salmonella. , Pseudomonas aeruginosa and the like.

Escherichia coli, group B streptococcus is the most common pathogen of neonatal meningitis; Staphylococcus aureus or Pseudomonas aeruginosa meningitis is often secondary to lumbar puncture, ventricular drainage and neurosurgery.

The most common three meningococcal pathogens are derived from the nasopharynx. Whether it can survive in the host tissue depends on whether there is an anti-phagocytic membrane or surface antigen, but multiple examinations of the carrier indicate that meningeal infection is impossible. Caused by the nasopharynx flora.

The most common route is bacteremia causing meningitis. Once bacteremia occurs, pneumococci, Haemophilus influenzae and meningococcus are most likely to cause meningitis. However, do these microbes invade the cerebrospinal fluid through the choroid plexus or through the meningeal blood vessels? It is not yet clear that it is speculated that bacteria enter the subarachnoid space and trauma, and that circulating endotoxin or the meninges themselves have viral infections that damage the blood-cerebrospinal fluid barrier.

In addition to blood infections, bacteria can directly infect the meninges through the following pathways, such as congenital neuroectodermal defects, cranial incision sites, middle ear and paranasal sinus diseases, skull fractures, dural tears caused by trauma, etc., brain abscesses occasionally Breaking into the subarachnoid space or ventricles, thereby invading the meninges, separating anaerobic streptococci, Bacteroides, Staphylococcus and mixed flora from the cerebrospinal fluid, often suggesting that meningitis is associated with brain abscess ulceration.

Iatrogenic infection (10%):

A small number of cases are iatrogenic infections, caused by neurosurgery, and very few cases are caused by invasive diagnosis and treatment of the central nervous system.

Pathogenesis

Pathogenesis

After the bacteria enter the subarachnoid space, the antigenic material of the bacterial wall and some cytokines that mediate the inflammatory reaction stimulate the vascular endothelial cells, adhere and cause the neutrophils to enter the central nervous system and trigger the inflammatory process. The purulent exudate is filled with subarachnoid space, the intercerebral space pool and the optic chiasm pool, etc., the intraventricular effusion can make the middle cerebral water tube, the fourth side of the brain outside the hole blocked or the arachnoid inflammatory adhesion, affecting the circulation of cerebrospinal fluid As a result of hydrocephalus, inflammation at the base of the brain can affect multiple groups of cranial nerves, lack of humoral factors and phagocytic cells in the central nervous system, pathogens rapidly divide and multiply, and release cell wall or membrane components, leading to the rapid evolution of meningitis and Injury to vascular endothelial cells, blood-cerebrospinal fluid barrier permeability increases, resulting in angioedema, a large number of neutrophils enter the subretinal space, release of toxic substances can cause brain cell toxic edema, cerebral edema and purulent exudate Cortical veins and some meningeal arteries, cortical vein thrombosis can cause hemorrhagic cortical infarction, such as combined sagittal sinus thrombosis, Infarction area is extensive and serious. If it is not treated in time or is under treatment, it may be secondary to brain abscess. Infarction of bridge vein may cause subdural effusion. Bacterial invasion of the cavity may cause empyema. Brain edema may affect cerebral blood circulation. Venous blood flow disorder and cerebral ischemia caused by venous venous inflammation aggravate brain edema. In severe cases, cerebral palsy can be formed and life-threatening.

2. Pathological changes

The basic pathological changes of acute suppurative meningitis caused by various pathogenic bacteria are soft meningitis, meningeal vascular congestion and inflammatory cell infiltration, early pia mater and superficial cerebral vascular congestion, expansion, neutrophils enter the arachnoid Under the gap, the subarachnoid space is filled with purulent secretions, containing a large amount of bacteria to make the cerebrospinal fluid mixed, purulent exudate covering the surface of the brain, often deposited in the sulci and brain basal cistern, etc., also found in the ventricles Inside, the color of the pus can vary depending on the pathogen.

With the expansion of inflammation, the superficial pia mater and ependymal membrane are granular due to fibrin exudate. In the later stage of the disease, the midbrain can be caused by exudate in the cerebral ventricle, and the fourth ventricle is blocked or arachnoid. Inflammatory adhesions, causing cerebrospinal fluid circulation and absorption disorders, leading to traffic or non-communicating hydrocephalus.

Subdural effusions and empyema often occur in children's cases. According to Snedeker and colleagues, about 40% of infants with meningitis less than 18 months have subdural effusions, and occasionally venous sinus thrombosis.

Cerebral venous or cerebral endarteritis can cause brain softening, infarction, microscopic examination of inflammatory cell infiltration of the meninges, early neutrophils, many contain phagocytic bacteria, increased number of tissue cells, and fibrin The original and other plasma proteins exuded, and in the later stage, lymphocytes and plasma cells were dominant, and fibroblasts increased significantly, causing arachnoid fibrosis and exudate to be encapsulated. The ependymal and choroid also often had inflammatory cell infiltration. Vascular congestion, thrombosis, and occasional small abscesses in the brain parenchyma.

Acute suppurative meningitis prevention

1. Enhance physical fitness and pay attention to prevent upper respiratory tract infections.

2. Newborns and children actively implement planned immunization as required.

3. Early comprehensive treatment to reduce complications and sequelae.

Acute suppurative meningitis complications Complications sinusitis hydrocephalus brain abscess thrombosis cerebral infarction pneumonia septic arthritis

Suppurative meningitis can occur in a variety of intracranial complications during the course of the disease.

Subdural effusion, more common in infants under 2 years of age, Snedeker et al reported that younger age, rapid progression of the disease, low white blood cell count in cerebrospinal fluid and rapid protein increase are related to effusion formation.

Subdural empyema is common in young adults, adults, usually with sinusitis or otogenic infections, patients often have fever, seizures, and localized neurological signs.

Hydrocephalus, brain abscess, venous sinus thrombosis and cerebral infarction are rare.

Systemic complications such as DIC, bacterial endocarditis, pneumonia and septic arthritis can also occur.

Acute suppurative meningitis symptoms Common symptoms Dyspnea, drowsiness, hyperthermia, shock, increased intracranial pressure, convulsions, meningeal irritation, convulsions, jaundice

Most cases are fulminant or acute onset. Adults and children often have fever, severe headache, vomiting, generalized convulsions, disturbance of consciousness or neck stiffness.

There may be a history of upper respiratory tract infection before the illness. Newborns and babies often have high fever, irritability, lethargy, difficulty breathing, jaundice, etc., and may have convulsions, angulation and apnea, and the nervous system is rarely performed. Before neonatal disease, there may be premature birth, birth injury or prenatal maternal infection history. There may be meningeal irritation in the early stage of physical examination. For example, the neck is hard, Kernig is positive, Brudzinski is positive, but the infant's neck stiffness is often not obvious. The front is full and the horn is reversed.

Pneumococcal and Haemophilus influenzae infection may have local brain signs at an early stage, manifested as persistent local brain damage and uncontrollable seizures. The course may have cranial nerve disorders later, and eye movement disorders are more common in pneumococci. The incidence of meningitis is the highest, in addition to conscious disturbances and fundus edema, due to increased intracranial pressure can sometimes cause cerebral palsy, during the epidemic of meningitis, such as rapid progression of the disease, accompanied by skin mucosal deposition or The ecchymosis, and rapid expansion, and shock, meningococcal meningitis should be considered.

Examination of acute suppurative meningitis

1. The peripheral blood leukocyte count (WBC) count is significantly increased in the acute phase, mainly neutrophils, and immature cells may appear.

2. Cerebrospinal fluid (CSF) pressure increased, appearance turbid, pus-like, WBC count in 1000 ~ 10000 / mm3, a few cases higher, mainly neutrophils, can account for more than 90% of the total number of white blood cells, sometimes pus cells It is a blocky substance. At this time, the smear and pathogenic bacteria culture are mostly positive. Occasionally, the first lumbar puncture is normal. After a few hours, the examination becomes purulent, the protein is increased, and it can reach 1.0g/L or more, and the sugar content is reduced. It may be less than 0.5 mmol/L, and the chloride content is also lowered.

3. Common methods for determination of bacterial antigens include polymerase chain reaction (PCR), convective immunoelectrophoresis (CIE), latex agglutination test (LPA), enzyme-linked immunosorbent assay (ELISA), and radioimmunoassay (RIA).

4. Other optional examination items include blood routine, blood electrolytes, blood sugar, urea nitrogen, and urine routine.

5. X-ray film inspection

(1) Chest radiographs in patients with purulent meningitis are particularly important, and pneumonia lesions or abscesses can be found.

(2) cranial and sinus flat films can be found in skull osteomyelitis, paranasal sinusitis, mastoiditis, but the CT examination of the above lesions is more clear.

6. CT, MRI examination of early CT or brain MRI examination can be normal, there are neurological complications can be seen ventricular enlargement, narrow sulci, brain swelling, brain shift and other abnormal manifestations, and can be found ependymitis, Subdural effusion and localized brain abscess, enhanced MR scan is more sensitive to diagnosis of meningitis than enhanced CT scan, and can enhance meningeal exudation and cortical response when MR scan is performed. Appropriate technical conditions can be used to show venous occlusion and corresponding sites. Infarction.

Diagnosis and diagnosis of acute suppurative meningitis

Diagnose based on

1. fulminant or acute onset.

2. fever, headache, meningeal irritation.

3. Inflammatory changes mainly in the cerebrospinal fluid with lobular granulocyte increase.

4. Newborns and infants with fever accompanied by unexplained vomiting, wilting, convulsions, fullness of headache and headache and other suspicious meningitis suspicious symptoms, even if there is no neurological objective testimony should be worn as early as possible, sometimes even need to repeat Multiple cerebrospinal fluid examinations to confirm the diagnosis.

5. The exact diagnosis of this disease should be based on etiology. In addition to bacterial smears for cerebrospinal fluid, bacterial culture of cerebrospinal fluid should be routinely performed. In recent years, bacterial antigen assay technology has developed rapidly, and its sensitivity specificity is high, and Affected by the application of antibiotics, the positive rate is much higher than the current positive rate of bacterial culture in China. The method is simple and rapid, so it is currently used as a rapid diagnostic tool in the early stage.

Differential diagnosis

The diseases that should be identified are: viral meningitis, tuberculous meningitis, fungal meningitis and spirochete meningitis, and different changes in cerebrospinal fluid are the main differential diagnosis basis.

The increase of lactic acid (LA) and lactate dehydrogenase (LDH) in cerebrospinal fluid can be differentiated from viral meningitis, and the two continue to increase, indicating poor efficacy or complications.

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