Pediatric Brain Abscess

Introduction to Pediatric Brain Abscess Brain abscess (brainabscess) is a necrotic abscess formed by purulent pathogenic bacteria in the brain tissue. It is a common type of focal suppurative infection in the central nervous system. Although it is rare in pediatrics, it is very important because of improper diagnosis or treatment. It can cause serious adverse consequences and even death. In recent years, advances in diagnostic techniques such as CT and MRI have greatly improved the understanding of such focal infections. Although the treatment of this disease is very difficult, it may still achieve a better prognosis after timely and appropriate treatment. basic knowledge The proportion of illness: 0.001% Susceptible people: children Mode of infection: non-infectious Complications: convulsion in children, disturbance of consciousness, optic disc edema, ataxia, cerebral palsy

Causes of pediatric brain abscess

Suppurative infection (30%):

Most microorganisms (such as bacteria, fungi or parasites) can cause focal suppurative infections in the central nervous system. The most common bacteria causing brain abscesses are streptococci, staphylococci, intestinal bacteria and anaerobic bacteria, most brains. Abscess is a mixed infection, Streptococcus and Gram-negative bacteria, such as Citrobacter, Salmonella, Serratia, Proteus, Enterobacter and Bacteroides, are common bacteria causing neonatal brain abscess The possibility of brain abscess in neonatal group B hemolytic streptococcus and citrate bacillus meningitis is very high, so CT, MRI or B-ultrasound should be routinely performed for cases with unsuccessful treatment to exclude brain abscess. In patients with chronic otitis media or agranulocytosis, the incidence of P. aeruginosa infection increases.

Neutrophil defects (30%):

After bone marrow transplantation or HIV infection, the incidence of brain abscess is significantly increased, most of which are caused by fungi. Common fungi are Candida and Aspergillus; Cryptococcus usually causes meningitis, but can also cause brain abscess, buds , tissue brain bacteria and coccidioidozoa can also cause brain abscesses, other pathogenic microorganisms that can cause brain abscesses include lytic tissue amoeba, acanthamoeba, schistosomiasis, paragonimiasis and toxoplasma, various worms The body, such as A. faecalis, Trichinella, guinea sac, etc., can also migrate to the central nervous system to cause brain abscess.

Brain abscess pathogens are different (30%):

The common pathogens of frontal lobe brain abscess are micro-aerobic staphylococci, anaerobic bacteria and enterobacteria. The common pathogens of brain abscess caused by head trauma are Staphylococcus aureus and streptococcus, and middle ear mastoiditis complicated with temporal lobe brain abscess. And cryptogenic small intraabdominal abscess (diameter below 1 ~ 1.5cm, common in parietal lobe), common pathogens include anaerobic bacteria, aerobic streptococcus and enterobacteria, congenital cyanotic heart disease, endocarditis, Most of the brain abscess caused by purulent thrombophlebitis, sepsis, osteomyelitis and other blood-borne spreads are distributed along the middle cerebral artery. The pathogens include micro-aerobic streptococci, anaerobic bacteria, and Staphylococcus aureus.

Pathogenesis

1. Brain abscess formation mechanism The formation of brain abscess is divided into two categories according to its mechanism: blood-borne infection (blood dissemination) and the spread of adjacent infections.

(1) Hematogenous dissemination: It is a common cause of brain abscess in children. Heart, lung, skin and other parts of the infection can pass through the blood circulation to the brain. Cyanotic congenital heart disease is often accompanied by blood concentration, prone to thrombosis or pus , is the most common cause of blood-borne brain abscess in children, especially caused by tetralogy of Fallot, children with infective endocarditis are also prone to blood-borne brain abscess, chronic suppurative lung disease, such as Lung abscess, empyema, bronchiectasis is also an important cause. The severity and duration of bacteremia is an important factor in the occurrence of brain abscess. Brain abscess can be used as a peripheral purulent infection (such as osteomyelitis, teeth, skin, digestion). Metastasis caused by bacteremia or sepsis caused by Dao et al., cryptogenic brain abscess can not find the primary infection, in fact, it is mostly blood-borne.

(2) Direct spread of adjacent tissue infection: the spread of adjacent infections (usually middle ear, sinus, eyelids, and scalp skin) is the second common cause of brain abscess, middle ear, mastoiditis and paranasal sinus infection It is the most common infection site in the vicinity of the spread. It is especially common in otogenic brain abscess. In most cases, the spread of adjacent infection spreads through the already existing anatomical passage, but it can also spread through thrombophlebitis or osteomyelitis. Patients with meningitis may also cause brain abscess formation in the event of severe tissue damage. Brain surgery or intraventricular drainage may be accompanied by brain abscess, head penetrating through the wound, and local infection may occur due to bone fragments or foreign bodies entering the brain.

2. The occurrence of staged brain abscess can be roughly divided into three phases:

(1) acute encephalitis period: infection affects the brain causing focal suppurative encephalitis, local brain tissue appears edema, necrosis or softening.

(2) suppuration period: inflammatory necrosis and softening lesions gradually enlarge, fuse, form a large abscess, irregular granulation tissue formed in the periphery of the abscess, accompanied by a large number of neutrophil infiltration, severe edema of the brain tissue around the abscess.

(3) The formation period of the capsule: the lesion gradually forms a capsule, which is generally formed in the course of 1 to 2 weeks, and is formed completely in 3 to 8 weeks. In infants and young children, the abscess is often large due to poor tolerance to infection. Without a complete capsule, brain abscesses, such as broken into the ventricles, form suppurative ventriculitis, causing sudden deterioration of the condition, high fever, coma, and even death.

Pediatric brain abscess prevention

1. Prevention and treatment of infectious diseases

Bacteremia or sepsis can be disseminated to the brain by blood to cause this disease, and should be actively prevented and treated. In particular, children with cyanotic congenital heart disease are prone to thrombosis; other children with congenital heart disease are prone to bacterial endocarditis, and they are prone to form purulent emboli and cause this disease.

2. Prevention and treatment of local infections

Such as paranasal sinus, middle ear, papillary septic inflammation, scalp infection, etc., can spread to the local infection health search caused by this disease, should be actively treated.

3. Prevent trauma

Especially to prevent open trauma to the head.

Pediatric brain abscess complications Complications, convulsions, dysfunction, optic disc edema, ataxia, cerebral palsy

Common seizures, disturbance of consciousness, optic disc edema, emotional abnormalities, personality changes, aphasia, contralateral hemiplegia or sensory disturbances, ataxia, sports seizures, etc.

1, cerebral palsy formation: temporal lobe abscess is prone to sputum leaf hook back sputum, cerebellar abscess often causes cerebellar tonsil sputum, and the cerebral palsy caused by abscess develops more rapidly than brain tumors. Sometimes cerebral palsy is the first symptom to mask other local signs.

2, abscess rupture caused by acute meningoencephalitis, ventricular ependygitis: when the abscess close to the ventricle or brain surface, due to force, cough, lumbar puncture, ventriculography, inappropriate abscess puncture, etc., the abscess suddenly collapsed, causing suppuration Complications of meningitis or ventriculitis. Often manifested by sudden high fever, headache, coma, meningeal irritation, angular arch reversal, epilepsy and so on. The cerebrospinal fluid can be purulent, similar to acute suppurative meningitis, but its condition is more dangerous, and there are many signs of focal nervous system.

Symptoms of pediatric brain abscess Common symptoms Meningeal irritation sign Increased intracranial pressure Convulsions irritability Low tachycardia Increase vertigo Brain abscess Hyperthermia

The clinical symptoms of brain abscess are affected by many factors. Different parts of the abscess may have different symptoms and signs. Usually, the frontal or parietal abscess can be asymptomatic for a long time. Only when the abscess enlarges, it has obvious occupying effect or affects the key brain function area. Symptoms and signs will appear when the cerebral cortex is affected by the pathogenicity of the pathogen and the immune status of the host organism. The clinical manifestations of brain abscess mainly include the symptoms of infection and poisoning. Increased intracranial pressure symptoms and focal signs, in the acute encephalitis period, mainly manifested as symptoms of infection, common high fever, headache, vomiting, irritability, irritability and seizures, such as complicated meningitis, especially symptoms, and Typical meningeal irritation, suppuration and capsule formation are mainly manifested by increased intracranial pressure or focal signs, normal or low body temperature, common severe or persistent headache, jet vomiting, disturbance of consciousness, elevated blood pressure, heart rate Increased, optic disc edema, enlarged head circumference or anterior sacral bulging, focal seizures, etc., focal signs and abscess parts are closely related, amount Abscesses common affective disorder, apathy or personality changes, aphasia; contralateral frontal and parietal lobes abscess may have paralysis or sensory disturbance, focal seizures common; cerebellar abscess visible ataxia, nystagmus, dizziness, poor muscle tone and so on.

A small abscess in the brain, that is, a brain abscess with a diameter of 1 to 1.5 cm or less, is common in the parietal lobe, and the clinical manifestations are mostly mild. In most cases, the onset of focal or motor seizures may occur, and individual intracranial pressure may be increased. , focal signs are rare.

Examination of pediatric brain abscess

Laboratory inspection

1. Blood routine examination Blood routine examination has no special significance in the diagnosis of focal suppurative infection of central nervous system. About 50% of children with brain abscess have mild increase in peripheral blood leukocytes, and patients with meningitis have significantly increased white blood cells ( >20×109/L), there may be a left shift of the nucleus (more than 7% of the rod-shaped core).

2. Blood test C-reactive protein has certain value for the identification of intracranial suppurative diseases (such as brain abscess) and non-infectious diseases (such as tumors). C-reactive protein is higher than leukocytosis or erythrocyte sedimentation rate prompts for intracranial abscess. More sensitive, but not specific.

3. Blood culture blood culture positive rate is low (about 10%), but if it is positive, it has specific significance for diagnosis.

4. Cerebrospinal fluid examination in the stable period of brain abscess cerebrospinal fluid without obvious abnormalities, may have a slight increase in protein, white blood cells slightly higher or normal, mildly reduced sugar, most of the increase in pressure, especially in the early stage of the disease, especially with meningeal inflammation, Cerebrospinal fluid can have significant abnormalities.

The positive rate of cerebrospinal fluid culture is not high, and the positive rate of culture is increased when meningitis or brain abscess is broken into the subarachnoid space.

Because most of the brain abscess is accompanied by increased intracranial pressure, the complications caused by lumbar puncture are significantly increased; therefore, lumbar puncture should not be classified as a routine examination of brain abscess, such as clinically suspected brain abscess, should be diagnosed first by neuroimaging, except Lumbar puncture is contraindicated before the increase in intracranial pressure.

Neuroimaging

CT and MRI are the first choice for the diagnosis of brain abscess, which can make early diagnosis, accurate location, and direct use for guiding treatment. With the application of CT and MRI, the mortality of brain abscess is reduced by 90%.

1. CT The typical CT findings of a general brain abscess are:

(1) The abscess has a circular or round-like low-density area.

(2) The wall of the abscess can be an equal-density or slightly high-density annular shadow, and the enhanced scan is annularly enhanced, and the wall thickness is generally 5-6 mm.

(3) edema around the abscess, showing a wide range of low-density areas, mostly characterized by irregular fingers or leaves.

(4) The larger abscess sees the mass effect. The diameter of the abscess is generally 2 to 5 cm. It is worth noting that although the above performance is highly suspected of brain abscess, other lesions (such as tumor, granuloma, hematoma in absorption or infarction) There may be similar CT findings. In addition, CT abnormalities are usually manifested several days after the onset of clinical symptoms. Normal CT can not rule out brain abscess, and should be reviewed for highly suspected patients.

2. MRI MRI is more sensitive and more specific than CT. The lesions can be detected earlier. Some MRIs that are not detected by CT can be clearly displayed, and can accurately identify cerebrospinal fluid and pus, which can help determine the rupture of abscess. Therefore, MRI is considered to be the first choice for the diagnosis of intracranial suppurative infection. In addition, MRI can also help the follow-up treatment. It takes 1 year to obtain CT information for the treatment of brain abscess, and MRI changes are 2 It can be determined within a month.

3. Leukocyte scan (Leukocyte scan) I-labeled white blood cell scan helps identify brain abscesses and intracranial tumors. The inflammatory response of intracranial infection is stronger than that of tumors. Therefore, there is a significant accumulation of I-labeled white blood cells around the brain abscess. Negative, this technique is non-invasive, with a sensitivity and accuracy of up to 96%. The disadvantage is that the labeled white blood cells need to be developed at 24 hours, so it is only suitable for patients with good general conditions, not suitable for emergency, and when a large number of hormone antibiotics The application of inflammatory cell reactions and tumor necrosis may also lead to sham or false positive reactions. Currently, 99mTc HMPAO-labeled leukocytes are used for single-photon positive electro-emission tomography (SPECT) to make the sensitivity higher.

4. Magnetic resonance spectroscopy (MRS) The magnetic resonance spectrum of brain abscess is different from that of tumor, which is helpful for distinguishing brain abscess and cystic tumor and tumor necrosis. Extracellular proteolysis or bacterial metabolites caused by inflammation For acetate, succinate and various amino acids, it is an inflammatory spectrum; while the tumor spectrum is mostly choline, lactic acid and lipid waves. In addition, tumor necrosis is low signal on MRI diffusion-weighted image, showing high dispersion. Coefficient; pus showed a high signal on the diffusion-weighted image with a low diffusion coefficient.

Diagnosis and diagnosis of brain abscess in children

diagnosis

If the child has peripheral purulent lesions, especially otitis media, mastoiditis, skin infection or sepsis, or cyanotic congenital heart disease or infective endocarditis, or open cranial injury, etc., once it appears Central nervous system syndrome, that is, the possibility of brain abscess should be considered. CT or MRI examination can confirm the diagnosis. The cryptogenic brain abscess is difficult to diagnose because of the lack of the above history of peripheral infection. The diagnosis still depends on neuroimaging.

Small abscesses in the brain are often characterized by focal seizures. Therefore, for children with focal epilepsy of unknown cause, CT scan should be performed routinely, and MRI should be performed to rule out the possibility of small abscess in the brain. The main points of diagnosis of small internal abscesses are:

1. Concealed onset, no clear history of infection.

2. No obvious symptoms of infection.

3. With focal epileptic hair as the first and main symptoms, there are often no obvious signs of focal.

4. Cerebrospinal fluid tests are mostly normal, or only a slight increase in pressure or protein.

5. CT scan of the abscess is unclear, the boundary between the abscess and the surrounding brain edema is blurred, and it is an irregular low-density area of 2~5cm in size. The CT value is 5~27Hu, and the enhancement is agglomerate after scanning. Ring shape, enhanced shadow diameter <1.5cm, mostly in the vicinity of low density areas.

6. Most of them are located in the near-cortical area of the screen, with the most common top leaves, mostly single.

Differential diagnosis

1. Suppurative meningitis has a rapid onset, systemic symptoms of acute infection and meningeal irritation are severe, and the focal signs of the nervous system are not obvious.

Cerebrospinal fluid can be purulent, cell growth is obvious, pus cells can be found, mainly differentiated from brain abscess encephalitis, some patients can hardly be distinguished in the early stage, and CT scan of the brain can help identify.

2. Both subdural and epidural abscesses may be associated with brain abscesses and brain abscesses. X-ray films of epidural abscess can be found in skull osteomyelitis, which can be confirmed by CT scan or MRI scan.

3. Otogenic hydrocephalus due to chronic otitis media, transverse sinus embolism caused by mastoiditis leads to hydrocephalus, clinical manifestations of headache, vomiting and other signs of increased intracranial pressure, but generally longer course, systemic symptoms are lighter, no Significant signs of neurological focal signs, scans or MRI scans only show some enlargement of the ventricles.

4. Intracranial venous sinus embolism is more common in chronic otitis media, mastoiditis and other sinus inflammatory sinus embolism, systemic infection symptoms and increased intracranial pressure, but no neurological focal signs, the disease of lumbar puncture pressure At the time of the unilateral neck test, there is no response on the disease side, which is helpful for diagnosis.

However, the intracranial pressure should be carefully performed and can be identified by CT scan and MRI scan.

5. Clinical signs of purulent labyrinth are like cerebellar abscess, such as dizziness, vomiting, nystagmus, ataxia and forced head position.

However, unlike cerebellar abscess, the headache is light or absent, and the intracranial pressure and meningeal irritation are not obvious. CT scan and MRI scan are negative.

6. Tuberculous meningitis Atypical tuberculous meningitis can have no obvious history of tuberculosis, tuberculosis and tuberculosis, and need to be longer.

The clinical symptoms are milder than the brain abscess. The cerebrospinal fluid examination is similar to the brain abscess, but the lymphocyte and protein are significantly increased, and the sugar and chloride can be significantly reduced, and the anti-tuberculosis treatment is effective.

7. Brain tumors Some cryptogenic brain abscesses or chronic brain abscesses are not obvious because of the symptoms of systemic infection and meningeal irritation in the clinic, and it is difficult to distinguish them from brain tumors. Even the "circulation sign" shown by CT scan is not a brain abscess. Unique, can also be seen in brain metastases, glial mother cells.

Occasionally, it can be seen in chronic dilated intracerebral hematoma, and even after surgery, it should be confirmed. Therefore, the medical history should be carefully analyzed, combined with various laboratory tests, and further identified by various contrast, CT and MRI scans.

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