Brain abscess

Introduction to brain abscess Brain abscess refers to purulent encephalitis caused by purulent bacterial infection, chronic granuloma and brain abscess capsule formation, and a small part can also be caused by fungal and protozoal invasion of brain tissue. The clinical manifestations of brain abscess may vary depending on the speed, size, location and pathological development stage of abscess formation. Brain abscess can occur at any age and is most common in young adults. basic knowledge The proportion of illness: 0.06% Susceptible people: more common in young children Mode of infection: non-infectious Complications: ventriculitis meningitis pneumonia septic arthritis sepsis diffuse intravascular coagulation symptomatic epilepsy syndrome hydrocephalus

Cause of brain abscess

Infection (60%):

Middle ear inflammation, mastoiditis, sinusitis, skull osteomyelitis and intracranial sinusitis and other purulent infections can spread directly into the brain, forming brain abscesses, of which brain edema caused by chronic otitis media and mastoiditis is the most common. It is called otogenic brain abscess, accounting for about 50% to 66% of all brain abscesses. However, due to many otitis media in recent years, mastoiditis has been cured in time, the proportion of otogenic brain abscess has been significantly reduced, otogenic Most of the brain abscesses are chronic otitis media. The acute exacerbation of mastoiditis and cholesteatoma leads to brain abscess. The infection path is mostly through the tympanic cap or sinus sinus and the middle and posterior part of the intracranial temporal lobe, accounting for about 2% of otogenic brain abscess. 5, the other part of the subdural side of the dura mater plate and the outer part of the cerebellum, especially the child's mastoid bone is thin, infected with the Trautman triangle (ie below the sinus, above the facial nerve canal, in front of the sigmoid sinus, formed by the three Triangle) involving the cerebellum, but the pediatric tympanic cavity and mastoid are not well developed, so pediatric otogenic brain abscess is rare, cerebellar abscess accounts for about 1/3 of otogenic brain abscess, otogenic brain abscess can also be retrogradely transferred to the vein Distant part, Such as the amount, top, occipital lobe, and even occasionally transferred to the contralateral brain, otogenic brain abscess is mostly single, common pathogenic bacteria are mainly Proteus and anaerobic bacteria, anaerobic bacteria are mostly streptococcus, Followed by bacilli, can also be a mixed infection. Brain abscess caused by sinusitis is called nasal brain abscess. It is rare, and it occurs mostly in the bottom of the frontal lobe. It is mostly single, occasionally multiple or multiple atrial, mostly mixed bacteria infection, scalp spasm, Intracranial sinusitis and brain abscess caused by skull osteomyelitis occur in the vicinity of the primary lesion, brain abscess and epidural, subdural or mixed abscess, mostly mixed infection, may also be Fungal infection.

Cardiovascular disease (10%):

Brain abscess caused by bacterial endocarditis, congenital heart disease, especially cyanotic heart disease, called cardiogenic brain abscess, congenital heart disease in infants and young children, often with polycythemia and hemagglutination Hyperfunction, because the sick child has arteriovenous blood communication, the peripheral venous blood can be directly transmitted into the brain to form an abscess if there is a purulent bacterial infection. The abscess that is spread by the artery is often located in the white matter or white matter and cortex of the middle cerebral artery. At the junction, it is good for the forehead, top, and temporal lobe; while the infection on the face occurs in the frontal lobe, and the pathogenic bacteria are mainly hemolytic Staphylococcus aureus.

Trauma (8%):

Trauma or surgical debridement is not complete, not timely, there are foreign bodies or broken bone fragments remaining in the brain, can form abscess within a few weeks, a few can form abscesses in the months or years or even decades after the injury, generally 3 The abscess caused within a month is called early abscess, more than 3 months is called advanced abscess, and the abscess is mostly located at or near the trauma site. The pathogens are mostly Staphylococcus aureus or mixed bacteria.

Other factors (5%):

In recent years, reports of brain abscess caused by immune dysfunction have been increasing, and there are still some unexplained brain abscesses.

Pathogenesis

After the bacteria enter the brain parenchyma, the pathological process is roughly divided into three stages, but there is a continuous process of change between the three, and there is no obvious boundary between the stages. The development process is due to the pathogen, the species and the individual conditions. The difference is different.

1. Acute encephalitis (1 to 3 days after infection)

After the early pathogen invaded the brain parenchyma for 24 hours, there was local inflammatory cell infiltration, necrosis in the center of the lesion, inflammatory cell exudation in the outer membrane sheath around the lesion, destruction of the focal brain tissue, followed by liquefaction, which could form multiple liquefaction stoves. The white matter around the lesion appears edema, and the cerebral membrane may also have an inflammatory reaction, but the site does not necessarily correspond to the lesion site. In this stage, in addition to focal symptoms, systemic inflammatory response, there may also be meningeal irritation, and cerebrospinal fluid may occur. The inflammation changes and so on.

2, suppuration

Inflammatory lesions in the brain parenchyma are further necrotic, liquefied, fused to form pus, gradually enlarged to form a abscess, according to the extent of the lesion can form single or multiple or multiple abscesses, at this stage there is glial cell hyperplasia or inflammation around the abscess The granulation tissue is formed, and the surrounding brain tissue may have an edema reaction, but the abscess wall has not yet fully formed. As the inflammation begins to be limited, the symptoms of systemic infection tend to improve, but the focal occupancy effect also tends to be obvious.

3, abscess envelope formation period

In this stage, the inflammation is further localized, that is, the capsule around the abscess is formed. The inner layer of the capsule is mainly pus cells and degenerated white blood cells, the middle layer is the granulation tissue of fibrous tissue hyperplasia, and the outer layer is glial cells and glial fibers. For the thin layer of the capsule, a clear abscess capsule is formed gradually. The abscess is mostly single, but it can also be multiple rooms. Multiple abscesses scattered in different parts are rare. The speed of capsule formation depends on various factors, such as pathogenesis. The type of bacteria, toxicity, response to antibiotics and the strength of the individual's body, the location of the abscess, such as otogenic brain abscess, the pathogenic bacteria are mostly Proteus, Staphylococcus aureus, easy to form a capsule, forming time It is also short. If the pathogenic bacteria are anaerobic bacteria, the formation of the capsule is difficult. In addition, if the lesion is in the vicinity of the ventricles or brainstem, the disease develops rapidly and the performance is also heavier, that is, the capsule has not formed well and the condition is critical. .

Once the abscess is formed, it is a space-occupying lesion. There is cerebral edema around the abscess. The mass effect causes the intracranial pressure to increase and the brain tissue to shift. With the development of the disease, if it is not treated in time, the cerebellar incision or the occipital foramen can be caused., oppression of the brain stem and further increase of intracranial pressure, leading to a sharp deterioration of the disease, and even death, in addition to the increase in pus, increased pressure in the abscess, can lead to ulceration of the abscess, the spread of pus, causing purulent meningitis Or suppurative ventriculitis, resulting in increased disease, increased treatment difficulty, brain abscess can also be combined with localized meningeal response, showing serous meningitis, arachnoiditis, individual brain abscess can be combined with subdural abscess and / or dura mater External abscess and so on.

Brain abscess prevention

The incidence and mortality of brain abscess is still high. Before the application of antibiotics, the mortality rate is as high as 60-80%. In the 40s and 70s, due to the increase in antibiotic application and diagnosis and treatment, the mortality rate was reduced to 25-40%. After CT application, The mortality rate is not significant, still 15 to 30%, which is difficult to find in the early stage of this disease (especially blood-borne). When the patient comes to the clinic, the abscess is advanced, and the general operative mortality is related to the preoperative patient consciousness. The awake person is 10-20%, and the coma is 60-80%. Various therapies have sequelae of varying degrees, such as hemiplegia, epilepsy, visual field defect, aphasia, mental consciousness change, hydrocephalus, etc. Therefore, brain abscess The treatment should be more important than treatment, and pay attention to early diagnosis and treatment, such as focusing on the cure of otitis media, lung infection and other primary lesions, in order to prevent problems before they occur.

Brain abscess complications Complications ventriculitis meningitis pneumonia septic arthritis septic diffuse intravascular coagulation symptomatic epilepsy syndrome hydrocephalus

Complications include purulent encephalitis, ventriculitis, meningitis, subdural effusion, empyema, infectious intracranial venous sinus thrombosis, bacterial endocarditis, pneumonia, septic arthritis, sepsis, diffuse Intravascular coagulation (DIC) and multiple organ failure, etc., common sequelae are symptomatic epilepsy, hydrocephalus, various nervous system disorders, such as limb paralysis, aphasia and so on.

Brain abscess symptoms Common symptoms Apathy, nausea, neonatal neutropenia, septicemia, fatigue, toxemia, neonatal gaze

The clinical manifestations of brain abscess may vary depending on the speed, size, location and pathological development stage of abscess, and usually have the following four aspects.

1, acute infection and symptoms of systemic poisoning

In general, patients have a history of infection of the primary lesion. After a period of different incubation periods, brain symptoms and systemic manifestations appear. The general onset is acute, fever, chills, headache, nausea, vomiting, fatigue, lethargy or agitation, muscle soreness, etc. Check the neck resistance, Klinefelter and Brine's sign positive, the surrounding blood picture increased, these symptoms can last for 1 to 2 weeks, but can also be up to 2 to 3 months, the symptoms vary, and treated with antibiotics, Some patients can be cured, some infections are focal, the symptoms of systemic infection are gradually relieved, and the symptoms of focal localization and increased intracranial pressure are gradually obvious. If this group of symptoms is not obvious, it can be regarded as the incubation period, and the duration can be as long. Weeks or months, or even years.

2, increased intracranial pressure symptoms

Symptoms of increased intracranial pressure can occur in the acute encephalitis stage. As the abscess develops and gradually increases, the symptoms are further aggravated. Headache, vomiting, and optic disc edema are the three main signs. The headache is mostly on the affected side, and the abscess is under the curtain. Pain in the occipital and forehead is mainly involved, and it involves neck pain. The pain is mostly persistent, and there is a paroxysmal aggravation. It is often aggravated in the morning or when exerting force. Vomiting can be jetting. The cerebellum abscess is more obvious. When the headache is aggravated. Vomiting is also aggravated. There are different degrees of optic disc edema in the fundus. In severe cases, there may be retinal hemorrhage and exudation. The incidence of optic disc edema is as high as 50% to 80% before CT examination, with the improvement of examination methods. Early diagnosis, treatment, and optic disc edema have also decreased. Others have compensated pulse slow, high blood pressure, slow breathing, and patients may have different levels of mental and conscious disturbances, such as apathy, unresponsiveness, lethargy, and irritability. Uneasy, etc., if the coma is late.

3, focal location signs

According to the location, size and nature of the abscess lesions, corresponding neurological localization signs may appear. For example, involving the main hemisphere, various aphasia may occur, such as involving movement, sensory center and conduction beam, which may result in different degrees of central hemiplegia. And unilateral sensory disturbances, but also due to the stimulation of the sports area and other various seizures, affecting the visual path may appear in different degrees of the same direction of contralateral hemianopia, frontal lobe often appear personality changes, emotional and memory disorders, Cerebellar abscess often presents with horizontal nystagmus, ataxia, forced head position, Romberg sign positive and other localized signs, brain stem abscess can appear a variety of brain nerve damage and long beam signs of brain stem damage specific complex signs, rare Pituitary abscess can change the pituitary gland dysfunction, non-main hemisphere of the temporal lobe and frontal lobe, abscess is not obvious.

4, crisis

When the abscess develops to a certain extent, especially the temporal lobe, the cerebellar abscess is prone to cerebral palsy. Once the cerebral palsy appears, it must be urgently treated. It is one of the common emergency problems in neurosurgery. If the treatment is not timely, it may endanger life. Another crisis That is, the abscess is ruptured, and the ruptured pus can enter the ventricle or subarachnoid space to form acute suppurative ventriculitis and meningitis. The patient may have sudden fever, coma, meningeal irritation or seizure, blood routine examination of white blood cells and Neutrophils are elevated, and cerebrospinal fluid examination can be a purulent cerebrospinal fluid, which is complicated to handle.

Brain abscess check

Laboratory inspection

1. Peripheral blood

After the formation of the abscess, the peripheral blood is more normal or slightly elevated, 70% to 90% of patients with brain abscess erythrocyte sedimentation rate is accelerated, C-reactive protein is increased, which can be differentiated from brain tumors.

2, pus examination and bacterial culture

Through the examination and culture of pus, the type of infection can be further understood. The drug sensitivity test has a guiding effect on the selection of antibiotics. Therefore, after puncture pus or surgical removal of the abscess, it should be promptly sent for examination. If anaerobic culture is carried out, the test is carried out. The utensils should be sealed and sent to the air for inspection. It can also be used for bacterial smear staining and microscopy. Especially for the pus has broken into the brain and ventricles, and the cerebrospinal fluid is purulent. The microscopic examination can immediately understand the types of pathogenic bacteria. To guide medication.

According to the nature of the pus, the type of bacteria can also be roughly judged. For example, the pus of Staphylococcus aureus is yellow and sticky, the streptococci are yellowish white and thin, the proteus is grayish and thin and stench, and the E. coli is fecal-like stench, green. Pseudomonas is green and stinky. The fungus is common with cryptococcus and actinomycetes. It can be dyed with Indian ink. The paragonimiasis is rice-like pus or cheese-like. There are eggs in the pus. The amoeba pus is chocolate-colored and sticky. Unscented, protozoa trophozoites can be found on the pus.

3, lumbar puncture and cerebrospinal fluid examination

Through lumbar puncture, you can know whether there is increased or increased intracranial pressure, but those with increased intracranial pressure, especially when the condition is critical, lumbar puncture should be regarded as "dangerous" operation, generally not done, if you need to check, then The operation should be very careful. After the puncture is successful, the pressure measuring device should be quickly turned on. After the pressure measurement, the liquid should be discharged very slowly, leaving a small amount of cerebrospinal fluid for examination. After the operation, the patient should be supine for 6 hours, and dehydration and hypotension should be given. The cerebrospinal fluid examination can have increased white blood cells. Generally, at (50-100)×106/L (50-100/mm3), the protein is also often elevated, and the sugar and chloride changes little or slightly. When the early brain abscess or abscess is close to the brain surface or ventricle, Cerebrospinal fluid changes significantly, if there is a purulent change, it means that the abscess collapses.

Film degree exam

In order to further clarify whether there are brain abscesses and abscesses in nature and location, auxiliary examination is indispensable. With the development of diagnosis and treatment techniques, the examination methods are also constantly updated, such as EEG, brain ultrasound, ventriculography, and pyography. Cerebral angiography, radionuclide and other diagnosis of brain abscess have been rarely used, and currently rely mainly on CT scan or MRI scan, but lumbar puncture and X-ray film on the examination of some areas of the lesions still have important diagnostic significance.

1, X-ray film

Such as otogenic abscess can be found in the tibial rock bone destruction, tympanic cap and mastoid small room blurred or disappeared, nasal brain abscess can have frontal sinus, ethmoid sinus, maxillary sinus and other poor inflation or liquid gas surface, even bone Mass destruction, traumatic brain abscess can be found in skull fracture fragments, intracranial metal foreign body, brain abscess caused by skull osteomyelitis, can be found in the skull with osteomyelitis, individual cases can be seen abscess calcification, children with chronic brain abscess can have skull The fracture of the bone is split, the bone plate is thinned, and the adult has occasional enlargement of the sella, posterior bed and saddle back absorption and other changes in intracranial pressure.

2, brain CT scan

Early diagnosis of brain abscess before CT was difficult. Since the clinical application of CT examination, the diagnosis of brain abscess has become easy and accurate, and its mortality has also decreased significantly.

The CT findings of brain abscess vary according to the stage of development of the lesion. In the acute encephalitis stage, the lesion has a low-density area with blurred edges, which has a mass effect. The enhanced low-density area of the scan does not strengthen, and the initial stage of abscess formation still shows low density. Space-occupying lesions, but the enhanced scan can be slightly enhanced around the low density, showing a complete irregular shallow ring enhancement. After the abscess wall is completely formed, the low-density edge density is higher, and a few can show the abscess wall. Enhanced scanning can be seen as a complete, uniform thickness of the annular enhancement, surrounded by obvious irregular cerebral edema and mass effect, low-density area is necrotic brain tissue and pus, such as gas-producing bacilli infection, can present gas and liquid level, If it is multi-atrial, there may be one or more intervals in the low-density area. According to clinical and experimental studies, the abscess ring sign indicated by CT does not necessarily indicate the pathological abscess capsule, and some studies have found encephalitis. After 3 days, the ring-enhanced sign can appear, which is related to the inflammation-related blood-cerebrospinal fluid barrier, the formation of new blood vessels around the inflammation and the infiltration of inflammatory cells around the blood vessels. The initial formation of the tumor takes 10 to 14 days, and it takes 6 weeks to fully mature. A few abscesses can also be confused with the encephalitis period. Therefore, the diagnosis of brain abscess should not be blindly dependent on CT. It is also necessary to combine medical history and other examinations. To make an accurate objective diagnosis, but the vast majority of brain abscess can be based on CT scan to determine the location, size, shape, single or multi-room abscess, single or multiple nature of the abscess, CT scan is not only helpful for diagnosis, It also helps to select the timing of the surgery and determine the treatment plan, while also tracking the treatment effect.

3, brain MRI examination

It is another new examination method after CT scan. According to the time of brain abscess formation, the performance is also different. In the acute encephalitis period, it only shows the long T1 with long irregular boundary in the brain, and the long T2 signal has Occupation sign, this period must be differentiated from glioma and metastasis. Enhanced scan shows the encephalitis stage earlier than CT scan. When the envelope is formed intact, T1 shows high signal shadow, and there are fashion points to the circular point. Vascular flow emptiness, usually 5 to 15 minutes after injection of Gd-DTPA can be abnormal contrast enhancement, delayed scan enhancement can be further expanded outward, is the destruction of blood-cerebrospinal fluid barrier around the abscess.

Diagnosis and differentiation of brain abscess

diagnosis

According to the medical history, clinical manifestations and necessary auxiliary examinations, comprehensive analysis, generally can be diagnosed, especially CT examination plays a decisive role, because the majority of brain abscess is a purulent lesion secondary to other parts of the body, so patients often have chronic otitis media Acute exacerbation of mastoiditis, sinusitis, purulent infection of the chest and lungs, bacterial endocarditis, congenital heart disease, bloated skin and phlegm, osteomyelitis, cranial osteomyelitis, sepsis and septicemia A history of inflammatory disease, or an open head trauma, especially in patients with broken bone fragments or foreign bodies remaining in the brain. On this basis, after a period of incubation, the patient has symptoms and signs of purulent encephalitis, treated with antibiotics, etc. After the disease is relieved, the signs of increased intracranial pressure and localized signs of recurrence appear again. That is, the possibility of brain abscess should be considered first. Further, after auxiliary examination, most of the lesions can be located and qualitatively diagnosed.

Differential diagnosis

1, purulent meningitis

More onset, acute systemic symptoms and meningeal irritation are more serious, neurological focal signs are not obvious, cerebrospinal fluid can be purulent, leukocytosis is obvious, pus cells can be found, mainly differentiated from brain abscess encephalitis, Some patients are almost indistinguishable in the early stage, and CT scans of the brain are helpful for identification.

2, subdural and epidural abscess

Both can be combined with brain abscess, and the course of disease is similar to brain abscess. X-ray film 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. The clinical manifestations are signs of increased intracranial pressure such as headache and vomiting, but the general course of disease is longer, the systemic symptoms are milder, and there are no obvious signs of nervous system. CT scans or MRI scans only show some enlargement of the ventricles.

4, intracranial venous sinus embolization

More common in chronic otitis media, mastitis and other sinus inflammatory sinus embolism, systemic infection symptoms and increased intracranial pressure, but no neurological focal signs, this disease, lumbar puncture pressure, unilateral compression There is no response on the disease side during the test, which is helpful for diagnosis, but should be performed cautiously when the intracranial pressure is high. It can be identified by CT scan and MRI scan.

5, suppurative labyrinthitis

Clinical signs like cerebellar abscess, such as dizziness, vomiting, nystagmus, ataxia and forced head position, but different from cerebellar abscess is mild or no headache, increased intracranial pressure and meningeal irritation, CT scan and MRI The scans were all negative.

6, tuberculous meningitis

Atypical tuberculous meningitis may have no obvious history of tuberculosis, tuberculosis and tuberculosis, and need to be differentiated from brain abscess with longer course of disease and milder symptoms. Cerebrospinal fluid examination is similar to brain abscess, but lymphocyte and protein increase are obvious, and Both sugar and chloride can be significantly reduced, anti-tuberculosis treatment is effective, CT and MRI scans are helpful to identify.

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, so they are not easy to distinguish from brain tumors. Even the "circulation sign" shown by CT scan is not unique to brain abscess. It can also be found in brain metastases, glioblastoma, and occasionally in chronic dilated intracerebral hematoma. It can not be confirmed until surgery. Therefore, it should be carefully analyzed, combined with various laboratory tests, and then with various Contrast, CT and MRI scans were further identified.

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