Methods for detecting meningitis

There are many types of meningitis. When a patient goes to the hospital for examination, the hospital will examine the patient based on his symptoms to find out what type of meningitis the patient has. First, the type of meningitis can be roughly judged by the patient's symptoms. Secondly, high technology can be combined to check the type of meningitis the patient has. Finally, the type of meningitis the patient has can be determined by combining the two.

1. Purulent meningitis: The most easily confused one is Haemophilus influenzae meningitis, because it is more common in children under 2 years old, and the cerebrospinal fluid cell count is sometimes not very high. The second most common diseases are meningococcal meningitis and pneumococcal meningitis. In addition to the history of contact with tuberculosis, tuberculin reaction and lung X-ray examination, the important thing for diagnosis is cerebrospinal fluid examination. When the cell count is higher than 1000×106/L (1000/mm2) and neutrophils and polymorphonuclear granulocytes account for the majority of the classification, purulent meningitis should be considered; but more important is the cytological examination.

2. Viral central nervous system infection: mainly viral encephalitis. Viral meningoencephalitis and viral myelitis can all be confused with tuberculous encephalitis. Among them, sporadic viral encephalitis needs to be differentiated more than epidemic ones. The key points for diagnosing various viral meningitis are: ① They often have specific epidemic seasons. ② Each has its own special systemic manifestations. For example, enterovirus may be accompanied by diarrhea, rash or myocarditis. ③ Except for the cell count and classification that are difficult to distinguish from tuberculous meningitis, the biochemical changes in cerebrospinal fluid are different. In viral meningoencephalitis, the sugar and chloride levels in the cerebrospinal fluid are normal or slightly higher, and the protein level is not significantly increased, mostly below 1g/L (100mg/dl). ④ Various viral encephalitis or meningitis have their own specific laboratory diagnostic methods, such as serological examination and virus isolation (refer to the relevant special chapters). It is difficult to differentiate between mild viral encephalitis and early tuberculous encephalitis. The principles of treatment are: ① First treat with anti-tuberculosis drugs, and at the same time perform various examinations, such as tuberculin test, lung X-ray, etc. to assist in diagnosis. ② No hormone treatment is needed. If the cerebrospinal fluid returns to normal within a short period of time, it is mostly viral encephalitis rather than tuberculous encephalitis. ③ Do not inject any drugs into the sheath to avoid changes in the composition of cerebrospinal fluid and increase the difficulty of differential diagnosis.

3. Neoformans cryptococcal meningoencephalitis: Its clinical manifestations, chronic course and cerebrospinal fluid changes may be similar to tuberculous meningitis, but the course is longer and may be accompanied by spontaneous remission. The symptoms of chronic progressive intracranial hypertension are more prominent and are not equal to other manifestations of meningitis. This disease is less common in children and is easily misdiagnosed as tuberculous encephalitis. The diagnosis is confirmed by cerebrospinal fluid smear. When stained with ink and black ground reflection method, round cryptococcal spores with thick capsule refraction can be seen. New cryptococci can grow on Sabouraud culture medium.

4. Brain abscess: Children with brain abscess often have a history of otitis media or head trauma, sometimes secondary to sepsis. Often accompanied by congenital heart disease. Children with brain abscesses often have focal brain signs in addition to symptoms of meningitis and increased intracranial pressure. When there is no secondary purulent meningitis, the number of cells in cerebrospinal fluid can range from normal to several hundred, most of which are lymphocytes, sugar and chloride are mostly normal, and protein is normal or increased. Differential diagnosis is made with the help of examinations such as ultrasound, electroencephalogram, brain CT and cerebral angiography.

5. However, the differences between brain tumor and tuberculous meningitis are: ① Less fever. ② Convulsions are less common, and even if they occur, the patient is usually conscious after the convulsion, which is different from children with late-stage tuberculous encephalitis who fall into a coma after a convulsion. ③Coma is less common. ④The symptoms of high intracranial pressure are not parallel to the brain signs. ⑤ There are few or mild changes in cerebrospinal fluid. ⑥The test for leukocyte antigen was negative and the lungs were normal. To confirm a brain tumor, a brain CT scan should be performed promptly to assist in diagnosis.

6. Typical tuberculous meningitis is relatively easy to diagnose, but some atypical cases are more difficult to diagnose. There are several cases of atypical tuberculous encephalitis: ① In infants and young children, the onset is acute and the progression is rapid, and sometimes convulsions may be the first symptom. ② Symptoms of brain damage appear early, manifested as chorea or mental disorders. ③ Early stage cerebrovascular damage manifested as limb paralysis. ④When combined with brain tuberculoma, it may present similar symptoms to an intracranial tumor. ⑤ Tuberculosis lesions in other parts of the body are extremely severe and can mask the symptoms and signs of meningitis, making them difficult to identify. ⑥ When meningitis occurs during anti-tuberculosis treatment, it often manifests as an abortive type. For the above atypical scale conditions, diagnosis should be particularly cautious to prevent misdiagnosis.