The innermost layer of the cerebral capsule is called the pia mater.Thin and transparent, close to the surface of the brain, and deep intoCerebral fissureAnd the bottom of the sulcus.The blood vessels that supply the brain branch in the pia mater.
Chinese name
Pia mater
Foreign name
Pia mater
Meaning
A transparent film clinging to the surface of the brain
The pia mater is composed of glial fibers and elastic fibers of connective tissue.The pia mater is rich in small blood vessels, which is important for nourishing the brain.The small blood vessels extend into the brain tissue, and the pia mater and arachnoid membrane also enter into the brain tissue, but they do not tightly wrap the blood vessel wall. There are gaps in them, called vascular gaps.The vascular space communicates with the subarachnoid space and contains cerebrospinal fluid.The pia mater tissue disappears when it extends to the capillaries, so there is no gap around the capillaries.The blood vessel wall in brain tissue also has the terminal foot and basement membrane of astrocytes.Therefore, brain tissue and blood are separated by endothelial cells, astrocytes and basement membrane.This structural feature of cerebral vessels has a selective penetration effect and constitutes the blood brain barrier.In a certain part of the ventricle, the pia mater and its blood vessels together with the ependymal epithelium of this part constitute the choroid tissue.In some parts, the blood vessels of the choroid tissue repeatedly branch into clusters, and together with the pia mater and ependymal epithelium on its surface, they protrude into the ventricle to form the choroid plexus.Choroid plexus is the main structure that produces cerebrospinal fluid.Meningitis is a common clinical disease. The main lesion is the pia mater.
2、 Imaging examination
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The meninges are composed of three layers of dura, arachnoid and pia mater. MRI is considered to be the best method for detecting meningeal lesions. Its sensitivity and accuracy are superior to other imaging methods, and it is non-invasive and can perform multi axial imaging.
3、 Related diseases and treatment
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1. Meningitis refers to the mild inflammatory changes of the pia mater. Because the meninges are connected with the spinal cord membrane in terms of tissue anatomy, the inflammation of the meninges often affects the spinal cord membrane, so meningitis can also be called encephalomyelitis.
2. Tuberculous meningitis (TBM) is a non suppurative inflammation of the meninges and spinal membranes caused by Mycobacterium tuberculosis. It is a serious destructive disease of the central nervous system, and its high mortality and disability rate is still one of the most serious diseases in developing countries.
3. Risk factors and etiology
① The risk factors of tuberculous meningitis include age, HIV infection, malnutrition, recent measles infection in children, alcoholism, malignant tumors, the use of immunosuppressive drugs in adults and the prevalence of community diseases.The incidence of TBM in children, especially children under 5 years old, is significantly higher.
② The pathogenic bacterium of tuberculous meningitis is Mycobacterium tuberculosis.Mycobacterium tuberculosis is a kind of gram-positive, necessary, spore forming, non motile actinomycetes..Mycobacterium tuberculosis is mainly transmitted through droplets.Mycobacterium tuberculosis mainly propagates in alveolar macrophages.Through blood circulation, bacteria spread to extrapulmonary tissues, meninges and adjacent parts of brain parenchyma to produce tuberculous granuloma within 2-4 weeks.These lesions usually exist in the meninges and the pia mater or subependyma on the surface of the brain.Mycobacterium tuberculosis in granuloma may remain dormant for several years.When mycobacterium tuberculosis in caseous granuloma enters the subarachnoid space, it can develop into tuberculous meningitis.
4. Clinical manifestations
The course of TBM patients can be divided into three stages: stage I patients are fully conscious and have no focal neurological symptoms;Stage II patients may have sensory abnormalities and focal neurological deficit symptoms such as hemiparesis and cranial nerve paralysis;Stage III patients may have coma and severe neurological damage, such as multiple cranial nerve damage, severe hemiplegia or paraplegia.
5. Clinical treatment and prognosis
Treatment: TBM patients should start anti tuberculosis treatment early.Antituberculous treatment often requires empirical treatment before TB bacilli are found.Common first-line anti tuberculosis drugs include isoniazid, rifampicin, pyrazinamide, streptomycin, and ethambutol.Second line anti tuberculosis drugs include ethionium isoniazid, cycloserine, p-aminosalicylic acid, capreomycin, etc.Quinolones are mainly used for antibacterial treatment of drug-resistant tuberculosis.Most first-line anti tuberculosis drugs (except ethambutol) can pass through the blood-brain barrier well.
Prognosis: ① Early diagnosis and treatment of TBM is the key to improve the prognosis.However, anti TB treatment can only prevent less than 50% of patients from death and disability.The use of corticosteroids in adults is significantly associated with the decline in mortality.Starting to use hormones at the early stage of the disease can significantly reduce mortality and disability rates.Some studies believe that the proportion of cells in cerebrospinal fluid, especially the decrease of white blood cell count, is positively related to mortality.The proportion of lymphocytes in surviving patients and cerebrospinal fluid decreased and the proportion of neutrophils increased, suggesting that the proportion of neutrophils has a protective effect. ②The mortality rate of patients aged 50 years and whose course of disease exceeded 2 months was the highest.A pediatric study found that only 20% of patients could recover completely after treatment, and 80% of patients died or were disabled.In most studies, disease stage is a key factor related to mortality.Some studies have pointed out that five major factors are related to prognosis: stage III of the disease, hypoglycemia level, CSF/peripheral blood glucose ratio, CSF protein level, and imaging abnormalities.In the multivariate logistic regression analysis of the prognosis of TBM patients, race, disease stage, convulsion, motor function, brain stem dysfunction and cerebral infarction were independent risk factors for the prognosis of TBM.TBM patients with HIV infection have higher mortality.In a comparative study, the mortality rate of HIV infected patients was 63.3%, while that of HIV negative patients was only 17.5%.
