What Is an Anaplastic Astrocytoma?

Astrocytomas and anaplastic astrocytomas are the most common in neuroepithelial tumors, accounting for 21.2% to 51.6% of gliomas. More men than women, can occur at any age, the peak incidence is 20 to 40 years old. Astrocytomas can occur in any part of the central nervous system. Adults are more common in the brain. Cerebellar astrocytomas account for 30% of children's brain tumors. Astrocytomas often occur in the frontal, parietal, and temporal lobes, and rarely in the occipital lobe. The prognosis of astrocytoma is closely related to the age of the patient, and young people have a longer survival period.

Astrocytoma and anaplastic astrocytoma

Overview of astrocytoma and anaplastic astrocytoma

Key points for astrocytoma and anaplastic astrocytoma

Clinical manifestations of astrocytoma and anaplastic astrocytoma

Astrocytoma and anaplastic astrocytoma grow slowly and have a long course of disease. It takes an average of 2 years from the onset of symptoms to consultation. Clinical symptoms include general symptoms and local symptoms, the former mainly depends on the increase of intracranial pressure, while the latter depends on the pathological type and biological characteristics of the lesion site and tumor. The continuous growth of tumors occupies the intracranial space, cerebral edema, tumor clog fluid circulation blockage caused by cerebrospinal fluid reabsorption disorders, etc. can cause increased intracranial pressure. Symptoms of increased intracranial pressure in tumors at different sites will be different sooner or later. Cerebellar tumors tend to compress and obstruct the fourth ventricle, and intracranial pressure increases earlier, while cerebral hemisphere tumors appear later, and brainstem tumors appear before local symptoms. Symptoms of increased intracranial pressure include headache, vomiting, disc edema, visual field changes, epilepsy, diplopia, enlarged head (childhood), and changes in vital signs.

The symptoms and signs of astrocytoma vary from site to site.

1. Cerebral hemisphere astrocytoma

About 60% of patients with epilepsy tumors that are close to the surface of the brain are prone to occur. About one-third of patients have epilepsy as the first symptom or main symptom, and then increase intracranial pressure and focal symptoms. The type of seizure is related to the location of the tumor. The frontal lobe is mostly a seizure, the central area and parietal lobe are mostly focal seizures, and the temporal lobe tumors are psychomotor seizures. The extensively invading frontal tumors, especially those invading the corpus callosum into the contralateral hemisphere, show significant mental disorders. Phantom vision and visual field defects can occur when the temporal occipital lobe involves the visual conduction pathway or visual center. Contralateral hemiplegia of varying degrees often occurs near the central frontal gyrus after the forehead. Participants in the lower parietal gyrus and superior marginal gyrus may have miscalculation, misreading, apraxia, and naming disorders. Motor or sensory aphasia may occur when dominant hemisphere movement or sensory speech central damage occurs. Parietal cortical lesions can cause cortical paresthesia. Due to the existence of the so-called "dumb zone" in the cerebral hemisphere, tumors in this area (mainly the frontal and frontal lobe) have no local symptoms, accounting for about 20%.

2. Cerebellar astrocytoma

Most are located in the cerebellar hemisphere, followed by the vermicompost and the fourth ventricle. Children are more common than adults. Most patients in the cerebellar hemisphere showed ataxia of the affected limb, and the upper limb was more obvious than the lower limb. Those who are located near the midline of the earthworm or cerebellar hemisphere may have balance disorders, unstable walking and standing. Tumors in the upper vermicompost showed a tilted forward, and tumors in the lower vermicompost tilted mostly backward. Severe cerebellar damage can result in dysarthria and explosive language. Those with cerebellar subtonsillar hernia can show neck resistance, forced head position and even cerebellar crisis.

3 Brain stem astrocytoma

Most tumors are located in the pons, followed by the medulla oblongata, which are rare in the midbrain. Early occurrence of affected side cerebral nerve palsy, midbrain tumors with oculomotor nerve palsy; pontine tumors involve the abductor, facial nerve or trigeminal nerve; medullary tumors may have posterior cerebral nerve palsy. Contralateral limb movement and sensory disturbances occur at the same time, that is, "cross paralysis". Patients with sensory disturbances and cerebellar ataxia are very common. In the later stages, bilateral cranial nerve palsy, bilateral pyramidal tract signs, and increased intracranial pressure may be present.

Imaging examination of astrocytoma and anaplastic astrocytoma

1. X-ray examination

In most patients, plain radiographs of the skull show signs of increased intracranial pressure. Partial or arcuate calcification of the tumor was seen. Cerebral angiography shows vascular compression and displacement, rare tumor staining and pathological blood vessels.

2. CT examination

Astrocytomas are usually a non-uniform mass on CT. The boundary of the lesion is less clear than glioblastoma, and there is often no obvious edema around the tumor. 20% of astrocytomas are calcified on CT. The enhancement of the tumor usually depends on the grade of the tumor. About 40% of the tumors in astrocytoma grade ~ are not strengthened. In the case of tumor enhancement, there are various modes of enhancement, which can be focal, nodular, circular, or uniformly enhanced.

3 MRI examination

In benign astrocytomas, due to the increase in intra- and extra-cellular water, T1 and T2 are prolonged, showing that the T1 weighted image shows a low signal, and the T2 weighted image shows a high signal. The signal intensity is uniform, the peritumoral edema is slight, and the enhancement of Gd-DTPA is not obvious. Cystic changes in the tumor cause uneven MRI signals. Tumors and surrounding edema are less easily distinguished from T1 weighted images than T2 weighted images, and tumors may be slightly enhanced. Malignant astrocytoma presents mixed signals in T1-weighted images, with low signals as the main, and occasionally lower or high signals, which reflects intratumor necrosis or bleeding. The T2-weighted image shows a high signal, and the signal intensity is uneven, and a curved or dot-shaped low signal region caused by tumor blood vessels can be seen. On proton density weighted (long TR short TE) images, the tumor signal is lower than the surrounding edema signal, while the signal inside the tumor necrosis area is higher than the surrounding edema signal; on the long TR long TE image, the signal intensity of the tumor internal necrosis area is similar to The intensity of the surrounding edema signal is relatively reduced. Due to the glial hyperplasia of the tumor tissue, a circle of low signal halo is sometimes seen around the tumor, which is between the tumor and edema, which is more common in tumors with high malignancy. Malignant patients often have significant abnormal contrast enhancement with a long duration of enhancement. The enhanced part is plaque-shaped, line-shaped, rosette-shaped or nodular, but no contrast enhancement occurs in the tumor necrosis or bleeding area (Figure 18-1).

MRI Grade II MRI findings of astrocytoma and anaplastic astrocytoma

Neuroelectrophysiology examination EEG examination is helpful to those with epilepsy as the first symptoms. Visual evoked potential (VEP) examination is helpful for temporal occipital tumors, and brainstem auditory evoked potentials (BAEP) are helpful for the diagnosis of tumors in the brainstem, cerebellum and other parts.

Overview of astrocytoma and anaplastic astrocytoma treatment

The treatment of astrocytoma and anaplastic astrocytoma is comprehensive treatment such as surgery, radiotherapy, chemotherapy, and biotherapy, mainly surgical resection. According to the location and scope of the tumor, tumor resection, lobectomy or decompression is performed. If obstructive hydrocephalus is not resolved, cerebrospinal fluid shunt surgery can be performed to relieve the increase in intracranial pressure. If a focal cystic cerebellar astrocytoma has a large cystic cavity and a tumor nodule on one side, as long as the tumor nodule is removed, it can achieve the goal of radical cure. Generally, it is difficult to perform a radical resection of solid astrocytoma. Comprehensive treatment such as radiotherapy and chemotherapy should be given after surgery. Class I astrocytoma (hair cell astrocytoma, ependymal giant cell astrocytoma) requires only complete surgical resection, and generally does not require chemotherapy or radiotherapy. ^[1]