An oligoastrocytoma is a mixed glioma that has portions of both an oligodendroglioma and portions of an astrocytoma. The brain tumors cause general signs of brain pressure.
What is an oligoastrocytoma?
Graphic illustration and infogram of a typical cancer cell. Oligoastrocytoma is a hybrid of an astrocytoma and an oligodendroglioma. Oligodendroglioma, formerly also called oligodendrocytoma, is a tumor that originates from oligodendrocytes. It thus belongs to the neuroepithelial tumors. The oligodendrocytes are cells of the glia. Glia is a collective term for all cells in nervous tissue that are not neurons. For example, glial cells often perform support and holding functions in the nervous system. Astrocytomas are the most common tumors in the brain. They occur predominantly in middle age and arise from astrocytes. Astrocytes, like oligodendrocytes, belong to the glial cells and thus to the supporting tissue. Oligodendrogliomas, astrocytomas and thus also oligoastrocytomas belong to the gliomas. Gliomas are tumors of the central nervous system. In most cases, they occur in the brain, but they can also arise in the spinal cord and cranial nerves.
Causes
The cause of oligoastrocytomas is still unknown. Isolated cases attest to the tumors occurring after CNS radiation or brain injury. In these cases, they appear to develop from scar tissue. Oligoastrocytomas have also been observed in multiple sclerosis. There is also debate as to whether there is a genetic predisposition to oligoastrocytomas. The evidence on this hypothesis is conflicting.
Symptoms, complaints, and signs
The most common symptom of oligoastrocytoma is epileptic seizure. It occurs in more than 50 percent of patients and is due to infiltration and damage to adjacent nerve cells. As the tumor grows steadily in the skull, intracranial pressure increases. Therefore, other symptoms of oligoastrocytoma are signs of increased intracranial pressure. Cerebral pressure signs include nausea and vomiting. Patients suffer from headaches, some of which are severe, and fatigue. They are restless and have a slowed heartbeat. Blood pressure, on the other hand, is elevated. With the help of this so-called pressure pulse, the body tries to continue blood flow despite the increased intracranial pressure.
Diagnosis and course of the disease
With the help of an ophthalmoscope, a congestive papilla can be diagnosed. A congestive papilla is an accumulation of fluid at the junction of the optic nerve and the retina. On ophthalmoscopy, this edema is visible as swelling of the optic disc. Usually, the congestion papule is present bilaterally. If the symptoms are not recognized early and the intracranial pressure continues to rise, disturbances of consciousness occur. In the worst case, patients fall into a coma. Personality changes can also be a sign of oligoastrocytoma. Years before diagnosis, neurological signs such as headaches, paralysis or disturbances in cranial nerve function also become apparent. For example, affected individuals have mild visual disturbances, dizziness, or problems with facial expression. The five-year survival rate for men with oligoastrocytoma is 40 to 50 percent. After ten years, 20 to 30 percent of patients are still alive. In women, the prognosis is somewhat better. Here, the five-year survival rate is 65 percent. After ten years, 40 percent of female patients are still alive. Imaging techniques are used when oligoastrocytoma is suspected. The primary procedure is magnetic resonance imaging (MRI) without and with contrast medium administration. Often, the findings on examination resemble the findings in cerebral infarction. Computed tomography shows blurred hypodensities or edema. Cystic formations may also appear. Examination with contrast medium reveals round mass effects with enhancement of contrast medium. Patients in whom contrast agent accumulates in the tumor during the examination have a significantly increased risk of recurrence. Neither CSF findings nor cerebral angiography are abnormal. In the positron emission scan of glucose metabolism, the oligoastrocytoma appears as a cold nodule. Thus, the tissue has decreased energy and metabolic rate. Within the cold nodules, hot nodules sometimes appear with increased energy turnover. Histologically, it is very difficult to draw a line between the astrocytic and between the oligodendrial components.Graduation according to the WHO definition is also difficult in oligoastrocytomas. For example, mitosis in an astrocytoma is usually considered a reason to classify the tumor as grade III. In oligodendrogliomas, multiple mitoses may occur and the tumor is still classified as grade II only. Because oligoastrocytoma is a hybrid of both tumors, the gradings differ depending on the neuropathologist. Because the classifications require different therapeutic approaches, the diagnostic distinction is actually very important.
Complications
The tumor in the brain generally causes the usual symptoms of a tumor. Usually, it can also spread to other regions of the body and damage the healthy tissue there as well. In most cases, the life expectancy of the patient is significantly reduced by the mixed glioma. Furthermore, patients suffer from epileptic seizures and severe headaches. These pains significantly reduce the quality of life and lead to vomiting and nausea. Likewise, the patient experiences reduced resilience and fatigue. Sufferers appear restless and suffer from slow breathing. Loss of consciousness may also occur. The symptoms can also lead to cardiac death. It is not uncommon for personality changes or coma to occur as well. Those affected continue to suffer from dizziness and visual disturbances. Relatives may also experience psychological disturbances and depression due to the symptoms of mixed glioma. The tumor is treated with radiation therapy or chemotherapy. Complications do not occur, although chemotherapy is usually associated with various side effects. Whether there is a reduction in life expectancy cannot generally be predicted.
When should you see a doctor?
As a brain tumor, a mixed glioma basically belongs in the hands of a doctor, so that even if a tumor is suspected, it is necessary to go to the doctor. In the course of diagnostics and therapy, there will always be appointments with the doctor. Doctor’s visits are also important after treatment in order to be able to detect and treat a possible recurrence at an early stage. Directly after the treatment of a mixed glioma, these controls will usually be carried out more closely than after a number of years with no symptoms and no recurrence. However, even without an appointment with the doctor, the patient should visit him for certain reasons. This is always the case when the patient experiences symptoms that could possibly indicate a relapse. The symptoms that require a visit to the doctor are manifold in the case of a brain tumor and also depend on the location of the tumor and any recurrence. They range from sensory disturbances and paralysis in the limbs to speech and vision problems, memory problems and epileptic seizures. Radiation and chemotherapy may also require a visit to the doctor. This applies, for example, to states of weakness that may indicate a poor blood count and should be treated quickly by the doctor. Psychological stress due to the severity of the disease is also always a reason for a visit to the doctor.
Treatment and therapy
In therapy, surgical removal is the primary treatment. In the past, tumors were operated on as early as possible. Today, with improved diagnostic techniques, the diagnosis is often made before symptoms are present; therefore, it is now advocated to operate only when neurologic deficits are present. Studies have shown that survival rates increase in patients treated with radiation therapy prior to surgery. However, whole-head radiation can also cause radiation necrosis of brain tissue. Chemotherapy has no role in the treatment of oligoastrocytomas. The main cause of failure in therapy is the development of local recurrence. If the tumor grows again after removal, a biopsy is performed first. This is followed by close radiological monitoring. If growth continues, further resection becomes necessary.
Outlook and prognosis
The prognosis in mixed glioma depends on several factors. The location in the brain is crucial, as is the size of the tumor.If it can be removed completely, the prognosis is better than for a tumor of which a remnant remains after surgery or which cannot be operated on in the first place. The shape of the tumor also plays a role. If it is rather clearly limited, it can often be removed more successfully than the tumor that grows radiatively into the tissue. The accessibility of a tumor to chemotherapy and radiotherapy also has an influence in terms of its prospects. A mixed glioma often has portions that respond to a particular therapy, while other portions do so less. It is therefore necessary to find this right therapy that will treat the tumor in its entirety in the best possible way. It is also important to know that in mixed glioma, some parts of the tumor may grow faster than others. The slower the tumor spreads as a whole, the later it comes to pressure increase through the skull as a natural boundary, which leads to the typical symptoms such as pain and deficits in the affected patient and can have an unfavorable effect on the prognosis. Radiation therapy is limited in the number of Gray. Affected individuals who have not yet received radiation to the head thus also have a better prognosis.
Prevention
The exact origin of oligoastrocytoma is unclear, so there is currently no prevention. If headaches occur over a long period of time or if neurological deficits are observed, a physician should be consulted for clarification. The earlier oligoastrocytoma is treated, the better the chances of cure.
Follow-up
As with all tumorous diseases, the first step after treatment is close follow-up. This is necessary to detect any new tumors or metastases at a very early stage. In the case of a brain tumor, follow-up checks are therefore scheduled several times a year at intervals of a few months. If there are no negative findings, the intervals between the next check-ups are increased. MRI or CT scans are used to check whether new growths have occurred. Because malignant brain tumors often have a high risk of recurrence despite initially successful treatment, it is important that those affected keep their follow-up appointments regularly. The prognosis for new tumors is more favorable the earlier they are detected. New brain tumors do not always cause symptoms immediately, which should alert the patient. Often, findings that require treatment are discovered more by chance during follow-up. However, if unusual pain is noticed outside of the follow-up checks, this is always a reason to see the treating physician promptly. He or she can decide whether the next follow-up appointment should be brought forward in order to rule out the possibility that new tumors have formed.
What you can do yourself
Mixed glioma definitely requires medical treatment. Self-help measures focus on supporting medical therapy and alleviating individual symptoms. In the event of an epileptic seizure, first aid must be administered. This means loosening clothing around the neck, moving dangerous objects out of reach, and reassuring the sufferer as much as possible. Nausea and vomiting can be relieved by bed rest and a gentle diet. Headaches and fatigue are also best countered with gentleness. Sometimes it is useful to take a walk in the fresh air. The doctor will provide the patient with other strategies that can help alleviate the symptoms of a brain tumor. Apart from that, the disease should be worked through therapeutically. Talking to relatives, a psychologist or other affected persons can address fears and thus gain a new perspective on life with the disease. After treatment, body and mind are often very exhausted. Through physiotherapy, a change in diet and the pursuit of hobbies and passions, those affected can recharge their batteries for a cancer-free life.