Gliomas - Find information and specialists

Glioma is an umbrella term for brain tumors that develop in the glial cells of the nervous tissue. Depending on the type and localization of the cell of origin, they are divided into different types. In this article, we have briefly summarized what you need to know about the signs, diagnosis and treatment of gliomas.

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Gliomas - a brief definition

"Glioma" is the name for a series of brain tumors that develop within the central nervous system (CNS) from the so-called glial cells. These are not the nerve cells of the brain itself. They are supporting cells whose functions optimize neurophysiological processes and tasks or make them possible in the first place. In adults, gliomas prefer to grow in the cerebrum, whereas in children they tend to develop in the brain stem and cerebellum. Gliomas account for around 30 to 50 % of all intracranial brain tumors . With a ratio of 6:4, men are affected slightly more frequently. Most cases occur between the ages of 40 and 65. However, the actual cause of the disease is still largely unknown.

Tumors always develop when physiological cell division is disrupted. In every cell, "renovation work" is carried out every day as part of cell division and metabolic activity, including on the genetic material - the DNA. In some cases, these DNA repairs do not keep up with the damage and mutations or defective DNA sections are formed. This can lead to the degenerated cells multiplying uncontrollably and forming pathological tissue. In technical jargon, these cases are referred to as neoplasia.

Within gliomas, there is a small subgroup whose genetic alterations are of genetic origin - such as neurofibromatosis I or tuberous sclerosis. In addition, gliomas can occur as a long-term consequence after radiotherapy, meaning that previous cancers are a risk factor for new gliomas.

The WHO grading determines the degree of malignancy of gliomas

According to the common WHO grading (World Health Organization classification), gliomas are classified in grades I to IV, which means that there are both benign and malignant forms. This WHO classification is generally used when a degree of malignancy is to be determined. This essentially means that the cellular origin, cell composition and growth pattern of the gliomas are determined. This allows a statement to be made as to how benign or malignant the tumor actually is.

According to the WHO classification, a distinction can be made between four different degrees of malignancy:

• WHO grade I: benign (benign tumors)
• WHO grade II: still benign
• WHO grade III: already malignant
• WHO grade IV: malignant (malignant tumors)

The WHO classification of gliomas into further subcategories

The subgroups of gliomas are differentiated according to the exact cells from which they have grown. The cells of origin usually give the tumor class its name:

• Astrocytomas: Astrocytomas develop from astrocytes. In the supporting apparatus of the central nervous system, these cells have the task of separating the nerve tissue from the surface of the brain and the blood vessels. Astrocytomas are divided into further subgroups based on the degree of severity according to the WHO classification. While pilocytic astrocytomas are classified as WHO grade I, diffuse astrocytomas are classified as grade II and anaplastic astrocytomas as grade III.
• Glioblastoma: These tumors also arise from astrocytes and represent a malignant, usually very aggressive form of astrocytoma. They are therefore classified as grade IV. Primary glioblastomas arise directly from healthy astrocytes. Secondary glioblastomas arise from existing tumor tissue in this region of the brain. This means that grade II and III astrocytomas can transform into a glioblastoma.
• Oligodendroglioma: If oligodendrocytes, which coat the individual nerve tracts in the brain, form a glioma, this is an oligodendroglioma. This brain tumor occurs in WHO grades II and III and usually has a better prognosis than astrocytomas of the same grade.
• Ependymomas: A kind of irrigation system is built into the human brain. It consists of inner and outer cerebrospinal fluid spaces in which cerebrospinal fluid is formed every day, transported outwards and reabsorbed there. The inner cerebrospinal fluid spaces are lined with ependymal cells, which are a subgroup of glial cells. If these ependymal cells degenerate, they are referred to as ependymomas, which can correspond to a WHO grade between I and III. Ependymomas can develop in the inner ventricles of the brain as well as in the central canal of the spinal cord.
• Gangliogliomas: If ganglion or Schwann cells are affected by tumor growth, these are gangliogliomas. As we have these cells everywhere in the central nervous system, gangliomas can occur in many places. They preferentially grow in the cerebellum, hypothalamus or temporal lobes. They are usually classified as grade I, but can also occur in grades II and III.

There are also other diffuse gliomas and mixed forms of the above categorizations.

Signs and symptoms of gliomas

Gliomas can manifest themselves gradually or suddenly. The symptoms are often varied. This is mainly due to the fact that gliomas develop in different parts of the central nervous system and can therefore affect different functions.

The growth of gliomas has often already begun some time ago before symptoms become visible and noticeable. Unlike some other cancers, early detection is almost impossible - there are no specific tumor markers for gliomas, only imaging techniques.

The first signs and symptoms of gliomas can be varied, often very diffuse and dependent on the location. The following symptoms may occur:

• Headaches - especially in the morning and at night;
• Nausea and vomiting
• Fatigue and insomnia
• Reduced performance;
• seizures
• Changes in character
• Speech difficulties
• signs of paralysis
• Sensory disturbances
• Coordination disorders and gait instability
• Visual disturbances

How gliomas are diagnosed

If the above symptoms give rise to the suspicion of a brain tumor or glioma, an MRI scan is required as soon as possible. An acute stroke is often ruled out at the beginning using CT. However, detailed imaging of the fine tissue structures of the brain is only possible with MRI.

• CT: Computer tomography is a readily available imaging method that can be used to obtain an overview and rule out strokes.
• MRIwith contrast medium: Imaging is carried out in a magnetic resonance tomograph. In the case of WHO grade III and IV gliomas, the tumor cells usually absorb contrast medium. This allows the tumor to be visualized even better. For surgical planning, the MRI sequences are performed in 3D and occasionally 4D. In addition to the tumor, functional centers and fiber tracts can also be recorded and displayed in relation to the tumor. This information is very important for precise surgery. For diffuse tumors, metabolic imaging (PET, positron emission tomography) is helpful, in which radioactive amino acids make particularly active areas visible.
• Biopsy: Cells are removed during a minor operation. The cells can then be examined and precisely determined in the laboratory. This provides information about the origin and degree of malignancy. The final diagnosis, which is essential for the design of an optimal treatment regimen, can only be made through this histopathological examination. For this reason, surgery or a biopsy to obtain tissue is always necessary.

Treating and combating gliomas

As some forms of glioma are highly malignant and can grow rapidly, early treatment is necessary once the disease has been detected. The therapy is individualized for each patient and tailored to the person with the disease. Factors such as

• age,
• general condition and
• degree of malignancy and
• extent of the tumor

play an important role.

Like most other brain tumors, gliomas are treated with surgery, radiation and/or chemotherapy:

Surgery:

The aim of surgery to treat gliomas is to resect the tumor as completely as possible and to remove tissue for histopathological examination. In WHO grade I, complete tumor removal is possible in many cases. The location of the glioma is often problematic, as it prevents macroscopically complete removal without risking consequential damage. The principle of "function over resection" therefore often determines the prognosis for gliomas. For this reason, various techniques are used during the operation to optimize the resection result while at the same time protecting vital brain tissue. Among other things, neurosurgery makes use of intraoperative imaging techniques such as MRI and ultrasound combined with intraoperative 3D navigation. In addition, various brain functions such as motor function, various cranial nerves or sensory perception can be monitored using intraoperative electrophysiology. This involves measuring the distance to nerve pathways in real time during the operation, similar to an electrical radar. This allows the surgeon to perform the operation as radically as possible while preserving function. In some cases, awake operations are also performed in which speech function can be monitored.

Subsequent chemotherapy and/or radiotherapy

As soon as the final diagnosis has been determined by histopathology, an interdisciplinary team of neurosurgeons, neuroradiologists, oncologists, radiotherapists and neurologists will consult with each other. In a joint discussion, each patient case is discussed individually and the best possible concept is developed depending on the diagnosis. Depending on the WHO class and WHO grade, subsequent radiotherapy or chemotherapy may be advisable. If necessary, these are combined.

Tumor therapy fields

In the case of glioblastomas, so-called tumor treatment fields(TTF) can also be used. By applying a cap, magnetic fields are generated that can inhibit the cell growth of the tumor. Studies have proven the effectiveness of this method. It should therefore always be considered as an option in the case of glioblastomas.

Risks and prognosis

The final prognosis for a glioma patient depends on the location and size as well as the biological characteristics of the glioma. Malignant gliomas often grow rapidly and destructively if left untreated and it is therefore particularly important to make an early diagnosis and start treatment before the tumor growth is far advanced. The best possible microsurgical tumor resection using all available technical means and methods is the central element in improving the long-term prognosis.