The great majority of primary brain tumors appear as spontaneous mutations with no observable cause. Some tumors may have their origin in remnant embryonic cells that normally would have developed into mature tissue, but have continued to grow uncontrolled. A few cases are linked to hereditary genetic or chromosomal syndromes.
In addition, it has been shown that the radiotherapy used in treatment of aggressive brain tumors is related with the appearance of meningiomas, usually benign, several years later.
The most common symptom is headache, which occurs in 54% of cases. It is usually an oppressive and progressive headache, which affects the entire head or its frontal region, but it is a non-specific symptom in itself. It is caused by increased intracranial pressure, which, if severe enough, will also cause vomiting.
There are as many possible associated symptoms as there are different eloquent areas of the brain and the nerves that depend directly on it, including the sensory organs. That is, there is an anatomical relationship between the place in the brain where the tumor grows and the type of symptoms it creates. In 45% of cases motor skills will be affected to a greater or lesser degree.
When the tumor grows in the cerebral cortex, and especially in types of low or intermediate aggressiveness that slowly exert their effect on the brain, epileptic seizures can appear (26%). These seizures may not manifest as convulsions, sometimes there is just involuntary movement in a single limb, or disconnections that last only a few seconds (absences), or strange sensations of taste, smell, sight or hearing.