Brainstem gliomas are a group of primary brain tumors that arise from glial (helper) cells in the brainstem part of the brain. Brainstem gliomas are most frequent and aggressive in children. They are responsible for 10 to 20% of all central nervous system tumors in children. Contrary to the previously held notion, pediatric brainstem gliomas are found to have a different set of mutations than their adult counterparts. These mutations are responsible for their aggressive nature. This aggressive nature of tumors leads to another problem; they cannot be surgically removed due to their proximity to vital parts of the brain, making brainstem gliomas hard to treat. Brainstem gliomas are known to have a short survival period and high mortality rates. The progression is so rapid that, on average, there is only a lag period of one month between the presentation of symptoms and the diagnosis.
The heterogeneous nature of brainstem gliomas requires them to be classified based on their anatomical location. Following are some of the common types of brainstem gliomas according to their location on the brainstem:
1. Diffuse intrinsic pontine glioma (DIPG): DIPG is the most common and aggressive form of brainstem gliomas. They constitute about 80% of all brainstem tumors. DIPG appears as a striking diffuse enlargement of the brainstem on magnetic resonance imaging (MRI). 2. Exophytic medullary glioma: They are low-grade astrocytomas with a median survival of 5 years. They constitute about 10% of all brainstem tumors and arise from the cervicomedullary junction or the floor of the fourth ventricle. 3. Tectal glioma: These tumors are relatively benign. They are low-grade astrocytomas in nature arising from the retroaqueductal region of the midbrain. Their mean age at diagnosis is 7 to 10 years. They account for less than 5% of all brainstem gliomas.
According to an estimate, brainstem gliomas make up 4.2 % of all gliomas. This ratio rises to 20% in children. In adults, they account for only 2% of all intracranial tumors. The aggressive nature of these tumors is evident by the fact that, on average, children affected by brainstem gliomas survive for only 1 year.
A study published in 2009, reviewed a total of 656 Indian patients with primary brain tumors and found that 18 of these cases had brainstem gliomas. In India, the median age of diagnosis of primary brain tumors is slightly lower than the global average, but pediatric brainstem gliomas have similar age of diagnosis as the rest of the world.
Signs and symptoms
Brainstem gliomas show long tract symptoms and those arising from cranial nerve damage. These symptoms include:
Ataxia (uncoordinated movements)
Diplopia (double vision)
Weakness of a leg or arm
Dysphagia (difficulty swallowing)
Dysarthria (speech difficulty)
Hydrocephalus (accumulation of fluid in brain cavities; occurs in 10% of patients)
Some rare symptoms are: