Brain Diseases and Disorders

19

lymphoma to be called primary brain lymphoma, there must be no involve-

ment other than CNS at the time of diagnosis [136].

While brain lymphomas are usually seen as leptomeningeal involvement,

brain parenchymal infiltration is rare and usually seen in advanced stages. Pri-

mary brain lymphomas are the second most common extranodal lymphomas

that can develop as a result of immunodeficiency in organ transplantation

and autoimmune diseases, use of immunosuppressant drugs, AIDS (acquired

immunodeficiency syndrome) and other causes such as congenital immunode-

ficiencies and Hodgkin lymphoma treatment. Brain metastases can be seen in

approximately 1/3 of systemic cancer patients [137].

1.7.3

Glioma

Gliomas are tumors originating from neuroglia and are grouped into four

stages. Stages I and II are low-grade tumors, and III and IV are high-stage

tumors [138]:

• Stage I: Tumors that grow slowly and show the most distant feature from

the natural structure.

• Stage II: Tumors that grow slowly, are adherent to adjacent tissue, have

the ability to invade, and can recur with higher grades of malignancy.

• Stage III: Tumors in which abnormal cells actively proliferate and can

infiltrate into healthy tissue.

• Stage IV: Tumors that spread quickly and immediately invade nearby

tissues. As a result of the tumors’ rapid growth, new blood vessels are

formed, and the center region exhibits necrosis. This type is the most

malignant.

These neuroepithelial tumors also have different sub-titles such as Ependy-

moma, Glioblastoma, Medulloblastoma, and Oligodendroglioma [138].

Ependymomas are gliomas that originate from ependymal cells in the wall

of the ventricles, grow inside the ventricle, and adhere to the brain tissue [133].

70% of ependymomas occur in the fourth ventricle and cause deterioration in

balance, walking, muscle coordination, and especially fine motor skills. Shunt

intervention is useful in the treatment of hydrocephalus, which develops when

the tumor obstructs the CSF circulation pathways. When ependymoma occurs

anatomically in the brain stem or upper spinal cord, it causes neck pain in

patients [133].

Glioblastoma multiforme (GBM) is the most common and aggressive ma-

lignant primary CNS tumor in adults [139]. GBM accounts for approximately

70% of all adult brain tumors [140]. Standard treatment includes surgical re-

section with radiation therapy and temozolomide chemotherapy, which does

not improve overall patient survival [141]. Despite maximum treatment, in the

majority of cases, cancer relapses. High resistance to established treatments,