Tentorium Cerebelli - Clinical Significance

Clinical Significance

Clinically, the tentorium is important because brain tumors are often characterized as supratentorial (above the tentorium) and infratentorial (below the tentorium). The location of the tumor can help in determining the type of tumor, as different tumors occur with different frequencies at each location. Additionally, most childhood primary brain tumors are infratentorial, while most adult primary brain tumors are supratentorial. The location of the tumor may have prognostic significance as well.

Since the tentorium is a hard structure, if there is a volume expansion in the parenchyme above the tentorium, the brain can get pushed down partly through the tentorium. This is called herniation and will often give mydriasis on the affected side, due to pressure on cranial nerve III (N. Oculomotorius). Tentorial herniation is a serious symptom, especially since the brainstem is likely to be compressed as well if the intracranial pressure rises further. See uncal herniation for a common subtype of a tentorial herniation.