Concept and Etiology: Brain Herniation
Brain herniation occurs when there is something inside the skull that
produces pressure that moves brain tissue. Often associated with
brain swelling or bleeding from injuries, stroke, or a tumor. As brain
herniation is due in part to pressure being introduced, it can occur in
any "direction" as it were. From side to side, up or down, it can put
pressure on the pituitary gland as a result. Brain herniation can put
pressure on parts of the brain that control consciousness, thus,
resulting in a stupor or coma. This deviates from normal brain
functions and is life-threatening.
Brain herniation can be classified as intracranial or extracranial.
Intracranial hernias can be transtentorial or tonsillar. Transtentorial
herniation involves "the upper part of the brain (cerebrum) being
forced through the tentorial notch, which divides the cerebrum from
the lower parts of the brain (cerebellum and brain stem). In people
with this type of herniation, consciousness is reduced. The side of
the body opposite the tumor may be paralyzed. The pupil of the eye
on the side of the herniation may widen (dilate) and may not narrow
(constrict) in response to bright light." Tonsillar herniation involves "a
mass (tumor or bleeding) in the lower part of the brain that pushes
the lowest part of the cerebellum (cerebellar tonsils) through the
opening at the base of the skull (foramen magnum). As a result, the
brain stem, which controls breathing, heart rate, and blood pressure,
is compressed and malfunctions."
Signs and symptoms include high blood pressure, irregular or slow
pulse, severe headache, weakness, cardiac arrest, loss of
consciousness/coma, loss of all brainstem reflexes (blinking, gagging,
and pupils reacting to light).
Testing can be done to determine if a brain hernia is present such as
an x-ray of the skull and neck, CT scan of the head, MRI of the head,
and if a bleeding disorder is suspected blood tests can be done. Brain
herniation is a severe life-threatening brain injury, usually caused by
other serious disorders such as a brain tumor. Treatment is necessary
and depending on timing can save someone's life.
U.S. National Library of Medicine. (2020, August 2). Brain Herniation:
MedlinePlus medical encyclopaedia. MedlinePlus. Retrieved from Brain
herniation: MedlinePlus Medical Encyclopaedia
Maiese, K. (2021, November 17). Brain herniation - brain, spinal cord,
and nerve disorders. Merck Manuals Consumer Version. Retrieved
from Brain Herniation - Brain, Spinal Cord, and Nerve Disorders -
Merck Manuals Consumer Version
