CONDITIONS AFFECTING THE BRAIN
Brain tumors
There are a wide
variety of tumors and masses that can occur in or around the brain. They
range from very slow-growing, benign growths that may not need any treatment,
to very aggressive, fast-growing tumors that are difficult to treat. A
brief description of the more common tumors are included below.
Acoustic neuromas
These are tumors that grow on one of the nerves going
into the ear canal. The eighth cranial nerve carries information from
the ear to the brainstem. The tumors are actually on the portion of the
nerve that is responsible for balance and equilibrium (vestibular), but
this runs adjacent to the nerve for hearing (acoustic).
The tumors arise from the covering or sheath around the nerve. These are
slow-growing tumors that are benign. Because of their location, as these
tumors grow, they can affect the hearing in that ear. There are other
important nerves and structures nearby, so large tumors can cause many
other symptoms. For example, the neighboring facial nerve is responsible
for muscle strength in the face. Small tumors can be observed (frequent
MRI's), and gamma-knife treatment is a good non-operative option for many
patients. However, some tumors, particularly larger ones, are best treated
with surgery.
Gliomas
Gliomas arise from the brain tissue. There are many different
types, but the most common are astrocytomas. This includes the malignant
tumor, glioblastoma multiforme.
Treatment usually involves surgery. This may be a biopsy or tumor resection.
In many cases, this is followed by chemotherapy and possibly some form
of radiation therapy. A newer treatment involves implantation of a specialized
reservoir that is filled with a tumor-fighting substance.
Meningiomas
Meningiomas are benign tumors that arise from the covering
of the brain. As they grow larger, they can compress or distort the brain,
the cranial nerves, or other structures. Fortunately, aggressive (invasive
or malignant) tumors are uncommon. However, meningiomas can be located
near very critical structures making surgery risky and complete resection
unsafe.
Some meningiomas may only need close observation- particularly small tumors
not causing symptoms. Some may be good candidates for gamma-knife treatment,
a very focal form of radiation. In some instances, these non-operative
options are chosen due to the patient's age, medical condition, or the
tumor location.
Larger tumors and tumors causing symptoms may be cured with surgery. In
some cases, the tumor can grow back, usually years after surgery. Fortunately,
most meningiomas grow slowly.
Pituitary adenomas
These are benign growths of the pituitary gland. This
gland produces a variety of important hormones. It is located just beneath
the brain and behind the eyes. Unfortunately, the optic nerves are just
above this gland. These are the nerves responsible for carrying vision
back to the brain. For this reason, as the pituitary gland gets larger
from tumor growth, the vision can be adversely affected. Symptoms related
to hormone abnormalities can also be seen with these tumors.
Treatment depends on the type and size of the tumor, as well as the patient's
symptoms and overall medical condition. Some types of tumors respond to
medication. Gamma-knife treatment is a good, non-operative option for
some cases. However, surgery may be the best option in many cases.
Brain conditions other than tumor:
There are several types of Chiari malformations. Previously referred to as "Arnold-Chiari malformations," they describe abnormal development of certain parts of the nervous system. The most common type is the Chiari 1 malformation. When the lower part of the brain is "cramped," it can be pushed downward toward the spinal canal. This may disrupt the flow of cerebrospinal fluid in the head or the spinal cord. Symptoms can include pain in the back of the head and neck, numbness and tingling in the hands, or even clumsiness. Treatment involves decompression, which essentially makes more room for the crowded brain tissue and restores normal flow of cerebrospinal fluid.
Hydrocephalus
Hydrocephalus refers to an increase in the amount of cerebrospinal fluid in the cranium. The cerebrospinal fluid, or CSF, is like water. It is produced by cells near the brain, and it surrounds the brain and spinal cord. The fluid flows around the brain and down into the spinal canal. Normally it is absorbed at the same rate it is produced, so that there is no net gain in fluid. In hydrocephalus, however, the fluid builds up either because it is blocked (by a tumor, cyst, or other mass) or because it cannot be absorbed fast enough.
Buildup of spinal fluid can cause increased pressure on the brain. Symptoms can include headaches, blurred vision, nausea, and vomiting. In severe cases, this can progress to confusion, lethargy, and possibly coma and death if not treated. Not all forms of hydrocephalus present with these symptoms, however.
Treatment involves diverting the spinal fluid out of the head, usually into the abdominal cavity. The lining of the abdominal wall absorbs the fluid. This is called a VP shunt (ventriculoperitoneal shunt: a shunt from the ventricle to the peritoneum). A small catheter and tubing system is tunneled under the skin, and a valve controls the amount of flow.
In some cases, the flow of cerebrospinal fluid can be restored by opening up membranes through a small scope (endoscope) inserted through a small hole in the skull. In these cases, the need for a permanent shunt can be avoided.
Normal pressure hydrocephalus
There are variations of hydrocephalus. As mentioned above, not all hydrocephalus is due to blockage of CSF. In normal pressure hydrocephalus, the buildup of CSF is very gradual. It is seen in older adults, and is an uncommon cause of dementia. Symptoms include memory problems, gait problems (difficulty walking), and urinary incontinence. In appropriate cases, treatment with a VP shunt can improve these symptoms.
Pseudotumor cerebri
Pseudotumor cerebri is another uncommon condition that usually affects young, overweight females. Also known as idiopathic intracranial hypertension, an increase in intracranial pressure results in severe headaches and worsening vision. If left untreated, vision loss can occur. Fortunately, many cases respond to medications, decompression of the optic nerves (nerves for vision), and in some cases, lumbar punctures ("spinal taps") to drain fluid and relieve the pressure in the head. In refractory cases, placement of a VP shunt may be necessary. Dramatic improvement can also be seen with weight loss.
