Brain - Diagnosis
Brain Tumors
Subaracnoid Hemorrhage
Normal Pressure Hydrocephalus
Brain Tumors
A tumor is an abnormal mass of tissue that grows on or inside the body. It is known as primary if located where its growth first started, or secondary if it began growing elsewhere in the body and metastasized, or spread, to its present location. Most primary brain tumors do not metastasize outside the brain.
Inside the skull, tumors can grow almost anywhere: within brain tissue, from the meninges, or inside the ventricular system. They can be encapsulated (self-contained) or interwoven with blood vessels, nerves, or other brain structures from which they cannot be removed without devastating consequences. Metastatic tumors are usually well localized, may occur alone or in clusters, and may spread throughout much of the brain.
A benign tumor usually is encapsulated, does not spread to other areas of the body, grows slowly, and often causes problems by compressing brain tissue. A malignant tumor grows uncontrollably, spreads throughout the brain, and destroys brain tissue.
What symptoms can it cause?
A brain tumor may at first cause the vague feeling of being "unwell." This may be followed by other, more specific symptoms: dull, persistent headache; nausea or vomiting; generalized weakness; vision problems. Because the left side of the brain governs the right side of the body, and vice versa, a tumor will cause specific weakness or loss of movement on the opposite side of the body. Some symptoms may be caused by the increased pressure inside the skull from brain swelling, which can temporarily be treated with a steroid medication.
Because brain tissue is irritated by the tumor, the brain can temporarily "short-circuit" as its normal electrical activity is interrupted. These periods of uncontrolled brain activity can cause seizures, which may be generalized and cause contractions of all parts of the body, loss of consciousness or bladder and bowel function. The seizures may instead be of a focal nature, affecting only one arm, a leg, or part of the face. Seizures usually can be controlled with anticonvulsant medications.
How is it evaluated?
A detailed history-taking of the patient's symptoms and a physical examination are done first, followed by any of several tests, such as x-ray studies, Computerized Tomography (CT) scans, Magnetic Resonance Imaging (MRI), and angiograms. All findings are used to evaluate the patient's symptoms, determine the tumor's exact location, and provide the physician with a tentative diagnosis of the tumor type.
During surgery, ultrasound imaging may be used to pinpoint the tumor's precise location and help the surgeon plan his approach for its removal.
If an emergency craniotomy is required, an extensive workup may not be possible.
Meningioma
Growing from abnormal cells of the meninges, meningioma is a slow-growing tumor that shares the dura's rich blood supply. It is very often attached to dura and so may be immediately visible when the dura is opened.
It is usually a benign tumor and well encapsulated, but removal may be complicated by its size, firmness, and attachment to vital blood vessels or brain tissues.
A large meningioma or one that is difficult to remove may require a long, tedious surgery and can cause further brain swelling and blood loss.
Often the dura removed during tumor surgery may be replaced with other body tissue (fascia) or a dura substitute.
Glioma
Glial cells support the brain's functioning nerve network and are the site of tumors inside the brain. Gliomas are "graded" according to their degree of malignancy.
Often when the dura is opened, the brain is swollen but otherwise may appear normal.
The "center" of the glioma may readily be identified, but because the tumor gradually spreads into surrounding tissue the boundaries of a glioma are harder to identify.
It may take months for the cells around the edges of the tumor to appear abnormal, yet they can be affected long before they "show" themselves. This is why glioma usually cannot be removed completely, as even one remaining cell can continue the tumor's growth.
Metastatic tumor
Often lying close to the brain's surface, where it irritates the normal tissue around it, a metastatic tumor is one that began in another body organ and traveled in the bloodstream to the brain.
Grown from a "seed" of non-brain tissue (from the breast, kidney, or lung, for example) a metastatic tumor often can be separated from the surrounding brain more easily. It only a single lesion exists, all or part of it usually can be surgically removed.
Subaracnoid Hemorrhage
Hemorrhage is the medical term for bleeding. The rupture of one of the brain's blood vessels can cause bleeding into the subarachnoid space - beneath the arachnoid membrane, on top of the pia mater - and into brain tissue. The bleeding usually stops, at least temporarily, when a clot forms over the ruptured area.
Why does it happen?
The most frequent cause of spontaneous subarachnoid hemorrhage (not due to injury) is the rupture of a small aneurysm, or bulging sac, on one of the blood vessels that supplies the brain. It is usually impossible to determine why the aneurysm forms and bursts, but the condition is common in adults and may be associated with aging, diabetes, pregnancy, hypertension (high blood pressure), heredity, or trauma.
Cerebral aneurysms are usually of three types: saccular with a narrow "neck" (called "berry" aneurysms because of their shape and their tendency to occur in clusters); saccular with a broad base; and fusiform, in which a short section of the artery bulges all the way around. Each shape determines the degree of difficulty a surgeon faces in attempting to treat the problem.
An aneurysm ruptures spontaneously - even during sleep - and therefore is not related to the strain of hard work, sexual intercourse, or other physical activity.
Although it is not always possible to discover the exact source of bleeding, other causes of spontaneous subarachnoid hemorrhage include: arteriovenous malformations, small angiomas, certain types of infections, and bleeding disorders.
What symptoms can it cause?
A ruptured cerebral aneurysm at first causes severe headache, which can be followed by nausea, vomiting, double vision or sensitivity to light, neck pain or stiffness, weakness, memory loss, paralysis, coma, or death.
How severe the symptoms are and how long they last will depend on the amount and location of the bleeding. Blood in and around the brain can cause pressure, swelling, and brain irritation, which can lead to drowsiness, confusion, weakness or paralysis, memory loss, speech problems, behavior changes, or coma (complete loss of consciousness).
What complications can occur?
The blood vessels around the aneurysm are irritated by the blood from the hemorrhage and will at times go into a state of spasm, tightening and narrowing. This vasospasm ("vaso" meaning vessel) can occur any time after the rupture until the hemorrhaged blood has been absorbed by the body, and it can increase any or all symptoms. It is the body's own attempt to prevent a second hemorrhage by restricting the flow of blood through the vessels around the aneurysm. Vasospasm thus reduces pressure on the delicate aneurysm but unfortunately also reduces the normal blood supply to parts of the brain.
Ongoing research is being done to discover a medicine that will control vasospasm; as yet, none has proven effective.
Other complications from subarachnoid hemorrhage, such as hydrocephalus, hematoma (blood clot), and brain swelling, involve the brain; but other body systems can also be affected because of the severe nature of the illness. Pulmonary embolus, heart abnormalities, and bleeding from an ulcer may cause further complications.
How is it diagnosed?
Several tests are used to confirm the diagnosis of ruptured cerebral aneurysm. Some are explained in the latter portion of this section.
Because cerebrospinal fluid flows within the subarachnoid space, a sample of CSF taken during a spinal tap at the base of the spine will show blood from the hemorrhage. A CT scan will show blood inside the skull and indicate how much bleeding has occurred.
To find the source of the hemorrhage, an angiogram is performed, which may have to be repeated to try to pinpoint the aneurysm's exact location.
Hospitalization
Activity
Because the aneurysm can rupture again, a quiet, restful atmosphere is important. The patient usually is placed in the Intensive Care Unit (ICU), a highly specialized area providing close observation with specialized nursing care. Complete bedrest without physical strain is essential while the patient's condition stabilizes - usually in preparation for surgery.
Medications
Medications will be given when necessary to reduce pain, control blood pressure, relieve stress, and maintain fluid balance.
Breathing
If necessary, a respirator may be used to help the patient breathe and to control intracranial pressure. Most often, however, oxygen is merely administered to the patient through nasal prongs or a mask.
Monitoring devices
Various monitoring devices may be used to assess the patient's condition during recuperation. Among the most common are: an EKG (heart) monitor, an ICP monitoring device, a Swan-Ganz catheter to assess the patient's fluid balance, and an arterial line to continuously measure blood pressure and aid in drawing frequent blood samples for laboratory study.
Nutrition
Intravenous (I.V.) fluids may be given until liquids and food can be taken adequately by mouth. The amount of fluid given will be closely monitored until the dangers of brain swelling (edema) and vasospasm lessen.
Normal Pressure Hydrocephalus
One of the treatable causes of dementia (or difficulty thinking) is NPH, or normal pressure hydrocephalous. Inside the brain are cavities where the spinal fluid is made, these are called ventricles, at times they can be enlarged. Frequently, they are enlarged because of increased pressure in the brain. However, at times, they enlarge without this accompanying pressure at least on a constant basis, and this can result in a triad of symptoms:
- Dementia or difficulty thinking. Recent memory may be affected first.
- Difficulty ambulating. A magnetic gait is noted where the patient seems to be adherent to the floor, yet can sometimes walk fairly well with merely guidance holding a patient's fingertips (as opposed to complete support of the patient’s body) in order to ambulate. Great difficulty rising from a chair is frequently noted.
- Incontinence of urine. Losing a small amount of urine is frequent as we get older, especially in women, but serious loss of urine, can suggest the third leg of this triad of symptoms.
Not all 3 complaints are necessary for this diagnosis to made. There are pros and cons as to the various diagnostic techniques utilized to confirm this diagnosis. None are completely without problems.
An MRI scan and CAT scan can give a good idea as to the diagnosis especially when accompanied by the appropriate symptoms. At times, drainage of the spinal fluid in the hospital over several days can be useful in determining whether or not a shunt procedure may be helpful in treating this condition. There are increased risks for infection, including meningitis and there still may still be some error with this technique. A radionuclide cisternogram is a study performed with a radionuclide or radioactive material, to determine if the spinal fluid flow is abnormal. Used for decades to assist in making this diagnosis, recent literature suggests the usefulness of this technique is very limited.
Once the diagnosis of NPH is made, a shunt may be considered. This is a small tube, which is placed into the ventricles of the brain and brought beneath the skin, to the abdominal cavity, where the fluid is absorbed.
Some patients can report a remarkable response in reduction of symptoms. It truly is one of the few treatable causes of dementia commonly seen.
Newer techniques with adjustable valves (also, placed below the skin), make the “fine tuning” of spinal fluid regulation safer and more predictable.
Adjustment can be done after surgery in the doctor’s office without intervention, using a small magnetic instrument that calibrates the internal device. Please see the video on the treatment of normal pressure hydrocephalous patient on this website (under brain / surgery).
 View the Normal Pressure Hydrocephalus presentation |