In their article, "Electrographic seizures and periodic dischargesafter intracerebral hemorrhage," Dr. Claassen and colleaguesdiscuss several important issues that affect people who havebleeding into the brain (Neurology 2007;69:1356–1365).They used a retrospective review to study problems associatedwith bleeding within the brain. There are problems with thistype of study. However, it is this kind of study that oftenleads to further research.
In a retrospective study, the authors select a group of peoplewith a particular problem or illness. For instance, the authorsmight look for a group of people who have migraines. They startcarefully looking for problems that the group share. For instance,many people with migraine take pain medications. In a retrospectivestudy, the use of pain medications would be something sharedby a large number of these people. Two statements are possible.The first is that people who are in pain are more likely totake a pain medication. A second possibility is that the medicationcaused the headaches. Remember that the retrospective studyonly shows those things that a group of people have in common.It does not necessarily tell us whether the illness caused aproblem or vice versa.
Dr. Claassen et al. studied a group of people who had intracerebralhemorrhage. There were 615 people admitted to Columbia-PresbyterianHospital with this diagnosis between January 1, 1998, and September9, 2006. Of this group, 102 had testing called continuous electroencephalography(cEEG). In other words, 102 people had an EEG that ran for anaverage of 3 days. Many of these people were in the intensivecare unit (ICU). Many were very sick, and were not respondingwell to treatment. In most cases, their doctors ordered theEEG because the person was not getting better.
The people with intracranial hemorrhage received many treatments.Medicines were used to treat high blood pressure. Other medicineswere administered to treat the swelling that occurs when a personhas a bleed in the brain. Some people needed surgery to keepthe brain from swelling so much that they would die. Othershad high fevers, and were treated with a special blanket thathelped to bring down their temperature.
All of the people had a computed tomogram (CT) of the head.Most had several CT scans, designed to see if the bleeding hadstopped, or was still happening. Using measuring techniques,the doctor determined the volume of intracerebral blood. Bycomparing sequential CT scans, the doctor could determine ifthe bleeding was getting worse. Dr. Claassen et al. found thatif a person’s bleed got worse in the first 24 hours, heor she was more likely to have seizures.
The EEG used standard techniques to record brain waves. TheEEG showed seizures in 1 out of 5 people (18%). More than half(56%) had a seizure within 1 hour of starting the EEG. Three-fourths(72%) of people who had seizures experienced one in the first24 hours of the recording. Almost all (94%) had a seizure inthe first 2 days of the recording. What is interesting aboutthis that there was only one person in whom the seizure wasobvious to the medical staff. In other words, without the EEGrecording, the seizures would have not been recognized in 17of the 18 people who were having them.
These findings are important for several reasons. First, seizuresare common. They occurred in one-third of people who had bleedingwithin the brain. However, more than one-half (17%) of thisgroup had seizures that could not be recognized simply by watchingthe patient. Instead, cEEG was needed to detect the seizures.In 9 out of 10 people (94%) who had seizures and an EEG, theEEG captured the seizure in less than 2 days.
In addition to seizures, the cEEG also showed markers of seizurescalled periodic discharges. These markers are not seizures.Instead, they are brain wave patterns that tell doctors thatseizures are more likely to happen. One-fifth (17%) of peoplehad these markers. Often they also had seizures. Dr. Claassenet al. did not find an association between seizures and a pooroutcome. Instead, they found that the presence of periodic dischargesoccurred more often when a person was doing badly.
Retrospective studies are sometimes difficult to interpret.People who have intracerebral hemorrhage are likely to haveseizures. Sometimes, the seizures are so subtle that they canonly be "seen" with medical testing such as cEEG. This studyshowed that one-half of people who had seizures needed EEG todiscover the fact. This suggests that when a person is admittedto the hospital because of bleeding within the brain, cEEG shouldbe considered. At present, this is not a technology that isavailable everywhere. This study shows the importance of thiskind of testing in this specific situation.
In addition, the study showed that the presence of periodicdischarges on EEG was associated with a poor outcome. This isan EEG finding only. In other words, the study highlights asecond reason for doctors to consider cEEG in people with intracerebralhemorrhage.
Intracranial hemorrhage means bleeding somewhere inside theskull. It is often referred to as a hemorrhagic stroke. Thereare two kinds of bleeding in the skull. The first occurs inthe brain substance itself. This is called intracerebral hemorrhage.The subarachnoid space surrounds the brain, and is filled witha clear fluid called CSF. The brain floats in this watery layer.The water protects the brain, and cushions it from sudden trauma.If bleeding occurs into this watery layer, and not into thebrain itself, it is called a subarachnoid hemorrhage. In somepeople, both will occur at the same time.
The blood vessels that go to the brain run through the subarachnoidspace. Sometimes, a person develops an aneurysm. Aneurysms arelike balloons that form on the blood vessels themselves. Asthe "balloons" grow in size, the walls become thinner. At somepoint, the "balloon" may break, releasing the blood. When thisoccurs, it is called a subarachnoid hemorrhage. Subarachnoidhemorrhages are very serious. If not treated immediately, theycan cause death.
The second kind of bleeding occurs in the brain substance itself,called intracranial bleeding. There are many causes of bleedingwithin the brain. One of the most common is head trauma. Headtrauma can be caused by traffic accidents, falls, sports injuries,or acts of violence.
Second to this is high blood pressure. As the heart beats itpumps blood to the arteries and creates a pressure from theblood pumping into the arteries and the pressure that occurswhen the arteries resist the blood’s flow. Blood pressurechanges with the strength of the heartbeat and depends on theflexibility of the artery walls. Blood pressure is constantlychanging depending on physical activity, medications taken,emotional state, and temperature. If blood pressure goes highenough, it can cause blood vessels to burst, resulting in bleedinginto the brain.
Some people are born with an abnormal tangle of blood vessels(called a vascular malformation) in their brain. Usually, thistype of malformation is present at birth. Because the bloodvessels are abnormal, they may have very thin walls. Like aneurysms,if they are thin enough, they may break and cause bleeding.
Bleeding within the brain is serious and requires urgent treatment.Often a person with intracranial bleeding will stay in the intensivecare unit until they are stable.
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What did the authors...
What did the authors...
