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A computed tomography (CT) scan of the head is an imaging scan that uses X-rays to develop a 3D image of the skull, brain, and other related areas of the head.
A CT scan of the head can provide more detail than a traditional X-ray, which is particularly useful when a doctor wants to check the blood vessels and soft tissues in the body.
In this article, we explain why a doctor may order a CT scan of the head and what a person can expect if they need to undergo this procedure.
When do people need a CT head scan?
Some of the reasons why a doctor may order a head CT scan include:
- looking for possible damage after trauma to the head, such as soft tissue injuries, brain bleeding, and bone injuries
- assessing a person having stroke-like symptoms to see whether there are signs of a blood clot or brain bleeding
- looking for a possible brain tumor or other brain abnormality
- checking the effectiveness of medical treatments in shrinking a brain tumor
- assessing birth conditions that cause the skull to form abnormally
- evaluating a person with a history of hydrocephalus, a condition in which an accumulation of cerebrospinal fluid causes the enlargement of the brain ventricles
If a person is having brain-related symptoms, such as changes in personality or affected movement, a doctor may order a head CT scan to make sure that a brain abnormality is not the underlying cause.
A doctor should provide specific instructions for the day of the CT scan. These will include whether or not to refrain from eating or drinking for a certain period before the scan.
The doctor will also usually ask the person to take off any jewelry, removable dental work, or hairpins because these can affect the scan’s images.
Sometimes, people who take metformin (Glucophage) may need to refrain from using it for a few days before getting a CT scan with contrast dye. The combination of this drug and the dye can cause a severe reaction in some individuals.
Contrast dye is a substance that the person may receive by injection before a scan. It makes certain areas of the body show up more easily on a scan. However, not all CT scans require contrast dye.
The person will often complete a checklist before undergoing the scan. The checklist includes a medical history of conditions that can affect a person’s health, such as kidney disease, heart disease, asthma, and thyroid problems. Some health issues may affect a person’s ability to receive intravenous (IV) contrast.
The scanner usually looks like a circle shaped machine that has a hole in its center. In the center, there is a bed on which a person lies during the procedure. The scanner is usually open, which helps the person feel less claustrophobic.
A radiology technician may ask the person to change into a gown before going into the room with the CT scanner.
Before the scan, a radiology technician may put an IV line in place, usually in the person’s arm, if the scan uses contrast dye.
During the scan, the radiology technician will talk to the person via a speaker to let them know them when the scan is starting. The scanner will direct X-ray beams at the person’s head. The X-rays will come back to the scanner, transmitting the images back to a computer.
After the initial scan, the radiology technician may deliver the IV contrast material. They will then restart the CT scan. The technologist will review the images to ensure that they are of high quality and are free of blurring in any key areas.
The average CT scan of the head takes no more than 10 minutes.
CT head scans in children
As a CT scan is relatively quick, many children can stay still long enough for the technician to complete the scan. However, if a child cannot remain still for the scan — as is the case for babies — it may be necessary to perform the procedure with the child under anesthesia.
Children are typically more sensitive to radiation than adults. As a result, doctors tend to reserve CT scans for when they are necessary to make a diagnosis. A radiology technician can usually adjust the settings on a CT scanner to deliver the lowest possible dose of radiation.
The CT scan is a painless, noninvasive procedure, and doctors generally consider it to be safe. However, it carries some possible risks.
As a CT scan exposes a person to radiation, there is a risk that the person could develop cancer from excessive radiation doses. However, the risks for this after one CT head scan are minimal. A person can ask their doctor if they should be concerned about the radiation dose from a CT head scan.
Doctors will usually recommend that women avoid CT scans during pregnancy. However, as one CT scan is unlikely to pose a significant risk, a doctor can offer advice on whether the benefits outweigh the risks.
A CT scan can be noisy. Sometimes, this noise or the fear of being in an enclosed space can provoke anxiety in a person. For this reason, doctors may sometimes give a person sedating medicines before they go into the CT scanner.
If a person receives a contrast dye during the procedure, they could be at risk of experiencing an allergic reaction to the dye.
Contrast dye can also cause other symptoms that may be temporarily unpleasant but are not an allergic reaction. These may include a warm feeling throughout the body, a burning sensation, or a metallic taste in the mouth. Sometimes, a doctor may prescribe a steroid or advise a person to take diphenhydramine (Benadryl) before undergoing the scan.
A medical specialist called a radiologist will examine the imaging scans, looking for any abnormalities in the brain and surrounding tissues. They will write a report of their findings and send it to the doctor who ordered the scan.
If a person is in the hospital and undergoing the scan as an emergency, the radiologist will report any immediately concerning results as quickly as possible.
CT scan vs. MRI scan
While a CT scan is helpful in displaying some aspects of the head and brain, an MRI scan sometimes has higher sensitivity. As a result, it may be more effective in revealing disease processes in the brain and inflammation in the membranes covering the brain, which are known as the meninges.
Doctors will consider the advantages of each type of scan for scanning the head. The benefits of a CT scan compared with an MRI scan include:
- A CT scan is faster than an MRI scan, so doctors usually use it for emergencies.
- A CT scan generally costs less than an MRI scan.
- Doctors can perform a CT scan on a person who has metal devices, such as a pacemaker, nerve stimulator, or cochlear implant. A person with these devices cannot undergo an MRI because of the magnet’s attraction to metal.
The benefits of an MRI scan compared with a CT scan include:
- An MRI does not involve radiation exposure, making it preferable for children who may require multiple scans.
- MRI scans can show soft tissues and structures that bone may hide in a CT scan.
- A person requires a smaller amount of IV contrast for an MRI scan than for a CT scan.
People can talk to their doctor to evaluate the aspects of each scan and determine which is most appropriate for them.
A CT scan of the head is useful for helping a doctor assess damage after an accident or head trauma. It also allows them to look for brain abnormalities, such as tumors and skull defects.
Doctors consider CT scans to be relatively safe and noninvasive procedures, even though they involve exposure to radiation. People can discuss any possible risks with their doctor.
Increased intracranial pressure is a medical term that refers to growing pressure inside a person’s skull. This pressure can affect the brain if doctors do not treat it.
A sudden increase in the pressure inside a person’s skull is a medical emergency. Left untreated, an increase in the intracranial pressure (ICP) may lead to brain injury, seizure, coma, stroke, or death.
With prompt treatment, it is possible for people with increased ICP to make a full recovery.
In this article, we look at the symptoms, causes, and treatments of increased ICP.
Symptoms of increased ICP
The symptoms of increased ICP can vary depending on a person’s age.
Infants with increased ICP may have different symptoms to older children or adults with the condition, as discussed below.
Symptoms in adults
- pupils that do not respond to light in the usual way
- behavior changes
- reduced alertness
- muscle weakness
- speech or movement difficulties
- blurred vision
As raised ICP progresses, a person may lose consciousness and go into a coma. High ICP may cause brain damage if a person does not receive emergency treatment.
Symptoms in infants
Infants with increased ICP may show some of the same symptoms as adults. In addition, the shape of their heads may be affected.
Infants still have soft plates in their skull that fibrous tissue called skull sutures knit together. Increased ICP may cause the skull sutures to separate and the soft plates to move apart.
Increased ICP in infants may also cause their fontanel to bulge out. The fontanel is the soft spot on the top of the skull.
The following is a list of medical conditions and other causes that can lead to increased ICP:
- brain injury, which is often the result of a blow to the head
- hydrocephalus, or too much cerebrospinal fluid on the brain
- brain swelling
- bleeding or blood pooling in the brain
- brain aneurysm
- brain infection, such as meningitis or encephalitis
- high blood pressure
- brain tumor
- drug interaction
- hypoxemia, a blood oxygen deficiency
In infants, high ICP may be the result of child abuse.
If a person handles a baby or infant too roughly, it may cause them to develop a brain injury. This is known as shaken baby syndrome.
One source has estimated that between 1,000 and 3,000 children in the United States experience shaken baby syndrome each year. The condition may arise if an adult shakes a baby violently to stop them crying.
Anyone who suspects a child may be experiencing abuse can contact the National Child Abuse Hotline anonymously at 1-800-4-A-CHILD (1-800-422-4453).
If a person has the symptoms of increased ICP, they should see a doctor straight away. This is a medical emergency and may lead to brain injury if a person does not receive rapid treatment.
A doctor will measure the ICP in millimeters of mercury (mm/Hg). The normal range is less than 20 mm/Hg. When ICP goes above this, a person may be experiencing increased ICP.
To diagnose increased ICP, a doctor may ask if a person has:
- experienced a blow to a head
- a previous diagnosis of a brain tumor
Then, the doctor may carry out the following tests:
- neurological exam to test a person’s senses, balance, and mental state
- spinal tap that measures cerebrospinal fluid pressure
- CT scan that produces images of the head and brain
After these initial tests, the doctor may use an MRI scan to examine a person’s brain tissue in more detail.
If a person has a diagnosis of increased ICP, a doctor will immediately work to reduce the pressure inside the skull to lessen the risk of brain damage. They will then work to treat the underlying cause of the increased pressure.
Treatment methods for reducing ICP include:
- draining the excess cerebrospinal fluid with a shunt, to reduce pressure on the brain that hydrocephalus has caused
- medication that reduces brain swelling, such as mannitol and hypertonic saline
- surgery, less commonly, to remove a small section of the skull and relieve the pressure
A doctor may give the person a sedative to help reduce anxiety and lower their blood pressure. The person may also need breathing support. The doctor will monitor their vital signs throughout their treatment.
In rare cases, the doctor may put a person with high ICP into a medically induced coma to treat their condition.
Complications of increased ICP include:
- brain damage
Without proper treatment, increased ICP can be fatal.
A sudden increase in ICP is a medical emergency and can be life-threatening. The sooner a person receives treatment, the better their outlook. Many people respond well to treatment, and a person who has experienced increased ICP can make a full recovery.
Preventing increased ICP and its complications
Increased ICP is not always preventable, but it is possible to reduce the risk of some underlying conditions that may lead to increased ICP. We explore how below.
A person can reduce ther risk of stroke by exercising regularly.
Stroke may cause increased ICP. A person can reduce their risk of stroke in the following ways:
- taking steps to lower high blood pressure
- stopping smoking
- managing blood sugar levels
- controlling cholesterol levels
- exercising regularly
High blood pressure
High blood pressure may cause increased ICP. A person can maintain healthy blood pressure by:
- losing weight if overweight or maintaining a healthy weight
- avoiding drugs that increase blood pressure
- eating a healthful, balanced diet
- reducing salt intake
- exercising regularly
A head injury may cause increased ICP. Some examples of how a person can reduce their risk of head injury include:
- avoiding extreme sports or dangerous activities
- always wearing a helmet for activities such as riding a bike
- always wearing a seatbelt when in a car
Increased ICP is when the pressure inside a person’s skull increases. When this happens suddenly, it is a medical emergency. The most common cause of high ICP is a blow to the head.
The main symptoms are headache, confusion, decreased alertness, and nausea. A person’s pupils may not respond to light in the usual way.
A person with increased ICP may need urgent treatment. The immediate aim of treatment is to bring down the pressure on their brain tissue, which helps to reduce the risk of brain damage.
Without proper treatment, this condition may lead to seizure, coma, stroke, or brain damage. In severe cases, increased ICP can be fatal. Rapid treatment may improve a person’s outlook. Making a full recovery with timely treatment is possible.
Increased ICP is not always preventable, but a person can reduce their risk of some causes through lifestyle changes.