Head ct is a starting point for many symptoms that your doctor believes originate in the head. A head ct is a painless test done in a donut shaped machine that takes pictures of your brain and skull in cross sections. A specially trained radiologist doctor will interpret the images.
One of the more common reasons for obtaining a head ct is headache. These are most often benign tension or migraine headaches. There are some worrisome symptoms such as: worst headache of your life, neurological symptoms such as loss of strength or inability to walk without losing balance, altered mental status such as confusion or drowsiness, fever and neck stiffness. These indicate that the cause of your headache may be more serious. Your doctor will do a thorough history and physical exam to try to determine the cause.
Often a head ct is ordered to rule out conditions which may need immediate treatment. The test is fast and easy since it can be done at any time in most emergency rooms and hospitals. It’s not as detailed as an MRI, but this test is longer and hard to get at all times. Plus the head ct rules out things quickly which need treatment like a brain bleed, a mass, or stroke. There are many other causes of headache like brain aneurysm, meningitis, viral infections which do not show up on head CTs. Therefore, a head CT is just a quick start and by no means the end of a work up for headache.
Bleeds in the brain can be between the skull and brain, most commonly subdural hematoma. Often these are due to trauma. This trauma can be minor in the elderly or those on blood thinners. Sometimes subdural bleeds can go unnoticed and cause symptoms of dementia chronically. In some cases, a neurosurgeon may need to evacuate the bleed.
Other causes of bleeding in the brain can be due to subarachnoid hemorrhage when an aneurysm ruptures or in the brain itself for various reasons such as trauma, high blood pressure or an underlying lesion of the brain. The head CT will show the location of the bleed and sometimes the cause.
Tumors can also cause headaches and show up on a head ct. There will be a mass and pushing of adjacent structures. If there is a lot of shift of the structures, and the midline of the brain, then surgery may be needed. Strokes will have a typical clinical presentation such as weakness, difficulty speaking or numbness. A head ct may not show a stroke when it is within the first hours.
A negative head ct will give your doctor assurance that many serious conditions that require prompt treatment are not present. Some serious conditions will however not show on a head ct done for headache. For example, meningitis and aneurysm will not show up. Meningitis will often require a spinal tap to diagnose. An aneurysm will require a special ct called an angiogram of the blood vessels.
It is therefore critical that your doctor takes a detailed history, does a physician exam and orders testing in addition to head ct in many cases. A brain mri is also often needed to investigate the cause of a headache. A brain mri is more detailed and shows structures in the brain to greater detail. A specialty trained neurologist can be consulted to guide further diagnosis and treatment.