Head CT

Alternative names 
Cranial CT scan; CT scan - skull; CT scan - head; CT scan - orbits; CT scan - sinuses

A cranial CT scan involves computed tomography of the head, including the skull, brain, orbits (eyes), and sinuses.

How the test is performed

A head CT will produce an image from the upper neck to the top of the head. If the patient cannot keep his/her head still, immobilization may be necessary. All jewelry, glasses, dentures, and other metal should be removed from the head and neck to prevent artifacts.

A contrast dye may be injected into a vein to further evaluate a mass. (The mass becomes brighter with contrast dye if it has a lot of blood vessels). Contrast dye is also used to produce an image of the blood vessels of the head and brain.

The total amount of time in the CT scanner is usually a few minutes.

How to prepare for the test

Generally, there is no preparation necessary.

Infants and children:
The physical and psychological preparation you can provide for this or any test or procedure depends on your child’s age, interests, previous experiences, and level of trust. For specific information regarding how you can prepare your child, see the following topics as they correspond to your child’s age:

How the test will feel

As with any intravenous iodinated contrast injection, there may be a slight temporary burning sensation in the arm, metallic taste in the mouth, or whole body warmth. This is a normal occurrence and will subside in a few seconds.

Otherwise, the CT scan is painless.

Why the test is performed
A CT scan is recommended to help:

  • evaluate acute cranial-facial trauma  
  • determine acute Stroke  
  • evaluate suspected subarachnoid or intracranial hemorrhage  
  • evaluate headache  
  • evaluate loss of sensory or motor function  
  • determine if there abnormal development of the head and neck

CT scans are also used to view the facial bones, jaw, and sinus cavities.

What abnormal results mean
There may be signs of:

  • trauma  
  • bleeding (for example, chronic subdural hematoma or intracranial hemorrhage)  
  • Stroke  
  • masses or tumors  
  • abnormal sinus drainage  
  • sensorineural hearing loss  
  • malformed bone or other tissues  
  • brain abscess  
  • cerebral atrophy (loss of brain tissue)  
  • brain tissue swelling  
  • hydrocephalus (fluid collecting in the skull)

Additional conditions under which the test may be performed:

  • acoustic neuroma  
  • acoustic trauma  
  • acromegaly  
  • acute (subacute) subdural hematoma  
  • amyotrophic lateral sclerosis  
  • Arteriovenous malformation (cerebral)  
  • benign positional vertigo  
  • throat cancer  
  • central pontine myelinolysis  
  • cerebral aneurysm  
  • Cushing’s syndrome  
  • deep intracerebral hemorrhage  
  • delirium  
  • dementia  
  • dementia due to metabolic causes  
  • drug-induced tremor  
  • encephalitis  
  • epilepsy  
  • essential tremor  
  • extradural hemorrhage  
  • familial tremor  
  • general paresis  
  • generalized tonic-clonic seizure  
  • Hemorrhagic stroke  
  • hepatic encephalopathy  
  • Huntington’s disease  
  • hypertensive intracerebral hemorrhage  
  • Hypopituitarism  
  • intracerebral hemorrhage  
  • juvenile angiofibroma  
  • labyrinthitis  
  • lobar intracerebral hemorrhage  
  • Ludwig’s angina  
  • mastoiditis  
  • melanoma of the eye  
  • Meniere’s disease  
  • meningitis  
  • metastatic brain tumor  
  • multi-infarct dementia  
  • multiple endocrine neoplasia (MEN) I  
  • neurosyphilis  
  • normal pressure hydrocephalus (NPH)  
  • occupational hearing loss  
  • optic glioma  
  • orbital cellulitis  
  • otitis media; chronic  
  • otosclerosis  
  • partial (focal) seizure  
  • partial complex seizure  
  • petit mal seizure  
  • pituitary tumor  
  • primary brain tumor  
  • primary lymphoma of the brain  
  • prolactinoma  
  • retinoblastoma  
  • Reye’s syndrome  
  • schizophrenia  
  • senile dementia/Alzheimer’s type  
  • acute Sinusitis  
  • stroke secondary to atherosclerosis  
  • stroke secondary to cardiogenic embolism  
  • stroke secondary to FMD  
  • stroke secondary to syphilis  
  • subarachnoid hemorrhage  
  • syphilitic aseptic meningitis  
  • temporal lobe seizure  
  • Toxoplasmosis  
  • transient ischemic attack (TIA)  
  • Wilson’s disease

What the risks are

Iodine is the usual contrast dye. Some patients are allergic to iodine and may experience a reaction that may include hives, itching, nausea, breathing difficulty, or other symptoms.

As with any x-ray examination, radiation is potentially harmful. Consult your health care provider about the risks if multiple CT scans are needed over a period of time.

Special considerations
A CT scan can decrease or eliminate the need for invasive procedures to diagnose problems in the skull. This is one of the safest means of studying the head and neck.

Johns Hopkins patient information

Last revised: December 6, 2012
by Dave R. Roger, M.D.

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