Tests and diagnosis
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Because people in coma can't express themselves, doctors must rely on physical clues and information provided by families and friends. Be prepared to answer a number of questions about: <br>
 
 
    * What happened leading up to the coma <br>
 
    * The affected person's medical history, including other diagnoses <br>
 
    * Recent changes in the affected person's health or behavior <br>
 
    * The affected person's drug use, including prescription and over-the-counter medications as well as illegal, recreational drugs
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Physical exam <br>
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Doctors will check your reflexes, response to painful stimuli and pupil size. Squirting ice cold or warm water into the ear canals also can be informative. In unconscious people, these tests will cause reflexive eye movements of different types, depending on the cause of unconsciousness. <br>
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Laboratory tests <br>
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Blood samples will be taken to check for:
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    * Complete blood count <br>
 
    * Electrolytes, glucose and liver function <br>
 
    * Carbon monoxide poisoning <br>
 
    * Drug overdose <br>
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A spinal tap (lumbar puncture) can check for signs of infections. During a lumbar puncture procedure, a doctor inserts a needle into your spinal canal, measures the pressure and collects fluid for analysis. The entire procedure usually takes about 10 minutes.
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Brain scans <br>
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Imaging tests help doctors pinpoint areas of brain injury. Tests may include: <br>
 
 
    * CT. A CT scan uses a sophisticated X-ray machine linked to a computer to produce detailed images of your brain. This is the best imaging test for assessing brain injuries because it can show a hemorrhage or brain tissue swelling. The scan takes only a few minutes. <br>
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    * MRI. This scan uses a magnetic field and radio waves to generate images of the brain. You lie inside a cylindrical machine for 15 minutes to an hour. MRI scans are particularly useful for examining the brainstem and deep brain structures. Sometimes a dye is injected into your bloodstream during the procedure. The dye can help distinguish damaged brain tissue from healthy tissue. <br>
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    * Electroencephalography (EEG). An EEG measures the electrical activity inside the brain. Small electrodes are attached to the scalp with paste or an elastic cap. The electrodes pick up the brain's electrical impulses, which are recorded on the EEG machine. This test can determine if you're having nonconvulsive seizures, which can cause comas.

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