Diagnosis of Coma

Medical History and Coma Diagnosis

As with most neurological problems, the first step in diagnosing what is causing a coma or other state of unconsciousness is to obtain a complete medical history. Obviously, there is no way to get this information from the comatose patient, so physicians must rely on friends and family for these details. It is important to know how the coma developed—whether it was sudden or slow. It is also helpful to know about any medical problems that the comatose person has, including diabetes mellitus, high blood pressure, kidney disease, liver disorders, or a history of seizures.

Physical Exam & Neurological Evaluation and Coma Diagnosis

The physical exam will evaluate a comatose person's breathing pattern and cardiovascular function, as well as look at the skin and limbs for any noticeable abnormalities. Sometimes, particular breathing patterns are related to specific abnormalities in the brain, and they can be used to identify the underlying problem.

Eye Examination and Coma Diagnosis

The eyes will be examined carefully. Like a person's breathing pattern, the way the eye moves is sometimes related to specific abnormalities in the brain and can be used to identify the underlying problem. A fundoscope is used to examine the optic nerve in the back of the eye for any signs of swelling, which indicates that there may be increased intracranial pressure.

Laboratory Tests and Coma Diagnosis

Usually, a full set of laboratory tests are done on the comatose patient. These include blood tests that check the liver, kidney and thyroid function, glucose levels, and the presence of any toxins. The results of the various lab tests may provide clues as to what has caused the coma.

Imaging Studies and Coma Diagnosis

A CT (computerized axial tomography) and MRI (magnetic resonance imaging) can both be used to visualize most abnormalities in the brain. In some cases, a lumbar puncture, known as a spinal tap, may be done to remove some of the cerebrospinal fluid for evaluation.

EEG and Coma Diagnosis

If a seizure is suspected, an electroencephalography (EEG) can be done to confirm it or rule it out. An EEG tests the electrical activity in the brain.

Publication Review By: Stanley J. Swierzewski, III, M.D.

Published: 01 Jan 2000

Last Modified: 08 Sep 2015