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- Patient Comments: Coma - Causes
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- What is a coma?
- What is the Glasgow Coma Scale?
- What are the causes of a coma?
- Bleeding (hemorrhage)
- Epidural, subdural, and subarachnoid hemorrhages
- Lack of Oxygen
- Hypoglycemic coma
- How is coma diagnosed?
- What tests help diagnose coma?
- What is the prognosis for coma?
How is coma diagnosed?
When a patient presents in coma, diagnosis and treatment begin simultaneously. Initial treatment is aimed at addressing immediate life-threatening issues:
- Are the ABCs intact? Is the patient's airway open? Are they breathing? Do they have good circulation (a heartbeat and blood pressure)?
- Is the patient hypoglycemic? The blood sugar can be checked quickly by a quick fingerstick bedside test and if it is low, glucose can be administered in the mouth or intravenously. Patients with diabetes also may have a Glucagon injection kit at home that can be administered to rescue them from diabetic coma.
- Did the patient ingest a narcotic? Naloxone (Narcan) may be given intravenously to reverse an overdose situation.
History remains the important key to the diagnosis. Since the patient cannot be the source of information, questions are asked of family, friends, bystanders, and rescue personnel. For example, imagine a person sitting at a bar who falls down, hits his head and is in a coma. While it might be easy to jump to the conclusion that he was intoxicated, fell, and bled in his brain, other scenarios need to be considered. Did he have a heart attack, did he suffer a stroke, or was this perhaps a diabetic medication reaction that resulted in low blood sugar?
Once the patient has been stabilized with acceptable vital signs, a more complete physical examination will likely include a complete neurologic assessment. Examination of the eyes including the pupils and the interior of the eye where blood vessels and nerves enter the globe (fundi), facial movements to assess cranial nerves including gag reflex, extremity movement and reaction to stimulation, tendon reflexes and other testing of spinal cord function. There is special attention paid to symmetry in the neurology exam, since lack of movement or response on one side of the body may be caused by bleeding inside the skull or by stroke.
Pupil size and response to light are commonly assessed. If a pupil is widely dilated, it is either because of direct trauma to the eye or more ominously, it is a pre-death event where the brain is herniating because of increased intracranial pressure. Unequal pupil size (anisocoria) is a common occurrence as a normal variant in 10% of the population. A dilated pupil in a fully awake patient is not usually a sign of raised pressure within the brain.
The Glasgow Coma Scale score will be documented; the deeper the coma, the lower the score. Please appreciate that a person with a "normal" Glasgow Coma Scale of 15 may still have altered mental status. Repeated neurologic assessment is key to monitoring the status of the patient and determining if the coma is improving, worsening or remaining stable.
What tests help diagnose coma?
The tests required to evaluate a coma will depend upon the suspected cause. Many times, the cause involves many factors and the sequence of events will require serious detective work. Blood tests, electrocardiogram and CT scan of the head are most often obtained. Further test options depend upon the patient's situation.