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Neurology – Coma
Whiteboard Animation Transcript
with Michel Shamy, MD, MA, FRCPC
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Coma is a state of unresponsiveness in which the patient cannot take in information from the environment and cannot respond to it in a meaningful way. In coma, the patient lies with eyes closed and cannot be aroused to respond appropriately to stimuli even with vigorous stimulation.
Coma is a clinical syndrome that can be produced by a many different pathologies. There are three key regions in the brain that may be affected to produce coma: the bilateral cerebral cortex, the thalamus, and the brainstem. The approach to the patient in coma involves 7 elements, which often proceed simultaneously.
1. Consider the ABCDs: Is the airway secure? A comatose patient may not be able to protect her own airway, and therefore may need to be intubated. High blood pressure and a low heart rate can point to elevated intracranial pressure. Always check the glucose!
2. Rule out mimics. Make sure the patient does not have “locked-in” syndrome by asking her to blink and move her eyes horizontally and vertically.
3. Try to localize the lesion through the history and examination. Is there evidence of involvement of the bilateral cerebral hemispheres, the thalamus or the brainstem? Examine for the response to pain and the brainstem reflexes.
4. Consider the potential etiologies based on your localization.
5. Order investigations to help you identify the cause of the coma. Obtain a CT scan of the brain as soon as possible. Blood work, ECG and EEG may also be helpful.
6. Are there steps you can take to reverse the state of coma? This will depend on the etiology. In the acute setting: naloxon, glucose and thiamine are sometimes given.
7. While you may be thinking about prognosis, do not rush to judgment until the patient has been stabilized, until you understand the clinical picture and you know the patient’s premorbid functional and medical status.
