A clinician may need to deal with two scenarios when evaluating a patient with loss of consciousness. In the first scenario, the patient is unconscious and will fully and spontaneously regain consciousness in a brief time, often without intervention, which in retrospect is syncope. In the second scenario, the patient is unconscious, and will remain unconscious until intervention, or will regain conscious without full recovery, which is prolonged loss of consciousness. Because of the clinical overlap with syncope, portions of this clinical mind map include differentials for syncope. However, these portions are applicable only in retrospect, and therefore any case of loss of consciousness must be treated as a case of prolonged loss of consciousness, instead of syncope, which requires full intervention until proven otherwise.
Differentials which usually lead to prolonged loss of consciousness are basically failure of the organ system from which the pathology arises. This damage has to be extensive enough to disrupt the reticular activating system, which maintains consciousness. If the damage is not extensive, a patient may not become unconscious. For example, most patients with myocardial infarction, arrhythmias, stroke, fluid loss, or diabetic ketoacidosis do not become unconscious, but if the damage is extensive, the loss of consciousness will occur at some point in the process. A clinician must keep these phenomena in mind, and quickly review the initial stabilization of the patient, the past medical history, recent medical events, medications, and drug use to weigh differentials and remove anchor bias.
All of this information is listed next to the differentials on the clinical mind map. Because loss of consciousness is an urgent situation, patient stabilization comes first, followed by pursuit of any information which might give a clue to the underlying pathology. Since a clinician cannot ask high yield questions or medium yield questions from the patient, information is gathered rather randomly while stabilization and intervention are taking place.
One of the differentials in this clinical mind map is neurologic causes. Among these, if cerebrovascular accident is a cause of the loss of consciousness, a clinician has an opportunity to apply knowledge from a variety of areas in the basic sciences, such as neuroanatomy and physiology. The rule of 4 is described in this clinical mind map to help with linkage of clinical features with the location of the lesion. In practice, most patients will quickly receive neuroimaging, and the location and type of lesion will be discovered.