Assessing LOC involves determining an individual's response to external stimuli. Speed and accuracy of responses to questions and reactions to stimuli such as touch and pain are noted. Reflexes, such as the cough and gag reflexes, are also means of judging LOC. Once the<unk>  of consciousness is determined, clinicians seek clues for the cause of any alteration. Usually the first tests in the ER are pulse oximetry to determine if there is hypoxia, serum glucose<unk> s to rule out hypoglycemia. A urine drug screen may be sent. A CT head is very important to obtain to rule out bleed. In cases where meningitis is suspected, a lumbar puncture must be performed. A serum TSH is an important test to order. In select groups consider vitamin B12<unk> s. Checking serum ammonia is particularly advised in neonatal coma to discern inborn errors of metabolism. Differential diagnosis A lowered<unk>  of consciousness indicate a deficit in brain function.<unk>  of consciousness can be lowered when the brain receives insufficient oxygen (as occurs in hypoxia); insufficient blood (as occurs in shock, in children for example due to intussusception); or has an alteration in the brain's chemistry. Metabolic disorders such as diabetes mellitus and uremia can alter consciousness. Hypo- or hypernatremia (decreased and elevated<unk> s of sodium, respectively) as well as dehydration can also produce an<unk>  LOC. A pH outside of the range the brain can tolerate will also alter LOC. Exposure to drugs (e.g. alcohol) or toxins may also lower LOC, as may a core temperature that is too high or too low (hyperthermia or hypothermia). Increases in intracranial pressure (the pressure within the skull) can also cause<unk>  LOC. It can result from traumatic brain injury such as concussion. Stroke and intracranial hemorrhage are other causes. Infections of the central nervous system may also be associated with decreased LOC; for example, an<unk>  LOC is the most common symptom of encephalitis. Neoplasms within the intracranial cavity can also affect consciousness, as can epilepsy and post-seizure states. A decreased LOC can also result from a combination of factors. A concussion, which is a mild traumatic brain injury (MTBI) may result in decreased LOC.
Altered level of consciousness
Altered state of consciousness
Clouding of consciousness
Psychomotor agitation
Snatiation
Catalepsy
Mental distress
Transient loss of consciousness