First, be grateful. A patient in psychogenic coma is better than one who is angry and combative. Approach the patient incorrectly, and you can awaken the patient to a hostile alert state. Do a careful neurologic examination. Open the eyelids. If the eyes deviate upward and only the sclera show (Bell’s phenomenon), you should suspect psychogenic coma. When the eyelids are opened in a patient with true coma, the lids close slowly and incompletely. It is difficult to fake this movement. Lift the arm and drop it toward the face; if the face is avoided, this is most likely psychogenic coma. If this does not work, you may want to check some simple laboratory tests, including a Dextrostix. If the patient remains comatose, irritating but nonpainful stimuli, such as tickling the feel with a cotton swab, may elicit a response. Remember that this test is not a test of wills between you and the patient. There is no indication for repeated painful stimulation because it can make the patient angry and ruin attempts at therapeutic intervention.

If all else fails, perform cold caloric testing. The presence of nystagmus confirms the diagnosis of psychogenic coma.

Although CT scans have revolutionized the practice of neurology, they are not indicated in every comatose patient. A good history, physical examination, and a few simple laboratory tests are adequate in most cases seen in the Emergency room because drug and alcohol abuse are common. If a structural lesion is suspected, however, a CT scan should be ordered immediately. If the condition of a patient with a suspected metabolic coma worsens or does not improve after a period of observation, a CT scan should be obtained.

Obtain a rapid blood glucose (Dextrostix), and correct hypoglycemia if it is found. If alcohol intoxication is suspected, determine the alcohol level with either a Breathalyzer or serum blood alcohol. If the pupils are constricted or if narcotic ingestion is suspected, intravenous naloxone should be given. If hypoglycemia or alcohol intoxication is not found to be the cause of the patient’s confusion, further tests are warranted. A complete blood count, electrolytes, blood urea nitrogen, glucose, and oxygen saturation should be obtained. Toxicologic screens may be done in a patient with a suspected ingestion, but they are expensive and do not detect routinely every possible ingested substance. Liver function tests, ammonia level, calcium level, carboxyhemoglobin level, and thyroid function studies may be helpful in selected patients.

A cervical spine series must be obtained in any comatose patient with suspected trauma because physical examination is unreliable. A chest radiograph may be helpful if hypoxemia or pulmonary infection is suspected. Skull series are rarely indicated and have been supplanted by CT scan.

• If a confused patient is suspected of being postictal, look in the mouth. A tongue laceration supports the diagnosis of a seizure.
• Put on gloves and inspect the scalp. Occult trauma is often overlooked, and you may find a laceration or dried blood. An old scar on the scalp may tip you off to a posttraumatic seizure disorder.
• Do not be fooled by a positive blink test in a patient with suspected psychogenic coma. When you rapidly flick your hand at a comatose patient who has open eyes, air movement may stimulate a corneal reflex in a patient who is truly comatose.
• Do not be misled by the odor of alcohol. Alcohol has almost no detectable odor, which is why alcoholics drink vodka at work. Other spirited liquors such as brandy have a strong odor. The comatose executive who “smells drunk” may have had a sudden subarachnoid hemorrhage and spilled brandy on his shirt.

The eyes should be examined for position, reactivity, and reflexes. When the eyelids are opened, note the position of the eyes. If the eyes flutter upward, exposing only the sclera, suspect psychogenic coma. If the eyes exhibit bilateral roving movements that cross the midline, you know that the brainstem is intact. Pupil reactivity is the best test to differentiate metabolic coma from coma caused by a structural lesion because it is relatively resistant to metabolic insult and usually is preserved in a metabolic coma. Pupil reactivity may be subtle, necessitating use of a bright light in a dark room. Testing of the eye reflexes is the best method for determining the status of the brainstem
Two methods can be used:
(1) oculocephalic (doll’s eyes)
(2) oculovestibular (cold calorics)
Oculocephalic testing requires rapid twisting of the neck, which is a bad idea in the unconscious patient because occult cervical trauma may be present. Oculovestibular testing is easy to do and can be done without manipulating the neck. The ear canal is irrigated with 50 mL of ice water. A normal awake patient has two competing eye movements: rapid nystagmus away from the irrigated ear and slow tonic deviation toward the cold stimulus. Remember the mnemonic COWS (Cold Opposite, Warm Same), which refers to the direction of the fast component.A patient with psychogenic coma has normal reflexes and exhibits rapid nystagmus. A comatose patient with an intact brainstem lacks the nystagmus phase, and the eyes deviate slowly toward the irrigated ear. If the eyes do anything else (usually not a good sign), refer to Goetz to determine the location of the lesion (Goetz CG: Neurology. Philadelphia, W.B. Saunders, 1999).

Check the cardiac monitor. Bradycardia or arrhythmias can alter cerebral perfusion and cause altered sensorium. Carefully count respirations. Tachypnea may indicate the presence of hypoxemia or a metabolic acidosis, and diminished respiratory efforts may require assisted ventilation. Check the blood pressure. Do not assume that hypotension has a CNS cause. Look for hypovolemia or sepsis as a cause for hypotension, but remember that adults (in contrast to infants) cannot become hypovolemic from intracranial bleeding alone. Hypertension may be a result of increased intracranial pressure, but uncontrolled hypertension also may cause encephalopathy and coma. Do not forget to obtain the fifth vital sign–measurement of oxygen saturation with a pulse oximeter.