1. Emergency evaluation.
    1. Establish airway
    2. Blood pressure. - If hypotension is present, determine whether hemorrhage is present; if so, stem and replace lost blood volume. Severe hypertension should be treated by avoiding precipitous drops to hypotensive level.
    3. Temperature. - If febrile and head trauma and potentially associated cervical spine injury are not factors, chin should be flexed on chest to determine the presence of rigidity due to meningeal irritation (meningitis, meningoencephalitis). During chin-on-chest maneuver observe for knee and hip flexion (Brudzinski's sign), which when present confirms meningeal irritation.
    4. Observe and plapate for evidence of head trauma. - Evaluate tympanic membranes for presence of middle-ear blood (indicates skull fracture) and infection (suggests possible portal of entry for bacterial meningitis). If trauma is evident or suspected, manipullation of the neck should be minimized (head-neck-shoulders fixed with blocks or sandbags if possible) until cervical spine films rule out fracture or dislocation.
    5. Glucose level in blood. - This can be carried out in several minutes using dip-stick technique, confirmed later by more accurate laboratory analysis. After drawing blood, give 50 gm glucose intravenously to avoid any delay in treating possible hypoglycemia (along with 100mg of thiamine).
    6. Intravenous (5% dextrose in water) to be started with large-gauge needle also capable of delivering whole blood rapidly.
    7. Indwelling urinary catheter to be placed in the patient who is deeply stuporous or comatose.
    8. Consider administration of the opiate antagonist naloxone or the benzodiazepine antagonist flumazenil.
    9. History, if available from relatives, bystanders, or patient himself.
  2. Neurologic evaluation.
    1. Level of consciousness.
    2. Respiratory pattern.
    3. Pupil size and function
    4. Oculomotor-vestibular function.
    5. Motor function.
  3. Laboratory evaluation (as indicated by history, emergency, and neurologic evaluations) (see also chap. 23).
    1. Computerized axial tomography (CT scan) of cranium if available and indicated. Emergency indications include suspected trauma, stroke, or mass lesions.
    2. Cervical x-rays or CT scan if evidence or suspicion of head trauma.
    3. Blood chemistries. - Arterial: oxygen, carbon dioxide, pH; venous Na, Cl, K, bicarbonate, BUN, creatinine, Ca, Mg, liver function tests, drug screen.
    4. Urinalysis.
    5. Lumbar puncture. - Only indicated as an emergency in comatose patient if suspect CNS infection; otherwise contraindicated for fear of precipitation of rostrocaudal deterioration with supratentorial and occasionally subtentorial mass lesions.
    6. Electroencephalogram. - To aid in differentiating true coma (diffuse electric slowing) from hysterical coma (normal pattern). This is not an emergency procedure as a rule. However, if herpes simplex encephalitis is suspected, temporal lobe slowing may be seen before the CT scan or MRI are positive. For the patient with hysterical coma, the neurologic examination is adequate to make the distinction from true coma. The neurologic examination is adequate to make the distinction. Occasionally comatose patients with destruction of the reticular formation in the pons, midbrain, or lower diencephalon have a persistent alpha frequency (8-13 cps) background rhythm that normally is associated with an alert, sentient state. However, the alpha rhythms of normal individuals disappear on sensory stimulation, while those of "alpha coma" persist. The normal alpha pattern tends to be seen predominantly in the posterior cranial (occipital) leads, while in alpha coma the rhythm is diffusely present. Under any circumstance one should determine with utmost care the presence or absence of the "locked-in" state when an alpha pattern is present by evaluating vertical eye functions (see above and chap. 4) before assuming the presence of alpha coma.
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