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touching the eyelashes, and finally loss of blink with corneal touch. Both eyes
should be tested to detect asymmetry.
Limb movement and postural changes seen in comatose patients include the
bilateral restless movements of the limbs of patients in light coma. Unilateral
jerking muscular movements may indicate focal seizure activity or generalized
convulsions in a patient with hemiparesis. Decerebrate rigidity refers to stiff
extension of limbs with internal rotation of the arms and plantar flexion of the
feet. It is not a posture that is held constantly; it usually occurs intermittently in
patients with midbrain compression, cerebellar lesions, or metabolic disorders.
Decorticate rigidity, when arms are held in flexion and adduction and legs are
extended, indicates CNS dysfunction at a higher anatomic level, usually in
cerebral white matter or internal capsule and thalamus. Signs of meningeal
irritation include Kernig sign, resistance to bent knee extension with the hip in 90
degrees flexion, and Brudzinski sign, involuntary knee and hip flexion with
passive neck flexion. In infants, meningeal irritation may be manifest as
paradoxic irritability, in which picking up the baby to soothe results in pain and
worsening crying.
The abnormal breathing pattern most commonly seen in comatose patients is
Cheyne–Stokes respirations, where intervals of waxing and waning hyperpnea
alternate with short periods of apnea. Other abnormal breathing patterns that
occur with brainstem lesions include central neurogenic hyperventilation, which
can produce respiratory alkalosis, and apneustic breathing, in which a 2- to 3second pause occurs during each full inspiration.

Laboratory and Radiologic Studies
Immediate bedside glucose, sodium, blood gas, and hemoglobin determination
should be performed on every patient with nontraumatic ALOC. Other laboratory
tests indicated for evaluation of coma in the absence of trauma include
electrolytes, blood urea nitrogen, creatinine, blood gas, hemoglobin, hematocrit,
osmolality, ammonia, and antiepileptic levels. Toxicologic screening of both
blood and urine should be obtained in patients with ALOC of unknown origin. A
noncontrast CT scan of the brain can reveal many causes of coma, such as

cerebral edema, hydrocephalus, malignancy, hematomas, and abscesses.
Infarction, thrombosis, and inflammatory conditions may require the addition of
contrast or the use of magnetic resonance imaging.

Vital Sign Abnormalities
Evaluation and treatment of airway, breathing, and circulatory compromise
always take precedence in the child with ALOC. Both airway patency and