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