particularly the brain and liver (see Chapter 97 Neurologic Emergencies ) An epidemiologic association exists between the disorder and an antecedent viral illness (including varicella) from which a patient is recovering Patients with Reye syndrome typically develop severe vomiting, followed by combative delirium that progresses to coma Cerebral edema, increased ICP, and central herniation may occur Miscellaneous Conditions Other causes of coma or ALOC in children are less easily categorized Children with intussusception, the most common cause of bowel obstruction in childhood, may present with significant apathy and lethargy As a result, they may be treated for dehydration, sepsis, or meningitis before the appropriate diagnosis is discovered CNS involvement in hemolytic uremic syndrome may produce a comatose state because of cerebral infarction, most commonly in the basal ganglia Breastfed infants of vegan mothers have presented in coma from severe vitamin B12 deficiency Children with adrenoleukodystrophy may present acutely with coma due to CNS neuron demyelination Psychiatric disorders may produce a true stuporous or catatonic state More commonly, neurologically intact behavioral health patients may appear unresponsive, and be remarkably successful at remaining immobile despite painful stimuli The nature of their illness may be discovered by a detailed neurologic examination Conscious patients will usually avoid hitting their face with a dropped arm, may resist eyelid opening, will raise their heart rate to auditory or painful stimuli, and will have intact deep tendon, oculovestibular, and oculocephalic reflexes EVALUATION AND DECISION An approach for the evaluation of pediatric patients presenting with coma is summarized in Figure 17.1 All patients need rapid assessment of their airway, breathing, and circulation, followed by a focused history, physical examination with careful neurologic evaluation, and consideration of laboratory and imaging studies This approach is based on the selective use of the following critical clinical and laboratory findings: (i) Vital signs; (ii) a history of recent head trauma, seizure activity, or ingestion; (iii) signs of increased ICP or focal neurologic abnormality; (iv) fever; (v) laboratory results; (vi) brain CT scan results; and (vii) CSF analysis The evaluation of the comatose patient should follow an orderly series of steps, addressing the more life-threatening problems of hypoxia, hypotension, or increased ICP before investigating less urgent disorders