A 4-year-old boy is brought to the emergency department by his parents due to fever, runny nose, cough, and unusual behavior. The boy has been at home for the past 3 days since his fever started; his parents note that he has become increasingly restless over the past 2 days, and yesterday he began making odd comments about his dog being in the room when the dog was clearly not there. Since he has been at home, the parents have treated his cold symptoms with over-the-counter nasal decongestants and antihistamines and humidified the air in his bedroom, without much benefit. Temperature is 38.3 C (101 F), blood pressure is 110/60 mm Hg, pulse is 100/min, and respirations are 26/min. Physical examination shows a slightly erythematous oropharynx with no exudate, clear nasal discharge, clear lung fields, and normal S1 and S2. The abdomen is soft and nontender. Neurologic examination is within normal limits. During the examination, the patient starts talking to something in the room, saying that he can see a "bunny sitting on the bed" with him and that "the animals have followed us to the hospital." Which of the following is the most likely explanation for this boy's visual hallucinations?

Question

A 4-year-old boy is brought to the emergency department by his parents due to fever, runny nose, cough, and unusual behavior.  The boy has been at home for the past 3 days since his fever started; his parents note that he has become increasingly restless over the past 2 days, and yesterday he began making odd comments about his dog being in the room when the dog was clearly not there.  Since he has been at home, the parents have treated his cold symptoms with over-the-counter nasal decongestants and antihistamines and humidified the air in his bedroom, without much benefit.  Temperature is 38.3 C (101 F), blood pressure is 110/60 mm Hg, pulse is 100/min, and respirations are 26/min.  Physical examination shows a slightly erythematous oropharynx with no exudate, clear nasal discharge, clear lung fields, and normal S1 and S2.  The abdomen is soft and nontender.  Neurologic examination is within normal limits.  During the examination, the patient starts talking to something in the room, saying that he can see a "bunny sitting on the bed" with him and that "the animals have followed us to the hospital."  Which of the following is the most likely explanation for this boy's visual hallucinations?

Quizplus · Accepted Answer

This previously well child has been receiving medication for his cold for the past 3 days, and his acute onset of hallucinations within that period is most likely due to a medication side effect. Over-the-counter antihistamines (eg, diphenhydramine, doxylamine) that decrease nasal discharge also have anticholinergic properties that can cause confusion and hallucinations. Alpha-adrenergic agents (eg, phenylephrine, pseudoephedrine) constrict blood vessels, decreasing nasal congestion; they can also result in agitation and psychosis via sympathomimetic properties. In addition, the cough suppressant dextromethorphan, which is an NMDA antagonist, can result in dissociative symptoms and hallucinations. Side effects of over-the-counter medications may be cumulative when used in combination or in excess of recommended doses. However, side effects may also be seen at prescribed doses in sensitive individuals. (Choices A and D) This child's symptoms (erythematous oropharynx, cough, runny nose) are consistent with a respiratory infection, not an infection of the brain parenchyma. He does not have other signs suggestive of encephalitis or a brain abscess, such as focal neurological deficits, seizures, or ataxia. (Choice B) Brief psychotic disorder is not diagnosed if psychotic symptoms are due to a medication/substance. (Choice C) Children often use imaginary friends to comfort themselves in times of stress. However, the acute onset of hallucinations following initiation of new medications is more likely a medication side effect, especially considering that the parents have reported this as unusual behavior for the child. (Choice E) Hyperpyrexia can cause delirium and hallucinations but is more commonly seen with higher fevers, usually >39.4 C (103 F). It would be unlikely with a low-grade fever of 38.3 C (101 F). (Choice G) Reye syndrome is characterized by hepatic failure, altered mental state, vomiting, seizures, and coma that develop a few days after the apparent resolution of a viral illness. The risk of Reye syndrome is increased by the use of salicylates. Educational objective: Over-the-counter cold and cough medications often contain ingredients that can have unwanted side effects, including confusion and hallucinations. These medications should be used cautiously in young children, with recommended doses not exceeded nor used in combination. References: Cold preparation use in young children after FDA warnings: do concerns still exist? (http://www.ncbi.nlm.nih.gov/pubmed/23539689) Self-medication for cough and the common cold: information needs of consumers. (http://www.ncbi.nlm.nih.gov/pubmed/26590496) Safety and efficacy of over-the-counter cough and cold medicines for use in children. (http://www.ncbi.nlm.nih.gov/pubmed/20001764)

A 4-Year-Old Boy Is Brought to the Emergency Department by His