A 15-year-old boy is brought to the emergency department by his father, who found the patient unconscious on his bedroom floor. It is unclear how long the patient had been unconscious, but his father saw him walking upstairs 5 minutes before finding him. The patient's father was able to rouse him quickly, but the patient continued to feel drowsy and said he was dizzy. His speech was slurred, and he was unsteady on his feet. At the time of evaluation an hour later, the patient's symptoms have resolved, and he denies any knowledge of why he lost consciousness. The father shares that the patient has come home drunk on several occasions. Medical history is noncontributory. Temperature is 36.7 C (98 F), blood pressure is 100/60 mm Hg, and pulse is 70/min. The patient is alert and fully oriented. On physical examination, heart and lung sounds are normal. Sensation is decreased in bilateral lower extremities. Liver function tests are slightly elevated. ECG is normal. Intoxication with which of the following is the most likely cause of this patient's condition?
This adolescent's initial symptoms and physical findings are consistent with inhalant abuse. Commonly abused inhalants include glue, toluene, nitrous oxide ("whip-its"), amyl nitrite ("poppers"), and spray paints. Inhalants may be abused by sniffing, huffing (ie, inhaled from a saturated cloth), or bagging (ie, inhaled from a bag over mouth or nose) to concentrate the inhaled substance. Signs of acute intoxication vary depending on the chemicals inhaled and may include transient euphoria and loss of consciousness. Inhalants are highly lipid soluble and produce immediate effects that typically last 15-45 minutes. They act as central nervous system depressants and may cause death.
Other symptoms of inhalant abuse include nose bleeds, headaches, and dermatitis ("glue sniffer's rash") around the mouth or nostrils due to chemical exposure. Liver function tests may be elevated with repeated use. Chronic abuse of nitrous oxide is associated with vitamin B12 deficiency and resultant polyneuropathy, as seen in this patient. Boys age 14-17 are at highest risk for inhalant abuse. Abnormal odor on the breath or clothes and empty solvent bottles or gauze found in the trash are clues to use. However, when common household products are used, paraphernalia may not be found, making it difficult to detect.
(Choices A and B) Although this patient may have a history of alcohol use, substantial amounts of alcohol or benzodiazepines would be needed to cause loss of consciousness and would have resulted in a longer period of intoxication.
(Choice C) Cocaine is a central nervous system stimulant that typically produces increased arousal, psychomotor agitation, and increased heart rate and blood pressure, not the loss of consciousness, unsteadiness, and slurred speech seen in this patient.
(Choice D) Hallucinogen intoxication is associated with impaired coordination, and some hallucinogens have a short duration of action. However, hallucinogens are not expected to cause loss of consciousness and are accompanied by perceptual changes (eg, depersonalization, hallucinations), tachycardia, diaphoresis, and tremors, which are not seen in this patient.
(Choice F) Opioid intoxication can cause loss of consciousness; however, such a loss of consciousness would likely last longer than a few minutes and would not be associated with a rapid recovery.
Educational objective:
Inhalant abuse usually occurs in boys age 14-17, can involve one of several common household chemicals, and is characterized by rapid onset and short duration of intoxication, euphoria, and loss of consciousness. Chronic use can result in B12-related neuropathy and abnormal liver function tests.