What are the medical consequences of inhalant abuse?

I nhalant abusers risk an array of devastating medical consequences. Prolonged sniffing of the highly concentrated chemicals in solvents or aerosol sprays can induce irregular and rapid heart rhythms and lead to heart failure and death within minutes of a session of prolonged sniffing. This syndrome, known as "sudden sniffing death," can result from a single session of inhalant use by an otherwise healthy young person. Sudden sniffing death is particularly associated with the abuse of butane, propane, and chemicals in aerosols. Inhalant abuse also can cause death by:

•  Asphyxiation - from repeated inhalations, which lead to high concentrations of inhaled fumes displacing the available oxygen in the lungs;

•  Suffocation - from blocking air from entering the lungs when inhaling fumes from a plastic bag placed over the head;

•  Convulsions or Seizures - caused by abnormal electrical discharges in the brain;

•  Coma - the brain shuts down all but the most vital functions;

•  Choking - from inhalation of vomit after inhalant use; or

•  Fatal injury - from accidents, including motor vehicle fatalities, suffered while intoxicated.

Animal and human research shows that most inhalants are extremely toxic. Perhaps the most significant toxic effect of chronic exposure to inhalants is widespread and long-lasting damage to the brain and other parts of the nervous system. For example, both animal research and human pathological studies indicate that chronic abuse of volatile solvents such as toluene damages the protective sheath around certain nerve fibers in the brain and peripheral nervous system. This extensive destruction of nerve fibers is clinically similar to that seen with neurological diseases such as multiple sclerosis.

The neurotoxic effects of prolonged inhalant abuse include neurological syndromes that reflect damage to parts of the brain involved in controlling cognition, movement, vision, and hearing. Cognitive abnormalities can range from mild impairment to severe dementia. Other effects can include difficulty coordinating movement, spasticity, and loss of feeling, hearing, and vision.

Inhalants also are highly toxic to other organs. Chronic exposure can produce significant damage to the heart, lungs, liver, and kidneys. Although some inhalant-induced damage to the nervous and other organ systems may be at least partially reversible when inhalant abuse is stopped, many syndromes caused by repeated or prolonged abuse are irreversible.

Abuse of inhalants during pregnancy also may place infants and children at increased risk of developmental harm. Animal studies designed to simulate human patterns of inhalant abuse suggest that prenatal exposure to toluene or trichlorethylene (TCE) can result in reduced birth weights, occasional skeletal abnormalities, and delayed neurobehavioral development. A number of case reports note abnormalities in newborns of mothers who chronically abuse solvents, and there is evidence of subsequent developmental impairment in some of these children. However, no wellcontrolled, prospective study of the effects of prenatal exposure to inhalants in humans has been conducted, and it is not possible to link prenatal exposure to a specific chemical to a specific birth defect or developmental problem.