Childhood poisoning frequently presents with delirium, seizures, and decreased level of consciousness. Neurologists are often called upon to evaluate children with these presentations. As children age, distinct patterns of poisoning emerge. Ingestions in children under the age of 5 are almost always unintentional, the result of toddler exploratory behavior. As children enter adolescence, there is an increase in attempts at self-harm, as well as in the use of recreational drugs.
Many types of ingestion can be deceptively dangerous. It is, therefore, important to be aware of the signs of common and serious ingestions and to be able to treat dangerous ingestions appropriately. This article will focus on the common syndromes of poisoning and those toxins that may present with injury to, or symptoms referable to, the nervous system.
• Childhood poisoning is a common medical problem.
• Neurologic manifestations are a common result of toxic exposures.
• Important in diagnosis is the recognition of common toxidromes.
• Most laboratory investigation, including toxicologic screening, is of little value in diagnosing acute toxicity.
Historical note and terminology
Although medical attention on poisoning in the 20th century has focused on childhood poisoning, with the development of the Poison Information Center system, the new millennium has presented new challenges to toxicologists, pediatricians, and neurologists. Illicit drug availability, environmental exposures to well-known toxins like lead, and newer complex organic industrial compounds have made trauma from toxins a commonplace and urgent clinical dilemma.
The rise of the environmental movement in the 1960s, following publication of Rachael Carson’s Silent Spring, continued as the Consumer Product Safety Commission took on responsibility, and since then, a number of legislative acts have mandated compensation for exposure to various environmental toxins. Medical toxicologists became essential figures in the clinical management of both adults and children. The list of potential hazards has grown to include not only accidental and intentional self-exposures, but medical errors, chemical terrorism, gas disasters, warfare, occupational chemical mass exposures, radiation disasters, and mass food poisonings, as well. In addition, 2 new disciplines – toxicogenomics and nanotoxicology – have been developed. Toxicogenomics refers to the genetic susceptibilities that pertain to toxic substances (such as idiosyncratic drug reactions). Nanotoxicology is the toxicology of tiny particles usually smaller than 100 nanomillimeters. This refers particularly to the translocation of these tiny particles to new sensitive target sites such as the central nervous system and the bone marrow (65).
The impact of toxins of multiple origins has made the potential for neurologic dysfunction and disruption more commonplace and an important part of the differential diagnosis of most clinical neurologic symptoms in both children and adults.
Chemical and drug poisoning in children results in significant morbidity, mortality, and health care expenditure. Exposures in children represent more than half of the 2.4 million calls made to U.S. poison control centers annually (38). Children suffer more than 20 million nonfatal injuries annually at a cost of 7 million to the health care system (56).
The 2018 Annual Report of the American Association of Poison Control Centers reveals 2,530,238 calls made to 55 certified Poison Centers in the country which, in turn, made over 2.6 million follow-up calls. Total encounters showed a 2.96% decline from 2017, and health care facility (HCF) human exposure cases showed a slight decrease of 0.261%. Human exposures with less serious outcomes have decreased 2.33% per year since 2008, whereas those with serious outcomes (moderate, major, or death) have increased 4.45% per year since 2000. The top 5 substance classes most frequently involved in all human exposures were analgesics (10.8%), household cleaning substances (7.28%), cosmetics/personal care products (6.53%), sedatives/hypnotics/antipsychotics (5.54%), and antidepressants (5.22%). For those human exposures with more serious outcomes, sedative/hypnotics/antipsychotics exposures were the class that increased most rapidly, by 9.21% per year over the past 18 years. Antidepressant exposure increased most rapidly, by 7.02% per year, for cases with the most serious outcomes (19).
In 2018, there were 1354 total fatalities (excluding the outcome of “death, indirect”). The age distribution of reported fatalities showed an increase in deaths among children (less than 20 years old) compared to 2017, with 86 cases representing 6.35% of fatalities. Children less than or equal to 5 years old were involved in most exposures, but the deaths in this group comprised just 1.03% of the exposure-related fatalities. Sixty-five adolescent fatalities (13 to 19 years) were reported with documented reason for exposure, an increase of 42.2% from 2017. Fifty-six of these fatalities were intentional. Of note, the National Poison Data System (NPDA) statistical analyses indicate that adolescent suicide attempts by self-poisoning declined after 2000, reaching a low in 2010, before rapidly increasing through 2018, confirming a trend seen in other data sources (19).