Incense Caused This Child’s Seizures

A young girl experienced a rare case of pediatric seizures following repeated exposure to incense sticks burned at home.

The patient was diagnosed with chronic salicylate intoxication, which in children can “present subtly yet carry life-threatening consequences,” ranging from seizures and brain swelling to severe acid-base imbalance and organ dysfunction, as Priyanka Shekhawat, MD, of a Mass General Brigham facility in Dover, New Hampshire, and colleagues wrote in the American Journal of Case Reports.

“However, with timely treatment, outcomes are often good,” Shekhawat told MedPage Today.

Salicylates are compounds derived from salicylic acid that are found in a range of over-the-counter and prescription medications, including aspirin, topical analgesics, keratolytic agents, and certain medicinal oils.

From the 1950s to the 1970s, salicylate intoxication was the number one cause of poisoning death for children. Regulatory changes, including a reduction in the concentration of aspirin per pill and child-resistant packaging, helped curb cases. Declining aspirin use in children due to its association with Reye’s syndrome also helped bring down incidence. However, household products, such as scented candles and incense sticks, remain a potential source of exposure.

In this case, a home investigation revealed that the child had been regularly exposed to fumes from incense sticks containing 10% to 20% salicylates, which appeared to be the likely source of chronic intoxication, as no other possible sources were found. The gradual exposure might have built up a reservoir in the central nervous system tissue over time, leading to more intense symptoms than might be expected from any single exposure, Shekhawat said.

Toxicology tests that include salicylates are standard when a child comes to an emergency department with new-onset seizures. However, when there’s no identifiable salicylate source, it’s important for clinicians to also consider inhalation as a route of exposure, Shekhawat said.

“We always think of accidental causes,” such as whether a child might have swallowed a pill, “but could it be something that’s just in the air?” Shekhawat asked.

The 3-year old girl was brought to the emergency department after her first non-febrile, generalized tonic-clonic seizure. The child showed no signs of ill health until her mother noticed the onset of a generalized seizure, involving shaking in both arms and a “fixed forward gaze” that lasted about 5 minutes. The child was not foaming at the mouth and did not experience urinary or fecal incontinence or head trauma, the authors noted.

She vomited in the ambulance while driving to the hospital.

In the emergency department, examination showed her vitals to be stable, with temperature and respiratory rate in the normal range. The girl was initially drowsy but became alert after her mouth was examined. Overall, the physical exam was unremarkable, with normal muscle tone, reflexes, and Babinski sign. She showed no truncal ataxia or signs of meningitis.

The girl’s initial serum salicylate concentration was 19 mg/dL, which fell to 17 mg/dL following a second test 5 hours later. While that was within the 10-30 mg/dL range expected when aspirin is intentionally used, “chronic salicylate toxicity may occur despite serum levels within or below this range, particularly with ongoing exposure,” the researchers wrote. “This is because, in chronic salicylate exposure, serum salicylate concentrations do not reliably reflect total body burden or central nervous system penetration.”

After finding salicylates in the blood, the team suspected a clinical correlation. And finding both respiratory alkalosis and metabolic acidosis on arterial blood gas analysis, “you think ‘Absolutely, this whole picture together totally makes sense,'” Shekhawat said.

“Salicylate toxicity characteristically produces a mixed acid-base picture, where the patient is hyperventilating (causing alkalosis) while the toxin simultaneously causes metabolic acid buildup (causing acidosis),” she added by email.

While in the pediatric ICU, the girl had two more seizures and was given fosphenytoin (Cerebyx). The parents said their daughter had no history of head injury or prior illness and had not been exposed to any toxins. The girl was also meeting her developmental milestones, was able to speak in full sentences, and was up to date on her immunizations. Electroencephalography and MRI of the child’s brain showed no abnormalities.

A diagnosis of exclusion was arrived on after ruling out febrile seizures, epilepsy, meningitis, and other potential causes. However, Shekhawat stressed that no definitive causal relationship to incense could be established.

Poison control was alerted by the team. After stopping incense use and counseling the parents, the girl continued to be seizure-free and showed normal development on follow up.

“All salicylate-containing products should include clear and standardized warning labels,” wrote Shekhawat and colleagues, adding that “a detailed environmental history including prolonged incense use in enclosed spaces should be considered in any child presenting with unexplained seizures with concurrent acid-base imbalance.”