Infantile Status Epilepticus and No Evident History of Exposure – Can it Still be Organophosphate Poisoning?

Abstract

To the Editor : Organophosphate poisoning (OPP) is rare during infancy and difficult to suspect when present with atypical presentation. A 4-mo-old, previously healthy baby girl was referred to us gasping in status epilepticus [multifocal seizures (first episode)] after receiving midazolam, phenytoin and mannitol from outside. There was no history of fever or abnormal birth events. She had hypotonia, depressed deep tendon reflexes, bilateral pinpoint pupils, normal anterior fontanelle and poor response to pain. She was treated as sepsis and ventilated. Her blood investigation, cranial imaging and CSF were normal. During monitoring, profuse oral, endotracheal secretions and sweating were noted. This along with miosis fitted into OPP. Atropine and Pralidoxime were started empirically. She improved with antidote therapy and was extubated on 6th day. Later OPP was confirmed with low pseudocholinesterase levels <1 kU/L (3.93-10.80). Possibility of OPP in this infant was remote due to 1) its uncommonness in this age group; 2) it rarely causes seizures (Moreover with excessive secretions and respiratory insufficiency hypoxia may be a cause of seizures) and most important; 3) absent history of exposure to the toxin. Younger children are prone to poisoning accidently due to their active and curious nature [1]. In new born, OPP can be explained by trans-placental acquisition of the chemical if mother ingests the compound during delivery [2]. During infancy homicidal attempt can be thought of, as female infanticide is common in north India. But such a history was unavailable. Moreover the secretion of these chemicals in breast milk is not known and future studies would be required to know if this can be the source of the chemical during infancy. Possible source of OPP may have been dermal contact with adult skin/clothes, floor as the father was a gardener and used to keep OP compounds at home. The presence of toxidrome of OPP like excessive secretions was disregarded initially as excessive salivation can be associated with seizure. This later on along with miosis and low heart rate made the basis of our suspicion. Further, absence of fever propelled us to think noninfectious causes of seizures. Though rarely, seizure can occur in OPP [3]. It is also possible that patient had muscle fasciculation and those were recorded as multifocal seizures but then these will not subside with antiepileptics. We recommend that full consideration should be given to the symptom constellation of OPP even in the absence of history of exposure as this is not uncommon and is fully treatable.

Sudden bilateral hearing loss after organophosphate inhalation

“…OP poisoning commonly occurs following ingestion, inhalation, and absorption of OP compounds4, 5 The most common mechanism of ototoxicity associated with OP poisoning is production of reactive oxygen species (ROS) 6 . OPs also affect acetylcholinesterase, whose function is to hydrolyze acetylcholine that most important neurotransmitter in the central and peripheral nervous systems 1, 2, 5…”