Effects of Deliberate Ingestion of Organophosphate or Paraquat on Brain Stem Auditory-Evoked Potentials

Abstract

Organophosphate (OP) and paraquat (PQ) ingestion is a serious health problem. A common pathology behind OP or PQ poisoning is the generation of reactive oxygen species (ROS) which is known to cause ototoxicity. The aim of the study was to identify the effects of deliberate ingestion of OP or PQ on brain stem auditory-evoked potentials (BAEPs). Consecutive patients with deliberate self-poisoning with OP or PQ who were admitted to a secondary and a tertiary care hospital in the Southern province of Sri Lanka and matched controls were recruited. BAEPs were performed at 1 week (first assessment) and 6 weeks (second assessment) after the exposure. Interpeak latencies of I–III, III–V, and I–V were measured. There were 70 and 28 patients in the OP and PQ arms with the mean age of 32 ± 12 and 29 ± 12 years, respectively. There were 70 controls and their mean age was 33 ± 12 years. In OP and PQ poisoning, 53/70 and 18/28 came for the second assessment, respectively. The interpeak latency was not statistically different in the controls vs the first assessment, controls vs the second assessment, and the first vs the second assessment. There were no significant lesions in the auditory pathway in OP or PQ poisoned patients. The generation of ROS within the perilymphatic space following the ingestion of OP or PQ may not be sufficient to cause lesions in the auditory pathway. Further studies with the assessment of auditory threshold are needed.

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…”

“…Jayasinghe et al stated that there were no significant changes in brain stem auditory-evoked potentials in patients with acute suicidal exposure of OP 6 . They believed that even though this condition is associated with the generation of ROS within the perilymphatic space following the ingestion of OP, the auditory pathway is not sufficiently affected to result in lesions.…”

Effect of organophosphate insecticides on vestibulocochlear system

“…Aynı çalışmada SOD mimetiğinin PQ toksisitesine karşı tüy hücrelerini bütün derişimlerde hasardan koruduğunu ve bu bileşiğin peptid olmamasından dolayı beyin omuriliği sıvısı (BOS)'ndan geçme avantajına sahip olduğunu belirtmişlerdir. Jayasinghe ve Pathirana [14] intihar amaçlı OP ve PQ kullanan ve akut intoksikasyon şüphesi ile acil servise getirilen 98 hasta üzerinde yaptıkları çalışmada hastalara intoksikasyonun birinci gününde ve altıncı haftasında işitsel beyinsapı cevabı testi yapıp 1-3,3-5,1-5 interpeak latanslarda kontrol grubu ile anlamlı bir fark bulamamışlardır. Ancak çalışmada hastaların hangi dozda OP veya PQ aldığı ve hastaların semptomatik olup olmadığı hakkında bilgi verilmemiştir.…”

Construction and validation of an instrument to assess the reading comprehension of students from the third to the fifth grades of elementary school

“…However, when there is an accumulation of acetylcholine neurotransmitters, this situation could lead to acute intoxication by cholinesterase inhibition (6) . Another hypothesis is that the ototoxicity consequential of intoxication by organophosphates is the result of the genesis of reactive oxygen species (7) .…”