The Spectrum of Intermediate Syndrome Following Acute Organophosphate Poisoning: A Prospective Cohort Study from Sri Lanka

Abstract

BackgroundIntermediate syndrome (IMS) is a major cause of death from respiratory failure following acute organophosphate poisoning. The objective of this study was to determine repetitive nerve stimulation (RNS) predictors of IMS that would assist in patient management and clinical research.Methods and FindingsSeventy-eight consenting symptomatic patients with organophosphate poisoning were assessed prospectively with daily physical examination and RNS. RNS was done on the right and left median and ulnar nerves at 1, 3, 10, 15, 20, and 30 Hz. The study was conducted as a prospective observational cohort study in the Central Province, Sri Lanka. IMS was diagnosed in ten out of 78 patients using a priori clinical diagnostic criteria, and five of them developed respiratory failure. All ten patients showed progressive RNS changes correlating with the severity of IMS. A decrement-increment was observed at intermediate and high frequencies preceding the onset of clinical signs of IMS. As the patient developed clinical signs of IMS, decrement-increment was progressively noted at low and intermediate frequencies and a combination of decrement-increment and repetitive fade or severe decrement was noted at high frequencies. Severe decrement preceded respiratory failure in four patients. Thirty patients developed forme fruste IMS with less severe weakness not progressing to respiratory failure whose RNS was characterized by decrement-increment or a combination of decrement-increment and repetitive fade but never severe decrements.ConclusionsCharacteristic changes in RNS, preceding the development of IMS, help to identify a subgroup of patients at high risk of developing respiratory failure. The forme fruste IMS with the characteristic early changes on RNS indicates that IMS is a spectrum disorder. RNS changes are objective and precede the diagnosis and complications of IMS. Thus they may be useful in clinical management and research.

Beyond the cholinergic crisis

“…Although it was recommended to calculate the changes in CMAP size between the first and the fourth or the fifth response of a train of stimuli (15) we took the second response as well, since Maselli et al (2004) and Jayawardana et al (2008) observed the maximum decrement at the second stimulus (27,31). The data set of the current study showed the maximum decrement either at the second or the third stimulus.…”

“…NMJ dysfunction has been demonstrated by fast repetitive nerve stimulation with OP poisoning before clinical recovery (27), but there is no evidence whether these changes persist over the long term.…”

Anaesthetic Management of a Ectopic Pregnancy Patient With Organophosphorous Poisoning

“…However, in some cases muscle paralysis occurs24 to 96 hours after OP ingestion (intermediate syndrome), and this weakness, characteristic of IMS, may lead to respiratory failure and death. [5] MECHANISM OF ACTION: (Irreversible binding and permanent enzyme inactivation (aging). The mechanism of action of OP compounds that has well been known for more than 70 years, is the inhibition of cholinesterase.…”

Can Galantamine Act as an Antidote for Organophosphate Poisoning? A Review

“…The neurodegeneration observed commonly in organophosphate toxicity in hippocampus, pyriform cortex and amygdala may cause these delayed cognitive effects. The increased level of ACh in the synaptic cleft for a long duration may also be considered as the reason for this syndrome [14,15] .…”