Life-threatening organophosphate-induced delayed polyneuropathy in a child after accidental chlorpyrifos ingestion

Role of intravenous lipid emulsion therapy and packed red blood cell transfusion as adjuvant treatment in the management of a child with severe organophosphate poisoning (chlorpyrifos)

A previously well 3-year-old child presented with rapidly deteriorating clinical status minutes after ingestion of an orange-coloured liquid housed in a soda bottle (HomeTrek-chlorpyrifos). She had miotic pupils, copious oral secretions, crackles on lung auscultation, hyperactive bowel sounds, impending signs of respiratory failure and declining sensorium. A diagnosis of severe organophosphate (OP) toxicity was made. Despite resuscitation and atropine administration, she deteriorated and exhibited atropine toxicity. She was given 20% intravenous lipid emulsion therapy and red blood cell (RBC) transfusion as adjunctive therapy with favourable outcome. She was discharged after 11 days and her RBC cholinesterase levels were 45% and 17% below normal, taken on day 10 and day 35 postingestion, respectively. She showed no signs of intermediate syndrome and delayed polyneuropathy. This case highlights the need for timely recognition of severe OP poisoning, and the role of lipid emulsion therapy and packed RBC transfusion as adjunctive treatment.

A Review of Treatment of Bilateral Vocal Fold Movement Impairment

Purpose of Review

Bilateral vocal fold immobility is a challenging life-threatening problem involving multiple treatment options and nuanced clinical decision making. We aim to provide relevant background on the etiology, diagnosis, and management of bilateral vocal fold movement impairment (BVFMI).

Recent Findings

Over the last 20 years, the management of bilateral vocal fold immobility has advanced significantly with the addition of multiple endoscopic approaches as well as procedures with the goal of returning dynamic function to the larynx, among them: selective reinnervation. Chemodenervation has also demonstrated promising results as a temporizing procedure in appropriately selected patients with BVFMI.

Summary

Tracheostomy remains the mainstay of emergent treatment for airway obstruction secondary to bilateral vocal fold immobility. However, recent advances in endoscopic approaches allow for avoidance of tracheostomy in many patients. Developments in dynamic procedures with the aim of restoring laryngeal function allow for adequate airway management while maintaining voice quality and limiting aspiration risk.

Surgical Management of Bilateral Vocal Fold Paralysis in Children: A Systematic Review and Meta-analysis

OBJECTIVES

To examine and compare the outcomes of various types of glottic widening surgery (GWS) for initial management of bilateral vocal fold paralysis (BVFP) in children, the outcomes of different GWS procedures in children who underwent initial tracheostomy, and the rate of decannulation in children who underwent tracheostomy alone versus tracheostomy followed by GWS.

DATA SOURCES

PubMed, Web of Science, Cochrane Library, and Embase were searched following the PRISMA guidelines (Preferred Reporting Items for Systematic Reviews and Meta-analyses) on September 9, 2019, with no date restriction.

REVIEW METHODS

Articles focusing on GWS or tracheostomy for initial management of BVFP were included. Articles describing patients who received no surgical intervention for BVFP were excluded.

RESULTS

A total of 5989 articles were reviewed: 67 articles met inclusion criteria, and 240 patients were incorporated into the analysis. Patients who underwent primary GWS had an eventual tracheostomy rate of 6.0% (5/83). There were no statistically significant differences in the rate of tracheostomy, reoperation, or mortality among cricoid split, suture lateralization, and cordectomy/cordotomy. Patients who underwent primary tracheostomy failed to achieve decannulation in 36.9% (58/157) of cases. Decannulation was more likely in tracheostomized children who received GWS than those who did not (odds ratio, 6.336; P < .0001).

CONCLUSIONS

Most children who undergo primary GWS for BVFP avoid tracheostomy or reoperation. These data demonstrated no differences in surgical outcomes among the most common types of GWS for BVFP. For children who receive a tracheostomy as their first intervention for BVFP, GWS is associated with a significantly improved rate of decannulation.

Outcome of patients with chlorpyrifos intoxication

INTRODUCTION

There is a paucity of literature analyzing outcome of chlorpyrifos intoxication.

METHODS

A total of 40 patients with chlorpyrifos intoxication were seen at Chang Gung Memorial Hospital between 2008 and 2017. Patients were stratified into two subgroups according to their prognosis, as good (n = 12) or poor (n = 28). Good prognosis group were defined as patients who survived without serious complications, and poor prognosis group included patients who died and survived after development of severe complications. Demographic, clinical, laboratory, and mortality data were obtained for analysis.

RESULTS

Patients aged 53.8 ± 16.3 years and most were male (80.0%). All patients (100.0%) developed acute cholinergic crisis such as emesis (45.0%), respiratory failure (42.5%), tachycardia (30.0%), kidney injury (22.5%), and seizure (7.5%). Intermediate syndrome developed in 12.5% of patients, but none had delayed neuropathy (0%). The poor prognosis group suffered higher incidences of respiratory failure (p = 0.011), kidney injury (p = 0.026), and prolonged corrected QT interval (p = 0.000), and they had higher blood urea nitrogen level (p = 0.041), lower Glasgow coma scale score (p = 0.011), and lower monocyte count (p = 0.023) than good prognosis group. All patients were treated with atropine and pralidoxime therapy, but six patients (15.0%) still died of intoxication. In a multivariate logistic regression model, blood urea nitrogen was a significant risk factor for poor prognosis (odds ratio: 1.375, 95% confidence interval: 1.001-1.889, p = 0.049). Nevertheless, no mortality risk factor could be identified.

CONCLUSION

The mortality rate of patients with chlorpyrifos intoxication was 15.0%. Furthermore, acute cholinergic crisis, intermediate syndrome, and delayed neuropathy developed in 100.0%, 12.5%, and 0% of patients, respectively.

Organophosphate-Induced Delayed Polyneuropathy

Organophosphate-induced delayed polyneuropathy (OPIDP) is a rare toxicity resulting from exposure to certain organophosphorus (OP) esters. It is characterised by distal degeneration of some axons of both the peripheral and central nervous systems occurring 1-4 weeks after single or short-term exposures. Cramping muscle pain in the lower limbs, distal numbness and paraesthesiae occur, followed by progressive weakness, depression of deep tendon reflexes in the lower limbs and, in severe cases, in the upper limbs. Signs include high-stepping gait associated with bilateral foot drop and, in severe cases, quadriplegia with foot and wrist drop as well as pyramidal signs. In time, there might be significant recovery of the peripheral nerve function but, depending on the degree of pyramidal involvement, spastic ataxia may be a permanent outcome of severe OPIDP. Human and experimental data indicate that recovery is usually complete in the young. At onset, the electrophysiological changes include reduced amplitude of the compound muscle potential, increased distal latencies and normal or slightly reduced nerve conduction velocities. The progression of the disease, usually over a few days, may lead to non-excitability of the nerve with electromyographical signs of denervation. Nerve biopsies have been performed in a few cases and showed axonal degeneration with secondary demyelination. Neuropathy target esterase (NTE) is thought to be the target of OPIDP initiation. The ratio of inhibitory powers for acetylcholinesterase and NTE represents the crucial guideline for the aetiological attribution of OP-induced peripheral neuropathy. In fact, pre-marketing toxicity testing in animals selects OP insecticides with cholinergic toxicity potential much higher than that to result in OPIDP. Therefore, OPIDP may develop only after very large exposures to insecticides, causing severe cholinergic toxicity. However, this was not the case with certain triaryl phosphates that were not used as insecticides but as hydraulic fluids, lubricants and plasticisers and do not result in cholinergic toxicity. Several thousand cases of OPIDP as a result of exposure to tri-ortho-cresyl phosphate have been reported, whereas the number of cases of OPIDP as a result of OP insecticide poisoning is much lower. In this article, we mainly discuss OP pesticide poisoning, particularly when caused by chlorpyrifos, dichlorvos, isofenphos, methamidophos, mipafox, trichlorfon, trichlornat, phosphamidon/mevinphos and by certain carbamates. We also discuss case reports where neuropathies were not convincingly attributed to fenthion, malathion, omethoate/dimethoate, parathion and merphos. Finally, several observational studies on long-term, low-level exposures to OPs that sometimes reported mild, inconsistent and unexplained changes of unclear significance in peripheral nerves are briefly discussed.

Late onset polyneuropathy due to organophosphate (DDVP) intoxication

BACKGROUND

Organophosphate intoxication can cause some well-known life threatening acute neurological complications such as seizures, paralysis, neuromuscular and cardiac conduction disorders. Less often, a predominantly motor and delayed axonal neuropathy can occur. This syndrome is due to inhibition of neuropathy target esterase.

CASE REPORT

A 30-year-old woman attempted suicide by drinking approximately 1,000mg/kg dimethyl-2,2-dichloro vinyl phosphate (DDVP). After a muscarinic and cholinergic syndrome lasting four days, she developed a purely motor distal axonal polyneuropathy on the fifth week after ingestion confirmed by electroneuromyography and sural nerve biopsy. Neurological examination and electroneuromyography revealed a slight recovery at the end of the 21st month.

CONCLUSION

This case of late onset polyneuropathy caused by organophosphate intoxication had unusual features such as intact sensory nerves and worse prognosis when compared to previously reported cases.

Onset of grip- and pinch-strength impairment after acute poisonings with organophosphate insecticides

The course of organophosphate-induced delayed polyneuropathy (OPIDP) in humans has not been quantitatively measured in epidemiologic studies. This study evaluated the association of acute OP poisonings with motor neurologic impairment. Hand grip and pinch strength were evaluated among 62 Nicaraguan men hospitalized for acute OP poisoning between 1992 and 1996; 39 cattle ranchers and fishermen who had never experienced pesticide poisoning were controls. Exposure categories were moderate and severe poisonings with neuropathic and non-neuropathic OPs. Strength was measured at hospital discharge and seven weeks after poisoning. Grip and pinch strength were impaired among all OP-poisoned subjects at both examinations, more noticeably among those poisoned with OPs with suspected neuropathic effects, methamidophos and chlorpyrifos. In those with severe poisonings with neuropathic OPs, impairments were more marked among intentional than among occupational poisonings. The performances of suicidal subjects worsened at the second examination, consistent with OPIDP. Early motor impairment at the time of hospital discharge is consistent with cholinergic depolarization blockade after acute poisoning. The persistence of deficits in motor strength in all severely poisoned patients regardless of pesticide type was unexpected, and may reflect persistent cholinergic blockade or intermediate syndrome, neuropathy, or a combination of these.

Evaluation of acute sensory--motor effects and test sensitivity using termiticide workers exposed to chlorpyrifos

Sensory and motor testing was performed on a group of termiticide workers primarily using chlorpyrifos-containing products to evaluate both the acute effects from current exposure and sensitivity of the measures to detect effects. The study group comprised 106 applicators and 52 nonexposed participants. Current exposure was measured by urinary concentrations of 3,5,6-trichloro-2-pyridinol (TCP) collected the morning of testing. The mean TCP value for the 106 applicators was 200 microg/g creatinine. Participants received 4--5 h of testing and were evaluated using a sensory--motor test battery recommended by a National Institute for Occupational Safety and Health (NIOSH)-sponsored advisory panel to be appropriate for testing effects from pesticide exposures. Measurements testing olfactory dysfunction, visual acuity, contrast sensitivity, color vision, vibrotactile sensitivity, tremor, manual dexterity, eye--hand coordination, and postural stability were analyzed. Study results indicated limited acute effects from exposure to chlorpyrifos using urinary TCP as a measure of current exposure. The effects occurred primarily on measures of postural sway in the eyes closed and soft-surface conditions, which suggests a possible subclinical effect involving the proprioceptive and vestibular systems. Several other tests of motor and sensory functions did not show any evidence of acute exposure effects, although statistically significant effects of urinary TCP on the Lanthony color vision test scores and one contrast sensitivity test score were found. The visual measures, however, were not significant when a step-down Bonferroni correction was applied. Information also is presented on the sensitivity of the measures to detect effects in an occupationally exposed population using standard error of the parameter estimates.

Vocal cord paralysis in infants and children

Vocal cord paralysis is the second most common cause of neonatal stridor. Recognition of laryngeal paralysis warrants further evaluation for an underlying etiology as it is frequently a manifestation of a multisystem anomaly. Initial intervention must concentrate on airway stabilization and treatment of any underlying conditions. Management strategies should be individualized and focus on maintenance of a safe and stable airway, acquisition of intelligible speech, and deglutition without aspiration.

Bilateral vocal cord paralysis following anterior cervical discectomy and fusion. Case report

The authors report a rare case of bilateral vocal cord paralysis following anterior cervical discectomy and fusion (ACD/F) in a patient who had a preexisting, clinically silent, and unrecognized unilateral vocal cord paralysis from a remote cardiac surgical procedure. The patient, a 41-year-old woman who developed acute respiratory stridor and respiratory insufficiency at the time of extubation after undergoing a C6-7 ACD/F, required emergency reintubation and ventilation. Otolaryngological evaluation revealed bilateral vocal cord paralysis with one vocal cord showing evidence of acute paralysis and the other showing evidence of chronic paralysis. She eventually required a permanent tracheotomy. The patient had undergone previous cardiac surgical procedures to correct Fallot's tetralogy as a neonate and as a child. At those times, there were no recognized symptoms of transient or permanent vocal cord dysfunction. This case emphasizes the importance of identifying patients with preexisting unilateral vocal cord paralysis before performing neurosurgical procedures such as ACD/F, which can place the only functioning vocal cord at risk for paralysis. Guidelines for identifying patients with preexisting unilateral vocal cord paralysis and for modifying the surgical procedure for ACD/F to prevent the catastrophic complication of bilateral vocal cord paralysis are discussed.

Update of the morbidity experience of employees potentially exposed to chlorpyrifos

OBJECTIVES

Chlorpyrifos, an organophosphate ingredient of several important insecticides, has been manufactured at The Dow Chemical Company for 25 years. A previous morbidity study among employees of The Dow Chemical Company found no increased prevalence of illness or symptoms among employees potentially exposed to chlorpyrifos from 1977 to 1985 compared with matched controls. The purpose of the current study was to update the original study to 1994, thereby increasing the statistical power.

METHODS

In the present study, 496 potentially exposed subjects were identified and matched for age, race, sex, pay, and year of hire to 911 control subjects. Morbidity data were abstracted from company medical records.

RESULTS

The prevalence of peripheral neuropathy was not significantly increased among this group of employees potentially exposed to chlorpyrifos. Significantly increased prevalence odds ratios were identified for five diagnostic categories: diseases of the ear and mastoid process; acute respiratory infections; other diseases of the respiratory system; general symptoms, signs, and ill defined conditions; and symptoms, signs, and ill defined conditions involving the digestive system. There was a strong association of diagnosis with duration of observation period, indicating that the exposed workers were more likely than unexposed workers to have a diagnosis abstracted from the company medical records due to their longer mean period of follow up. Analyses by exposure classification and mean plasma cholinesterase activity did not show a dose response.

CONCLUSIONS

These data do not support a cause and effect relation of the diagnoses mentioned and exposure to chlorpyrifos.

Laryngeal paralysis in organophosphorous poisoning

Organophosphorous poisoning causing isolated laryngeal paralysis has only been rarely reported before. We describe a case of difficult extubation in a patient with organophosphorous poisoning, the cause of which was found to be bilateral vocal fold palsy. This is a type of intermediate paralysis that recovers with time. Such a condition should be thought of as a cause of dyspnoea or difficult extubation in patients with organophosphorous poisoning.

Assessment of the neurotoxic potential of chlorpyrifos relative to other organophosphorus compounds: a critical review of the literature

Chlorpyrifos (diethyl 3,5,6-trichloro-2-pyridyl phosphorothionate) is a broad-spectrum organophosphorus (OP) insecticide. Anticipated increases in the already extensive use of this compound have prompted this reassessment of its neurotoxicity. Because chlorpyrifos and other OP insecticides are designed to produce acute cholinergic effects through inhibition of acetylcholinesterase (AChE) and some OP compounds can cause OP compound-induced delayed neurotoxicity (OPIDN) via chemical modification of neurotoxic esterase (neuropathy target esterase, NTE), this review focuses on the capacity of chlorpyrifos to precipitate these and other adverse neurological consequences. Chlorpyrifos exhibits only moderate acute toxicity in many mammalian species, due largely to detoxification of the active metabolite, chlorpyrifos oxon, by A-esterases. Rats given large doses of chlorpyrifos (sc in oil) have prolonged inhibition of brain AChE, possibly due to slow release of the parent compound from a depot. Associated cognitive and motor deficits return to normal well before recovery of AChE activity and muscarinic receptor down-regulation, as expected from classic tolerance. Controlled studies of OP compound exposures in humans also indicate that cognitive dysfunction requires substantial AChE inhibition. Information is relatively sparse on neurological dysfunction that is secondary to theoretical reproductive, developmental, or immunological effects, but the best available data indicate that such effects are unlikely to result from exposures to chlorpyrifos. In accord with the much greater inhibitory potency of chlorpyrifos oxon for AChE than for NTE, clinical reports and experimental studies indicate that OPIDN from acute exposures to chlorpyrifos requires doses well in excess of the LD50, even when followed by repeated doses of the OPIDN potentiator phenylmethanesulfonyl fluoride (PMSF). Likewise, studies in hens show that subchronic exposures at the maximum tolerated daily dose do not result in OPIDN. Although exposure to chlorpyrifos as a result of normal use is unlikely to produce classical OPIDN, a recent report stated that mild reversible sensory neuropathy had occurred in eight patients who had been exposed subchronically to unknown amounts of chlorpyrifos. It is not clear whether these cases represent an incorrect linkage of cause and effect, a newly disclosed reversible sensory component of OPIDN, or an entirely new phenomenon. The question of the potential for chlorpyrifos to cause this mild sensory neuropathy could be resolved by the use of quantitative tests of sensory function in animal experiments and/or prospective studies of humans with known exposures to chlorpyrifos.