Jiin Ger

Acetylcholinesterase Inhibition and the Extrapyramidal Syndrome: A Review of the Neurotoxicity of Organophosphate

Organophosphate poisonings are not uncommon, and are the leading cause of death in suicide patients in Taiwan. Acute cholinergic crisis caused by the inhibition of synaptic acetylcholinesterase is the major manifestation of organophosphate poisoning and may cause death within minutes. Delayed neurotoxicities include intermediate syndrome and delayed polyneuropathy have also been described. However, these symptoms may not characterize the complete picture of organophosphate poisoning. Among the 633 patients ever admitted to our hospital with organophosphate poisoning, three patients were found exhibiting impermanent neuromuscular dysfunction, including blepharoclonus, oculogyric crisis, intermittent dystonia, rigidity, and tremor, with two of them developing mask face, dyskinesia and akathisia later, following acute cholinergic crisis. The symptoms appeared within 4 days with the duration ranging from 25 days to 2 months. Other causes of the extrapyramidal syndrome noted on these patients have been excluded, and we consider the extrapyramidal syndrome a possible neurotoxic manifestation of organophosphate poisoning, which is transient, needs no treatment, and may be missed because of the critical condition, in a minority of patients. The mechanism remains to be identified, but may be related to the impediment of the function of acetylcholinesterase to modify nigrostriatal dopaminergic system, which is independent of hydrolyzing acetylcholine. More detailed observation for organophosphate poisoned patients and more studies for the biological functions of acetylcholinesterase including the influence on the nigrostriatal dopaminergic system are needed.

Prolonged Severe Withdrawal Symptoms After Acute-on-Chronic Baclofen Overdose

INTRODUCTION Baclofen is frequently used to treat muscle spasticity due to spinal cord injury and multiple sclerosis. Baclofen overdose can lead to coma, respiratory depression, hyporeflexia, and flaccidity. An abrupt decrease in the dose of baclofen due to surgery or a rapid tapering program may result in severe baclofen withdrawal syndrome manifesting hallucinations, delirium, seizures, and high fever. Severe baclofen withdrawal syndrome secondary to intentional overdose, however, has not received mention. CASE REPORT A 42-year-old male receiving chronic baclofen therapy, 20 mg/d, attempted suicide by ingesting at least 800 mg of baclofen. He was found in coma 2 hours postingestion with depressed respirations, areflexia, hypotonia, bradycardia, and hypotension. Treatment with intravenous fluids, atropine, dopamine, and hemodialysis was associated with restoration of consciousness within 2 days but disorientation, hallucinations, fever, delirium, hypotension, bradycardia, and coma developed during the following week. Baclofen withdrawal syndrome was not diagnosed until hospital day 9, when reinstitution of baclofen rapidly stabilized his condition. Oral overdosage of baclofen causes severe neurological and cardiovascular manifestations due to its GABA and dominant cholinergic effects. Severe baclofen withdrawal syndrome is manifest by neuropsychiatric manifestations and hemodynamic instability. Caution should be exercised after a baclofen overdose in patients receiving chronic baclofen therapy.

Acute Toxicities of Betel Nut: Rare but Probably Overlooked Events

Background: Betel nut chewing has long been a social habit in Taiwan and other Asian and tropical countries. It produces various autonomic and psychoneurologic effects including tachycardia, flushing, warmth, cholinergic activation, alertness, and euphoria. Although the oral carcinogenic effects are well known, data concerning its acute toxicity are few. To better understand the toxicity of betel nut, cases reported to the Taiwan Poison Control Center as probable or possible betel nut–related toxicity (January 1988–June 1998) were reviewed. In the 17 cases suitable for review (14 males, 3 females, age 21 to 60 years), the most common manifestations were tachycardia/palpitations ; tachypnea/dyspnea ; hypotension and sweating ; vomiting, dizziness, and chest discomfort ; abdominal colic, nausea, numbness, and coma ; and acute myocardial infarction and related manifestations . The reported quantity of betel nut used was low (1 to 6 nuts), except an extract of 100 betel nuts was used in 1 case and 66 chewed in another. Most cases recovered within 24 hours after the exposure. One patient developed probable acute myocardial infarction and ventricular fibrillation and died despite repeated cardiac defibrillation. Although betel nut chewing is widespread, significant toxicity as reported to a poison center is rare. Because most betel nut–related effects are transient and mild in nature, the incidence of such events is likely to be underreported. Nevertheless, betel nut chewing can produce significant cholinergic, neurological, cardiovascular, and gastrointestinal manifestations. It is possible that it may aggravate cardiac diseases in susceptible patients but this hypothesis must be further investigated. Treatment is symptomatic. With timely support, rapid and complete recovery is anticipated but a small risk of major complications cannot yet be discounted.

The Clinical Significance of Hyperamylasemia in Organophosphate Poisoning

OBJECTIVE Hyperamylasemia with a presumptive diagnosis of acute pancreatitis has been reported following organophosphate poisoning but there are no large-scale studies incorporating more specific diagnostic criteria. METHODS Retrospective review of the medical records of 159 patients with a diagnosis of organophosphate poisoning over 3 years. Serum amylase, pancreatic amylase, salivary amylase, lipase and cholinesterase levels, and the clinical manifestations were analyzed. RESULTS Serum amylase data was available for 121 of the 159 study patients. Hyperamylasemia (amylase > or = 360 U/L) was found in 44 patients (36%). Lipase was measured in 28 patients with hyperamylasemia; 9 of 28 had hyperlipasemia (lipase > or = 380 U/L). The finding of hyperamylasemia was closely related to clinical severity and presence of shock. A presumptive diagnosis of painless acute pancreatitis was diagnosed by hyperlipasemia associated with hyperamylasemia, clinical severity, serum LDH, and leukocyte counts. Two patients with presumptive pancreatitis died. Shock, coma, and hypoalbuminemia were the factors predicting fatality. CONCLUSIONS Hyperamylasemia is frequent in severe organophosphate poisoning. However, hyperamylasemia is not synonymous with acute pancreatitis and pancreatic amylase is not a reliable parameter in the diagnosis of organophosphate-induced pancreatitis due to its low sensitivity and specificity. Lipase assay is indicated in patients with hyperamylasemia for early diagnosis of pancreatitis. Proper image studies and even pathological examination are also needed to confirm the extent of pancreatic injury. With prompt diagnosis and appropriate treatment, a complete recovery can be anticipated unless the patient has otherwise unrelated complications.

Tetramethylammonium hydroxide poisoning

Introduction. Tetramethylammonium hydroxide (TMAH) is widely used as a developer or etchant in semiconductor and photoelectric industries. In addition to alkalinity-related chemical burn, dermal exposure to TMAH may also result in respiratory failure and/or sudden death. The latter toxic effect has been of great concern in Taiwan after the occurrence of three fatalities in recent years. To better understand the toxicity following dermal exposure to TMAH, we analyzed all cases with TMAH exposure reported to the Taiwan Poison Control Center (PCC-Taiwan). Case reports. In total, there were 13 cases of such exposure, including three patients who died after being exposed to 25% TMAH. A worker also developed severe effects manifesting muscle weakness, dyspnea, hyperglycemia, and chemical burn (28% of total body surface area) shortly after an accidental exposure to 2.38% TMAH. He received endotracheal intubation with assisted ventilation for 2 days and survived. Conclusion. Skin corrosive injury related to the alkalinity of TMAH and the ganglionic toxicity of tetramethylammonium ion might contribute to the clinical manifestations that occurred after dermal TMAH exposure. Thorough skin decontamination followed by prompt respiratory support should be the mainstay in the management of dermal TMAH exposure. Preventive strategies are warranted as well to decrease future occupational TMAH exposures.

Food Poisoning Due to Methamidophos-Contaminated Vegetables

Background: Organophosphate poisoning is well known for its characteristic symptoms and signs, but food poisoning caused by pesticide-contaminated food is seldom reported. Case Report: We report three incidents of food poisoning that resulted from exposure to the organophosphate insecticide methamidophos in vegetables. These outbreaks caused a cholinergic syndrome in 4 patients. The cholinergic overactivity led us to suspect organophosphate food poisoning. All patients recovered well following appropriate therapy. The clinical diagnosis of organophosphate poisoning was confirmed by reduced levels of erythrocytes and plasma cholinesterase and the presence of methamidophos in the vegetable leftovers. The implicated vegetables and levels of methamidophos were: Ipomoea batatas 255 ppm, Gynura bicolor 110 ppm, and red cabbage 26.3 ppm. Since methamidophos is normally applied to vegetables during planting, improper selection and/or overuse of pesticide or improper harvest times may explain the occurrence of these high residue levels of methamidophos.

Children poisoning in Taiwan

Poisoning is a well known cause of morbidity and mortality in children. In Taiwan, little information has been published regarding the status of pediatric poisoning exposures. To provide more information on pediatric poisoning exposures for the purpose of poison prevention, a retrospective study was designed and conducted to analyse the data of National Poison Centre (NPC), Taiwan. All telephone inquiries concerning poisoning exposures in those under 19 years of age, received by NPC-Taiwan from July 1985 through December 1993, were included in this study. The age, sex, reason for exposure, route of exposure, substances involved and clinical outcome of those telephone calls were then analyzed. A total of 5,812 inquiries concerning poisoning exposures in children were recorded. Male exposures were more prevalent than females (59%)Vs. 41%) Accidental exposures accounted for 77.7% of the cases and most were exposed by the oral route. Substances most frequently ingested were household products, benzodiazepines and pesticides. The data revealed a mortality rate of 1.4%.Accidental poisoning exposures from household products and drugs remain a significant problem for those younger than 6 years of age. Further education of parents and care takers and the employment of child-resistant containers are needed to prevent cases of pediatric poisoning. Reduction of amphetamine abuse in adolescents is also of major concern and deserves more attention.

Acute human Glufosinate-containing herbicide poisoning

Abstract Background. Glufosinate-containing herbicides are commonly used worldwide. Data on acute human glufosinate poisoning however remain scarce. Methods. We retrospectively reviewed the medical records of all glufosinate poisoned cases reported to the Taiwan National Poison Control Center and two medical centers in Taiwan from August 1993 through February 2010. Their demographic and clinical data were then analyzed to identify potential predictors of severe effects following acute glufosinate poisoning. Results. One hundred and thirty-one patients, including 115 oral and 16 non-oral exposures, were eligible for final analysis. Among patients with oral exposure, 25 were asymptomatic, while the others developed gastrointestinal, neurological, cardiovascular, and/or respiratory manifestations. Seven patients (6.1%) died following deliberate glufosinate ingestion. The median dose of glufosinate ingestion was 30.4 grams (interquartile range 18.5–45.6 grams) in the severe/fatal group compared to 6.8 grams (interquartile range 3.7–16.2 grams) in the non-severe group (p <0.001). Older age (≥61 years; adjusted OR 4.9, 95% CI 1.3–17.9) and larger amount of glufosinate ingestion (≥13.9 grams; adjusted OR 25.2, 95% CI 4.8–132.5) were positively associated with the development of severe toxicity, whereas ethanol consumption (adjusted OR 0.1, 95% CI <0.1–0.5) was inversely associated with the risk of severe toxicity. Conclusion. Although glufosinate is generally thought to be of low toxicity to humans, severe effects can occur and may be associated with older age, larger amount of ingestion and absence of concomitant ethanol consumption.

Acute Severe Chromium Poisoning After Dermal Exposure to Hexavalent Chromium

Severe acute chromium poisoning related to dermal involvement has rarely been reported in the literature. We report a case of acute severe chromium poisoning through skin exposure as a result of a chemical burn of 15% of the body surface area and multiple organ failure after short-term exposure. Medical interventions, including mechanical ventilation, continuous venovenous hemofiltration, and plasmapheresis were performed. In addition, a chelating agent, dimercaptopropane sulfonic acid, was infused intravenously, combined with intravenous N-acetylcysteine and ascorbic acid as adjuvant therapy. The patient was discharged on day 33 without long-term sequelae. The consequence of transdermal exposure of hexavalent chromium should not be overlooked.

Human Melia azedarach poisoning

Introduction. In traditional Chinese medicine, Melia azedarach (Ku-lian) is used orally and topically as an antiparasitic and antifungal agent. Although toxicity of this plant has been widely described in veterinary literature, human poisoning is rarely reported. We describe five patients with M. azedarach poisoning who recovered with supportive care. Case series. Five patients were identified retrospectively from the database of the Taiwan National Poison Center at the Taipei Veterans General Hospital. Three cases were on-site patients, and two were telephone consultations from outside hospitals. Neurological symptoms were the major manifestation in four cases: weakness, myalgia, numbness, and ptosis. Treatment was symptomatic and supportive; all patients recovered without sequelae. Discussion. It is not known which limonoids are responsible for human toxicity. In the Chinese medical literature, human M. azedarach poisoning is said to occur if six to nine fruits, 30 to 40 seeds, or 400 g of the bark is consumed. Onset of symptoms typically occurs within 4–6 h, but as short as 0.5 h had been documented. In our patients, the onset of M. azedarach poisoning was variable, ranging from a few hours to up to 3 weeks after consumption of the herb. Conclusions. M. azedarach poisoning may result in gastrointestinal, cardiovascular, respiratory, or neurological effects, and death in severe cases.