Cyanide-induced parkinsonism: clinical, MRI, and 6-fluorodopa PET studies

A 46-year-old man ingested 1,500 mg of potassium cyanide in a suicide attempt. He survived, but later developed a severe parkinsonian syndrome. MRI revealed multiple areas of low-signal intensity in the globus pallidus and posterior putamen. A 6-fluorodopa PET study revealed bilateral decreased uptake in the basal ganglia. This evidence of functional impairment of dopaminergic nigrostriatal neurons is related either to direct toxicity of cyanide or to the effects of cerebral hypoxia secondary to cyanide intoxication.

Brain lipid peroxidation and antioxidant protectant mechanisms following acute cyanide intoxication

The status of brain antioxidant enzymes and glutathione levels in mice intoxicated with KCN were correlated with lipid peroxidation in brain membranes. KCN (7 mg/kg, s.c.) rapidly increased conjugated dienes in brain lipids, with peak levels observed 30 min after cyanide treatment. At 60 min post cyanide, conjugated diene levels were only slightly elevated above controls. Temporal changes in activity of most antioxidant enzymes corresponded with the observed time course of cyanide-induced membrane lipid peroxidation. Thirty minutes after KCN, brain catalase (CA), glutathione peroxidase (GPX) and glutathione reductase (GR) activities were significantly reduced (percent inhibition compared to control: CA 44%, GPX 30%, and GR 41%). At 60 min, CA and GPX enzyme activity returned to control levels, whereas GR was elevated 34% above control activity. Superoxide dismutase was not significantly inhibited 30 min after KCN, but declined to 71% of control activity at 60 min. Brain levels of reduced glutathione declined 42% below control 30 min after cyanide and returned to within 9.4% of control at 60 min. At 30 and 60 min after cyanide, oxidize glutathione levels were not significantly changed from control levels. These studies suggest that membrane lipid peroxidation and subsequent membrane dysfunction observed in cyanide intoxication is related in part to a compromised antioxidant defense.

Cyanide-induced parkinsonism: a clinicopathologic report

An 18-year-old man ingested 975 to 1,300 mg of potassium cyanide in a suicide attempt. He was treated and survived the poisoning episode, but then had severe parkinsonian syndrome, characterized primarily by akinesia and rigidity. He died 19 months after the drug overdose. At autopsy, major destructive changes were found in the globus pallidus and putamen, whereas the melanin-containing zone of substantia nigra was intact. This is the first clinicopathologic report of parkinsonism as a result of cyanide poisoning.

Neurological sequelae of cyanide intoxication--the patterns of clinical, magnetic resonance imaging, and positron emission tomography findings

We report 2 patients with neurological sequelae of oral cyanide intoxication who were evaluated clinically and neuropsychologically, with high-resolution magnetic resonance imaging and one of them with positron emission tomography. The clinical syndrome was characterized by extrapyramidal motor and cerebellar symptoms such as bradykinesia, hypomimia, slowed speech, anteropulsion, and marked retropulsion, but little tremor. The sensory and pyramidal motor systems were normal or relatively spared. On neuropsychological testing the intellectual capacity and memory functions were normal, whereas the speed of motor reaction and verbal fluency were reduced. Magnetic resonance imaging showed damage of the globus pallidus, putamen, substantia nigra, subthalamic nucleus, and cerebellum in both patients, whereas the sensory-motor cortex and hippocampus were relatively spared. 18F-6-Fluoro-dopa positron emission tomography revealed a symmetrical reduction of striatal dopa uptake by 42% on average that was similar in the putamen and caudate. 18F-2-Fluoro-2-deoxyglucose positron emission tomography showed a regional reduction of the glucose metabolism in the posterior putamen and temporo-parieto-occipital and cerebellar cortex.

Reversal of cyanide inhibition of cytochrome c oxidase by the auxiliary substrate nitric oxide: an endogenous antidote to cyanide poisoning?

Nitric oxide (NO) is shown to overcome the cyanide inhibition of cytochrome c oxidase in the presence of excess ferrocytochrome c and oxygen. Addition of NO to the partially reduced cyanide-inhibited form of the bovine enzyme is shown by electron paramagnetic resonance spectroscopy to result in substitution of cyanide at ferriheme a3 by NO with reduction of the heme. The resulting nitrosylferroheme a3 is a 5-coordinate structure, the proximal bond to histidine having been broken. NO does not simply act as a reversibly bound competitive inhibitor but is an auxiliary substrate consumed in a catalytic cycle along with ferrocytochrome c and oxygen. The implications of this observation with regard to estimates of steady-state NO levels in vivo is discussed. Given the multiple sources of NO available to mitochondria, the present results appear to explain in part some of the curious biomedical observations reported by other laboratories; for example, the kidneys of cyanide poisoning victims surprisingly exhibit no significant irreversible damage, and lethal doses of potassium cyanide are able to inhibit cytochrome c oxidase activity by only approximately 50% in brain mitochondria.

Simultaneous determination of cyanide and thiocyanate in blood by ion chromatography with fluorescence and ultraviolet detection

An ion chromatographic method for the simultaneous determination of cyanide and thiocyanate in blood has been developed. After extraction by adding water and methanol to blood, cyanide was derivatized with 2,3-naphthalenedialdehyde and taurine to give a fluorescent product of 1-cyanobenz[f]isoindole. This compound was detected with high sensitivity by fluorometry and the underivatized thiocyanate was detected by ultraviolet absorption. The detection limits were 3.8 pmol ml(-1) for cyanide and 86 pmol ml(-1) for thiocyanate, and the recoveries from blood were ca. 83% and ca. 100%, respectively. The proposed method was successfully applied to the analysis of both anions in blood from smokers, non-smokers and fire victims.

Efficacy of hydroxocobalamin for the treatment of acute cyanide poisoning in adult beagle dogs

INTRODUCTION

The efficacy of hydroxocobalamin for acute cyanide poisoning was compared with that of saline vehicle in dogs.

METHODS

Anesthetized adult beagle dogs were administered potassium cyanide (0.4 mg/kg/min, IV) until 3 min after the onset of apnea. Hydroxocobalamin (75 mg/kg [n = 19] or 150 mg/kg [n = 18], IV) or saline vehicle [n = 17] was then infused over 7.5 min while animals were ventilated with 100% oxygen, which was stopped after 15 min.

RESULTS

In vehicle-treated animals cyanide produced deterioration that culminated in a moribund state requiring euthanasia within 4 h in 10 of 17 animals and in neurological deficits necessitating euthanasia within 2-4 d in an additional 4 animals (mortality rate 82%). Survival through 14 d was observed in 15 of 19 animals administered hydroxocobalamin 75 mg/kg (mortality rate 21%), and 18 of 18 administered hydroxocobalamin 150 mg/kg (mortality rate 0%).

CONCLUSION

Hydroxocobalamin reversed cyanide toxicity and reduced mortality in a canine model.

Acute cyanide poisoning

OBJECTIVE

Cyanide intoxication is an extremely rare event. We report a case of a teenager presenting with unresponsiveness, hemodynamic instability, and profound anion gap metabolic acidosis secondary to elevated lactate levels. It was later confirmed that he was a victim of cyanide poisoning.

DESIGN

Individual case report.

SETTING

Pediatric intensive care unit of a tertiary care hospital.

PATIENT

A 17-yr-old male presented with seizures, apnea, and cardiovascular collapse. His laboratory evaluation revealed extreme anion gap metabolic acidosis, elevated lactate levels, and absent arteriovenous saturation difference.

INTERVENTIONS

The patient required inotropic support and external cardiac pacing for hemodynamic instability. Serial measurements of electrolytes and arterial and central venous blood gases were performed. When cyanide poisoning was suspected he received antidote therapy, administered initially with interval dosing and then as a continuous infusion. The antidote infusions were stopped because of a high level of resultant methemoglobinemia and the belief that all ingested cyanide had been cleared, given the time from exposure. The patient never recovered neurologic function, was declared brain dead, and became a tissue and organ donor.

CONCLUSION

Cyanide poisoning is a rare and potentially fatal event. Prompt recognition of its possibility in a critically ill patient can lead to early intervention with antidote therapy and decrease the extent of morbidity and mortality.

In vitro and in vivo attenuation of experimental cyanide poisoning by alpha-ketoglutarate

Treatment of cyanide poisoning generally includes methemoglobin forming agents, like amyl nitrite and/or sodium nitrite (SN), in combination with sodium thiosulphate (STS). However, in many instances of cyanide poisoning, use of nitrites are contraindicated due to their strong vasoactive properties. alpha-Ketoglutarate (alpha-KG) antagonises cyanide by cyanohydrin formation and is considered a promising antidote for cyanide poisoning. In the present study, pre-treatment (30 min) and simultaneous treatment (0 min) of alpha-KG (5 mM) was found to confer significant protection against 5 mM potassium cyanide (KCN) induced cytotoxicity in rat thymocytes as measured by eosin Y exclusion and leakage of intracellular lactate dehydrogenase (LDH), but could not prevent the mitochondrial dysfunction (MTT assay), depletion of cellular GSH (reduced glutathione) and DNA damage. The post-treatment (5 or 30 min) of alpha-KG did not offer any protection on any of the above parameters. Results of in vitro studies were also supported by in vivo data. Pre-treatment of peroral (p.o.) alpha-KG (0.125-2.0 g/kg) exhibited dose and time dependent effects and was found to be effective even when given upto 60 min prior to KCN (p.o.). Addition of STS significantly enhanced the protective efficacy of alpha-KG at all the doses and time intervals. A 10 min pre-treatment of alpha-KG increased the LD(50) of KCN 7.6-fold, which was further increased to 25.6-fold by the addition of both SN and STS. Simultaneous treatment of alpha-KG (2.0 g/kg) increased the LD50 of KCN 5.4-fold which was increased to 18.1-fold by the addition of STS. However, addition of SN did not confer any additional protection. In the presence of SN+STS, a decrease in the dose of alpha-KG exhibited a dose-dependent decrease in protection, but still a >10-fold protection could be observed at 1.0 g/kg dose of alpha-KG. Considering the efficacy and safety of peroral alpha-KG, a promising treatment regimen consisting of alpha-KG+STS or alpha-KG+SN+STS is proposed, depending upon the individual situation.

Delayed cyanide induced dystonia

A 16 year old man ingested 1 g potassium cyanide in 1969. A few days after an apparently full recovery he developed a severe dystonia syndrome. He had a positive response to an apomorphine test and showed improvement with levodopa treatment. A 21 year follow up showed minimal neurological sequelae; CT showed bilateral putaminal lucencies. Visual and brain stem auditory evoked potentials were normal.

Cyanide poisoning successfully treated without 'therapeutic methemoglobin levels'

A 24-year-old woman ingested an unknown amount of potassium cyanide in a suicide attempt. Coma and metabolic acidosis developed. Administration of the Lilly Cyanide Antidote kit (Eli Lilly and Co, Indianapolis) resulted in prompt resolution of symptoms and full recovery. Whole blood cyanide level was 13 micrograms/mL approximately one hour after ingestion. The highest measured methemoglobin level after sodium nitrite administration was 9.2%, demonstrating that attaining a "therapeutic methemoglobin level" of 25% is unnecessary to insure a satisfactory clinical outcome. Because severe hypotension or excessive methemoglobinemia can be caused by the sodium nitrite component of the Lilly kit, only enough to produce an acceptable clinical response should be administered.

Delayed onset generalised dystonia after cyanide poisoning

A 27 year old female developed delayed onset of persistent generalized dystonia following a suicidal attempt with potassium cyanide. Cranial CT scan showed bilateral putaminal hypodensities which were also seen on MRI scans to be hypointense on T1 and hyperintense on T2 weighted images. Multimodality evoked potentials were normal. An improvement was noted with levodopa.

Nitrite/thiosulfate treated acute cyanide poisoning: estimated kinetics after antidote

A 34 year old, 73 kg man ingested a 1 gram potassium cyanide pellet in a suicide attempt. Within one hour, coma, apnea, metabolic acidosis, and seizures developed. Sodium nitrite and sodium thiosulfate were administered. Dramatic improvement in the clinical condition occurred by the completion of antidote infusion. Methemoglobin level was 2% immediately after nitrite administration. Serial whole blood cyanide levels were obtained, documenting a highest measured level of 15.68 mcg/mL. Estimations of toxicokinetic parameters including terminal half-life (t 1/2) (19 hours), clearance (163 mL/minute), and volume of distribution (Vd) (0.41 L/kg) were calculated. The nitrite/thiosulfate combination was clinically efficacious in this case and resulted in complete recovery.

Synthesis and pharmacological evaluation of 1,2,3,4-tetrahydro-beta-carboline derivatives

A series of 1,2,3,4-tetrahydro-beta-carbolines has been synthesized and evaluated for cerebral protecting effects against lipid peroxidation and potassium cyanide intoxication in mice. Most of the compounds synthesized had potent effects against lipid peroxidation. Among them, 1-(3,5-dimethoxyphenyl)-2-propyl-1,2,3,4-tetrahydro-beta-carboline (22) was found to have a combination of potent effects against both lipid peroxidation and potassium cyanide intoxication. Structure-activity relationships are discussed.

The efficacy of superactivated charcoal in treating rats exposed to a lethal oral dose of potassium cyanide

Due to the apparent low binding capacity of activated charcoal for potassium cyanide (KCN) in vitro, the use of oral activated charcoal therapy for oral exposure to cyanide compounds is controversial. In our study, rats were given a lethal oral dose of ground granular KCN (35 or 40 mg/kg) in a gelatin capsule followed immediately by either 4 g/kg of superactivated charcoal in a 20% suspension or a similar volume of deionized water. Signs of cyanide toxicosis occurred rapidly, with a mean time to signs of 3.3 and 2.7 minutes in control animals receiving 35 or 40 mg/kg KCN, respectively. All 26 of the control rats showed signs, and all but one in the 35 mg/kg group died within 19 minutes. Only 12 of 26 rats treated with superactivated charcoal showed signs of KCN toxicosis and eight of those animals died. Oral exposure of rats to lethal doses of KCN can be treated effectively by immediate administration of superactivated charcoal.

Computer tomography and magnetic resonance imaging in cyanide poisoning

A 29-year-old chemistry student took 50 ml of a 1% potassium cyanide solution (500 mg) in an attempted suicide. He became comatose, mydriatic, and was admitted to hospital in an apneic state. He woke up after 7 h and developed Parkinsonism in the following weeks. This regressed slowly during the 2 months after the poisoning apart from dysarthria, bradykinesia of the upper limbs, and very brisk monosynaptic reflexes. At 3 weeks after the intoxication, computerized tomography was largely normal, and there was CSF-dense hypodensity in both putamina after 5 months. Sharply delimited signal elevation in T2 corresponding to the two putamina was detected by magnetic resonance imaging 8 weeks and 5 months after ingestion of the poison.

Treatment of acute cyanide intoxication with hemodialysis

A dramatic response was noted in a patient at our hospital who received hemodialysis therapy for severe acidosis secondary to an unknown toxin, subsequently identified as cyanide. We were unable to find any information concerning the hemodialysis clearance and extraction ratio of cyanide; thus, we studied the effect of hemodialysis in dogs receiving a constant infusion of cyanide with and without a simultaneous infusion of thiosulfate. The hemodialysis clearance of cyanide in the presence of thiosulfate was 38.3 +/- 5.4 ml/min with an extraction ratio of 0.43 +/- 0.06 (n = 4). Hemodialysis was found to increase the lethal dose of cyanide without thiosulfate infusion, and a further increase was noted with the thiosulfate infusion. Thiosulfate promotes mitochondrial metabolism of cyanide to thiocyanate. The end product, thiocyanate, is quickly removed by hemodialysis. We believe that the demonstrated effectiveness of hemodialysis in the treatment of acute cyanide intoxication is related not only to the hemodialysis clearance of cyanide, but also to the removal of its metabolic end product, thiocyanate. Based on our observations, we feel that hemodialysis is an effective adjunct in the treatment of acute cyanide intoxication.

Patient treated with antidote kit and hyperbaric oxygen survives cyanide poisoning

A 54-year-old man deliberately drank a potassium-gold cyanide solution that contained approximately 1,650 mg of potassium cyanide. He survived after treatment with the Lilly antidote kit and hyperbaric oxygen.

Antidotal effect of dihydroxyacetone against cyanide toxicity in vivo

Potassium cyanide (CN) intoxication in mice was found to be effectively antagonized by dihydroxyacetone (DHA), particularly if administered in combination with another CN antidote, sodium thiosulfate. Cyanide-induced convulsions were also prevented by DHA treatment, either alone or in combination with thiosulfate. Injection (i.p.) of DHA (2 g/kg) 2 min after or 10 min before CN (s.c.) increased LD50 values of CN(8.7 mg/kg) by factors of 2.1 and 3.0, respectively. Treatment with a combination of DHA and thiosulfate after CN increased the LD50 by a factor of 2.4. Pretreatment with a combination of DHA and thiosulfate (1 g/kg) increased the LD50 of CN to 83 mg/kg. Administration of alpha-ketoglutarate (2.0 g/kg), but not pyruvate, 2 min after CN increased the LD50 of CN by a factor of 1.6. Brain, heart and liver cytochrome oxidase activities were also measured following in vivo CN treatment with and without DHA. Pretreatment with DHA prevented the inhibition of cytochrome oxidase activity by CN and treatment with DHA after CN accelerated the recovery of cytochrome oxidase activity, especially in brain and heart homogenates. DHA is a physiological agent and, therefore, could prove to be a safe and effective antidote for CN, particularly in cases of fire smoke inhalation in which a combination of CN and carbon monoxide is present. In these cases the normally used antidote, sodium nitrite, to induce methemoglobin so as to trap the CN, is contraindicated because some of the oxygen-carrying capacity of the blood will have already been diminished by carbon monoxide.

The expression of P-selectin in inflammatory and non-inflammatory lung tissue

An initial attachment of leucocytes to blood vessel walls is mediated by selectins. A feature of adhesion mediated by P-selectin is the "rolling" of leucocytes on the endothelium. The time dependent expression of p-selectin in lung tissue was investigated in five groups of cases with different causes of death: carbon-monoxide and cyanide intoxication (n = 11), drowning (n = 5), hanging (n = 9), pneumonia (n = 13) and polytrauma with blunt thorax trauma (n = 14). In paraffin-embedded archival specimens immunostaining was achieved using an adapted APAAP-immunoperoxidase technique together with a wet autoclave method. P-selectin detection was scored by a semiquantitative method evaluating the intensity and incidence of positively stained endothelial cells. The distribution pattern of endothelial P-selectin of blood vessels in cases of pneumonia and septic shock were heterogenius and weak. In one case with lung contusion (survival time 3 h) moderate infiltrates of granulocytes were found near to septal and subpleural hemorrhages. In these inflammatory areas the positive endothelial immunostaining of small vessels was often weaker than in other lung segments or compared to the intensely stained platelets in corresponding vessels.

Cyanide intoxication: protection with oxygen

Prophylactic protection against cyanide intoxication in mice can be enhanced by the administration of oxygen, especially when it is used in combination with the conventional cyanide antidotes, sodium nitrite and sodium thiosulfate. The LD(50) values were compared in groups of mice premedicated with sodium thiosulfate or sodium nitrite, or both, in air and in oxygen. These results indicate that oxygen alone provides only minimal protection. Although oxygen enhances the protective effect of sodium thiosulfate to a minor degree, it does not enhance the protection of sodium nitrite at all; and yet, it potentiates the effectiveness of a combination of these two antagonists against cyanide intoxication.

Cyanide-induced akinetic rigid syndrome: Clinical, MRI, FDG-PET, β-CIT and HMPAO SPECT findings

A 35-year-old female ingested a lethal dose of potassium cyanide in a suicide attempt. She survived following antidote therapy and intensive care. Following artificial coma she presented with an agitative state for several days followed by akinetic mutism, buccofacial and ideomotoric aphasia. Severe rigid-akinetic syndrome, dysarthria, dysphagia and generalized dystonia developed weeks later. MRI revealed lesions in the caudate and lentiform nuclei, precentral cortex, and cerebellum. SPECT by [123-I] 2 beta-carbomethoxy-3-beta-(4-iodophenyl)-Tropan on two occasions revealed progressive loss of dopamine transporter suggestive of nigral neuronal apoptosis. Striatal and frontal hypometabolism and hypoperfusion were found by FDG-PET and HMPAO SPECT.