MRI brain findings in ephedrone encephalopathy associated with manganese abuse: Single-center perspective

Substance Use and the Nervous System

OBJECTIVE

This article informs and updates the practicing neurologist on the current landscape of known neurologic injuries linked to the use of illicit drugs, focusing on emerging agents.

LATEST DEVELOPMENTS

Synthetic opioids such as fentanyl and similar derivatives have exploded in prevalence, becoming the leading cause of overdose fatalities. The higher potency of synthetic opioids compared with semisynthetic and nonsynthetic opiates poses an increased risk for unintentional overdose when found as an adulterant in other illicit drug supplies such as heroin. Conversely, misinformation about the risk of symptomatic exposure to fentanyl through casual contact with the skin and ambient air has led to misdirected fear and stigma that threatens to impede valid harm-reduction measures for fentanyl users at risk of actual overdose. Finally, during the COVID-19 pandemic, overdose rates and deaths continued to climb, especially among those who use opioids and methamphetamine.

ESSENTIAL POINTS

A variety of potential neurologic effects and injuries can occur with illicit drug use owing to the diverse properties and mechanisms of action of the various classes. Many high-risk agents are not detected on standard drug screens, including so-called designer drugs, and the practicing neurologist is best served by recognizing the clinical features of the traditional toxidrome and other potential idiosyncratic effects of various illicit agents.

Novel Psychoactive Substances: The Razor's Edge between Therapeutical Potential and Psychoactive Recreational Misuse

BACKGROUND

Novel psychoactive substances (NPS) are compounds of natural and synthetic origin, similar to traditional drugs of abuse. NPS are involved in a contemporary trend whose origin lies in a thinner balance between legitimate therapeutic drug research and legislative control. The contemporary NPS trend resulted from the replacement of MDMA by synthetic cathinones in 'ecstasy' during the 2000s. The most common NPS are synthetic cannabinoids and synthetic cathinones. Interestingly, during the last 50 years, these two classes of NPS have been the object of scientific research for a set of health conditions.

METHODS

Searches were conducted in the online database PubMed using boolean equations.

RESULTS

Synthetic cannabinoids displayed protective and therapeutic effects for inflammatory, neurodegenerative and oncologic pathologies, activating the immune system and reducing inflammation. Synthetic cathinones act similarly to amphetamine-type stimulants and can be used for depression and chronic fatigue.

CONCLUSIONS

Despite the scientific advances in this field of research, pharmacological application of NPS is being jeopardized by fatalities associated with their recreational use. This review addresses the scientific achievements of these two classes of NPS and the toxicological data, ending with a reflection on Illicit and NPS control frames.

Manganese Encephalopathy Caused by Homemade Methcathinone (Ephedrone) Prevalence in Poland

Manganese encephalopathy is a known disorder in occupational medicine. A serious phenomenon has been the emergence of manganese encephalopathy in intravenous users of homemade methcathinone (ephedrone). A short survey was developed for clinical environments dealing with people who use psychoactive substances. The data were obtained from 72 rehabilitation therapy centers. Surveys carried out in about a third of Polish centers dealing with providing medical assistance to people addicted to substances other than alcohol and tobacco have shown that over 4% of people treated there had symptoms of manganese encephalopathy, of which more than half are people in whom the probability of a clinical diagnosis of this disorder is significant. It has been shown that knowledge of manganese encephalopathy is none or minimal in more than 70% of the surveyed institutions. An urgent need for personnel training in this field was pointed out. Attention was paid to the importance of disseminating good review articles on new and dynamically developing problem phenomena.

Behavioral and neurochemical studies of inherited manganese-induced dystonia-parkinsonism in Slc39a14-knockout mice

Inherited autosomal recessive mutations of the manganese (Mn) transporter gene SLC39A14 in humans, results in elevated blood and brain Mn concentrations and childhood-onset dystonia-parkinsonism. The pathophysiology of this disease is unknown, but the nigrostriatal dopaminergic system of the basal ganglia has been implicated. Here, we describe pathophysiological studies in Slc39a14-knockout (KO) mice as a preclinical model of dystonia-parkinsonism in SLC39A14 mutation carriers. Blood and brain metal concentrations in Slc39a14-KO mice exhibited a pattern similar to the human disease with highly elevated Mn concentrations. We observed an early-onset backward-walking behavior at postnatal day (PN) 21 which was also noted in PN60 Slc39a14-KO mice as well as dystonia-like movements. Locomotor activity and motor coordination were also impaired in Slc39a14-KO relative to wildtype (WT) mice. From a neurochemical perspective, striatal dopamine (DA) and metabolite concentrations and their ratio in Slc39a14-KO mice did not differ from WT. Striatal tyrosine hydroxylase (TH) immunohistochemistry did not change in Slc39a14-KO mice relative to WT. Unbiased stereological cell quantification of TH-positive and Nissl-stained estimated neuron number, neuron density, and soma volume in the substantia nigra pars compacta (SNc) was the same in Slc39a14-KO mice as in WT. However, we measured a marked inhibition (85-90%) of potassium-stimulated DA release in the striatum of Slc39a14-KO mice relative to WT. Our findings indicate that the dystonia-parkinsonism observed in this genetic animal model of the human disease is associated with a dysfunctional but structurally intact nigrostriatal dopaminergic system. The presynaptic deficit in DA release is unlikely to explain the totality of the behavioral phenotype and points to the involvement of other neuronal systems and brain regions in the pathophysiology of the disease.

Dietary Manganese Exposure in the Adult Population in Germany-What Does it Mean in Relation to Health Risks?

Manganese is both an essential nutrient and a potential neurotoxicant. Therefore, the question arises whether the dietary manganese intake in the German population is on the low or high side. Results from a pilot total diet study in Germany presented here reveal that the average dietary manganese intake in the general population in Germany aged 14-80 years is about 2.8 mg day^-1 for a person of 70 kg body weight. This exposure level is within the intake range of 2-5 mg per person and day as recommended by the societies for nutrition in Germany, Austria, and Switzerland. No information on the dietary exposure of children in Germany can be provided so far. Although reliable information on health effects related to oral manganese exposure is limited, there is no indication from the literature that these dietary intake levels are associated with adverse health effects either by manganese deficiency or excess. However, there is limited evidence that manganese taken up as a highly bioavailable bolus, for example, uptake via drinking water or food supplements, could pose a potential risk to human health-particularly in certain subpopulations-when certain intake amounts, which are currently not well defined, are exceeded.

The New Classes of Synthetic Illicit Drugs Can Significantly Harm the Brain: A Neuro Imaging Perspective with Full Review of MRI Findings

Synthetic drugs contain substances that are pharmacologically similar to those found in traditional illicit drugs. Some of the most commonly abused synthetic drugs include synthetic marijuana, bath salts, ecstasy, N-bomb, methamphetamine and anabolic steroids. Many of them share the same chemical properties and physiologic responses with the drugs they mimic and may exaggerate the pathologic response in the brain leading to addiction. These drugs have detrimental (and often irreversible) effects on the brain and primarily affect the central nervous system by two mechanisms: 1) Neural hyper stimulation via increasing activation of certain neurotransmitters (norepinephrine, dopamine, and serotonin), 2) Cause significant reduction in CNS neural connectivity affecting various brain regions such as the basal ganglia, hippocampus, cerebellum, parietal lobe, and globus pallidus. Furthermore these drugs sometimes have severe, life-threatening adverse effects on the human body. A few structural MRI studies have been conducted in synthetic drug abusers to reveal the effects of these drugs on the brain parenchyma. This review article will describe the potential brain imaging findings in synthetic drug abusers as demonstrated by several case reports and the primary literature.

Association of exposure to manganese and iron with relaxation rates R1 and R2*- magnetic resonance imaging results from the WELDOX II study

OBJECTIVE

Magnetic resonance imaging is a non-invasive method that allows the indirect quantification of manganese (Mn) and iron (Fe) accumulation in the brain due to their paramagnetic features. The WELDOX II study aimed to explore the influence of airborne and systemic exposure to Mn and Fe on the brain deposition using the relaxation rates R1 and R2* as biomarkers of metal accumulation in regions of interest in 161 men, including active and former welders.

MATERIAL AND METHODS

We obtained data on the relaxation rates R1 and R2* in regions that included structures within the globus pallidus (GP), substantia nigra (SN), and white matter of the frontal lobe (FL) of both hemispheres, as well as Mn in whole blood (MnB), and serum ferritin (SF). The study subjects, all male, included 48 active and 20 former welders, 41 patients with Parkinson's disease (PD), 13 patients with hemochromatosis (HC), and 39 controls. Respirable Mn and Fe were measured during a working shift for welders. Mixed regression models were applied to estimate the effects of MnB and SF on R1 and R2*. Furthermore, we estimated the influence of airborne Mn and Fe on the relaxation rates in active welders.

RESULTS

MnB and SF were significant predictors of R1 but not of R2* in the GP, and were marginally associated with R1 in the SN (SF) and FL (MnB). Being a welder or suffering from PD or HC elicited no additional group effect on R1 or R2* beyond the effects of MnB and SF. In active welders, shift concentrations of respirable Mn>100μg/m³ were associated with stronger R1 signals in the GP. In addition to the effects of MnB and SF, the welding technique had no further influence on R1.

CONCLUSIONS

MnB and SF were significant predictors of R1 but not of R2*, indicative of metal accumulation, especially in the GP. Also, high airborne Mn concentration was associated with higher R1 signals in this brain region. The negative results obtained for being a welder or for the techniques with higher exposure to ultrafine particles when the blood-borne concentration was included into the models indicate that airborne exposure to Mn may act mainly through MnB.

Manganese-Induced Parkinsonism Is Not Idiopathic Parkinson's Disease: Environmental and Genetic Evidence

Movement abnormalities caused by chronic manganese (Mn) intoxication clinically resemble but are not identical to those in idiopathic Parkinson's disease. In fact, the most successful parkinsonian drug treatment, the dopamine precursor levodopa, is ineffective in alleviating Mn-induced motor symptoms, implying that parkinsonism in Mn-exposed individuals may not be linked to midbrain dopaminergic neuron cell loss. Over the last decade, supporting evidence from human and nonhuman primates has emerged that Mn-induced parkinsonism partially results from damage to basal ganglia nuclei of the striatal "direct pathway" (ie, the caudate/putamen, internal globus pallidus, and substantia nigra pars reticulata) and a marked inhibition of striatal dopamine release in the absence of nigrostriatal dopamine terminal degeneration. Recent neuroimaging studies have revealed similar findings in a particular group of young drug users intravenously injecting the Mn-containing psychostimulant ephedron and in individuals with inherited mutations of the Mn transporter gene SLC30A10. This review will provide a detailed discussion about the aforementioned studies, followed by a comparison with their rodent analogs and idiopathic parkinsonism. Together, these findings in combination with a limited knowledge about the underlying neuropathology of Mn-induced parkinsonism strongly support the need for a more complete understanding of the neurotoxic effects of Mn on basal ganglia function to uncover the appropriate cellular and molecular therapeutic targets for this disorder.

Methcathinone "Kitchen Chemistry" and Permanent Neurological Damage

Methcathinone abuse is a significant cause of parkinsonism among young patients in the Eastern European countries. The drug is synthesized from over-the-counter cold remedies containing ephedrine or pseudoephedrine. The final mixture contains a high concentration of manganese if potassium permanganate is used as the oxidant agent. Though manganese is an essential trace element and its homeostasis is well maintained, exposure to a high level of manganese is neurotoxic. The use of manganese-contaminated methcathinone may cause permanent neurological damage and severe disability. Drug users develop a distinctive extrapyramidal syndrome that resembles classic manganese intoxication. Methcathinone could have additive neurotoxic effect to the progression of parkinsonism. The most prevalent symptoms are symmetrical bradykinesia, dystonias, and early postural, gait, and speech impairment. After cessation of exposure, the syndrome is generally irreversible and can even progress.