Cerebellar ataxia due to lead encephalopathy in an adult

Radiological changes in lead poisoning

INTRODUCTION

Lead poisoning in childhood remains an important public health concern. We highlight the radiological findings in a patient with a high blood lead concentration.

CASE SUMMARY

A 7-year-old girl presented to hospital with abdominal pain, nausea, and asthenia. Laboratory tests showed severe hypochromic microcytic anemia, punctate basophilic stippling of erythrocytes, and a blood lead concentration of 880 µg/L (4.3 µmol/L).

IMAGES

Radiographs of the femur, tibia, and fibula demonstrated dense metaphyseal bands ("lead lines"). On cranial computed tomography, we observed multiple speck-like and curvilinear hyperdensities involving subcortical regions, putamen, and left cerebellar hemisphere.

CONCLUSION

In patients with lead poisoning, imaging of the brain and bones may show characteristic features. These imaging findings may point to the diagnosis of lead toxicity when these radiographic findings are discovered during the evaluation of vague complaints such as abdominal pain or mental status changes or when a blood lead concentration is not readily available.

Encephalopathy following ingestion of Lead-contaminated opium; magnetic resonance imaging findings

Background

Encephalopathy is an uncommon but serious presentation of lead toxicity.

Objective

We aimed to determine and follow-up the brain magnetic resonance imaging (MRI) abnormalities in the patients with lead encephalopathy due to ingestion of lead contaminated opium.

Methods

In a cross-sectional study during lead-contaminated opium outbreak, all lead-poisoned patients with any signs/symptoms of encephalopathy were included.

Results

Of 19 patients with lead encephalopathy, five died early and other five could not be sent to MRI during their hospitalization period. Mean age was 51 ± 11 years and males were dominant (89%). Median [IQR] blood lead level (BLL) was 101 [81, 108] μg/dL (range; 50 to 200 μg/dL). There was no correlation between MRI findings and signs/symptoms. MRI was normal in six and abnormal in three. Bilateral symmetric involvement of parieto-occipital lobes was observed. Gray matter, gray-white matter junction, and subcortical white matter were also affected. Follow-up MRI was performed in two with abnormal MRI which showed complete and near complete resolution of the abnormalities after cessation of opium use and treatment. Conclusion: There was no correlation between MRI findings and BLL. Complete recovery of brain MRI lesions was detected after cessation of opium use.

Ascorbic Acid Ameliorates Gestational Lead Exposure-Induced Developmental Alteration in GAD67 and c-Kit Expression in the Rat Cerebellar Cortex

In the present study, we investigated the effects of ascorbic acid on lead-exposed developing cerebellum. Female rats were divided into the following three groups: control (distilled water), lead (0.2% lead acetate), and lead plus ascorbic acid (100 mg/kg/day, 10% solution). To evaluate the effect of lead exposure and ascorbic acid treatment accurately on the cerebellar development for the gestational period, we halted further treatment with lead and ascorbic acid in the dams after delivery of the pups. Although the ascorbic acid slightly decreased the lead level in pups, lead level was still high in the group treated with lead plus ascorbic acid group compared with the control group. The blood lead levels indicated that the ascorbic acid could facilitate both the excretion and transfer of lead from a dam to its pups via milk. At postnatal day 21, lead exposure significantly reduced the number of Purkinje cells in the cerebellar cortex of pups. Additionally, lead treatment induced degenerative changes such as reduction of glutamic acid decarboxylase (GAD67) and c-kit expressions are observed in the developing cerebellar cortex. In the cerebellum of the pups from the lead plus ascorbic acid group, reduction of the number of Purkinje cells, GAD67 expression, and c-kit immunopositivity were remarkably restored compared with the lead group. Our present results suggested that ascorbic acid treatment to lead-exposed dam exerted protective effects on the developing cerebellum against lead-induced neurotoxicity.

Ascorbic acid ameliorates lead-induced apoptosis in the cerebellar cortex of developing rats

We investigated the effects of the gestational administration of lead (Pb) and ascorbic acid on cerebellar development. Pregnant female rats were randomly assigned to the control, Pb, or Pb plus ascorbic acid (PA) groups; six offspring per cage were randomly selected for analysis. Compared to the control group, fewer Purkinje cells were observed in the Pb-exposed pups at postnatal day 21. However, co-administrating Pb and ascorbic acid inhibited the Pb-induced reduction in Purkinje cells. Terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) staining, which detected DNA fragmentation in the dying cells, showed more TUNEL-positive cells in the Pb group, while co-treatment with Pb and ascorbic acid mitigated the Pb-induced cellular degeneration. Using immunohistochemistry and immunoblotting, we additionally found that Pb exposure induced a rise in the apoptotic factor Bax in the cerebellum, while Pb plus ascorbic acid treatment ameliorated this Bax induction. Since, Pb competes with the iron in the cell and the accumulation of free iron triggers oxidative stress, we performed iron staining, which revealed that ascorbic acid prevented the Pb-induced rises in iron-reactive cells and iron-reactivity. The anti-oxidant enzyme manganese-dependent superoxide dismutase showed change patterns that were similar to those of iron in the cerebellum. Finally, the pups' blood Pb levels were highest in the Pb group but were reduced in the PA group. Our findings suggest that ascorbic acid effectively ameliorates Pb-induced apoptosis and oxidative stress in the cerebellum. The present results imply that ascorbic acid treatment during pregnancy may protect against Pb-mediated developmental impairments in the cerebellum.

Ataxia

Ataxia is a disorder of balance and coordination resulted from dysfunctions involving cerebellum and its afferent and efferent connections. While a variety of disorders can cause secondary ataxias, the list of genetic causes of ataxias is growing longer. Genetic abnormalities may involve mitochondrial dysfunction, oxidative stress, abnormal mechanisms of DNA repair, possible protein misfolding, and abnormalities in cytoskeletal proteins. Few ataxias are fully treatable while hope for efficacious gene therapy and pharmacotherapy is emerging. A discussion of the ataxias is presented here with brief mention of acquired ataxias, and a greater focus on inherited ataxias.

Rhazes and an Early Case With Possible Hypertensive or Reversible Encephalopathy

In one of Rhazes' medical treatises, Tales and Stories of Patients, descriptions, medical manifestations, and treatment approaches of 34 patients were mentioned. Among those, an epileptic patient with a florid face and congested veins was cured by performing venesection on his saphenous and basilic veins. Signs and symptoms of the case might correspond to hypertensive or reversible encephalopathy.

Catecholamine Contents of Different Region of Adult Rat Brain Are Altered Following Short and Long-term Exposures to Pb(+2.)

Catecholamine is a group of neurotransmitters that is believed to be responsible for the normal function of animal brain. Physiological and behavioral changes of human body have been reported due to the damage of the brain function following lead exposure. Due to the assumption of lead disposal in brain tissue with two year for its half-life, which results in alteration of brain function, we investigated the ability of lead to change the brain catecholamines during short and long-term studies. Rats were exposed daily with varying amounts of lead and catecholamine contents of cerebellum, mid-brain and brain cortex were determined. Acute peritoneal administration of single dose of lead as lead acetate (260 μmol/Kg) after 2 h reduced (p < 0.05) the catecholamine levels of cerebellum, mid-brain and cortex part by 34.9%, 35.44% and 23.8%, respectively. The extension of experiment time to 5 h, significant (p < 0.05) reductions in catecholamine levels of mentioned regions of brain by 32.35%, 12.35% and 19.3% were seen respectively. Daily intraperitoneal administration of 10 μmol/Kg lead for 30 and 60 days reduced catecholamines levels of cerebellum (22.22% and 30.44%), midbrain (12.48% and 26.27%) and brain cortex (11.58% and 26.7%) respectively. It might be concluded that brain dysfunction in lead intoxicated rat occurred through the reduction in the catecholamine levels of different parts of brain. Lead might be therefore considered as a probable factor in causing neurological disease in lead exposed man.

Toxic agents causing cerebellar ataxias

The cerebellum is particularly vulnerable to intoxication and poisoning, especially so the cerebellar cortex and Purkinje neurons. In humans, the most common cause of a toxic lesion to the cerebellar circuitry is alcohol related, but the cerebellum is also a main target of drug exposure (such as anticonvulsants, antineoplastics, lithium salts, calcineurin inhibitors), drug abuse and addiction (such as cocaine, heroin, phencyclidine), and environmental toxins (such as mercury, lead, manganese, toluene/benzene derivatives). Although data for the prevalence and incidence of cerebellar lesions related to intoxication and poisoning are still unknown in many cases, clinicians should keep in mind the list of agents that may cause cerebellar deficits, since toxin-induced cerebellar ataxias are not rare in daily practice. Moreover, the patient's status may require immediate therapies when the intoxication is life-threatening.

Proton magnetic resonance spectroscopy in adults with childhood lead exposure

BACKGROUND

Childhood lead exposure adversely affects neurodevelopment. However, few studies have examined changes in human brain metabolism that may underlie known adverse cognitive and behavioral outcomes.

OBJECTIVE

We examined the association between mean childhood blood lead levels and in vivo brain metabolite concentrations as adults, determined by proton magnetic resonance spectroscopy (MRS) in a birth cohort with documented low-to-moderate lead exposure.

METHODS

Adult participants from the Cincinnati Lead Study [n = 159; mean age (± SD), 20.8 ± 0.9 years] completed a quantitative, short-echo proton MRS protocol evaluating seven regions to determine brain concentrations of N-acetyl aspartate (NAA), creatine and phosphocreatine (Cr), cholines (Cho), myo-inositol, and a composite of glutamate and glutamine (GLX). Correlation and multiple linear regression analyses were conducted.

RESULTS

Mean childhood blood lead levels were associated with regionally specific brain metabolite concentrations adjusted for age at imaging and Full-Scale intelligence quotient. Adjusted analyses estimated for a unit (micrograms per deciliter) increase in mean childhood blood lead concentrations, a decrease of NAA and Cr concentration levels in the basal ganglia, a decrease of NAA and a decrease of Cho concentration levels in the cerebellar hemisphere, a decrease of GLX concentration levels in vermis, a decrease of Cho and a decrease of GLX concentration levels in parietal white matter, and a decrease of Cho concentration levels in frontal white matter.

CONCLUSIONS

Gray-matter NAA reductions associated with increasing childhood blood lead levels suggest that sustained childhood lead exposure produces an irreversible pattern of neuronal dysfunction, whereas associated white-matter choline declines indicate a permanent alteration to myelin architecture.

Effects of early low-level lead exposure on human brain structure, organization and functions

Advanced neuroimaging techniques offer unique insights into how childhood lead exposure impacts the brain. Volumetric magnetic resonance imaging affords anatomical information about the size of global, regional and subcomponent structures within the brain. Diffusion tensor imaging provides information about white matter architecture by quantitatively describing how water molecules diffuse within it. Proton magnetic resonance spectroscopy generates quantitative measures of neuronal, axonal and glial elements via concentration levels of select metabolites. Functional magnetic resonance imaging infers neuronal activity associated with a given task performed. Employing these techniques in the study of the Cincinnati Lead Study, a relatively homogeneous birth cohort longitudinally monitored for over 30 years, one can non-invasively and quantitatively explore how childhood lead exposure is associated with adult brain structure, organization and function. These studies yield important findings how environmental lead exposure impacts human health.

Lead encephalopathy in an infant mimicking a neurometabolic disorder

We report the case of a 7-month-old child who presented with regression of milestones, seizures, altered sensorium, and vomiting. An elder sibling had died of similar complaints. Lead encephalopathy was considered because of presence of microcytic hypochromic anemia and dense metaphyseal bands on wrist radiogram. Magnetic resonance imaging (MRI) of the brain revealed diffuse dysmyelination involving both periventricular and subcortical white matter. Such diffuse changes have not been described previously. The child's father was operating an illicit lead-acid battery manufacturing unit at home. The child was subjected to chelation therapy, which was accompanied by environmental exposure source modification. He showed significant improvement. Our case highlights the importance of taking a detailed occupational history and considering lead poisoning in the differential diagnosis of encephalopathy of unidentifiable cause.

Altered myelination and axonal integrity in adults with childhood lead exposure: a diffusion tensor imaging study

Childhood lead exposure is associated with adverse cognitive, neurobehavioral and motor outcomes, suggesting altered brain structure and function. The purpose of this work was to assess the long-term impact of childhood lead exposure on white matter integrity in young adults. We hypothesized that childhood lead exposure would alter adult white matter architecture via deficits in axonal integrity and myelin organization. Adults (22.9+/-1.5 years, range 20.0-26.1 years) from the Cincinnati Lead Study were recruited to undergo a study employing diffusion tensor imaging (DTI). The anatomic regions of association between water diffusion characteristics in white matter and mean childhood blood lead level were determined for 91 participants (52 female). Fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD) were measured on an exploratory voxel-wise basis. In adjusted analyses, mean childhood blood lead levels were associated with decreased FA throughout white matter. Regions of the corona radiata demonstrated highly significant lead-associated decreases in FA and AD and increases in MD and RD. The genu, body, and splenium of the corpus callosum demonstrated highly significant lead-associated decreases in RD, smaller and less significant decreases in MD, and small areas with increases in AD. The results of this analysis suggest multiple insults appear as distinct patterns of white matter diffusion abnormalities in the adult brain. Neurotoxic insults from the significant lead burden the participants experienced throughout childhood affect neural elements differently and may be related to the developmental stage of myelination at periods of exposure. This study indicates that childhood lead exposure is associated with a significant and persistent impact on white matter microstructure as quantified with diffusivity changes suggestive of altered myelination and axonal integrity.

Decreased brain volume in adults with childhood lead exposure

BACKGROUND

Although environmental lead exposure is associated with significant deficits in cognition, executive functions, social behaviors, and motor abilities, the neuroanatomical basis for these impairments remains poorly understood. In this study, we examined the relationship between childhood lead exposure and adult brain volume using magnetic resonance imaging (MRI). We also explored how volume changes correlate with historic neuropsychological assessments.

METHODS AND FINDINGS

Volumetric analyses of whole brain MRI data revealed significant decreases in brain volume associated with childhood blood lead concentrations. Using conservative, minimum contiguous cluster size and statistical criteria (700 voxels, unadjusted p < 0.001), approximately 1.2% of the total gray matter was significantly and inversely associated with mean childhood blood lead concentration. The most affected regions included frontal gray matter, specifically the anterior cingulate cortex (ACC). Areas of lead-associated gray matter volume loss were much larger and more significant in men than women. We found that fine motor factor scores positively correlated with gray matter volume in the cerebellar hemispheres; adding blood lead concentrations as a variable to the model attenuated this correlation.

CONCLUSIONS

Childhood lead exposure is associated with region-specific reductions in adult gray matter volume. Affected regions include the portions of the prefrontal cortex and ACC responsible for executive functions, mood regulation, and decision-making. These neuroanatomical findings were more pronounced for males, suggesting that lead-related atrophic changes have a disparate impact across sexes. This analysis suggests that adverse cognitive and behavioral outcomes may be related to lead's effect on brain development producing persistent alterations in structure. Using a simple model, we found that blood lead concentration mediates brain volume and fine motor function.

Pre- and posttreatment MR imaging findings in lead encephalopathy

A 41-year-old man suspected of having lead poisoning was evaluated with MR imaging before and after British antilewisite therapy. The MR imaging findings showed bilateral symmetric involvement of the occipital lobe, affecting predominantly the gray-white matter junction and the subcortical white matter. A right cerebellar lesion was noted, with focal hyperintensities involving the gray-white matter. Similar lesions were seen in the temporal, parietal, and frontal regions. These lesions resolved after chelation therapy.

The Effects of Early Lead Exposure on the Brains of Adult Rhesus Monkeys: A Volumetric MRI Study

Little is known about direct effects of exposure to lead on central nervous system development. We conducted volumetric MRI studies in three groups of 17-year-old rhesus monkeys: (1) a group exposed to lead throughout gestation (n = 3), (2) a group exposed to lead through breast milk from birth to weaning (n = 4), and (3) a group not exposed to lead (n = 8). All fifteen monkeys were treated essentially identically since birth with the exception of lead exposure. The three-dimensional MRI images were segmented on a computer workstation using pre-tested manual and semi-automated algorithms to generate brain volumes for white matter, gray matter, cerebrospinal fluid, and component brain structures. The three groups differed significantly in the adjusted (for total brain size) volumes of the right cerebral white matter and the lateral ventricles. A significant reduction was noted in right cerebral white matter in prenatally exposed monkeys as compared to controls (p = 0.045). A similar reduction was detected in the white matter of the contralateral hemisphere; however, this difference did not achieve statistical significance (p = 0.143). Prenatally exposed monkeys also had larger right (p = 0.027) and left (p = 0.040) lateral ventricles. Depending on the timing of exposure during development, lead may exhibit differential effects with resultant life-long alterations in brain architecture.

Lead encephalopathy: CT and MR findings

Lead is toxic to many organ systems, among them bone marrow, muscles, kidneys, endocrine glands, joints, and nervous system. Encephalopathy is a rare but severe complication of lead poisoning. Lead toxicity is much less common in adults. Adult lead poisoning results primarily from exposure by inhalation in the workplace. In this report, two cases of adult toxic encephalopathy due to lead poisoning are presented with CT and MR findings.