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Toxic Encephalopathy

Toxic encephalopathy is a distinct clinical entity characterized by brain injury following exposure to a toxic substance, predominantly organic solvents, heavy metals, and other occupational compounds. Exposure in the work setting is the primary risk factor, and the clinical presentation depends on the dose and potency of the substance. A thorough clinical workup, with an emphasis on patient history, is the key step in making the diagnosis.


Toxic encephalopathy is a term denoting brain injury and potentially life-threatening central nervous system (CNS) damage that can be induced by various toxic compounds. In the literature, the majority of patients suffer from this condition as a result of exposure to organic solvents or other lipophilic neurotoxins in the occupational setting [1] [2] [3], whereas several gases, chemotherapeutic drugs (such as L-asparagine, methotrexate), bacterial neurotoxins, recreational drugs, and ethanol can all be the underlying cause [4] [5] [6] [7]. Signs and symptoms of toxic encephalopathy appear in proportion to the amount of toxin that reaches the CNS, as well as the rate at which it damages the brain, thus a broad classification into acute and chronic forms has been made [1] [2] [3] [6]:

  • Acute toxic encephalopathy is characterized by the development of acute alterations in consciousness, euphoria, seizures, stupor and in most severe cases, coma and even sudden death [1] [7]. Symptoms appear within days or weeks after the initial toxin exposure. Some of the most important toxins are gasses (such as carbon monoxide (CO), cyanide, and hydrogen sulfide) and heavy metals, both inorganic and organic (mercury, lead, and tin) [1] [2].
  • Chronic toxic encephalopathy, on the other hand, causes a slowly progressive cognitive, intellectual, emotional and physical decline due to chronic exposure (months or even years) to a neurotoxic substance [1] [3] [6]. The severity of toxicity is divided into three stages. Initial symptoms (stage I) include mood changes and trouble concentrating, while attention and memory deficits, together with impaired learning, are typically encountered in stages II and III when a severe decline in psychomotor function is observed [1] [2] [3] [6].

In addition, toxic encephalopathy can also manifest through a specific subset of symptoms, such as cerebellar dysfunction (gait disturbances, ataxia, nystagmus, etc.) in methyl mercury (known as Minamata disease), methyl bromide, or organic tin toxicity, whereas chronic exposure to manganese produces Parkinson-like complaints accompanied by psychosis and various other neuropsychiatric symptoms, as it greatly interferes with the function of globus pallidus [1].

  • Persistent symptoms developed, an average, 16 years after exposure onset and included impaired memory (38), altered mood (21), imbalance (18), and headache (17).[ncbi.nlm.nih.gov]
  • The main clinical manifestation is headache accompanied by intracranial hypertension.[ncbi.nlm.nih.gov]
  • All were female workers who had been in contact with DCE and subsequently had had seizures or symptoms of intracranial hypertension, including headache, nausea, and vomiting.[ncbi.nlm.nih.gov]
  • In particular they suffered less from fatigue, headache, and dizziness. When diagnosed they had an average of seven out of ten typical neurasthenic symptoms included in the toxic encephalopathy syndrome.[ncbi.nlm.nih.gov]
  • Slight improvements with regard to headache and dizziness were reported by some. However, the neurological status, the neuropsychological impairment, and the cerebral atrophy, did not change significantly.[ncbi.nlm.nih.gov]
  • Encephalopathy causes confusion, abnormal thought processes, poor memory, hallucinations, and psychotic thinking.[healthcare-online.org]
  • Alcohol intoxication can cause __ in the nervous system Euphoria, ataxia, confusion, coma, death Alcohol withdrawal can cause __ in the nervous system Delirium tremens (Tremor, hallucinations, confusion, autonomic features); Seizures within 48 hours Wernicke's[quizlet.com]
  • Wernicke's encephalopathy a neurological disorder characterized by confusion, apathy, drowsiness, ataxia of gait, nystagmus, and ophthalmoplegia; it is due to thiamine deficiency, usually from chronic alcohol abuse.[medical-dictionary.thefreedictionary.com]
  • The clinical presentation of toxic leukoencephalopathy is extremely variable, ranging from minor cognitive impairment, easily confused with psychiatric illnesses, to severe neurological dysfunction.[radiopaedia.org]
  • He was intubated and spent 4 days in intensive care; on extubation he was confused and paranoid but was discharged after 10 days in hospital ( day 12 ), ‘99% back to normal’. Figure 1 Time line depicting the patient's clinical status.[pn.bmj.com]
  • Two patients lost their consciousness, while two patients had typical extrapyramidal tremor symptoms. Further neurological examination revealed various degrees of muscle strength impairment in these patients.[ncbi.nlm.nih.gov]
  • […] progressing to global dementia. hepatic encephalopathy a condition, usually occurring secondary to advanced liver disease, marked by disturbances of consciousness that may progress to deep coma (hepatic coma), psychiatric changes of varying degree, flapping tremor[medical-dictionary.thefreedictionary.com]
  • […] encephalopathy is: Impaired ATTENTION (early finding in delirium, late finding in dementia) Symptoms of encephalopathy include: Hallucinations, delusions, agitation or lethargy; Irritation to light touch; Withdraw limbs unequally; Asterixis, myoclonus, tremor[quizlet.com]
  • Significant tremors were present at rest, which increased on intention. There was lack of co-ordination of rapid alternating movements. The rest of the physical exam was non-contributory.[ijri.org]
  • Other neurological symptoms may include myoclonus (involuntary twitching of a muscle or group of muscles), nystagmus (rapid, involuntary eye movement), tremor, muscle atrophy and weakness, dementia, seizures, and loss of ability to swallow or speak.[sites.google.com]
  • A toxic encephalopathy characterized by depressed level of consciousness, marked irritability, and ataxia developed in seven children, 5 years of age and younger, following administration of an antiemetic combination of pentobarbital and pyrilamine maleate[ncbi.nlm.nih.gov]
  • Need WIDE variations to change neuronal and glial dysfunction Because the brain is location-based, global disruption of metabolic homeostasis can result in: Behavior change, poor coordination, ataxia, confusion, seizures, stupor and coma; May be a lag[quizlet.com]
  • Wernicke's encephalopathy a neurological disorder characterized by confusion, apathy, drowsiness, ataxia of gait, nystagmus, and ophthalmoplegia; it is due to thiamine deficiency, usually from chronic alcohol abuse.[medical-dictionary.thefreedictionary.com]
  • In addition, toxic encephalopathy can also manifest through a specific subset of symptoms, such as cerebellar dysfunction (gait disturbances, ataxia, nystagmus, etc.) in methyl mercury (known as Minamata disease), methyl bromide, or organic tin toxicity[symptoma.com]
  • Other persistent neurologic sequelae include cerebellar ataxia, cognitive dysfunction, optic neuropathy, sensori-neural hearing loss and equilibrium disorders. The most common syndrome is multifocal CNS involvement.[ijri.org]
Personality Change
  • This exposure to toxic substances can cause a wide variety of symptoms, including: Visual problems Altered mental status Memory loss Personality changes, including increased irritability Difficulty concentrating Seizures Dizziness Fatigue Lightheadedness[keefelaw.com]
  • The symptoms of acute and chronic toxic encephalopathy do not resolve with cessation of exposure and can include memory loss , small personality changes/increased irritability, insidious onset of concentration difficulties, involuntary movements (parkinsonism[en.wikipedia.org]
  • Depending on the type and severity of encephalopathy, common neurological symptoms are progressive loss of memory and cognitive ability, subtle personality changes, inability to concentrate, lethargy, and progressive loss of consciousness.[sites.google.com]
  • changes such as passivity The presence of pathological findings in terms of an objective measurement A relation in time between exposure and the development of symptoms and signs No other obvious cause of the disease Effects on the central nervous system[experttoxicologist.com]
  • Such injury may lead to chronic depression or other personality changes that can result in life-changing consequences. Even infants and children can suffer encephalopathy.[medicinenet.com]


Acute toxic encephalopathy can often be fatal and brain damage caused by chronic exposure to neurotoxic substances may be irreversible in the absence of an early diagnosis, implying that clinical suspicion toward this syndrome must exist early on. Several reports have emphasized the vital role of a properly obtained patient history, which will assess the patient's occupancy, potential exposure to substances that may induce CNS-related symptoms (both in acute or chronic forms), as well as the course and progression of symptoms [1] [2] [3] [6]. Furthermore, a complete neurological examination, including the examination of cranial nerves, muscle tone, sensation, cerebellar function and evaluation of mental function should be subsequently conducted [1]. When there is a clinical suspicion of a primary CNS disorder, electroencephalography (EEG) and imaging studies of the brain must be carried out promptly [1] [3] [6]. Computed tomography (CT) is a useful initial method to rule out hemorrhage and other acute vascular incidents in the brain, while magnetic resonance imaging (MRI), magnetic resonance spectroscopy (MRS), functional MRI (fMRI), single photon emission tomography (SPECT) and positron emission tomography (PET) have all been described as important modalities in the evaluation of toxic encephalopathy [1] [3]. However, clinical criteria and findings obtained during history taking remain the cornerstone in diagnosing this condition.

  • The purpose of this project was to investigate the psychological and physical effects of training of body awareness and slow stretching on persons with chronic toxic encephalopathy (CTE).[ncbi.nlm.nih.gov]
  • The results suggest that motor slowness or low-level visual factors do not explain the poor performance of CSE patients in visual search tasks.[ncbi.nlm.nih.gov]
  • This is attributed to cumulative slow damage to the lipophilic nervous system.[dizziness-and-balance.com]
  • Called also mad cow disease . boxer's encephalopathy ( boxer's traumatic encephalopathy ) a syndrome due to cumulative head blows absorbed in the boxing ring, characterized by slowing of mental function, occasional bouts of confusion, and scattered memory[medical-dictionary.thefreedictionary.com]
Triphasic Waves
  • Furthermore, in these cases, other epileptic patterns in the form of spikes or sharp waves can also be detected. [39] However, triphasic waves are not specific only for hepatic encephalopathy.[neurologyindia.com]
Generalized Slowing
  • In the cases of encephalopathy, EEG can register generalized slowing or suppression of the EEG reactivity, loss of fast rhythm with occurrence of diffuse slow activity (theta and delta), presence of particular EEG patterns (focal or generalized), intermittent[neurologyindia.com]
Brain Edema
  • Death occurred following rapid neurological detoriation resulting in brain edema despite intensive treatment. Evidence of brain edema may be a prediction factor for death.[ncbi.nlm.nih.gov]
  • The cranial MRI showed extensive brain edema in either the subcortical white matter, bilateral globus pallidus, and cerebellar nucleus dendatus, or the cortices.[ncbi.nlm.nih.gov]
  • Links: brain tissue brain edema central nervous system hbot[oxy.hr]
  • The typical cranial CT/MR scan of DCE toxic encephalopathy shows extensive brain edema and diffuse, symmetric, abnormal signal intensities in the cerebellar dentate nucleus, basal ganglia, and white matter in the bilateral cerebral hemispheres.[ncbi.nlm.nih.gov]
  • The lack of seizure history, although sedative (ethanol) withdrawal must be kept in mind, and the lack of evidence of expected brain edema make this possibility unlikely.[dartmouth.edu]


  • Ninety-five patients started treatment, 84 patients had complete data. Treatment satisfaction was high.[ncbi.nlm.nih.gov]
  • All tremor symptoms were completely resolved in these patients at 30 min, 50 min, and 70 min following treatment, respectively. After the hemoperfusion treatment, encephalopathy symptoms of two patients had completely disappeared.[ncbi.nlm.nih.gov]
  • High-dose intravenous haloperidol for severe agitation has been reported as an effective and safe treatment option for the hospitalized patient.[ncbi.nlm.nih.gov]
  • Treatment [ edit ] Treatment is mainly for the symptoms that toxic encephalopathy brings upon victims, varying depending on how severe the case is. Diet changes and nutritional supplements may help some patients.[en.wikipedia.org]
  • Dehydrating agents and glucocorticoids are the primary treatments. With early diagnosis and prompt treatment, promising results and recovery can be achieved. Effective prevention is expected to reduce the incidence of DCE toxic encephalopathy.[ncbi.nlm.nih.gov]


  • Prognosis is usually good but fatalities and neurological deficits have been reported. We report here two infants with Margosa Oil poisoning presenting with encephalopathy.[ncbi.nlm.nih.gov]
  • The prognosis of chronic toxic encephalopathy in former house painters was examined in a prospective study with a two-year observation period.[ncbi.nlm.nih.gov]
  • Thirty-eight patients and 21 family members participated in a 1-day education scheduled with short lectures on the clinical examination of chronic toxic encephalopathy and the prognosis.[ncbi.nlm.nih.gov]
  • […] showed a loss of hearing, 7 patients complained about tinnitus, and all patients had a history of exposure to both noise and organic solvents, which had not been observed at the initial examination, but seemed to have serious implications for their prognosis[ncbi.nlm.nih.gov]
  • "What is the prognosis?" . Disorders A-Z . National Institute of Neurological Disorders and Stroke . 2007-02-12 . Retrieved 2009-04-12 . Upledger, John (July 2004). "Toxic Brain Injury(Encephalopathy)" . Massage Today . MPA . Retrieved 2009-04-12 .[en.wikipedia.org]


  • Other alternative etiological entities were also excluded. Our findings indicate that long-term exposure to organic solvents may lead to a chronic brain syndrome.[ncbi.nlm.nih.gov]
  • The quality of the EEG changes gives prognostic signs, but is of restricted value in establishing the etiology without the anamnestic data of salicylate ingestion.[ncbi.nlm.nih.gov]
  • Applicable To Toxic encephalitis Toxic metabolic encephalopathy Code First Code First Help Certain conditions have both an underlying etiology and multiple body system manifestations due to the underlying etiology.[icd10data.com]
  • Abstract A … More Psychosis possibly linked to an occupational disease: an e-patient’s participatory approach to consideration of etiologic factors Summary: The purpose of … More[psychoticdisorders.wordpress.com]
  • The etiologic agent is also the cause of new variant Creutzfeldt-Jakob disease .[medical-dictionary.thefreedictionary.com]


  • Seite 69 - Epidemiology is defined as the study of the distribution and determinants of health-related states or events in specified populations, and the application of this study to control of health problems. ‎[books.google.com]
  • To be able to properly diagnose toxic encephalopathy, the professor believes doctors must have a specialized knowledge of the central and peripheral nervous systems, as well as toxicology, epidemiology and occupational medicine in order to understand[gesinjuryattorneys.com]
  • These hydrocarbons have been confirmed in multiple human epidemiological studies to induce toxic encephalopathy among workers chronically exposed to levels near the OSHA PEL.[experttoxicologist.com]
  • "There is no epidemiological evidence or biological foundation for this allegation, yet I've seen a number of patients who believe that they have contracted Lyme disease from a sexual encounter," says Dr. Gary P.[sites.google.com]
  • […] and Demographic Data Demographic and epidemiological data suggest that encephalopathy correlates with age.[neurologyindia.com]
Sex distribution
Age distribution


  • Providing basic knowledge of medical terminology, anatomy and physiology, and pathophysiology of diseases and conditions.[icd-10online.com]
  • The Centers for Medicare & Medicaid Services (CMS) assigns a lower severity to the nonspecific behavioral diagnosis of delirium than for the pathophysiological diagnosis of encephalopathy.[icd10monitor.com]
  • Encephalopathy may also develop in primary infections of CNS, as well as due to the prolonged effect of anesthetics and sedatives. [13] Pathophysiological mechanisms Pathophysiological mechanisms of encephalopathy are not fully understood.[neurologyindia.com]


  • According to the results of the study, conditions at work places ought to be changed in such a way that harmful exposure can be prevented in the future.[ncbi.nlm.nih.gov]
  • Early recognition of encephalopathy and measures to prevent brain edema may improve patient outcome.[ncbi.nlm.nih.gov]
  • Active therapeutic measures including exchange transfusions are needed to prevent irreversible metabolic and pressure changes in the brain.[ncbi.nlm.nih.gov]
  • Effective prevention is expected to reduce the incidence of DCE toxic encephalopathy.[ncbi.nlm.nih.gov]
  • […] of Taxanes Induced Neurotoxicity in Operable Breast Cancer Completed NCT02468739 Phase 3 EC-T or TC plus GM1;EC-T or TC plus placebo 46 Calcium Gluconate and Magnesium Sulfate in Preventing Neurotoxicity in Patients With Colon Cancer or Rectal Cancer[malacards.org]



  1. Kim Y, Kim JW. Toxic Encephalopathy. Saf Health Work. 2012;3(4):243-256.
  2. Triebig G, Hallermann J. Survey of solvent related chronic encephalopathy as an occupational disease in European countries. Occupational and Environmental Medicine. 2001;58(9):575-581.
  3. Ramos A, Jardim SR, Silva-Filho JF. Solvent-related chronic toxic encephalopathy as a target in the worker's mental health research. An Acad Bras Cienc. 2004;76(4):757-769.
  4. Frantzeskaki F, Rizos M, Papathanassiou M, et al. L-asparaginase fatal toxic encephalopathy during consolidation treatment in an adult with acute lymphoblastic leukemia. Am J Case Rep. 2013;14:311-314.
  5. Müller J1, Kralovánszky J, Adleff V, et al. Toxic encephalopathy and delayed MTX clearance after high-dose methotrexate therapy in a child homozygous for the MTHFR C677T polymorphism. Anticancer Res. 2008;28(5B):3051-3054.
  6. Sørensen AM, Shapiro AU, Lund SP, Brun B, Rosenberg T, Lykke J. Toxic encephalopathy and noise-induced hearing loss. Noise Health. 2006;8(33):139-46.
  7. Pourakbari B, Mamishi S, Kohan L, et al. Lethal toxic encephalopathy due to childhood shigellosis or Ekiri syndrome. J Microbiol Immunol Infect. 2012;45(2):147-150.

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Last updated: 2018-06-22 03:50