Diagnostic Considerations

Mercury poisoning can be misdiagnosed because of the insidious onset and nonspecific signs and symptoms. Without a complete history, mercury toxicity, especially in elderly individuals, can be misdiagnosed as Parkinson disease, senile dementia, metabolic encephalopathy, depression, or Alzheimer disease.

Testing for mercury exposure is warranted if examination findings are consistent with Minamata disease, particularly if the disease occurs in multiple patients without clear etiology. This is especially true in populations in whom fish is a major part of their diet.

Consider mercury intoxication in the differential diagnosis when unexplained neuropsychiatric disturbances are coupled with renal abnormalities.

Conditions to consider in the differential diagnosis of mercury toxicity include the following:

Adverse effects of therapeutic medication (eg, lithium, theophylline, phenytoin)
Alzheimer disease
Cerebellar degenerative disease or tumor
Delayed neuropsychiatric sequela of carbon monoxide poisoning
Ethanol or sedative hypnotic drug withdrawal
Lacunar infarction
Metabolic encephalopathy
Parkinson disease
Senile dementia

Conditions to consider in the differential diagnosis of inorganic mercury toxicity (mercury salts) include the following:

Acid ingestion
Alkali ingestion
Arsenic toxicity
Iron toxicity
Phosphorus toxicity
Similar to the causes of acute gastroenteritis

Conditions to consider in the differential diagnosis of organic mercury toxicity in neonates include the following:

Cerebral palsy
Intrauterine hypoxia
Teratogenic effects in the embryo

Differential Diagnoses

Acute Disseminated Encephalomyelitis
Amyotrophic Lateral Sclerosis in Physical Medicine and Rehabilitation
Ataxia with Identified Genetic and Biochemical Defects
Benign Positional Vertigo in Emergency Medicine
Brainstem Gliomas
Dementia in Motor Neuron Disease
Diabetic Neuropathy
Dizziness, Vertigo, and Imbalance
Essential Tremor
Neurological Manifestations of Arsenic Intoxication

Workup

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Media Gallery

This is a 1-view, abdominal, upright radiograph in a male patient who intentionally ingested 8 ounces of elemental mercury. Notice how the mercury outlines the large intestine from ascending to descending. Image courtesy of Fred P. Harchelroad, MD, and Ferdinando L. Mirarchi, DO.
Patient with intentional ingestion of mercury from blood pressure instrument. Note how mercury beads can be seen deposited in lung fields. Image courtesy of Shuchi Vyas, MD.

of 2

Author

David A Olson, MD Clinical Neurologist, Dekalb Neurology Group, Decatur, Georgia

David A Olson, MD is a member of the following medical societies: American Academy of Neurology

Disclosure: Nothing to disclose.

Specialty Editor Board

Nicholas Lorenzo, MD, CPE, MHCM, FAAPL Co-Founder and Former Chief Publishing Officer, eMedicine and eMedicine Health, Founding Editor-in-Chief, eMedicine Neurology; Founder and Former Chairman and CEO, Pearlsreview; Founder and CEO/CMO, PHLT Consultants; Former Chief Medical Officer, MeMD Inc

Nicholas Lorenzo, MD, CPE, MHCM, FAAPL is a member of the following medical societies: Alpha Omega Alpha, American Academy of Neurology, American Association for Physician Leadership

Disclosure: Nothing to disclose.

Chief Editor

Tarakad S Ramachandran, MBBS, MBA, MPH, FAAN, FACP, FAHA, FRCP, FRCPC, FRS, LRCP, MRCP, MRCS † Professor Emeritus of Neurology and Psychiatry, Clinical Professor of Medicine, Clinical Professor of Family Medicine, Clinical Professor of Neurosurgery, State University of New York Upstate Medical University; Neuroscience Director, Department of Neurology, Crouse Irving Memorial Hospital

Tarakad S Ramachandran, MBBS, MBA, MPH, FAAN, FACP, FAHA, FRCP, FRCPC, FRS, LRCP, MRCP, MRCS is a member of the following medical societies: American Academy of Neurology, American Academy of Pain Medicine, American College of Forensic Examiners Institute, American College of International Physicians, American College of Physicians, American Heart Association, American Stroke Association, National Association of Managed Care Physicians, Royal College of Physicians, Royal College of Physicians and Surgeons of Canada, Royal College of Surgeons of England, Royal Society of Medicine

Disclosure: Nothing to disclose.

Acknowledgements

Barry E Brenner, MD, PhD, FACEP Professor of Emergency Medicine, Professor of Internal Medicine, Program Director, Emergency Medicine, University Hospitals, Case Medical Center

Barry E Brenner, MD, PhD, FACEP is a member of the following medical societies: Alpha Omega Alpha, American Academy of Emergency Medicine, American College of Chest Physicians, American College of Emergency Physicians, American College of Physicians, American Heart Association, American Thoracic Society, Arkansas Medical Society, New York Academy of Medicine, New York AcademyofSciences, and Society for Academic Emergency Medicine

Disclosure: Nothing to disclose.

Timothy E Corden, MD Associate Professor of Pediatrics, Co-Director, Policy Core, Injury Research Center, Medical College of Wisconsin; Associate Director, PICU, Children's Hospital of Wisconsin

Timothy E Corden, MD is a member of the following medical societies: American Academy of Pediatrics, Phi Beta Kappa, Society of Critical Care Medicine, and Wisconsin Medical Society

Disclosure: Nothing to disclose.

Barry M Diner, MD, MPH, FACEP Assistant Clinical Professor, Department of Emergency Medicine, Emory University School of Medicine; Attending Physician, St Luke's Episcopal Hospital, Houston, Texas

Barry M Diner, MD, MPH, FACEP is a member of the following medical societies: American College of Emergency Physicians

Disclosure: Nothing to disclose.

Fred Harchelroad, MD, FACMT, FAAEM, FACEP Chair, Department of Emergency Medicine, Director of Medical Toxicology, Allegheny General Hospital; Associate Professor, Department of Emergency Medicine, Drexel University College of Medicine

Disclosure: Nothing to disclose.

Michael E Mullins, MD Assistant Professor, Department of Emergency Medicine, Washington University School of Medicine

Michael E Mullins, MD is a member of the following medical societies: American Academy of Clinical Toxicology and American College of Emergency Physicians

Disclosure: Johnson & Johnson stock ownership None; Savient Pharmaceuticals stock ownership None

Francisco Talavera, PharmD, PhD Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Medscape Salary Employment

David K Tan, MD, EMT-T, FAAEM Assistant Professor and Chief, EMS Section, Division of Emergency Medicine, Medical Director, Washington University EMS, Washington University in St Louis School of Medicine

David K Tan, MD, EMT-T, FAAEM is a member of the following medical societies: American Academy of Emergency Medicine and National Association of EMS Physicians

Disclosure: Nothing to disclose.

Asim Tarabar, MD Assistant Professor, Director, Medical Toxicology, Department of Emergency Medicine, Yale University School of Medicine; Consulting Staff, Department of Emergency Medicine, Yale-New Haven Hospital

Disclosure: Nothing to disclose.

Jeffrey R Tucker, MD Assistant Professor, Department of Pediatrics, Division of Emergency Medicine, University of Connecticut and Connecticut Children's Medical Center

Disclosure: Merck Salary Employment

John T VanDeVoort, PharmD Regional Director of Pharmacy, Sacred Heart & St. Joseph's Hospitals

John T VanDeVoort, PharmD is a member of the following medical societies: American Society of Health-System Pharmacists

Disclosure: Nothing to disclose.

Mary L Windle, PharmD, Adjunct Associate Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Nothing to disclose.