Abstract Details

Title Mercury-induced Neurotoxicity and Neuroinflammation: A Role for Heavy Metal Intoxication in the Pathogenesis of Autoimmune Diseases of the Nervous System

Topic Autoimmune Neurology

Presentation(s) P1 - Poster Session 1 (12:00 PM-1:00 PM)

Poster/Presentation
Number 15-001

Objective Mercury is a known environmental toxin of high risk to public health. It is a heavy metal that exists in elemental, organic, and inorganic forms. Though mercury toxicity commonly affects the nervous system, diagnosis remains a challenge. The pharmacokinetics are complex, the clinical presentation is variable, and prognosis remains uncertain. Herein, we describe the clinical course, diagnostic evaluation, and treatment of two cases of organic mercury intoxication.

Background A 19-year-old female and her 17-year-old brother presented with a 10-week history of severe back and abdominal pain, muscle spasms, migratory myalgias, arthralgias, paresthesias, constipation, weight loss, night sweats, blurry vision, and diffuse maculopapular rash. An extensive infectious workup for bacterial, viral, and parasitic zoonoses was negative. An MRI of the entire neuraxis and nerve conduction studies were unremarkable. Electromyography revealed myokymic discharges in rhythmic to semi-rhythmic bursts of doublets, triplets, and quadruplets, suggestive of neuromyotonia. Toxicology studies showed an elevated urine mercury concentration.

Design/Methods Not applicable.

Results Despite treatment with oral dimercaptosuccinic acid (DMSA), selenium, and N-acetylcysteine, the patients remained symptomatic and developed insomnia, autonomic dysfunction, seizure-like activity, and behavioral disturbances. Based on clinical and electrodiagnostic evidence of peripheral, autonomic, and central nervous system involvement, a diagnosis of acquired Morvan syndrome was suspected. Anti-VGKC, anti-LGI1, anti-Caspr2, anti-GAD, and anti-N-type calcium antibodies were positive in the serum. Treatment with a combination of IVIG and rituximab led to a dramatic improvement in symptoms.

Conclusions Morvan syndrome in association with mercury toxicity is extremely rare, with only a few cases reported in the literature to date. Though toxic effects of mercury on the nervous system are commonly described, the pathophysiologic association between heavy metal toxicity and immune-mediated disease remains unclear. Prompt recognition of secondary autoimmune phenomena and timely initiation of treatment is key to avoiding prolonged hospitalizations and reducing morbidity from associated complications.

Authors/Disclosures
Ekta G. Shah, DO, MS (Washington University in St. Louis) PRESENTER	No disclosure on file
Ian J. Butler, MD (UTHealth McGovern Medical School)	No disclosure on file
Pedro Mancias, MD (UTHSC At Houston)	No disclosure on file
Kelly L. Block, DO	Dr. Block has nothing to disclose.
Carlos A. Perez, MD (University of Texas Health Science Center At Houston)	Dr. Perez has received personal compensation for serving as an employee of Sanofi-Genzyme.