• Enrong Ran, Maohe Wang, Yanxia Yi, Mei Feng, and Yuanjun Liu.
• Department of Nephrology.
• Medicine (Baltimore). 2021 Aug 13; 100 (32): e26910e26910.

RationaleAcquired neuromyotonia syndrome is a rare form of peripheral nerve hyperexcitability syndrome. It is characterized by spontaneous and continuous muscle contractions. Acquired neuromyotonia syndrome is mainly observed in patients with autoimmune diseases or tumors, but it is a rare neurological clinical manifestation in patients with mercury poisoning.Patient ConcernsA 56-year-old woman presented with continuous and involuntary muscle twitching in her legs for 2 months; it was accompanied by a burning sensation in the lower limbs, insomnia, fatigue, and night sweats. These symptoms did not disappear during sleep.DiagnosesToxicological blood analysis via atomic fluorescence spectrometry revealed that the level of mercury was 0.07 μmol/L (normal level: <0.05 μmol/L). Her urinary mercury level measured using the cold atomic absorption method was 217.50 μmol/mol creatinine, which was considerably higher than the reference range (0-2.25 μmol/mol creatinine for people not in contact with mercury, 0-20 μmol/mol creatinine following long-term exposure). Upon further testing, a high level of mercury (10,572 mg/kg) was detected in the patient's cream. Accordingly, this patient was diagnosed with mercury poisoning.InterventionsTreatment with 2,3-dimercapto-1-propanesulfonic acid (DMPS) was initiated. Her urinary mercury level decreased to 9.67 μmol/mol creatinine, and her neuromyotonia syndrome and hyponatremia were relieved, with urine protein completely disappearing after 3 months of treatment.OutcomesAfter DMPS treatment, the clinical manifestations of the nervous system disappeared and electrolyte parameters returned to normal levels.LessonsAcquired neuromyotonia syndrome is a rare disorder caused by the hyperexcitability of peripheral nerves, resulting in spontaneous and continuous muscle contraction. Mercury poisoning should be considered in patients with neuromyotonia syndrome. Early detection of mercury poisoning can prevent unnecessary examinations and treatments.Copyright © 2021 the Author(s). Published by Wolters Kluwer Health, Inc.

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