Developmental Regression, Hypertension, and Pink Extremities in Childhood Mercury Poisoning

Mercury poisoning is very rarely described in children.[1] [2] If the source of intoxication is not reported in history, the idea will never spring to mind. The presence of encephalopathy,[3] however, in association with severe and unusual arterial hypertension and pink coloring of soles and palms, must prompt us to explore this differential even if the source of the intoxication is not initially reported.

Our described case was reviewed for 2 months and in two different hospitals before mercury poisoning was suspected. After this, suspicion was shared with parents, the child's mother remembered that the onset of symptoms a month and a half before while a sphygmomanometer containing mercury had been broken in the girl's room and removed only after 2 days. The 14-month-old child presented at examination with a previous history of normal development and reported history of symptoms of behavioral regression around 12 months of age. Within a few weeks, she had lost social smiling and autonomous walking and her playing strategies had regressed, so as her interaction skills. She was drowsy and in bed all day, going from sleep to a state of inactive wake, with poor appetite, poor motor activity, and poor language. She refused to play, sit, or walk, although she had no evidence of focal motor deficits. She also began to show hypertension and a desquamative and itchy erythema to the palms and soles of her hands and feet that had acquired a pink coloring. Electroencephalography (EEG) recordings performed in the hospital, where she had previously been reviewed in, showed either normal activity or subtle posterior slow transients. The finding of the clinical picture was unchanged when reviewed by us compared with the one reported during the first admission. We undertook a further EEG that showed irregular high-voltage diffuse delta activity when the child was awake and not stimulated ([Fig. 1]) and also showed theta-β desynchronization when the child was sitting up and aroused. Sleep was also disturbed with a lack of appropriate non rapid eye movement sleep N1- and N2-phase electrical markers and poorly represented slow activity (N3 phase). Virological and immunological investigations and brain magnetic resonance imaging (MRI) were normal. Skin manifestations persisted and feet and hands were pink and itchy ([Fig. 1]).

Fig. 1 (A) Quiet wakefulness, EEG shows paroxysmal theta-delta bursts and a slowing down of background activity. (B) When the child is stimulated, brain activity becomes desynchronized without paroxysms. (C) Typical pink soles of the feet. EEG parameters: Low frequency filter 1,600 Hz, High frequency filter 70 Hz, sensitivity 100 µV/cm, and speed 15 mm/sec. EEG, electroencephalography.

Moreover, blood pressure was so high that it required the contemporary use of three antihypertensive drugs. This was accompanied by initial signs of liver damage and a relative increase in urinary catecholamine. An abdominal computed tomography performed to rule out arterial kidney stenosis was negative. Routine cerebrospinal fluid screening was normal. Mercury blood and urine screening showed values of 2.6 (normal value: 0.13–1.19) and 4.7 (normal value: 0.10–5.0) μg/L, respectively, confirming exposure. In addition, both parents resulted equally exposed albeit asymptomatic. Spontaneous improvement of symptoms was taking place due to repeated hospital admissions, the child had often been away from her apartment. Environmental screening of the girl's home was performed and confirmed the presence of mercury. By monitoring mercury values, we observed a progressive reduction of mercury in her blood and a progressive increase in her urine ([Fig. 2]). It was not felt that there was an indication for chelation treatment.

Fig. 2 Mercury values of blood and urine in the child (µg/L). The arrows indicate when symptoms of the child disappeared and corresponding mercury value of blood and urine respectively of 1.5 and 14.2 μg/L to 2 months from the suspected poisoning and removal of exposure to mercury.

If an object containing mercury is broken, one should always make sure that the metal is completely reclaimed. Mercury is highly volatile and even small amounts can be inhaled and absorbed, giving way to symptoms.[4] [5] In our case, even low blood values resulted in severe signs and symptoms. Behavioral regression, EEG slowing, arterial hypertension, and pink palms and soles are elements that, if taken together, should be considered as highly suggestive of mercury poisoning. Timely diagnosis is important to remove the cause of intoxication.

Publikationsverlauf

Eingereicht: 29. September 2021

Angenommen: 23. Februar 2022

Accepted Manuscript online:
04. März 2022

Artikel online veröffentlicht:
28. August 2022

• References

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