Clinical Spectrum of Mercury Poisoning in India: Case-series from a Poison Control Center

Background: Mercury is a naturally occurring heavy metal that finds wide application in industrial and household settings. It exists in three chemical forms which include elemental (Hg0 ), inorganic mercurous (Hg+) or mercuric (Hg++) salts, and organic compounds. All forms are highly toxic, particularly to the nervous, gastrointestinal, and renal systems. Common circumstances of exposure include recreational substance use, suicide or homicide attempts, occupational hazards, traditional medicines, and endemic food ingestions as witnessed in the public health disasters in Minamata Bay, Japan and in Iraq. Poisoning can result in death or long-term disabilities. Clinical manifestations vary with chemical form, dose, rate, and route of exposure. Aims and objectives: To summarize the incidence of mercury poisoning encountered at an Indian Poison Center and use three cases to highlight the marked variations observed in clinical manifestations and long-term outcomes among poisoned patients based on differences in chemical forms and routes of exposure to mercury. Materials and methods: A structured retrospective review of the enquiry-database of the Poison Information Center and medical records of patients admitted between August 2019 and August 2021 in a tertiary care referral center was performed. All patients with reported exposure to mercury were identified. We analyzed clinical data and laboratory investigations which included heavy metal (arsenic, mercury, and lead) estimation in whole blood and urine samples. Additionally, selected patients were screened for serum voltage-gated potassium ion channels (VGKC)— contactin-associated protein-like 2 (CASPR2) antibodies. Three cases with a classical presentation were selected for detailed case description. Results: Twenty-two cases were identified between August 2019 and August 2021. Twenty (91%) were acute exposures while two (9%) were chronic. Of these, three representative cases have been discussed in detail. Case 1 is a 3.5-year-old girl who was brought to the emergency department with suspected elemental-mercury ingestion after biting a thermometer. Clinical examination was unremarkable. Chest and abdominal radiography revealed radiodense material in the stomach. Subsequent serial radiographs documented distal intestinal transit of the radiodense material. The child remained asymptomatic. This case exemplifies the largely nontoxic nature of elemental mercury ingestion as it is usually not absorbed from the gastrointestinal tract. Case 2 is a 27-year-old lady who presented with multiple linear nodules over both upper limbs after receiving a red intravenous injection for anemia. Imaging revealed metallic-density deposits in viscera and bones. Nodular biopsy was suggestive of mercury granulomas. A 24-hour urine mercury levels were elevated. She was advised chelation therapy with oral dimercaptosuccinic acid (DMSA). Case 3 is a 22-year-old lady who presented with acrodynia, neuromyotonia, tremulousness, postural giddiness, tachycardia, and hypertension for 2 months, associated with intractable, diffuse burning pain over the buttocks and both lower limbs, 1 month after completing a 3-week course of traditional medications for polycystic ovarian syndrome. A 24-hour urine normetanephrine levels and mercury levels were markedly elevated. Serum anti-VGKC antibodies were present. She was treated with glucocorticoids and oral DMSA with a favorable clinical response. Conclusions: The clinical manifestations of mercury toxicity are highly variable depending on the source, form, and route of mercury exposure and are related to its toxicokinetics.

Chest physiotherapy in pediatric practice.

Chest physiotherapy (CPT) in children is generally considered as a separate and specialized treatment modality that should be rendered only by a physiotherapist. Actually this is not difficult if one has a proper understanding of the basic concept and principle behind the maneuver. This article aims at making CPT simple, so that it could be incorporated in routine pediatric practice for managing respiratory ailments.

Bronchoscopist talks to you.

Fiberoptic bronchoscopy (FBS) is an important entry in the armamentarium of procedures listed in management of respiratory problems. It is a simple and a safe procedure. FBS has a great scope for diagnosis as well as therapy in pediatric respiratory illnesses. This article gives a practical overview of FBS in pediatric practice.

Fibrodysplasia ossificans progressiva.

A 2-year-old boy presented with low-grade fever and multiple progressive painful swellings over upper dorsal trunk and supraclavicular region with progressive stiffening of skin for the last 2 months. Examination revealed dysmorphic face, proximally placed thumb and bilateral hallux valgus. Hence, a diagnosis of Fibrodysplasia Ossificans Progressiva was entertained.

Empyema thoracis.

Parapneumonic effusion and empyema thoracis remains a significant source of morbidity in children, though the overall incidence of empyema thoracis has decreased in the past two decades. These conditions pose a dilemma regarding evaluation and treatment for the treating physician. This article discusses the practical strategies in the management of empyema thoracis in children.

Drug therapy of childhood asthma.

Drug therapy is used to prevent and control asthma, and also to reduce the frequency and severity of its exacerbations, and reverse airflow obstruction. Asthma medications are thus categorized into two general classes--bronchodilators (relievers) and anti-inflammatory drugs (preventers). Short acting beta2-agonists is the therapy of choice for relief of acute symptoms and prevention of exercise induced bronchospasm (EIB). Corticosteroids are the most potent and effective anti-inflammatory medication currently available. Inhaled form is used in the long-term control of asthma. Systemic corticosteroids are used to gain prompt control of the disease when initiating long-term therapy. Long acting bronchodilator used concomitantly with anti-inflammatory medications for long-term control of symptoms, especially nocturnal symptoms. Ipratropium bromide may provide some additive benefit to inhaled beta2-agonists in severe exacerbations. Sustained release theophylline is a mild to moderate bronchodilator used principally as adjuvant to inhaled corticosteroids for prevention of nocturnal asthma. Leukotriene modifiers may be considered as an alternative therapy to inhaled corticosteroids or cromolyn or nedocromil.

Flexible fiberoptic bronchoscopy.

The value of flexible fiberoptic bronchoscopy in children are increasing day by day, but still underutilized even in many advanced institutions. 630 Fiberoptic bronchoscopy procedures under local anaesthesia were performed for various clinical conditions for diagnosis and therapy. Nasal route is preferred than oral route. Therapeutic indications are more in children than adults. Nearly one third of children with collapse, consolidation have shown radiological clearance after repeated bronchoscopy.

Childhood asthma--advances in pathogenesis.

Increase in morbidity and mortality of asthmatics in the world is a cause of concern. Many researchers have described various aspects of etiopathogenesis which has thrown light on the better understanding of asthma. Our experience with nearly 3 lakhs of asthmatic children, over a period of twenty-five years and our studies in Asthma clinic of ICH & HC, Madras generated new ideas to propose a hypothesis on etiopathogenesis of asthma. "Asthma is a disease caused by a specific infective agent in a genetically predisposed individual resulting in altered cellular response initially leading to hyperactive bronchial tree which on exposure to various aggravating factors manifest clinically as recurrent cough, dyspnoea and wheeze". Category of wheezers who manifest asthma is also discussed.

Flexible fibreoptic bronchoscopy in 582 children--value of route, sedation and local anesthetic.

The value of route, sedation and local anesthetic was studied in 582 children aged 50 days to 12 years who were subjected to flexible fibreoptic bronchoscopy (FFBS) at the Institutes of Child Health, Madras, during January 1989 to July 1993. Pentax 3.5 mm and Olympus 4.9 mm bronchoscopes were used. Bronchoscopy was performed with sedation and/or local anesthetic through nasal/oral route after premedication with atropine. It was successfully carried out through nasal route in 97.4% and only in 40% through oral route. As nasal route proved advantageous, the oral route was abandoned.

Tuberculous disease in a pediatric referral centre: 16 years experience.

Children with evidence of tuberculous disease registered at the TB Clinic, Institute of Child Health, Madras during the years 1977 to 1992 were analyzed. Progressive primary complex, is the commonest thoracic form of tuberculosis while tuberculous meningitis is the commonest extra thoracic form. The overall prevalence of various clinical forms of tuberculosis has decreased over the last 16 years. There is an increasing trend in the prevalence of progressive primary complex among the BCG vaccinated group. The prevalence of pleural effusion, bone tuberculosis and abdominal tuberculosis is almost same over the last 16 years and is more in the BCG non vaccinated children. In tuberculous adenitis there is no significant variation between the two groups. The occurrence of tuberculous meningitis is in the ratio of 1:3 among BCG vaccinated and non-BCG vaccinated children. Though the prevalence of miliary tuberculosis is negligible, it is significantly more in BCG non-vaccinated children. There is a tendency for slight decrease in overall mortality due to tuberculosis in the last 10 years but the mortality due to tuberculous meningitis continues to be the same over the past 16 years.

Pulmonary cavitatory tuberculosis in children.

This study was undertaken to analyse children with pulmonary cavitatory tuberculosis which is a rare and infectious condition. The pretreatment characteristics, course and response to three different anti-tuberculous regimes in 27 children with cavitary pulmonary lesions registered at the TB Clinic, Institute of Child Health, are described. Male:Female ratio was 1.2:4. Thirty per cent of affected children were below 3 years of age and had predominant lower lobe involvement whereas in older children the upper lobes were affected. Eighty five per cent of children had definite history of contact with an adult with tuberculosis. Tuberculin test was positive in 70% of children. Cavitary lesion were observed in the right lung in 66% of cases. Follow up and surveillance was carried out in 23 children who completed the anti tuberculous treatment. Regimes with isoniazid, rifampicin, pyrazinamide and streptomycin were given to different groups. Response and compliance was also monitored. Eleven out of 23 children had persistence of radiological lesions even after completion of 9 months of therapy. Inclusion of streptomycin with 2 or 3 bactericidal drugs in the intensive phase showed a better response.