A Catastrophic complication of Methemoglobinemia induced Status Epilepticus due to Pica for Printing Inks and Dyes: A Case Report

Aim & Background : Nitrobenzene ingestion is extremely toxic & leads to the clinical condition of methemoglobinemia. This disorder is characterized by severe oxidation of iron inside the Hb molecule and that makes it unable to bind with oxygen. Clinical presentation depends on the methaemoglobin (MeHb) levels in blood. This case report narrates an unusual case of acute nitrobenzene poisoning due to an intentional inhalation attempt to satisfy the strange craving for printing inks and dyes by a young boy. Case description : Patient presented with symptoms of poisoning (vomiting, seizures) and subsequently landed into cardiac arrest. After revival, patient continued presenting with repeated episodes of seizures & bradycardia. Patient was medically managed by cardio-pulmonary resuscitation followed by endotracheal intubation along with pharmacological management of atropine, levipill, propofol, phenytoin, midazolam, thiamine & methylene blue (antidote of choice). Conclusion : Exposure of nitrobenzene may occur either by inhalation or through skin, mostly as an occupational hazard. Differential diagnosis of methemoglobinemia crosses the treating physician’s mind with the manifestations of refractory hypoxia, cyanosis-saturation gap and dark brown blood. Definitive diagnosis is made using co-oximetry by detecting MeHb levels along with saturation gap. Treatment of acquired methemoglobinemia includes supportive care, symptomatic management and discontinuation of the offending agent. Definitive treatment involves the transformation of methaemoglobin to a non-oxidized state using methylene blue. Clinical significance : Rebound-methemoglobinemia may recur within 12 hours of drug administration, for which methylene blue may be administered through continuous infusion. Glucose-6-phosphate dehydrogenase (G6PD) deficiency is a relative contraindication for consideration of methylene blue as an antidote to MeHb, and these patients needs to be treated with high doses of vitamin C along with vitamin B2. In case of refractory methemoglobinemia, to all of the mentioned treatment alternatives, complete erythrocyte transfusion and hyperbaric chamber transplantation may be an option to be contemplated.