Tardily accelerated neurologic deterioration in two-step thallium intoxication

The document reported a case of a 16-year-old who experienced two-step thallium intoxication, leading to delayed and accelerated neurologic deterioration. Initially, the patient developed neurologic symptoms such as visual loss, myalgia, and leg weakness 40 days after acute gastrointestinal symptoms and alopecia following the first ingestion. After a second ingestion 52 days later, the neurologic symptoms worsened rapidly without gastrointestinal or cutaneous symptoms. MRI showed bilateral optic nerve atrophy, and nerve conduction studies indicated severe peripheral neuropathies in the legs. Thallium intoxication was confirmed through increased urine thallium levels. While most neurologic symptoms improved over two years, visual loss remained. The case highlighted that divisional thallium intoxication could cause progressive optic and peripheral neuropathy without typical gastrointestinal or cutaneous symptoms, likely due to thallium's prolonged presence in the nervous system.