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626287 
Journal Article 
Cerebrospinal fluid analysis in fatal thallium poisoning: evidence for delayed distribution into the central nervous system 
Sharma, AN; Nelson, LS; Hoffman, RS 
2004 
Yes 
American Journal of Forensic Medicine and Pathology
ISSN: 0195-7910
EISSN: 1533-404X 
25 
156-158 
English 
The neurologic manifestations of thallium poisoning include a severely painful ascending peripheral neuropathy, autonomic dysfunction, cranial nerve abnormalities, and a toxic encephalopathy. Although thallium has a short half-life, these neurologic manifestations commonly progress, even as the blood concentration of thallium decreases. This suggests either that thallium persists in neuronal tissues or that it initiates an injury cascade that takes time to fully manifest. As the latter mechanism is consistent with many toxin exposures, the concept of a central nervous system reservoir for thallium is often discounted. A recent case provided a unique opportunity to evaluate this possibility.

A 48-year-old man was acutely and chronically thallium poisoned by his common-law wife. During his initial exposures, only gastrointestinal symptoms manifested. Following an acute ingestion, hospitalization was required. Over 3 days, his symptoms rapidly progressed from a severely painful neuropathy to slurred speech, ptosis, confusion, coma, respiratory insufficiency, and death. Because of considerations of alternative diagnoses, 2 lumbar punctures were performed, one on admission and another on the day of his death.

Serum thallium concentrations obtained from stored blood samples were paired with spinal fluid concentrations from the same days. On day 1, serum and spinal fluid concentrations were 8700 μ/L and 1200 μ/L, respectively. On day 3, although the serum concentration had fallen to 7200 μ/L, the spinal fluid concentration had increased to 2100 μ/L.

This case provides evidence to support the hypothesis that thallium distributes into the central nervous system more slowly than the blood compartment, and this may in part account for the progression of neurologic findings in the setting of decreasing serum concentrations. 
thallium; toxicity; spinal fluid analysis