martedì 9 giugno 2009

Paradichlorobenzene intoxication with encephalopathy


Shown are proton density and T2 axial images of the patient’s brain. The white matter is diffusely hyperintense on long TR sequences, including corticospinal tracts in the brainstem, cerebellar white matter and corpus callosum. The thalami and basal ganglia appear diffusely hypointense on long TR sequences.

Diagnosis: Paradichlorobenzene intoxication with encephalopathy (recreational mothball sniffing and eating)

Paradichlorobenzene (p-DCB, PDB; 1,4-DCB) is a volatile chlorinated hydrocarbon, a fat-soluble chemical. The primary exposure to 1,4-dichlorobenzene is from breathing contaminated indoor air. Acute (short-term) exposure to 1,4-dichlorobenzene, via inhalation in humans, results in irritation of the skin, throat, and eyes. Chronic (long-term) 1,4-dichlorobenzene inhalation exposure in humans results in effects on the liver, skin, and central nervous system (CNS). No information is available on the reproductive, developmental, or carcinogenic effects of 1,4-dichlorobenzene in humans.

Paradichlorbenzene (which constitutes over 95% of the content of mothballs), may be used as a recreational drug. There are very few cases reported of mothball abuse and toxicity, mostly due to underreporting of this habit by the patients, who are usually teenagers and young adults. Our patient, a 29 year old woman, presented to the hospital with complaint of generalized malaise, progressive mental decline over several weeks and headache leading to evaluation with brain MRI. The patient’s mental status had progressively deteriorated with no focal abnormalities on neurological exam. 6 days into her hospital stay, the patient became obtunded, responding to her name sluggishly and was unable to speak coherently. The woman’s laboratory studies revealed transaminitis and iron deficiency anemia. Note was made of faint smell of mothballs present in the patient’s room since her hospitalization. On focused questioning, the family reported an an odor of mothballs in her apartment for months. The patient explained this away as “getting ready for spring and cleaning out her closets.” After these facts were put together, the blood level of paradichlorbenzene was obtained and measured 15 mcg/mL, the highest level ever recorded in medicine, with normal being undetectable. The history emerged of her inhaling and EATING mothballs for months as a recreational mind-altering activity.

Paradichlorbenzene is a fat-soluble chemical and accumulates within body fat. The fat can serve as a long term repository. In high concentrations it may perpetuate patient’s clinical deterioration for a long time after cessation of substance abuse.

Differential diagnosis for MRI findings of paradichlorbenzene intoxication include toluene toxicity and carbon monoxide poisoning. In toluene intoxication, T2 fast-spin echo sequence shows diffuse white matter hyperintensity with hypointensity of thalami, basal ganglia, red nuclei and pars reticulata of the substantia nigra. In CO poisoning, T2 and FLAIR sequences show high signal within the globus pallidi, which are most sensitive to carbon monoxide poisoning, followed by involvement of the caudate nucleus, putamen and thalamus. Involvement of the brainstem and cerebellum may be a reflection of more severe poisoning, but the cerebral white matter is not involved.

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