Mothball Ingestion as a Manifestation of Pica, Leading to Paradichlorobenzene CNS Toxicity

Authors

Joon Yau Leong1, Margarita Gianniosis1, Ann Lee1, Elwin Tham1, Saman Zafar2, Yan Zhang2 1Sidney Kimmel Medical College, Thomas Jefferson University; 2Department of Neurology, Albert Einstein Medical Center Philadelphia

Introduction

Pica, a poorly understood psychiatric disorder presenting with ingestion of non-nutritious substances, is commonly associated with iron deficiency anemia. Some previously described ingested materials include ice, soil and paint. Mothball abuse may be a newer form of pica and since paradichlorobenzene (PDCB) is considered less toxic, it has largely replaced naphthalene as the primary component in mothballs1. A high index of suspicion for unusual toxin exposure aids in the diagnosis of pica patients presenting with unexplained neurodegenerative features.

Case Presentation

A 47-year-old female presented to the hospital with recurrent falls and declining cognition over the past year. Prior to all this, she was fully independent with activities of daily living, but now she is mostly housebound, having frequent falls and inability to care for herself. Past medical history is significant for menorrhagia, iron deficiency anemia and pica. She denies any allergies, surgical history, or significant family history. She is not on any long-term medications.

On examination, she was noted to have an unidentifiable chemical odor. She had a childlike affect, emotional lability, poor short term recall and inconsistencies in evaluation of her long-term memory. She also exhibited symmetrical 4/5 weakness in all four extremities, bilateral dysmetria on finger-nose testing and an ataxic gait. Her sensory exam was normal.

CBC and iron studies were consistent with iron deficiency anemia. MRI brain revealed symmetric ill-defined regions of T2 hyperintense signals predominantly affecting the middle cerebellar peduncles bilaterally.

The differential diagnosis for her clinical deficits and imaging, including Spinocerebellar Ataxia, Multiple System Atrophy and Fragile X Tremor-Ataxia Syndrome2,3, were excluded based on neurological assessment, family history and genetic PCR testing.

Collateral history from her daughter revealed that the patient has been ingesting mothballs for the past 5 years, with the quantity of mothballs increasing from 1/day to 6/day over the past year. Subsequently, serum PDCB levels were found to be elevated at 15 mcg/mL.

Discussion

This case was educational to us in several respects:

  • Iron deficiency anemia is associated with pica, which can lead to unusual toxin ingestions. Seeking out a history of chronic environmental ingestions in a patient with pica can be immensely helpful in making the diagnosis.
  • Toxic-metabolic insults to the central nervous system generally leads to symmetrical changes on diagnostic brain imaging, as opposed to other etiologies such as stroke. Previous case reports of PDCB neurotoxicity have reported diffuse or symmetrical changes on neuroimaging. To our knowledge, there has not been any reported cases in the literature with PDCB toxicity predominantly involving the middle cerebellar peduncles.
  • Mothball ingestion may be a manifestation of pica, and present with neurological findings such as cognitive deficits and ataxia.

References

  1. Dubey D, Sharma VD, Pass SE, et al. Para-dichlorobenzene toxicity - a review of potential neurotoxic manifestations. Ther. Adv. Neurol. Disord. 2014;7c177-187.
  2. Okamoto K, Tokiguchi S, Furusawa T, Ishikawa K, Quardery AF, Shinbo S, Sasai K. MR features of diseases involving bilateral middle cerebellar peduncles. AJNR Am J Neuroradiol. 2003 Nov-Dec;24(10):1946-54.
  3. Scaglione C, Ginestroni A, Vella A, Dotti MT, Nave RD, Rizzo G, De Cristofaro MT, De Stefano N, Piacentini S, Martinelli P, Mascalchi M. MRI and SPECT of midbrain and striatal degeneration in fragile X-associated tremor/ataxia syndrome. J Neurol. 2008 Jan;255(1):144-6.

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