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|Year : 2021 | Volume
| Issue : 1 | Page : 167-169
Unusual Cause of Encephalopathy and Seizures in a Child
Bharat Hosur, Sameer Vyas, Renu Suthar, Arundhati Mukherjee, Nirmalya Ray, Tany Chandra
Department of Radiodiagnosis and Pediatric Neurology, PGIMER, Chandigarh, Punjab, India
|Date of Submission||09-Dec-2018|
|Date of Decision||20-Jul-2019|
|Date of Acceptance||28-May-2020|
|Date of Web Publication||24-Feb-2021|
Department of Radiodiagnosis and Imaging, PGIMER, Chandigarh
Source of Support: None, Conflict of Interest: None
Toxic encephalopathy is an important differential diagnosis in a child with encephalopathy and seizures. Subtle circumstantial evidence and apt neuroimaging features can significantly contribute to management, especially in a case of accidental exposure. 2, 4-D (ethyl ester) poisoning is a rare diagnosis, despite the common usage of this toxic compound as weedicide in northern India. The clinical similarity to the anticholinesterase poisoning, especially in the setting of agrochemical exposure is the main cause of under-diagnosis with usually fatal outcomes. We present an interesting case of accidental 2, 4-D (ethyl ester) poisoning in a child with typical neuroimaging features. A review of the literature regarding neuroimaging patterns of bilaterally symmetrical signal abnormalities involving basal ganglia in brain magnetic resonance imaging (MRI) from the point of view of clinical significance, is also discussed.
Keywords: 2,4-D (ethyl ester), basal ganglia, OP poisoning, neuroimaging
Key Message: Accidental exposure to the agrochemical toxins can be a rare cause of encephalopathy and seizures in the pediatric age group. MRI features can aid in the diagnosis and its timely management.
|How to cite this article:|
Hosur B, Vyas S, Suthar R, Mukherjee A, Ray N, Chandra T. Unusual Cause of Encephalopathy and Seizures in a Child. Neurol India 2021;69:167-9
Organophosphorus (OP) poisoning, a common mode of deliberate self-harm in tropical countries, may have a fatal endpoint in up to 6 out of 10 affected patients. Accidental exposure is another significant factor, especially in agrochemical poisoning. Most of the inciting toxins are usually anticholinesterases with nicotinic and muscarinic effects eliciting specific clinical presentations. 2, 4-D (ethyl ester) [IUPAC name - ethyl 2-(2,4-dichlorophenoxy) acetate; PubChem CID: 10780] poisoning is a paradoxically rare diagnosis despite common usage of this toxic compound as weedicide in Northern India. The clinical similarity to the anticholinesterase poisoning especially in the setting of agrochemical exposure is the main cause of underdiagnosis. The role of imaging is limited in the emergent phase of the cholinergic crisis. However, the multipoint utility of MRI in the management evolves once the clinical improvement ensues. We present a rare case of 2, 4-D (ethyl ester) poisoning in a pediatric survivor with the brain MR imaging features and associated conundrum.
| » Case Report|| |
An 18 months old boy, previously developmentally normal, presented with a history of vomiting, diarrhea, and fever for ten days. He had four episodes of generalized tonic-clonic seizures on day three of illness. Fever was intermittent, documented up to 102°F, and lasted for a week. The parents noticed regression of developmental milestones with this febrile illness in terms of loss of head control, regression of speech, and the ability to recognizing parents. He was the fourth child of a nonconsanguineous marriage and no history of similar illness existed in the family. On examination, the child was irritable, with a lack of following verbal output and visual fixation. He had variable tone with brisk reflexes and extensor plantar response suggestive of upper motor neuron involvement. He also had choreiform movements in the upper limbs and oro-facial dyskinesia. The fundus examination was normal. A clinical possibility of acute onset viral encephalitis, autoimmune encephalitis, and acute disseminated encephalomyelitis was kept.
On review of history, it was revealed that the relatives recovered a bag of [2, 4-D (ethyl ester) 38%] from the sand pile beside the nearby construction site where the child was playing on the day of falling ill. It was confirmed from the owners of the plot that the weedicide was prepared on the sand pile and spread all over. Since the child had a history of pica ingestion before, it was retrospectively deduced by parents that the child might have ingested the contaminated sand, from the abnormal smell of the loose stools. The exposure was also confirmed by the mother, who had observed abnormal petrochemical smell from the child's mouth at that time.
He was investigated further, cerebrospinal fluid (CSF) examination was acellular and CSF protein and glucose were normal. His blood and CSF cultures were sterile. MRI of the brain revealed bilaterally symmetric hyperintensities involving basal ganglia [Figure 1] and cerebral crura [Figure 2] on T2 weighted/fluid-attenuated inversion recovery (FLAIR) images with diffusion restriction, maximal at globus pallidi interni. No abnormal susceptibility changes or contrast enhancement were discernible. 3D time-of-flight magnetic resonance (MR) angiography did not reveal vascular abnormalities. The thalami, corpus callosum, and both supra- and infratentorial white matter signal characteristics were normal. In the absence of associated ventriculomegaly, abnormal meningeal enhancement, and mass effect, a working diagnosis of toxic encephalopathy was made. Since the child presented to us at the second week of illness, he was managed symptomatically with anticholinergics, tetrabenazine, and glycopyrrolate. He showed a gradual response and regained the normal muscle tone and improved speech with a significant reduction in the choreiform movements at discharge.
|Figure 1: Axial T2 weighted (a), FLAIR (b), contrast-enhanced T1 weighted (c), diffusion (at b = 1000 s/mm2) weighted (d), apparent diffusion coefficient (e) and susceptibility weighted (f) images of MRI Brain, at the level of basal ganglia showing symmetrical T2 and FLAIR hyperintensities with restricted diffusion and absence of contrast enhancement or susceptibility changes|
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|Figure 2: Axial T2 weighted (a), FLAIR (b), T1 weighted (c), diffusion (at b = 1000 s/mm2) weighted (d), apparent diffusion coefficient (e) and susceptibility weighted (f) images of MRI Brain, at the level of cerebral crura showing symmetrical T2 and FLAIR hyperintensities with restriction of diffusion|
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| » Discussion|| |
The imaging phenotype of bilaterally symmetric abnormalities of basal ganglia on MRI can result from a wide spectrum of etiopathologic phenomena. A systematic approach to the location, signal, and extent of the abnormalities with added information from the preceding history and management details can establish a clinically relevant diagnosis. Owing to the high metabolic activity, lentiform nuclei are rich in mitochondria, vascularity, and neurotransmitters and hence are innately more vulnerable to hypoxic and hypoglycemic metabolic insults. The other differential diagnosis of bilateral symmetric hyperintense signal changes involving lentiform nuclei in young infant and children include neurometabolic disorders as Leigh's disease, organic acidemia, viral encephalitis (Japanese encephalitis, dengue encephalitis, rabies encephalitis, mycoplasma encephalitis), acute necrotizing encephalopathy, postinfectious demyelination, rarely in extrapontine myelinolysis, and posterior reversible encephalopathy syndrome.
Acute intoxications targeting mitochondrial respiratory chain namely cyanide, carbon monoxide, methanol poisoning, and hypoxic insult are the predominant etiologies for bilateral lentiform nuclei changes. While methanol intoxication causes differential T2 prolongation in putamina and optic neuritis, carbon monoxide may preferentially involve globus pallidi with T1 shortening with a delayed leukoencephalopathy. Intense enhancement with delayed hemorrhagic necrosis is typical of cyanide poisoning. The organophosphate (OP) poisoning can involve basal ganglia in its various phases of natural history and management.
OP poisoning can have varied imaging appearances based on its clinical phenotype, i.e., acute cholinergic crisis, intermediate syndrome, organophosphate-induced delayed polyneuropathy (OPIDN), and chronic organophosphate-induced neuropsychiatric disorder (COPIND). The propensity to involve basal ganglia is maximum with cholinergic crises, similar to the index case with symmetric T2 weighted hyperintensities in the bilateral basal ganglia. T2. Srinivasan et al. reported the “eye of the tiger” sign in a known case of OP poisoning with hemorrhagic necrosis of basal ganglia. The combination of the dark rim of iron around the cavitating central pallidal gliosis being the reason for the appearance. Rarely basal ganglia infarcts may result due to OP poisoning. The isolated splenial focus of diffusion restriction has been described by Wang et al. in a case of OPIDN. Bhanu et al. effectively demonstrated the value of MR perfusion as a tool to assess brain injury earlier without the radiation-associated risks of single photon emission computed tomography (SPECT) imaging in OP poisoning.
Jearth et al. have reported a similar clinical course of this very rare poisoning in a 19- year-old male. Unlike adults, a forthcoming specific input about the source and the mode of toxic exposure may be lacking in pediatric patients. Forced alkaline diuresis and a thorough gastric lavage (when ingested) are the most effective modes of management since no specific antidote is available for 2, 4-D (ethyl ester). Clinical history, circumstantial evidence of toxin exposure, neuroimaging evidence, and recovery may help in early diagnosis of toxic encephalopathy. Information from a complete clinical story and neuroimaging evidence can significantly contribute to early diagnosis. To the best of our knowledge, neuroimaging features of 2,4-D (ethyl ester) poisoning is rarely reported in the literature. Long term clinical and radiological follow-up of an index patient with 2, 4-D (ethyl ester) intoxication may provide better insights to its pathogenesis and may aid to evolve apt management strategies.
| » Learning Points|| |
- Toxic poisoning should be kept as a differential diagnosis in bilateral symmetrical abnormalities involving basal ganglia/white-matter. A proper history of exposure must be taken
- Organophosphorus poisoning can have varied imaging patterns based on its clinical phases, which may be a significant tool in diagnostic and prognostic aspects of management
- Bilateral symmetrical signal abnormalities involving basal ganglia in brain MRI can deduce clinically relevant information with a systematic imaging approach and added clinical inputs
- 2, 4-D (ethyl ester) poisoning is a rare type of agrochemical poisoning, which needs differentiation from anticholinesterase poisoning to prevent fatal outcomes.
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2]