MRI brain in monohalomethane toxic encephalopathy: A case report
A 29-year-old female, working in a pharmaceutical company, presented with sudden-onset diplopia, slurred speech, imbalance while walking, and behavioral changes which had developed over a period of 2-3 days. She reported to have headache for 2 weeks. On examination, she had cerebellar signs, bilateral extensor plantar reflexes, and bilateral VI nerve palsy. After ruling out other possibilities clinically, the clinician raised the possibility of probable toxic encephalopathy. A detailed personal and occupational history was obtained. Occupational history revealed that the pharmaceutical company used MI as a chemical intermediate. There was increase in its production in last 2 months probably leading her to sudden exposure of excessive amounts of MI before she presented. In view of the rapid onset of neuropsychiatric symptoms, acute MI toxic encephalopathy was suspected and MRI brain was advised.\nMRI brain was done at our center. T2-weighted and fluid-attenuated inversion recovery (FLAIR) images revealed bilateral symmetrical hyperintense signal in peri-third ventricular thalami [], peri-aqueductal region [], dorsal pons in the region of superior colliculus [], medial leminiscus and abducens nuclei [], and dorsal medulla and inferior olivary nuclei []. Bilateral symmetrical hyperintense signal was also noted in dentate nuclei []. Dentate nuclei lesions had target appearance; they were extremely bright in the center on T2-weighted images and were surrounded by a rim of ill-defined mild hyperintensity.\nAll these lesions were hypointense on T1-weighted images []. No restriction of diffusion was noted on diffusion-weighted images (DWI) []. Mild cortical and cerebellar atrophy was evident. However, the basal ganglia appeared normal. No evidence of altered signal was noted in the corpus callosum. No contrast was administered and MR spectroscopy was not performed.\nBased on the clinical profile, possibility of MI toxic encephalopathy was considered and other differentials with similar MRI features were excluded. Patient was advised follow-up MRI after avoiding exposure to MI.\nRepeat MRI brain was done after 4 months which showed complete resolution of the above-mentioned findings [], confirming the diagnosis.