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E2185. Characterization and Differential Diagnosis of Bilateral Deep Gray Matter Abnormalities on Imaging
Authors
  1. Pouria Mossahebi; Medical College of Wisconsin Affiliated Hospitals
  2. Nour Dababo; Medical College of Wisconsin Affiliated Hospitals
  3. Manav Bhalla; Medical College of Wisconsin Affiliated Hospitals
  4. Andrew Klein; Medical College of Wisconsin Affiliated Hospitals
  5. Darren O'Neill; Medical College of Wisconsin Affiliated Hospitals
  6. David Smullen; Medical College of Wisconsin Affiliated Hospitals
  7. Mohit Agarwal; Medical College of Wisconsin Affiliated Hospitals
Background
Various toxic, metabolic and ischemic abnormalities affect the deep gray structures. The pattern of involvement and associated lobar abnormalities may, however, be different in different conditions. Pattern of involvement and signal changes on different MR sequences may be used to differentiate these conditions and narrow the differential diagnosis.

Educational Goals / Teaching Points
In this exhibit, we will: 1. Review the different toxic and metabolic abnormalities affecting the deep gray structures. 2. Review the pattern of involvement of the deep gray structures in these conditions. 3. Differentiate these conditions on the basis of imaging examples.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
Deep gray matter nuclei have high metabolic activity which make them vulnerable to different metabolic and systemic abnormalities. Different pathologic conditions can cause abnormal imaging findings within bilateral deep grey matter, including metabolic, toxic, vascular, and infectious and inflammatory processes. The goal of this educational exhibit is to characterize these abnormal imaging findings and utilize these findings to narrow the differential diagnosis. The spectrum of imaging findings in toxic encephalopathy could be due to impairment of the mitochondrial respiratory pathway due to vasoconstriction caused by toxic substances, e.g., in carbon monoxide, methanol, and cyanide poisoning with the main imaging finding being T2 prolongation within the basal ganglia. In cocaine and MDMA poisoning, stigmata of ischemic or hemorrhagic processes predominate. Heroin poisoning also affects the deep gray structures, and the pattern of imaging findings depends on the route of administration. Metabolic encephalopathies could be due to accumulation of substances such as copper (Wilson disease), or deficiency of nutrients (thiamine in Wernicke’s encephalopathy), with the imaging findings being different and unique in each case. Other metabolic conditions can be secondary to liver disease (acute hyperammonemia), cardiorespiratory failure (hypoxic ischemic encephalopathy), or acute changes in blood glucose levels. Recognition of the imaging findings can help in differentiation of these conditions.

Conclusion
Deep gray matter nuclei include the thalamus and basal ganglia, which are highly metabolic structures that can be affected by different pathologic conditions, such as metabolic, toxic, vascular, and infectious and inflammatory processes. Pattern of involvement of the deep gray structures and associated involvement of the lobar structures can help to narrow the differential diagnosis.