Expanding the Differential Diagnosis: Two Unique Cases of Abnormal Globus Palladi Signal
Elizabeth Fletman1, Matthew Hart1
1Neurology, Thomas Jefferson University Hospital
Objective:
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Background:
The thalami and basal ganglia are paired deep grey matter structures with extensive metabolic activity. These structures are susceptible to injury by a multitude of insults including ischemia, toxins, metabolic derangements, neurodegenerative conditions, focal inflammation, infection and neoplasms. We describe two patients presenting with encephalopathy found to have bilateral T2 hyperintensities in the globus pallidus to highlight the wide differential diagnosis associated with these imaging findings.
Design/Methods:
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Results:

A 89-year-old man presented with new onset seizure in the setting of fever and decreased oral intake. Electroencephalogram (EEG) showed left frontal subclinical seizures. He was started on empiric antibiotics for presumed meningitis. Cerebrospinal fluid (CSF) analysis demonstrated lymphocytic pleocytosis (21 WBC with 84% lymphocytes, 17 RBC, glucose 80 mg/dL, protein 269 mg/dL), positive West Nile Virus (WNV) IgM and negative WNV IgG. MRI brain demonstrated T2 hyperintense signal with intrinsic peripheral post contrast enhancement of the bilateral globus pallidi. He was diagnosed with WNV encephalitis. 

A 34-year-old woman with medical history significant for Type 1 Diabetes presented with severe encephalopathy and writhing movements of all extremities in the setting of hypoglycemia. Two lumbar punctures separated by 10 days were unremarkable, including paraneoplastic and autoimmune serum/CSF studies. MRI brain on day 15 showed new increased T2/FLAIR signal in the bilateral globus pallidus. She was treated with empiric IVIG and pulse dose steroids given persistent encephalopathy. Over time she demonstrated significant neurologic recovery, able to follow complex commands. Her encephalopathy was thought to be secondary to diabetic striatopathy vs seronegative autoimmune encephalitis.

Conclusions:
Abnormal globus palladi signal can be caused by a myriad of etiologies, including both primary neurological and systemic diseases. While history, exam, serology, and neurophysiology testing certainly aid in the workup of patients with encephalopathy, understanding the unique radiographic finding of bilateral globus palladi abnormalities can significantly narrow the differential diagnosis.
10.1212/WNL.0000000000211313
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