Case Presentation
A 89-year-old female with past medical history of hypertension and dementia presented to the emergency department due to altered mental status since this morning. Prior to going to bed last night, she could carry out her daily activities independently. Upon arrival, she was in a deep coma with Glasgow Coma Scale E1V1M1. Her pupils were symmetrical, size 3 × 3 mm, fixed and with sluggish reaction to light. Her blood test was non-contributory except for thrombocytopenia, a platelet counts of 25,000 u/L. A non-contrast computed tomography (CT) of brain was performed, and revealed diffuse edema and hypo-density of the cerebral hemispheres with sparing of the cerebellum and brainstem resulting in apparent brightness of the cerebellum (arrow), which is compatible with a radiological sign called white cerebellum sign ( Fig. 1 A). We informed the family about the poor prognosis. The patient’s family decided to sign do-not resuscitate (DNR) agreement, and took the patient home.
Fig. 1 . (A) Non-contrast coronal computed tomography (CT) shows diffuse edema and hypo-density of the cerebral cortex and relative hyper-density of the cerebellum (arrow). (B) Non-contrast axial CT shows diffuse brain edema with hyper-density over falx cerebri and tentorium cerebelli (arrow head), giving it a “pseudo-subarachnoid hemorrhage” appearance.
Discussion
The appearance of white cerebellum sign is indicative of hypoxic-ischemic encephalopathy of the brain, which can be seen in patients with severe head trauma, birth asphyxia, child abuse, drowning, status epilepticus and post-cardiac arrest hypoxia. 1 The white cerebellum sign, also known as the reversal sign, is a radiological sign that shows the reversal of gray-white matter densities, with relative preservation of normal to high density of the central structures and cerebellum. 2 , 3
Hypoxic injury of the brain results in diffuse edema of the supratenorial structures making it look hypo-dense on CT; the cerebellum and brainstem are spared and therefore appear relatively brighter, or “white” . The reversal sign is important in an emergency setting because it represents severe anoxic-ischemic brain injury and is associated with poor neurological outcome and prognosis. 1 , 3 In addition, emergency physicians should recognize this sign because it can be easily mistaken as subarachnoid hemorrhage (SAH). The reason for this is that due to the decreased attenuation of the cerebral cortex, the circulation blood within the basal cisterna may appear hyper-dense on CT, mimicking SAH, a finding known as “pseudo-SAH,” which was also evident in this case ( Fig. 1 B). 4 In conclusion, the appearance of white cerebellum sign on brain CT indicates hypoxic encephalopathy with poor prognosis.
Conflicts of Interest
The authors have no conflict of interest to declare and no prior presentation.
References
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