1. Case of the Month: February, 2019
Nanxi Zha, PGY-2
Radiology
McMaster University

2. Clinical Presentation
65-years-old female, hematemesis, collapsed at home, absent vital signs, CPR commenced and ROSC achieved en route to emergency department.
Past medical history:
Hypertension
Diabetes
Bipolar disorder
Hypothyroidism
Chronic kidney disease
Smoking

3. Clinical Presentation
On arrival to the ED,
Cardiac arrest five times
Multiple doses of vasopressors
6 units of RBC
On clinical exam:
Intubated, required ongoing vasopressors
Coffee ground emesis and melena
Emergent endoscopy showed pooled blood within the duodenum, no active bleed
Initial Hb 173, lactate 20
The patient went directly to OR for exploratory laparotomy. No active bleeds were found. Drains were left in situ. Unfortunately, the patient became hypotensive post-op. In addition to CT abdomen, a CT head was done to assess her neurological status.

4. CT Head Findings A B
Sulcal effacement (note convexity sulci appear effaced)
Reversal of the grey white matter differentiation (grey matter typically higher attenuation – normally appears brighter)
Pseudosubarachnoid hemorrhage sign (A) and hyperdense dural venous sinuses (B)
These findings are in keeping with early diffuse anoxic brain injury

5. Diffuse Anoxic Brain Injury Pathophysiology
Etiology
Hypoxia (drowning, carbon monoxide poisoning)
Ischemia (cardiac arrest, cerebrovascular disease)
Usually affects grey matter structures first because they are
Areas of high glutamate or other excitatory amino acid receptors
Areas of high energy demand

6. CT Signs Sulcal effacement: diffuse edema in CSF-containing spaces
Reversal of grey white matter differentiation:
Results in white matter having higher attenuation than grey matter
Within first 24 hours of anoxic brain injury
Poor prognosis
Irreversible brain injury
Decreased basal ganglia attenuation

7. CT Signs White Cerebellum Sign
Edema and hypoattenuation of the cerebrum results in relative high attenuation appearance of the cerebellum
Case courtesy of Dr Jan Frank Gerstenmaier, Radiopaedia.org, rID: 22747

8. CT Signs Pseudosubarachnoid hemorrhage sign
Diffuse cerebral edema led to hypoattenuation of the cerebral parenchyma, which results in hyperattenuating appearance of the subarachnoid space

9. CT Signs Diffuse loss of grey white matter differentiation
Secondary to diffuse cerebral edema
Poor prognosis
Case courtesy of A.Prof Frank Gaillard, Radiopaedia.org, rID: 6101

10. Outcome from our case
Clinically, the patient had absent gag reflex, absent pain response, and sluggish pupils.
CT angiogram of the abdomen and pelvis demonstrated arterial bleed within a small bowel loop within the right lower quadrant and small bowel ischemia.
Throughout the night, the patient required increased vasopressor support and did not show improvement in lactic acidosis.
She subsequently stopped triggering ventilation and pupils became fixed and dilated

11. Outcome from our case
Prognosis and possible interventions such as IR embolization of the arterial GI bleed were discussed with the family. The patient was subsequently switched to comfort care.

12. Learning Points Anoxic brain injury etiologies: hypoxic, ischemic
Pertinent clinical history: prolonged cardiac arrest
Grey matter structures are affected first
CT findings
Sulci effacement
Reversal of grey white matter differentiation
White cerebellum sign
Pseudosubarachnoid sign
Loss of grey white matter differentiation

13. References
Huang BY, Castillo M (2008) Hypoxic-ischemic brain injury: imaging findings from birth to adulthood. Radiographics 28:417–439; quiz
Kavanagh EC (2007) The reversal sign. Radiology 245:914–
Lin C-Y, Lai P-H, Fu J-H, et al (2014) Pseudo-Subarachnoid Hemorrhage: A Potential Imaging Pitfall. Canadian Association of Radiologists Journal 65:225–231.
Muzio BD Hypoxic-ischemic encephalopathy (adults and children) | Radiology Reference Article | Radiopaedia.org. In: Radiopaedia. and-children?lang=us. Accessed 28 Jan 2019