Cerebral Fat Embolism in Hemoglobin SC Disease

A 63-year-old Caribbean man was admitted to the hospital for low back and pelvic pain. His medical history included sickle cell hemoglobin (Hb) C disease with no vaso-occlusive crisis within the last 20 years, and chronic obstructive pulmonary disease treated with inhaled corticosteroids for the last 4 years.

A few hours after admission, respiratory distress with polypnea occurred, requiring an oxygen flow rate of 12 L per minute. At that time, a thrombocytopenia was detected in peripheral blood, with a platelet count of 112,000/mm3, as well as increased hemolysis (LDH 4990 IU/L; normal range 125-250). He was transferred to the Intensive Care Unit. The patient’s neurological and respiratory status got worse in the Intensive Care Unit, with agitation, confusion, and hypercapnic acidosis leading to his intubation. Disseminated intravascular coagulation, thrombocytopenia, and leukopenia developed. Chest computed tomography scan showed lung bilateral alveolar condensation in the posterior basal segment and bilateral pleural effusions. A bone marrow smear was performed and showed bone marrow necrosis. The diagnosis of pulmonary infection without bacterial identification was made; the patient required antibiotic therapy combination and blood transfusion. The wake-up after initial sedation was delayed and no real consciousness after 4 days without sedation was detected, therefore leading to further investigations.

An electroencephalogram, a lumbar puncture, and a cerebral magnetic resonance imaging (MRI) scan were performed: electroencephalogram showed neither pathognomonic sign of encephalopathy, localized abnormality, nor epileptic sign. The lumbar puncture was normal. The MRI findings were more conclusive.

Indeed, diffusion-weighted images showed multiple areas of increased intensity in the periventricular splenium of the corpus callosum, the deep and subcortical white matter corresponding to ischemic lesions (Figure 1, A and B). Because the MRI was performed 14 days after admission, the apparent diffusion coefficient map was normal (data not shown). They give the characteristic starfield pattern1 with several diffuse punctate foci of restricted diffusion in the bilateral white matter, predominantly in the splenium of the corpus callosum and the corticomedullary junction. These lesions were also detected with axial fluid-attenuated inversion recovery images (Figure 2). This reflects small parenchymal infarcts caused by cerebral fat embolism.2 Figure 3 is an axial gradient echo T2-weighted image. These punctate foci of low signal intensity are petechial hemorrhages.1, 2, 3 Based on clinical presentation involving lungs and brain in a patient with bone marrow necrosis and characteristic “starfield pattern” on MRI, a diagnosis of cerebral fat embolism syndrome was made.