Cerebral fat embolism syndrome following total knee replacement causing a devastating neurocognitive sequelae

F embolism syndrome (FES), caused by the release of fat globules into the systemic circulation, is characterized by a constellation of cerebral, pulmonary, cutaneous, and hematological symptoms of variable severity. The presentation varies from asymptomatic or with mild respiratory distress to a catastrophic clinical scenario with a triad of symptoms that include dyspnea, petechial hemorrhages of the skin, and confusion that may lead to coma or death. The FES is usually prevalent in 1-5% of patients following trauma to the pelvis and long bones and rarely described in elective orthopedic knee procedures.1 A 71-year-old male patient with controlled diabetes mellitus and hypertension was admitted to King Abdulaziz University Hospital, Jeddah, Kingdom of Saudi Arabia for scheduled bilateral total knee replacement (TKR) in July 2014. He had an 8-year history of progressive bilateral knee pain and limitation of walking due to severe osteoarthritis that did not improve with repeated local injections and physical therapy. Before surgical intervention, his vital signs were: sinus rhythm pulse of 78/min, blood pressure of 130/80, respiratory rate of 22/min, a temperature of 37°C, and oxygen saturation on room air was 98%. His physical and neurological examination was within normal. A routine preoperative laboratory tests (complete blood count, renal, liver, and coagulation profiles) were within normal limits: there was mildly elevated random blood sugar and cholesterol levels. Electrocardiography (ECG) and preoperative chest radiograph were unremarkable. Surgery was performed under mild hypotensive epidural anesthesia and intravenous Propofol sedation (100 mcg/kg/min) in a supine position with the application of thigh tourniquet. Bilateral 1-stage TKR surgery was uneventful; there was no intraoperative incidence during the 2 and half-hour of surgery, particularly disturbance of blood pressure and oxygen saturation. He was transferred to recovery room alert and in a good condition and postoperative knee x-rays was satisfactory (Figure 1A). However, 10 minutes later, he complained of chest tightness and difficulty breathing and became restless and combative with a Glasgow Coma Score (GCS) of 8. His vital signs revealed sinus tachycardia (90/min) and tachypnea (28/min), a blood pressure of 108/70, and an oxygen saturation of 90% on facemask with100% oxygen of 5 L/min. General physical examination revealed cutaneous trunk petechial hemorrhages and bilateral basal lung crepitation. He was immediately transferred to the Intensive Care Unit (ICU) where he required endotracheal intubation and mechanical ventilation due to desaturation and deteriorated level of consciousness. A chest radiograph showed bilateral infiltrates (Figure 1B). A postoperative laboratory test was unremarkable apart from a drop in hemoglobin from 13.4 to 8.7 g/100 ml, despite an estimated blood loss was around 250 ml in addition to 120 cc bloody fluid was in the subcutaneous drains within 12 hours, for which he received 2 units of packed red blood cells. His platelets have dropped from 379 to 209 billion cells/L and blood gasses showed evidence of respiratory acidosis (pH=7.23, PCO2=48 mm Hg, PO2=61 mm Hg, HCO3=25, and O2 saturation of 76%). Immediate ECG revealed sinus tachycardia with no ischemic changes; cardiac enzymes were not elevated, and trans-esophageal echocardiogram revealed no evidence of cardiac ischemia, thrombus, or atrial septal defect. Carotid doppler study revealed no atherosclerotic stenosis, and lower extremities duplex study was negative for deep venous thrombosis. An emergency plain computed tomography (CT) scan of the brain revealed extensive bilateral cerebral and cerebellar periventricular low-attenuation foci. These findings raised the suspicion of acute embolic infarction. An urgent magnetic resonance imaging (MRI) scan was performed which was unremarkable on T1-weighted images, but on T2-Weighted images, there were multiple diffuse small hyperintense foci in both cerebral and cerebellar hemispheres with a symmetrical distribution. These showed restricted diffusion in diffusion-weighted (DWI) and apparent diffusion coefficient (ADC) images, in keeping with acute infarction (Figure 1C). On susceptibility weighted MRI sequences these areas of acute infarction showed susceptibility artifacts in keeping with petechial hemorrhagic foci. The distribution of these multiple small foci of hemorrhagic infarctions described as a ‘starfield pattern’ as it simulates the appearances of a cluster of stars in the night sky on MRI scan. In the patient’s clinical context, these imaging findings were for cerebral fat embolism. The patient was stable hemodynamically with GCS varied from 7 to 9 for the first 7 days then gradually improved. Electroencephalography revealed no epileptic discharges. Intravenous low molecular weight heparin was started at 72 hours after TKR. After 3-week of ICU admission, he Clinical Note