Cerebral fat embolism detection with susceptibility-weighted images in sickle cell disease

Sickle cell disease and fat embolism: a rare complication of vaso-occlusive crisis

A 61-year-old woman was admitted to the hospital for management of a painful vaso-occlusive crisis. She had a history of sickle cell beta-thalassaemia and end-stage renal disease managed with intermittent haemodialysis. While hospitalised, she became lethargic and unresponsive and developed acute chest syndrome. Initial MR scan of brain, cerebrospinal fluid examination and continuous electroencephalogram were unremarkable, but subsequent MR scan of brain identified a right transverse venous sinus thrombosis and extensive supratentorial and infratentorial microhaemorrhages consistent with fat emboli. We; therefore, discuss a case of non-traumatic fat embolism syndrome, a rare complication of sickle cell disease.

Coma secondary to cerebral fat embolism syndrome due to sickle cell disease fully recovering following red cell exchange transfusion

A 51-year-old woman known for sickle cell disease presented with 2 weeks of headache and bilateral lower limb pain. During admission, she suffered from multiple generalised tonic-clonic seizures but had an unremarkable CT of the brain. Incidentally, she had worsening baseline renal function. She was admitted to the intensive care unit with an acute confusional state. A bedside electroencephalogram showed triphasic waves and diffuse slow activity suggestive of encephalopathy with no epileptiform discharges. She remained obtunded despite appropriate medical therapy of hydration, antiepileptic and pain control. Lumbar puncture failed to identify an infectious cause. An urgent MRI of the brain was done and revealed features compatible with fat embolism syndrome (FES). Her haemoglobin S was 84.2%. Urgent red cell exchange transfusion was done, and within 3 days she fully regained her orientation and motor function. This represents the first case of such profound obtundation due to FES with a complete response to exchange transfusion.

Microbleeds show a characteristic distribution in cerebral fat embolism

This systematic review aims to test the hypothesis that microbleeds detected by MRI are common and show a characteristic pattern in cerebral fat embolism (CFE). Eighty-four papers involving 140 CFE patients were eligible for this review based on a systematic literature search up to 31 January 2020. An additional case was added from hospital records. Patient data were individually scrutinised to extract epidemiological, clinical and imaging variables. Characteristic CFE microbleed pattern resembling a "walnut kernel" was defined as punctuate hypointensities of monotonous size, diffusely located in the subcortical white matter, the internal capsule and the corpus callosum, with mostly spared corona radiata and non-subcortical centrum semiovale, detected by susceptibility- or T2* weighted imaging. The presence rate of this pattern and other, previously described MRI markers of CFE such as the starfield pattern and further diffusion abnormalities were recorded and statistically compared. The presence rate of microbleeds of any pattern, the "walnut kernel microbleed pattern", diffusion abnormality of any pattern, the starfield pattern, and cytotoxic edema in the corpus callosum was found to be 98.11%, 89.74%, 97.64%, 68.5%, and 77.27% respectively. The presence rate between the walnut kernel and the starfield pattern was significantly (p < 0.05) different. Microbleeds are common and mostly occur in a characteristic pattern resembling a "walnut kernel" in the CFE MRI literature. Microbleeds of this pattern in SWI or T2* MRI, along with the starfield pattern in diffusion imaging appear to be the most important imaging markers of CFE and may aid the diagnosis in clinically equivocal cases.

Post-traumatic cerebral fat embolism syndrome with a favourable outcome: a case report

Background

Fat embolism syndrome (FES) is a change in physiology resulting from mechanical causes, trauma, or sepsis. Neurological manifestations of FES can vary from mild cognitive changes to coma and even cerebral oedema and brain death. Here, we present an unusual case of cerebral fat emboli that occurred in the absence of acute chest syndrome or right-to-left shunt.

Case presentation

A previously healthy 57-year-old right-handed male was admitted to our department because of unconsciousness after a car accident for 3 days. He suffered from multiple fractures of the bilateral lower extremities and pelvis. This patient had severe anaemia and thrombocytopenia. Head MRI showed multiple small lesions in the whole brain consistent with a “star field” pattern, including high signals on T2-weighted (T2w) and fluid-attenuated inversion recovery (FLAIR) images in the bilateral centrum semiovale; both frontal, parietal and occipital lobes; and brainstem, cerebellar hemisphere, and deep and subcortical white matter. Intravenous methylprednisolone, heparin, mannitol, antibiotics and nutritional support were used. Although this patient had severe symptoms at first, the outcome was favourable.

Conclusions

When patients have long bone and pelvic fractures, multiple bone fractures and deteriorated neurological status, cerebral fat embolism (CFE) should be considered. Additionally, CFE may occur without an intracardiac shunt. The early diagnosis and appropriate management of FES are important, and prior to and following surgery, patients should be monitored comprehensively in the intensive care unit. With appropriate treatment, CFE patients may achieve good results.

Neurologic Complications of Fat Embolism Syndrome

PURPOSE OF REVIEW

Fat embolism syndrome (FES) is a rare disorder with potentially devastating neurologic complications. This article reviews the history, pathophysiology, clinical features, diagnosis, and treatment of FES with a focus on its neurologic aspects.

RECENT FINDINGS

The neurologic complications of FES are more commonly recognized with current diagnostic testing and increase awareness of the disorder. FES may present initially with neurologic manifestations. Prompt diagnosis of FES and of its neurologic manifestations could be lifesaving. This includes respiratory support and management of neurological complications. The classic clinical triad of pulmonary insufficiency, neurologic disturbances, and petechial skin rash typically presents 24 to 72 h following an initial insult, most commonly a traumatic long bone fracture. Early onset (< 24 h) and delayed onset (> 72 h) have been described. Neurologic manifestations may include ischemic/hemorrhagic strokes, retinal ischemia, seizures, autonomic dysfunction, and diffuse brain injury. Diagnosis remains clinical. Management consists mainly of supportive care.

Cerebral fat embolism syndrome in sickle cell disease without evidence of shunt

Fat embolism syndrome (FES) is a known complication of sickle cell disease (SCD) that occurs secondary to vaso-occlusive crises, bone marrow infarction, and the subsequent release of fat globules into the venous circulation. Although neurologic involvement is common, the pathophysiology of cerebral fat emboli remains controversial. While fat microemboli can enter the arterial circulation through right-to-left shunts, the systemic release of free fatty acids may also cause indirect endothelial damage and disruption of the blood-brain-barrier. We present an unusual case of cerebral fat emboli in SCD that occurred in the absence of acute chest syndrome or right-to-left shunt, favoring a biochemical etiology. Treatment of FES includes supportive care and emergent red cell exchange transfusions.

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Cerebral fat embolism syndrome is a rare complication of sickle cell disease.

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Brain MRI shows multifocal punctate infarcts and hemorrhages in a “starfield” pattern.

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Fat microemboli can enter the brain through intrapulmonary or intracardiac shunts.

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In the absence of shunting, free fatty acids may cause indirect endothelial damage.

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Treatment involves supportive care and red cell exchange transfusions.

Neuroimaging findings in sickle cell disease

At least 25% of individuals with sickle cell disease will have a neurological complication over their lifetime, often as early as in childhood. Neuroradiological findings in patients with sickle cell disease are common and include acute territorial infarction, silent ischaemia and intracranial haemorrhage. Imaging abnormalities are typically, but not always, manifestations of the underlying vasculopathy. Coexisting acute and chronic pathology may pose challenges to interpretation.