An unusual case of early fulminant post-traumatic fat embolism syndrome

Cerebral fat embolism after traumatic bone fractures: a structured literature review and analysis of published case reports

Background

The incidence of cerebral fat embolism (CFE) ranges from 0.9–11%, with a mean mortality rate of around 10%. Although no univocal explanation has been identified for the resulting fat embolism syndrome (FES), two hypotheses are widely thought: the ‘mechanical theory’, and the ‘chemical theory’. The present article provides a systematic review of published case reports of FES following a bone fracture.

Methods

We searched MEDLINE, Web of Science and Scopus to find any article related to FES. Inclusion criteria were: trauma patients; age ≥ 18 years; and the clinical diagnosis of CFE or FES. Studies were excluded if the bone fracture site was not specified.

Results

One hundred and seventy studies were included (268 cases). The male gender was most prominent (81.6% vs. 18.4%). The average age was 33 years (±18). The mean age for males (29 ± 14) was significantly lower than for females (51 ± 26) (p < 0.001). The femur was the most common fracture site (71% of cases). PFO was found in 12% of all cases. Univariate and multivariate regression analyses showed the male gender to be a risk factor for FES: RR 1.87 and 1.41, respectively (95%CI 1.27–2.48, p < 0.001; 95%CI 0.48–2.34, p < 0.001).

Conclusions

FES is most frequent in young men in the third decades of life following multiple leg fractures. FES may be more frequent after a burst fracture. The presence of PFO may be responsible for the acute presentation of cerebral embolisms, whereas FES is mostly delayed by 48–72 h.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13049-021-00861-x.

Postmortem CT and MRI findings of massive fat embolism

OBJECTIVE

To elucidate postmortem computed tomography (PMCT) and postmortem magnetic resonance (PMMR) imaging findings suggesting massive fat embolism.

MATERIALS AND METHODS

Consecutive forensic cases with PMCT and PMMR scans of subjects prior to autopsy were assessed. For PMCT, 16- or 64-row multidetector CT scans were used; for PMMR, a 1.5 T system was used. MRI sequences of the chest area included T2- and T1-weighted fast spin-echo imaging, T2*-weighted imaging, T1-weighted 3-dimensional gradient-echo imaging with or without a fat-suppression pulse, short tau inversion recovery, and in-phase/opposed-phase imaging. At autopsy, forensic pathologists checked for pulmonary fat embolism with fat staining; Falzi's grading system was used for classification.

RESULTS

Of 31 subjects, four were excluded because fat staining for histopathological examination of the lung tissue could not be performed. In three of the remaining 27 subjects, histology revealed massive fat embolism (Falzi grade III) and the cause of death was considered to be associated with fat embolism. CT detected a "fat-fluid level" in the right heart or intraluminal fat in the pulmonary arterial branches in two subjects. MRI detected these findings more clearly in both subjects. In one subject, CT and MRI were both negative. There were no positive findings in the 24 subjects that were fat embolism-negative by histology.

DISCUSSION AND CONCLUSION

In some subjects, a massive fat embolism can be suggested by postmortem imaging with a "fat-fluid level" in the right heart or intraluminal fat in the pulmonary arterial branches. PMMR potentially suggests fat embolism more clearly than PMCT.

Fat embolism in right internal jugular vein: incidental ultrasound finding during internal jugular vein cannulation

Background

We report a case study of fat embolism seen on ultrasound at right internal jugular vein during central venous cannulation in a patient diagnosed with fat embolism syndrome. This case demonstrates the importance of ultrasound for evaluation of trauma cases with suspicion of fat embolism.

Case presentation

A 23-year-old trauma patient with closed fracture of left femoral shaft and left humerus presented to our emergency department (ED). 11 h after admission to ED, patient became confused, hypoxic and hypotensive. He was then intubated for respiratory failure and mechanically ventilated. Transesophageal ultrasound revealed hyperdynamic heart, dilated right ventricle with no regional wall abnormalities and no major aorta injuries. Whole-body computed tomography was normal. During central venous cannulation of right internal jugular vein (IJV), we found free floating mobile hyperechoic spots, located at the anterior part of the vein. A diagnosis of fat embolism syndrome later was made based on the clinical presentation of long bone fractures and fat globulin in the blood. Despite aggressive fluid resuscitation, patient was a non-responder and needed vasopressor infusion for persistent shock. Blood aspirated during cannulation from the IJV revealed a fat globule. Patient underwent uneventful orthopedic procedures and was discharged well on day 5 of admission.

Conclusions

Point-of-care ultrasound findings of fat embolism in central vein can facilitate and increase the suspicion of fat embolism syndrome.

Electronic supplementary material

The online version of this article (10.1186/s13089-019-0116-9) contains supplementary material, which is available to authorized users.

Autopsy diagnosis of fat embolism syndrome

The fat embolism syndrome (FES) is considered a clinical diagnosis. It typically occurs within several days following major traumatic injury, usually involving fractures of the pelvis and/or lower extremities. Fat embolism syndrome is characterized by the onset of respiratory, neurological, cutaneous, and hematologic manifestations and is thought to be related to intravascular embolization of fat, presumably arising from within the fractured bone marrow space. In its most severe form, FES can be lethal. The presence of fat emboli within the microvasculature of the lungs, brain, and sometimes other organs verifies the clinical impression of FES. Despite its relatively well-known clinical characterization, debate exists within the clinical literature regarding the most appropriate diagnostic criteria for FES. Given this fact, along with the fact that FES is a clinical diagnosis, it is not surprising that forensic pathologists may be somewhat reluctant to make a postmortem diagnosis of FES, especially in cases where insufficient clinical information is available. A case of fatal FES is presented in which rapid clinical deterioration occurred, followed by death, such that a clinical diagnosis of FES was never rendered. We propose that, given the correct circumstances, clinical scenario, and autopsy findings, it is appropriate and acceptable to make a postmortem diagnosis of FES. A multitiered approach to the postmortem diagnosis of FES is presented.

Two variants of fat embolism syndrome evolving in a young patient with multiple fractures

Fat embolism syndrome (FES) is a continuum of fat emboli. Variants of FES: acute fulminant form and classic FES are postulated to represent two different pathomechanisms. Acute fulminant FES occurs during the first 24 h. It is attributed to massive mechanical blockage pulmonary vasculature by the fat emboli. The classic FES typically has a latency period of 24-36 h manifestation of respiratory failure and other signs of fat embolism. Progression of asymptomatic fat embolism with FES frequently represents inadequate treatment of hypovolaemic shock. We present a rare case of two variants of FES evolving in a patient with multiple fractures to emphasis the importance of adequate and appropriate treatment of shock in preventing the development of FES. Since supportive therapy which is a ventilatory support remains as the treatment of FES, it is appropriate to treat FES in the intensive care unit setting.

Massive systemic fat embolism detected by postmortem imaging and biopsy

Postmortem computed tomography (pmCT) and pmCT angiography (pmCTA) provide a minimally invasive method to determine the cause of death. Postmortem image-guided biopsy allows for precise sampling of histological specimens. This case study describes the findings of lethal systemic fat embolism (FE) on whole-body unenhanced pmCT, pmCTA, and image-guided biopsy, with autopsy and histopathologic correlation. Unenhanced pmCT revealed a distinct fat level on top of sedimented layers of corpuscular blood particles and serum in the arterial system and pulmonary trunk. Subsequent pmCTA showed reproducible results, and image-guided biopsy confirmed fatal FE. pm CT/pmCTA combined with image-guided biopsy established the cause of death as right heart failure as a result of systemic fatal FE prior to autopsy. All imaging findings were consistent with traditional autopsy and histological specimens. This unique case demonstrates new imaging findings in massive, fatal FE and highlights that postmortem imaging, supplemented by image-guided biopsy, may detect the cause of death prior to traditional autopsy.

Brain Fat Embolism

Fat embolism syndrome [FES] is an uncommon but serious complication of traumatic injures, which can follow a wide range of other surgical and medical conditions and can manifest with a collection of respiratory, hematological, neurological and cutaneous symptoms. FES should be suspected in all cases of traumatic injures with altered mental status following a period of normal neurological function, especially after orthopedic fixation of long bone fractures. Neurological symptoms must not be related to the initial trauma. The objective of this study was to describe the characteristics of FES and to correlate the neuroradiological findings with the clinical symptoms and the outcome of two cases of cerebral FES which occurred in two young men after bone fractures of the extremities without cranial traumatism. Both patients were studied by brain computed tomography (CT) and by brain magnetic resonance (MR). While Cerebral CT was inadequate to the diagnosis, Cerebral MR, performed 48 hours after injury, showed several focal areas of pathological signal in the white matter of the subcortical, periventricular and centrum semiovale regions, as well as in the basal ganglia and cerebellum. The neuroradiological findings of the two patients were compared with their clinical symptoms and outcome. The patient with the worst prognosis showed more lesions on MR and a restricted diffusion on DWI-MR, due to cytotoxic edema, whereas the patient with the better outcome showed lesions due to vasogenetic edema without any restricted diffusion. Cerebral MR and DW-MR are sensitive indicators for the early diagnosis of FES and can give a vast amount of information on the prognosis and future outcome.