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

Venoarterial Extracorporeal Membrane Oxygenation Therapy in Patients with Sickle Cell Disease: Case Series and Review for Intensive Care Physicians

Sickle cell disease (SCD) is associated with substantial morbidity and early mortality in afflicted adults. Cardiopulmonary complications that occur at increased frequency in SCD such as pulmonary embolism, pulmonary arterial hypertension, and acute chest syndrome can acutely worsen right ventricular function and lead to cardiogenic shock. Mechanical circulatory support including venoarterial extracorporeal membrane oxygenation (VA ECMO) is being increasingly utilized to treat hemodynamic collapse in various patient populations. However, a paucity of literature exists to guide the use of mechanical circulatory support in adults with SCD where disease-related sequela and unique hematologic aspects of this disorder may complicate extracorporeal therapy and must be understood. Here, we review the literature and describe three cases of adult patients with SCD who developed cardiogenic shock from acute decompensated right heart failure and were treated clinically with VA ECMO. Using an in vitro ECMO system, we investigate a potential increased risk of systemic fat emboli in patients with SCD who may be experiencing vaso-occlusive events with bone marrow involvement given the high-volume shunting of blood from venous to arterial systems with VA ECMO. The purpose of this study is to describe available extracorporeal life support experiences, review potential complications, and discuss the special considerations needed to further our understanding of the utility of VA ECMO in those with SCD.

Abnormal Neurologic Findings in Patients With Sickle Cell Disease Without a History of Major Neurologic Events

Background and Objectives

Patients with sickle cell disease (SCD) are prone to symptomatic neurologic complications. Previous studies reported accrual of neural injury starting at early age, even without having symptomatic neurologic events. The aim of this study was to assess the prevalence and risk factors of abnormal neurologic findings in patients with SCD with no history of major symptomatic neurologic events.

Methods

Our study extracted patients diagnosed with SCD from the Cooperative Study of Sickle Cell Disease. Patients who underwent a neurologic evaluation were included in our analysis. Patients with previous documented major symptomatic neurologic events were excluded. We compared patients with SCD with abnormal neurologic findings with those without in terms of clinical and laboratory parameters using multivariate binary logistic regression.

Results

A total of 3,573 patients with SCD were included (median age = 11 [IQR = 19] years, male = 1719 [48.1%]). 519 (14.5%) patients had at least one abnormal neurologic finding. The most common findings in descending order were abnormal reflexes, gait abnormalities, cerebellar dysfunction, language deficits, nystagmus, abnormal muscle tone and strength, Romberg sign, Horner syndrome, and intellectual impairment. History of eye disease (odds ratio [OR] = 2.76, 95% confidence interval [CI] = 1.63-4.68) and history of osteomyelitis (OR = 2.55, 95% CI 1.34-4.84) were the strongest predictors of abnormal neurologic findings, followed by smoking (OR = 1.59, 95% CI 1.08-2.33), aseptic necrosis (OR = 1.57, 95% CI 1.06-2.33), hand-foot syndrome (OR = 1.48, 95% CI 1.04-2.12), and male sex (OR = 1.42, 95% CI 1.01-2.02).

Discussion

Neurologic deficits are relatively common in patients with SCD, even without documented major neurologic insults. They range from peripheral and ophthalmic deficits to central and cognitive disabilities. Patients with SCD should have early regular neurologic evaluations and risk factor modification, particularly actively promoting smoking cessation.

Successful therapeutic plasma exchange for a patient with sickle cell disease and fat embolism syndrome after a failure of a response to red cell exchange transfusion

BACKGROUND

Fat embolism syndrome (FES) is a rare complication, which was reported mostly with milder forms of heterozygous sickle cell disease (SCD). It may present in a catastrophic way with multi-organ failure, particularly involving the pulmonary and neurological systems. Diagnosis is often missed or delayed; and the standard recommended treatment is red cell exchange (RCE) transfusion, which has sub-optimal results, such as debilitating long-term neurological complications. Recently, few reports suggested that the addition of Therapeutic Plasma Exchange (TPE) might further improve the outcome.

CASE DESCRIPTION

A 23-year-old woman with homozygote SCD was admitted with bony pains and vaso-occlusive crises. However, her course evolved to respiratory failure requiring mechanical ventilation, decreased level of consciousness, skin rash, severe anemia and thrombocytopenia and a picture consistent with thrombotic microangiopathy. MRI of the brain showed scattered multi-focal ischemic foci and cytotoxic edema. The patient received RCE on the third day after admission without improvement. On the seventh day, TPE was instituted (2 L/day of fresh frozen plasma for 5 days), following which she regained her consciousness and showed an improvement in her laboratory abnormalities. On follow up, she had gradual full neurological recovery and resolution of the MRI findings within a few months.

CONCLUSION

FES remains a diagnostic and therapeutic challenge, with significant morbidity and mortality. Success in the management of this reported case with the addition of TPE to RCE supports the notion that TPE may be a potentially helpful modality that deserves further research.

Stroke in sickle cell disease and the promise of recent disease modifying agents

Sickle cell disease (SCD) is an inherited hemoglobinopathy affecting approximately 100,000 individuals in the United States. Cerebrovascular disease is among the most common and debilitating complications of SCA, with 53% experiencing silent cerebral infarct by age 30 and 3.8% experiencing overt stroke by age 40 years. This review highlights the burden of cerebrovascular disease in SCD, including both stroke and silent cerebral infarct (SCI). We then discuss the pathophysiology of stroke and cerebral fat embolism in the absence of a patent foramen ovale. This review also reveals that options for primary and secondary stroke prevention in SCD are still limited to hydroxyurea and blood transfusion, and that the role of aspirin and anticoagulation in SCD stroke has not been adequately studied. Limited data suggest that the novel disease-modifying agents for SCD management may improve renal dysfunction, leg ulcers, and lower the abnormally high TCD flow velocity. Further research is urgently needed to investigate their role in stroke prevention in SCD, as these novel agents target the main stroke contributors in SCD - hemolysis and vaso-occlusion. This literature review also explores the role of healthcare disparities in slowing progress in SCD management and research in the United States, highlighting the need for more investment in patient and clinician education, SCD management, and research.

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.

Diverse manifestations of a sickle cell crisis

We describe the case of a 21-year-old man with a background of sickle cell disease (SCD) who was on acute presentation in a sickle cell crisis required immediate intensive care admission with red blood cell exchange and ventilatory support. He had right frontal lobe infarcts and extensive bilateral deep white matter lesions most likely secondary to fat embolism. Inpatient investigations demonstrated a patent foramen ovale, explaining the route of spread of the fat embolus. He then had a transcatheter closure of the atrial defect. The patient needed prolonged inpatient rehabilitation. He was discharged from hospital in a wheelchair secondary to severe lower limb neurology and bilateral knee heterotopic ossification. He lives with the possibility of early onset dementia and cognitive decline, requiring constant care. The case highlights the multiple manifestations of SCD and their diverse and debilitating consequences.

Vascular Instability and Neurological Morbidity in Sickle Cell Disease: An Integrative Framework

It is well-established that patients with sickle cell disease (SCD) are at substantial risk of neurological complications, including overt and silent stroke, microstructural injury, and cognitive difficulties. Yet the underlying mechanisms remain poorly understood, partly because findings have largely been considered in isolation. Here, we review mechanistic pathways for which there is accumulating evidence and propose an integrative systems-biology framework for understanding neurological risk. Drawing upon work from other vascular beds in SCD, as well as the wider stroke literature, we propose that macro-circulatory hyper-perfusion, regions of relative micro-circulatory hypo-perfusion, and an exhaustion of cerebral reserve mechanisms, together lead to a state of cerebral vascular instability. We suggest that in this state, tissue oxygen supply is fragile and easily perturbed by changes in clinical condition, with the potential for stroke and/or microstructural injury if metabolic demand exceeds tissue oxygenation. This framework brings together recent developments in the field, highlights outstanding questions, and offers a first step toward a linking pathophysiological explanation of neurological risk that may help inform future screening and treatment strategies.