Hypertension and convulsions complicating sickle cell anaemia: possible role of transfusion

Logistics, risks, and benefits of automated red blood cell exchange for patients with sickle cell disease

Red blood cell (RBC) transfusions treat and prevent severe complications of sickle cell disease (SCD) and can be delivered as a simple or exchange transfusion. During an exchange, some of the patient's abnormal hemoglobin (Hb) S (HbS) RBCs are removed. An apheresis device can accomplish an automated RBC exchange, simultaneously removing patient's RBCs while returning other blood components along with normal RBCs. Automated RBC exchange is therefore an isovolemic transfusion that can efficiently decrease HbS RBCs while limiting iron loading and hyperviscosity. However, specialized equipment, trained personnel, appropriate vascular access, and increased RBC exposure are required compared to simple or manual RBC exchange. Therefore, risks and benefits must be balanced to make individualized decisions for patients with SCD who require transfusion.

Epidemiology of Stroke in Sickle Cell Disease

Sickle cell disease is the most common cause of stroke in childhood, both ischaemic and haemorrhagic, and it also affects adults with the condition. Without any screening or preventative treatment, the incidence appears to fall within the range 0.5 to 0.9 per 100 patient years of observation. Newborn screening with Penicillin prophylaxis and vaccination leading to reduced bacterial infection may have reduced the incidence, alongside increasing hydroxyurea prescription. Transcranial Doppler screening and prophylactic chronic transfusion for at least an initial year has reduced the incidence of stroke by up to 10-fold in children with time averaged mean of the maximum velocity >200 cm/s. Hydroxyurea also appears to reduce the incidence of first stroke to a similar extent in the same group but the optimal dose remains controversial. The prevention of haemorrhagic stroke at all ages and ischaemic stroke in adults has not yet received the same degree of attention. Although there are fewer studies, silent cerebral infarction on magnetic resonance imaging (MRI), and other neurological conditions, including headache, epilepsy and cognitive dysfunction, are also more prevalent in sickle cell disease compared with age matched controls. Clinical, neuropsychological and quantitative MRI screening may prove useful for understanding epidemiology and aetiology.

How I treat and manage strokes in sickle cell disease

Neurologic complications are a major cause of morbidity and mortality in sickle cell disease (SCD). In children with sickle cell anemia, routine use of transcranial Doppler screening, coupled with regular blood transfusion therapy, has decreased the prevalence of overt stroke from ∼11% to 1%. Limited evidence is available to guide acute and chronic management of individuals with SCD and strokes. Current management strategies are based primarily on single arm clinical trials and observational studies, coupled with principles of neurology and hematology. Initial management of a focal neurologic deficit includes evaluation by a multidisciplinary team (a hematologist, neurologist, neuroradiologist, and transfusion medicine specialist); prompt neuro-imaging and an initial blood transfusion (simple followed immediately by an exchange transfusion or only exchange transfusion) is recommended if the hemoglobin is >4 gm/dL and <10 gm/dL. Standard therapy for secondary prevention of strokes and silent cerebral infarcts includes regular blood transfusion therapy and in selected cases, hematopoietic stem cell transplantation. A critical component of the medical care following an infarct is cognitive and physical rehabilitation. We will discuss our strategy of acute and long-term management of strokes in SCD.

Post-transfusion hypertension and seizure in congenital hemolytic anemia: a case report and literature review

A rare syndrome of hypertension, seizures and intracranial bleed has been reported among patients with congenital hemolytic anemia who underwent multiple blood transfusions. We report this syndrome in a 12-year-old Malay girl with hemoglobin E-beta-thalassemia, who underwent intensive transfusion and subsequently had headache, visual loss, severe hypertension and seizures. A comprehensive literature review revealed 30 patients with this syndrome, of whom 15 had intracranial bleed and 12 among these 15 died. A less-intensive transfusion regimen among patients with chronic hemolytic anemia and prompt detection and management of hypertension may prevent this potentially fatal syndrome.

Primary hemorrhagic stroke in children with sickle cell disease is associated with recent transfusion and use of corticosteroids

OBJECTIVES

Primary hemorrhagic stroke is an uncommon complication of sickle cell disease, with reported mortality rates of 24% to 65%. Most reported cases are in adults; little is known about its occurrence in children. Proposed risk factors include previous ischemic stroke, aneurysms, low steady-state hemoglobin, high steady-state leukocyte count, acute chest syndrome, and hypertransfusion. We performed a retrospective case-control study to evaluate risk and prognostic factors for primary hemorrhagic stroke among children with sickle cell disease.

PATIENTS AND METHODS

Case subjects (sickle cell disease and primary hemorrhagic stroke) and control subjects (sickle cell disease and ischemic stroke) were identified at 2 children's hospitals from January 1979 to December 2004 by reviewing divisional records and the discharge databases.

RESULTS

We identified 15 case subjects (mean age: 10.4 +/- 1.3 years) and 29 control subjects (mean age: 5.2 +/- 0.4 years). An increased risk of hemorrhagic stroke was associated with a history of hypertension and recent (in the last 14 days) transfusion, treatment with corticosteroids, and possibly nonsteroidal antiinflammatory drugs. Average blood pressures at well visits (adjusted for age and gender) were similar between the 2 groups, suggesting that hypertension was intermittent.

CONCLUSIONS

In this group of children with sickle cell disease, hemorrhagic stroke was associated with a history of hypertension or antecedent events including transfusion or treatment with corticosteroids. Improved understanding of risk and prognostic factors, especially those that are modifiable, may help prevent this devastating complication in children with sickle cell disease.

Sickle cell disease: ischemia and seizures

Although the prevalence of seizures in children with sickle cell disease (SCD) is 10 times that of the general population, there are few prospectively collected data on mechanism. With transcranial Doppler and magnetic resonance imaging (MRI) and angiography, we evaluated 76 patients with sickle cell disease, 29 asymptomatic and 47 with neurological complications (seizures, stroke, transient ischemic attack, learning difficulty, headaches, or abnormal transcranial Doppler), who also underwent bolus-tracking perfusion MRI. The six patients with recent seizures also had electroencephalography. Group comparisons (seizure, nonseizure, and asymptomatic) indicated that abnormal transcranial Doppler was more common in the seizure (4/6; 67%) and nonseizure (26/41; 63%) groups than in the asymptomatic (10/29; 34%) group (chi2; p = 0.045), but abnormal structural MRI (chi2; p = 0.7) or magnetic resonance angiography (chi2; p = 0.2) were not. Relative decreased cerebral perfusion was found in all seizure patients and in 16 of 32 of the remaining patients with successful perfusion MRI (p = 0.03). In the seizure patients, the perfusion abnormalities in five were ipsilateral to electroencephalographic abnormalities; one had normal electroencephalogram results. These findings suggest that vasculopathy and focal hypoperfusion may be factors in the development of sickle cell disease-associated seizures.

Is "relative" hypertension a risk factor for vaso-occlusive complications in sickle cell disease?

Supine arterial blood pressure measurements of 89 patients with homozygous sickle cell disease and normal renal function were compared with those of an age-, race-, and sex-matched normal population and with those of individuals who had similar levels of anemia due to beta thalassemia. Consistent with previous reports, sickle cell patients had significantly lower blood pressure than the normal population. However, within most age groups, sickle cell patients tended to have higher than expected blood pressure than individuals with similar or less severe degrees of anemia. Furthermore, the authors have found an association between cerebrovascular accident and elevated blood pressure in men, even in a range of systolic and diastolic pressures that would be considered normal by conventional standards. These results reiterate the intricate relationship that exists between factors governing red cell rheology and microvascular tone. They also raise the possibility that "relative" hypertension may be associated with other vaso-occlusive manifestations of the sickle cell syndromes.

Cerebrovascular accidents (strokes) in children with sickle cell disease residing at high and low altitudes of Saudi Arabia

In a 3-year period, eight cases of cerebrovascular accident were seen out of 400 patients with sickle cell disease residing at high and low altitudes of Asir Province of Saudi Arabia. They were all Saudi nationals and comprised five boys and three girls of ages ranging from 3.5 to 9 years. They had varied clinical presentations of their cerebrovascular accident. Cranial computed tomography in seven of them showed abnormality in the region of the middle cerebral circulation. Management and some suggested factors contributing to the occurrence of the cerebrovascular accident are discussed.