Key Information
Abstract
Neurovascular complications are a common and major cause of morbidity and mortality in patients with sickle cell anemia (SCA). Prior studies have demonstrated cortical thinning as well as reduced cerebral volume in children with SCA when compared to age-matched controls, but data in adults are scarce. Chronic transfusion regimens have been shown to be neuroprotective in children with SCA, but their efficacy in adults is less clear. Automated erythrocytapheresis (red blood cell exchange transfusion) is the most aggressive disease modifying-treatment in SCA, by rapidly diluting sickle hemoglobin and replacing it with normal hemoglobin. Recently, 7 Tesla (7T) MRI have allowed for precise definition and quantitation of brain structures, specifically the delineation between gray and white matter, thereby facilitating the assessment of neurodegeneration in SCA. We hereby present a case of a woman in her late 30s (at the baseline) who was monitored for a period of 6 years (baseline + 2 time points) with 7T structural imaging. The patient has SCA and a remote history of right hemispheric stroke. Despite adherence to a chronic exchange transfusion program, the patient developed accelerated gray matter with a volume loss of 1.15% per year, on average, during the 6-year period. Our case report underscores the severity of accelerated brain atrophy in SCA.
Keywords: Sickle cell anemia, Cerebral atrophy, Chronic exchange transfusion therapy, 7T MRI
Introduction
Sickle cell anemia (SCA) is an inherited blood disorder due to a mutated hemoglobin (HbS) that leads to polymerization of hemoglobin, chronic hemolysis, vaso-occlusion, and tissue ischemia. Cerebrovascular disease is a well-known complication of SCA that includes strokes (both overt and silent), microvascular injury, and cognitive dysfunction [[1]external link, opens in a new tab, [2]external link, opens in a new tab, [3]external link, opens in a new tab, [4]external link, opens in a new tab]. It is estimated that about 37% of SCA patients will experience silent cerebral infarcts (SCI) by the age of 14 [5external link, opens in a new tab] and they are at higher risk of additional SCIs into adulthood [6external link, opens in a new tab]. Over the years, the use of quantitative MRI has uncovered other brain abnormalities in patients with SCA such as reduced cerebral volume and cortical thinning [7external link, opens in a new tab,8external link, opens in a new tab]. Cortical changes have been identified in posterior medial surfaces of both hemispheres in the older children with SCA [9external link, opens in a new tab] but evidence regarding cortical atrophy in adults is limited. Furthermore, the rate of progression of cerebral atrophy in individuals with SCA is unclear as most studies have been confined to cross-sectional data. In adults, Mackin et al. showed cortical thinning in the frontal lobe when compared to healthy controls and demonstrated an association between lower cerebral volume and lower performance IQ in addition to deficits in 2 other cognitive domains [10external link, opens in a new tab]. Our group has pioneered the development of 7 Tesla (7T) MRI hardware and processing techniques to better quantify neurodegeneration and cerebrovascular changes in patients with SCA and other diseases [7external link, opens in a new tab,11external link, opens in a new tab]. In a cross-sectional cohort of adult patients with sickle cell disease (SCD), we found that individuals with SCD displayed decreased volumes in various hippocampal subfields when compared to a control group [7external link, opens in a new tab].