Incidence of Stroke and Other Brain Imaging Findings in Adult Patients with Sickle Cell Disease: A Retrospective Study
Authors: Thomas Nithin , Liao Zean , Idowu Modupe 
Published: November 2021

Abstract
Background: Vaso-occlusion and hemolytic anemia are the main features of sickle cell disease. Central Nervous system complications of sickle cell disease (SCD) can include silent cerebral infarcts (SCI), hemorrhagic or ischemic strokes, seizures and Moyamoya syndrome. SCI is the most common neurological complications in SCD. SCI patients have abnormal Magnetic Resonance Imaging (MRI) of the brain with normal neurological examination and no history of stroke. More precisely, Casella et al in the Silent Cerebral Infarct Multi-Center Clinical trial (SIT) defined infarct as MRI signal abnormality that was at least 3 mm in one dimension and that was visible in two planes on fluid-attenuated inversion recovery T2 -weighted images, as determined by agreement of two of the three study neuroradiologists. SCI in children is associated with lower Intelligence Quotient and increased risk of stroke.
Methods: In this retrospective study we reviewed 100 adult patients at our Comprehensive Sickle Cell Center. We looked at the incidence of documented stroke and other neurological complications in SCD patients. We reviewed the hospital records of SCD patients for any incidental brain imaging (MRI brain or Computed Tomography(CT) brain) findings, done as inpatient or in the emergency room as part of hospital visits.
Results: Out of the 100 patients, 14 patients had documented stroke. On the review of other 86 patients, 10 patients had MRI brain, 23 patients had CT brain, and 53 patients had no brain imaging record. Out of the 10 patients with MRI brain, 7 patient had significant findings- 3 patients had small vessel ischemic changes, 1 patient with chronic petechial hemorrhage of cerebellar vermis, 1 patient with ischemic changes and Chiari malformation type 1 (CTM 1), 1 patient with CTM 1 and non-specific white matter changes and 1 patient with CTM 1 alone. Out of the 22 CT of the brain and 1 CT angiogram of brain, 2 imaging showed ischemic changes and the angiogram showed large cerebral vessel narrowing. Therefore, on our review, 19 patients out of 100 were found to have stroke and 24 out of 100 had significant neurological findings. However, only 14 out of 19 patients had documented stroke. 7 out the 10 patients with MRI brain had significant incidental neurological findings. The number of adult SCD patients with neurological findings in our cohort could have been higher, if we had brain imaging record for the 53 other patients.
Conclusion: This study shows that there is a heavy burden of neurological complications in SCD patients and SCI is under-diagnosed. MRI brain is superior to CT brain in detecting neurological complications in SCD patients. SIT showed that regular blood-transfusion significantly reduced the recurrence of cerebral infarct in children with SCI. Finding of SCI in adults also warrants consideration for follow up brain imaging, neurology referral and discussion of treatment modalities including chronic blood transfusion and hydroxyurea therapy. CTM 1 can also be associated with SCD. In CTM 1, tonsil herniates 5 millimeter or below foramen magnum. SCD may cause increased thickness of calvarium from extramedullary hematopoiesis in skull, which can result in cranio-cephalic disproportion with cerebellar ectopia and subsequent CTM 1. Because of high incidence of neurological complications in SCD patients, routine screening with MRI brain should be considered in adult SCD patients.

Disclosures
Idowu: Forma Therapeutics, Inc.: Research Funding; Pfizer: Research Funding; Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding; Global Blood Therapeutics: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Ironwood: Research Funding.