P1093 - Stroke Presentation in an Adolescent with mild Hemoglobin SC disease

Background: In individuals affected with Hemoglobin SC (HbSC) disease, one β globin gene is affected by the sickle mutation (position 6, a single-base pair change encodes valine instead of glutamine) while the other β globin gene contains a mutation for hemoglobin C (position 6, lysine is encoded instead of glutamine). In this compound heterozygous state individuals typically present with a milder sickle cell disease (SCD) course compared to those with homozygous HbS (HbSS) disease. Although children with HbSC disease experience a significant incidence of silent cerebral infarcts, acute stroke presentation is exceptionally rare. Herein we describe a case of an adolescent male with historically uncomplicated HbSC disease, and otherwise unremarkable sickle cell surveillance labs on admission presenting with new acute onset stroke.

Case Presentation: Our patient is a 16 year old male with uncomplicated HbSC disease and no history of hospitalizations for vasoocclusive crisis. He presented with 48 hours of difficulty focusing out of his left eye. Physical exam revealed impaired right eye adduction, left eye nystagmus on lateral left gaze, and decreased sensation to touch to the left hemi face and left arm. Strength and deep tendon reflexes were normal. Normal gait was observed and he had no dysdiadochokinesia. STAT MRI orbit and brain with contrast revealed multiple foci of acute infarct involving the pons and left cerebral peduncle. Vessel imaging with MRA was concerning for internuclear ophthalmoplegia secondary to stenosis in the posterior cerebral circulation. Vital signs were normal for age and labs were overall mild and unchanged from his baseline (WBC 8750/mcL, Hemoglobin 13.5g/dL, Platelets 290,000/mcL, Reticulocyte 2.11%, CRP <0.30mg/dL). Initial thrombophilia work up demonstrated no increase in antiphospholipid antibodies, normal homocysteine levels and fibrinogen levels. Fibrin D-dimer was mildly elevated at 0.55mcg/mL. Further thrombophilia evaluation is ongoing. A respiratory viral panel and COVID-19 testing were performed and were negative. The patient was treated with emergent complete exchange transfusion.

Discussion: This case highlights the importance recognizing the risk for acute stroke in patients with HbSC. Prior to this acute presentation of stroke, this patient had mild disease with no history of prior transfusions and mild vasooclussive crises managed as an outpatient. Early recognition, imaging and management for those who present with focal neurologic deficits is essential in preventing considerable morbidity and mortality. It is imperative that as a general pediatrician, one must be vigilant and not rely on reassuring labs or prior histories of mild disease presentations in patients with SCD. Unlike with HbSS, there is limited data and consensus guidelines for secondary stroke prevention in patients with HbSC, thus emphazing clinical judgement in initiation of exchange transfusion. We did proceed with exchange transfusion taking into consideration the data that supports improved outcomes in HbSS patients.