source: The American Society of Pediatric Hematology/Oncology

year: 2016

authors: Jolie S. Ramesar, Catherine Boston, Vandy Black

Background: Consensus guidelines recommend chronic transfusion therapy (CTT) for stroke prevention in patients with sickle cell disease (SCD) who have a history of overt stroke or abnormal transcranial Doppler (TCD) velocities, typically with the goal of maintaining baseline hemoglobin (Hb) S <30%. Observational studies report considerable variation in Hb S% in children on CTT, but outside of alloimmunization, reasons for such variability have not been well-studied.

Objectives: We report the possibility of chronic splenic sequestration as a cause of poor Hb S control in 3 patients with SCD on CTT for stroke prevention and suggest consideration of splenectomy to optimize transfusion parameters in select high-risk children.

Design/Method: Patients were ages 7-9 years with Hb SS disease managed with chronic, partial-exchange PRBC transfusions every 3-4 weeks following a standardized institutional protocol with poor Hb S control. Indications for CTT were prior stroke and abnormal TCD. Surveillance magnetic resonance angiography showed progressive CNS vasculopathy. Spleens measured 9.5-13.5 cms. There was no evidence of alloimmunization. After careful consideration, these patients underwent laparoscopic splenectomy. Mean hematologic parameters were compared by paired t-tests 6 months pre and post splenectomy.

Results: Prior to splenectomy, mean pre-transfusion Hb was 7.4 gm/dL, reticulocyte count 20.7%, and Hb S 56%. Post splenectomy Hb was 9.5 gm/dL, reticulocyte count 3%, and Hb S 17%. Following splenectomy, there was a mean reduction in Hb S of 39.77% (95% CI 34.3-45.3, p<0.001). With a mean follow-up of 19 months, there were no perioperative or infectious complications. One patient appeared to have reduced iron burden with a mean reduction in baseline serum ferritin of 1,500 ng/mL, perhaps in part because his transfusions were spaced out due to improved Hb S control.

Conclusion: This data suggest splenic sequestration may cause shortened red cell survival resulting in suboptimal Hb S control and increased risk of incident or recurrent stroke. Splenectomy may be a reasonable therapeutic option for select high-risk patients. Additional research is warranted into the causes of variable Hb S control in patients with SCD on CTT so that therapeutic options can be refined to reduce the risk of overt stroke.

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