Screening for Stroke Risk in Paediatric Sickle Cell Anaemia: Comparing Nonimaging with Imaging Transcranial Doppler Ultrasonography.

Abstract

Summary:

Stroke is a devastating and potentially fatal complication of Sickle Cell Disease (SCD), caused by an impairment in the morphology and blood flow pattern in the large cerebral vessels of the arterial circulation of the brains of affected individuals. Over the past decades, advances in technology have enabled the identification of asymptomatic children with SCD who are at increased risk of stroke by screening with the use of the Non-Imaging Transcranial Doppler(nTCD). This has greatly reduced the stroke incidences in children with SCD through preemptive interventions. Scarcity of this screening tool, (nTCD), necessitates the exploration of complementing it with more readily available and equally useful tool – the multipurpose ultrasound machine with Doppler capabilities. This study is aimed at comparing findings of intra-cranial arterial velocities obtained by the Imaging Transcranial Doppler (TCDI) with the widely studied Nonimaging Transcranial Doppler (nTCD) in determining the risk of stroke in children aged 2 to 16 years with SCD to explore the possibility of expanding the screening capacity of TCD in SCD children in our environment. One hundred and forty-five (145) children with SCA, aged 2 – 16years underwent both nTCD and TCDI examinations, not more than one hour apart, performed by a Sickle Cell Foundation of Nigeria (SCFN) sonographer and the researcher respectively, with the result from both studies blinded to each other. Non-corrected and Angle-corrected TCDI velocimetry at the terminal Internal Carotid Artery (ICA), Middle Cerebral Artery (MCA) and Anterior Cerebral Artery (ACA) bilaterally were obtained and compared with similar indices from nTCD. 13 randomly selected of the 145 participants underwent Magnetic Resonance Angiography (MRA) to correlate findings with nTCD and TCDI. Study data was analyzed using the Statistical Package for Social Sciences (SPSS) version 25.0 There were 145 children with sickle cell anaemia; 81 (55.9%) males and 64 (44.1%) females with a mean age of 7.98 ± 3.32 years, (age range 3 to 16 years) and age at diagnosis of sickle cell anemia being 3.24 ± 2.34 years (range1 -13 years). The Time Averaged Mean of Maximum Velocity (TAMMV) in TCDI in all the cerebral arteries measured were significantly lower than those of nTCD. Non-angle- corrected TCDI velocities were lower by 25% while Angle-corrected TCDI velocities by 17%. When only the velocities mostly implicated in Stroke (MCA and distal ICA) were compared, a difference of 18% and 10% respectively were recorded for the TCDI non-Angle corrected and Angle corrected TCDI, respectively. 17.9% of participants were classified as High risk by nTCD, while 9.7% and 4.8% were classified as High risk by angle- corrected and non-angle corrected TCDI respectively (p < 0.0001). TCDI can be safely used in resource poor areas to complement nTCD screening for complication of Stroke in SCD taking into cognizance, the subtle differences observed in this study.