Background: The relationship between sickle cell disease (SCD), hearing and cognitive impairment is intertwined due to the vaso-occlusive, vascular insults and tissue hypoxia associated with sickle cell disease.
Aim of the work: To assess the hearing ability and cognitive functions in patients with SCD. 
Material and methods: a cross sectional case-control study included 41 children with SCD who presented to Pediatric Hematology Clinic, Children Hospital, Cairo University. They were screened for auditory impairment using tympanometry and pure tone audiometer (PTA), they were also assessed for cognitive impairment using the Stanford-Binet Intelligence Scale, 4th Ed, and P300 event related auditory evoked potential. Another 41 healthy age and gender matched children were enrolled as controls for P300 data.
Results: The age of the children with SCD ranged from 6-17 years (mean± SD= 10.4±3.3 year), 15 (36.6%) were males and 26 (63.4%) females. Nine (22%) had impaired hearing detected by PTA. The cognitive dysfunction was encountered in 33 (80.5%) patients with SCD. The greater impairment was observed in older patients (p=0.082), and in those with hemoglobin SS type (p < 0.05). Twelve (29.3%) patients had abnormal P300 latency. P300 latency was higher (p=0.002) and amplitude was lower (p=0.008) in patients aged <10 years compared to their controls. 33 (80.5%) patients had low IQ (˂89), they had a significant lower P300 amplitude (p=0.004) but comparable latencies (p=0.3) to patients with normal IQ. Only one third of patients with low IQ had abnormal P300 values. Receiver operating (ROC) curves showed that area under the curve (AUC) of P300 latency was 0.632 indicating that overall predictability of cognitive dysfunction by P300 latency was not significant (p=0.243) and agreement between P300 latency and IQ test was low. No significant differences were found between patients with auditory dysfunction and patients who had normal hearing, regarding the IQ scoring (p=0.61), P300 latency (0.595) or amplitude (0.322).
Conclusion: Both cognitive and auditory impairments were prevalent among children with SCD. IQ tests were superior to P300 in the evaluation of cognitive impairment.