Intelligence Quotient Testing in Children With Cochlear Implantation: A Systematic Review and Meta-Analysis.

Objectives: Evaluate intelligence quotient (IQ) scores among children with bilateral hearing loss (HL) pre- and post-cochlear implantation (CI) and compared with normative means.

Databases reviewed: PubMed (MEDLINE), Embase, Cochrane, and CINAHL databases searched until December 2021.

Methods: Studies of patients 1) 18 years or younger (2) with bilateral sensorineural HL diagnosis who underwent CI, and (3) with ≥1 specific IQ score post-CI were included. Mean differences in IQ scores pre- and post-CI and compared with normal-hearing controls were meta-analyzed. Studies not amenable to meta-analysis were qualitatively analyzed.

Results: Included 15 articles (636 patients, 247 age-matched normal-hearing controls), with mean (SD) age in years at CI (4.1 [1.5]) and neurocognitive testing (8.6 [1.6]). Children with HL had significant performance IQ score improvement post-CI (MD, 7.0; 95% confidence interval, 1.95 to 12.05; I2 = 0%), and full-scale IQ scores comparable to normal-hearing group (MD 1.52; 95% confidence interval -4.46 to 7.50; I2 = 0%). Qualitatively, 9 of 12 studies evaluating performance IQ and 5 of 6 studies evaluating full-scale IQ showed mean scores of children with CI comparable to normative means, whereas 5 of 6 studies reported verbal IQ scores lower than normative means.

Conclusions: Children with CI show significant improvement in full-scale and performance IQ testing, with a significant proportion achieving normal ranges scores. Verbal IQ scores remain lower than normative means, even after CI, likely due to the reduced access to sound before CI. Earlier implantation and therefore earlier access to sound may help lessen the impact on verbal IQ in these children.