Neurosurgical conditions and procedures in infancy are associated with mortality and academic performances in adolescence: a nationwide cohort study

General anesthesia in children and long-term neurodevelopmental deficits: A systematic review

Background

Millions of children experienced surgery procedures requiring general anesthesia (GA). Any potential neurodevelopmental risks of pediatric anesthesia can be a serious public health issue. Various animal studies have provided evidence that commonly used GA induced a variety of morphofunctional alterations in the developing brain of juvenile animals.

Methods

We conducted a systematic review to provide a brief overview of preclinical studies and summarize the existing clinical studies. Comprehensive literature searches of PubMed, EMBASE, CINAHL, OVID Medline, Web of Science, and the Cochrane Library were conducted using the relevant search terms “general anesthesia,” “neurocognitive outcome,” and “children.” We included studies investigating children who were exposed to single or multiple GA before 18, with long-term neurodevelopment outcomes evaluated after the exposure(s).

Results

Seventy-two clinical studies originating from 18 different countries published from 2000 to 2022 are included in this review, most of which are retrospective studies (n = 58). Two-thirds of studies (n = 48) provide evidence of negative neurocognitive effects after GA exposure in children. Neurodevelopmental outcomes are categorized into six domains: academics/achievement, cognition, development/behavior, diagnosis, brain studies, and others. Most studies focusing on children <7 years detected adverse neurocognitive effects following GA exposure, but not all studies consistently supported the prevailing view that younger children were at greater risk than senior ones. More times and longer duration of exposures to GA, and major surgeries may indicate a higher risk of negative outcomes.

Conclusion

Based on current studies, it is necessary to endeavor to limit the duration and numbers of anesthesia and the dose of anesthetic agents. For future studies, we require cohort studies with rich sources of data and appropriate outcome measures, and carefully designed and adequately powered clinical trials testing plausible interventions in relevant patient populations.

Anesthetic Exposure During Childhood and Neurodevelopmental Outcomes: A Systematic Review and Meta-analysis

IMPORTANCE

Clinical studies of neurodevelopmental outcomes after anesthetic exposure have evaluated a range of outcomes with mixed results.

OBJECTIVE

To examine via meta-analyses the associations between exposure to general anesthesia and domain-specific neurodevelopmental outcomes in children.

DATA SOURCES

PubMed/MEDLINE, Embase, CINAHL, Web of Science and the Cochrane Library were searched from inception to August 31, 2021.

STUDY SELECTION

Inclusion criteria were exposures to procedures requiring general anesthesia at younger than 18 years and evaluation of long-term neurodevelopmental function after exposure. Studies lacking unexposed controls or focused on children with major underlying comorbidities were excluded.

DATA EXTRACTION AND SYNTHESIS

Extracted variables included effect size; hazard, risk, or odds ratio; number of exposures; procedure type; major comorbidities; age of exposure and assessment; presence of unexposed controls; and study design. Studies were independently reviewed by 2 coders, and review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Data were pooled using a random-effects model.

MAIN OUTCOMES AND MEASURES

The main outcomes were standardized mean differences (SMD) for scores in the neurodevelopmental domains of academics, behavioral problems, cognition, executive function, general development, language, motor function, nonverbal reasoning, social cognition, and hazard and risk of neurodevelopmental disorder diagnoses.

RESULTS

A total of 31 studies contributed data for meta-analysis. For each of the assessed neurodevelopmental domains, the numbers of children evaluated ranged from 571 to 63 315 exposed and 802 to 311 610 unexposed. Children with any exposure (single or multiple) had significantly worse behavioral problems scores, indicating more behavioral problems (SMD, -0.10; 95% CI, -0.18 to -0.02; P = .02), and worse scores in academics (SMD, -0.07; 95% CI -0.12 to -0.01; P = .02), cognition (SMD, -0.03; 95% CI, -0.05 to 0.00; P = .03), executive function (SMD, -0.20; 95% CI, -0.32 to -0.09; P < .001), general development (SMD, -0.08; 95% CI, -0.13 to -0.02; P = .01), language (SMD, -0.08; 95% CI, -0.14 to -0.02; P = .01), motor function (SMD, -0.11; 95% CI, -0.21 to -0.02; P = .02), and nonverbal reasoning (SMD, -0.15; 95% CI, -0.27 to -0.02; P = .02). Higher incidences of neurodevelopmental disorder diagnoses were also reported (hazard ratio, 1.19; 95% CI, 1.09 to 1.30; P < .001; risk ratio, 1.81; 95% CI, 1.25 to 2.61; P = .002).

CONCLUSIONS AND RELEVANCE

These findings support the hypothesis that associations between anesthetic exposure during childhood and subsequent neurodevelopmental deficits differ based on neurodevelopmental domain.

Early Childhood General Anesthesia and Neurodevelopmental Outcomes in the Avon Longitudinal Study of Parents and Children Birth Cohort

Background

Most common anesthetic agents have been implicated in causing neurodegeneration in the developing animal brain, leading to warnings regarding their use in children. The hypothesis of this study was that exposure to general anesthesia and surgery before 4 yr would associate with adverse neurodevelopmental outcomes at age 7 to 16 yr.

Methods

This cohort study comprised 13,433 children enrolled in the Avon Longitudinal Study of Parents and Children, a prospective, population-based birth cohort born between 1991 and 1993 in southwest England. Children were grouped by none, single, or multiple exposures to general anesthesia and surgery by 4 yr. Motor, cognitive, linguistic, educational, social, and behavioral developmental outcomes were evaluated at 7 to 16 yr using school examination results, validated parent/teacher questionnaires, or clinic assessments. Continuous outcomes were z-scored. P-value thresholds were corrected using false discovery rate procedures.

Results

This study compared 46 neurodevelopmental outcomes in 13,433 children: 8.3% (1,110) exposed singly and 1.6% (212) exposed multiply to general anesthesia and surgery. Of these, the following reached predefined levels of statistical significance (corrected P &lt; 0.00652): dynamic balance scores were 0.3 SD (95% CI, 0.1, 0.5; P &lt; 0.001) lower in multiply exposed children; manual dexterity performance was 0.1 SD (95% CI, 0.0, 0.2; P = 0.006) lower in singly and 0.3 SD (95% CI, 0.1, 0.4; P &lt; 0.001) lower in multiply exposed children; and social communication scores were 0.1 SD (95% CI, 0.0, 0.2; P = 0.001) and 0.4 SD (95% CI, 0.3, 0.5; P &lt; 0.001) lower in singly and multiply exposed children, respectively. General anesthesia and surgery were not associated with impairments in the remaining neurodevelopmental measures including: general cognitive ability; attention; working memory; reading, spelling, verbal comprehension and expression; behavioral difficulties; or national English, mathematics, and science assessments (all ≤0.1 SD; corrected P ≥ 0.00652).

Conclusions

Early childhood general anesthesia and surgery were not associated with a global picture of clinically and statistically significant neurodegenerative effects, providing reassurance about the neurotoxic potential of general anesthesia. Exposure to anesthesia and surgery was associated with significantly lower motor and social linguistic performance.

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What We Already Know about This Topic

What This Article Tells Us That Is New

Assessing Long-term Neurodevelopmental Outcome Following General Anesthesia in Early Childhood: Challenges and Opportunities

Neurodegeneration has been reported in young animals after exposure to all commonly used general anesthetic agents. The brain may be particularly vulnerable to anesthetic toxicity during peak synaptogenesis (in gestation and infancy). Human studies of long-term neurodevelopmental outcome following general anesthesia in early childhood report contradictory findings. This review assesses the strengths and deficiencies in human research methodologies to inform future studies. We identified 76 studies, published between 1990 and 2017, of long-term neurodevelopmental outcome following early childhood or in utero general anesthesia exposure: 49 retrospective, 9 ambidirectional, 17 prospective cohort studies, and 1 randomized controlled trial. Forty-nine studies were explicitly concerned with anesthetic-induced neurotoxicity. Full texts were appraised for methodological challenges and possible solutions. Major challenges identified included delineating effects of anesthesia from surgery, defining the timing and duration of exposure, selection of a surgical cohort and intervention, addressing multiple confounding life course factors, detecting modest neurotoxic effects with small sample sizes (median, 131 children; interquartile range, 50–372), selection of sensitive neurodevelopmental outcomes at appropriate ages for different developmental domains, insufficient length of follow-up (median age, 6 years; interquartile range, 2–12 years), and sample attrition. We discuss potential solutions to these challenges. Further adequately powered, multicenter, prospective randomized controlled trials of anesthetic-induced neurotoxicity in children are required. However, we believe that the inherent methodological challenges of studying anesthetic-induced neurotoxicity necessitate the parallel use of well-designed observational cohort studies.

Neuropsychological and Behavioral Outcomes after Exposure of Young Children to Procedures Requiring General Anesthesia: The Mayo Anesthesia Safety in Kids (MASK) Study

BACKGROUND

Few studies of how exposure of children to anesthesia may affect neurodevelopment employ comprehensive neuropsychological assessments. This study tested the hypothesis that exposure to multiple, but not single, procedures requiring anesthesia before age 3 yr is associated with adverse neurodevelopmental outcomes.

METHODS

Unexposed, singly exposed, and multiply exposed children born in Olmsted County, Minnesota, from 1994 to 2007 were sampled using a propensity-guided approach and underwent neuropsychological testing at ages 8 to 12 or 15 to 20 yr. The primary outcome was the Full-Scale intelligence quotient standard score of the Wechsler Abbreviated Scale of Intelligence. Secondary outcomes included individual domains from a comprehensive neuropsychological assessment and parent reports.

RESULTS

In total, 997 children completed testing (411, 380, and 206 unexposed, singly exposed, and multiply exposed, respectively). The primary outcome of intelligence quotient did not differ significantly according to exposure status; multiply exposed and singly exposed children scoring 1.3 points (95% CI, -3.8 to 1.2; P = 0.32) and 0.5 points (95% CI, -2.8 to 1.9; P = 0.70) lower than unexposed children, respectively. For secondary outcomes, processing speed and fine motor abilities were decreased in multiply but not singly exposed children; other domains did not differ. The parents of multiply exposed children reported increased problems related to executive function, behavior, and reading.

CONCLUSIONS

Anesthesia exposure before age 3 yr was not associated with deficits in the primary outcome of general intelligence. Although secondary outcomes must be interpreted cautiously, they suggest the hypothesis that multiple, but not single, exposures are associated with a pattern of changes in specific neuropsychological domains that is associated with behavioral and learning difficulties.

Association between Exposure of Young Children to Procedures Requiring General Anesthesia and Learning and Behavioral Outcomes in a Population-based Birth Cohort

BACKGROUND

Exposure of young animals to general anesthesia causes neurodegeneration and lasting behavioral abnormalities; whether these findings translate to children remains unclear. This study used a population-based birth cohort to test the hypothesis that multiple, but not single, exposures to procedures requiring general anesthesia before age 3 yr are associated with adverse neurodevelopmental outcomes.

METHODS

A retrospective study cohort was assembled from children born in Olmsted County, Minnesota, from 1996 to 2000 (inclusive). Propensity matching selected children exposed and not exposed to general anesthesia before age 3 yr. Outcomes ascertained via medical and school records included learning disabilities, attention-deficit/hyperactivity disorder, and group-administered ability and achievement tests. Analysis methods included proportional hazard regression models and mixed linear models.

RESULTS

For the 116 multiply exposed, 457 singly exposed, and 463 unexposed children analyzed, multiple, but not single, exposures were associated with an increased frequency of both learning disabilities and attention-deficit/hyperactivity disorder (hazard ratio for learning disabilities = 2.17 [95% CI, 1.32 to 3.59], unexposed as reference). Multiple exposures were associated with decreases in both cognitive ability and academic achievement. Single exposures were associated with modest decreases in reading and language achievement but not cognitive ability.

CONCLUSIONS

These findings in children anesthetized with modern techniques largely confirm those found in an older birth cohort and provide additional evidence that children with multiple exposures are more likely to develop adverse outcomes related to learning and attention. Although a robust association was observed, these data do not determine whether anesthesia per se is causal.

Oral Clefts and Academic Performance in Adolescence: The Impact of Anesthesia-Related Neurotoxicity, Timing of Surgery, and Type of Oral Clefts

OBJECTIVE

Early life exposure to anesthesia and surgery is suspected to associate with cognitive impairment later in life. We compared academic achievement among adolescents with cleft lip only (CL), cleft palate only (CP), and cleft lip and cleft palate (CLP) with a noncleft control group to investigate whether outcome depends on timing and number of operations during childhood and/or type of oral cleft.

DESIGN

Nationwide register-based follow-up study.

SETTING

Danish birth cohort 1986 to 1990.

PARTICIPANTS

Five hundred fifty-eight children with isolated CL (n = 171), CLP (n = 222), or CP (n = 195), of which 509 children had been exposed to anesthesia and one or more cleft operation(s), and a 5% sample of the birth cohort (n = 14,677).

MAIN OUTCOME MEASURE(S)

Test score in the Danish standardized ninth-grade exam and proportion of nonattainment, defined as "results for ninth-grade exam unavailable." Data adjusted for sex, birth weight, parental age, and parental level of education.

RESULTS

Compared to controls, children with CL achieved higher scores (mean difference 0.12, 95% CI -0.05; 0.29) and children with CLP presented with lower scores (mean difference -0.06, 95% CI -0.21; 0.09), albeit both statistically insignificant. Children with CP achieved significantly lower scores, mean difference -0.20 (95% CI -0.38; -0.03). Odds ratios for nonattainment at final exam were: CL 0.79 (95% CI 0.46; 1.35), CLP 1.07 (95% CI 0.71; 1.61), CP 2.59 (95% CI 1.78; 3.76).

CONCLUSIONS

Oral cleft type rather than number and timing of anesthesia and operations associate to poorer academic performance. Although a potential neurotoxic effect due to anesthetic agents is not reflected in the data, it cannot be completely excluded.

Anesthesia-related neurotoxicity and the developing animal brain is not a significant problem in children

A multitude of animal studies have shown that virtually all general anesthetics used in clinical practice possibly during a vulnerable period of brain development (i.e., brain growth spurt, peak of synaptogenesis) may lead to neurodegeneration (particularly apoptosis) and abnormal synaptic development with functional deficits in learning and behavior later in life. Initial studies were mainly performed in immature rodent pups, but more recent studies have included nonhumans primates (rhesus monkeys). Given the number of neonates, infants, and young children anesthetized annually worldwide, these findings could have significant public health implications. So far, relatively few human (cohort) studies focusing on this topic have been published with inconsistent results. While some studies have indicated an association between exposure to anesthesia and surgery, other studies have indicated no such association. Prospective studies are underway, but the result will not be available for several years. This paper reviews some of the preclinical background behind anesthesia-related neurotoxicity but focuses mainly on the human studies so far. It is concluded that although disturbing, the animal data lack verification in humans. Fortunately, the humans studies performed so far have been unable to confirm these animal data. A single brief anesthetic seems safe in infants. Multiple anesthetic and surgical exposures on the other hand are different. But there may be other reasons for this than merely the anesthetics. Currently, there is no need to change current anesthetic clinical practice or to postpone or cancel truly urgent surgeries in young children.