Anatomic and etiological classification of congenital limb deficiencies

Associated Anomalies in Radial Ray Deficiency

Radial ray deficiency (RRD) may be isolated, without other congenital anomalies or co-occurring with other, non-RRD, congenital anomalies. The prevalence and the types of co-occurring anomalies are variable in the reported studies. The aim of this study was to obtain the prevalence and the types of co-occurring congenital anomalies among cases with RRD in a geographically well-characterized population of 387,067 consecutive births in northeastern France from 1979 to 2007 including live births, stillbirths and terminations of pregnancy. During the study period 83 cases with RRD were ascertained (prevalence of 2.14 per 10,000 births), 63 cases (75.9%) had co-occurring anomalies. Cases with co-occurring anomalies were divided into chromosomal anomalies (18 cases, 22%), syndromic conditions (syndromes and associations, 23 cases, 28%), and multiple congenital anomalies (MCA) (22 cases, 26%). Trisomies 18 and autosomal deletions were the most common chromosomal abnormalities. Thrombocytopenia absent radii syndrome, VACTERL association, Fanconi anemia, Roberts syndrome, and Holt-Oram syndrome were the most common syndromic conditions. Anomalies in the musculoskeletal, the cardiovascular, the urinary, and the orofacial system were the most common co-occurring anomalies in cases with MCA. As cases with RRD have often co-occurring congenital anomalies, a multidisciplinary checkup of these cases is recommended.

Demographic and clinical characteristics of children with limb loss in Saudi Arabia: A retrospective study

PURPOSE

The aim of this study was to describe the demographic and clinical characteristics of children with limb loss in Saudi Arabia.

METHODS

This is a retrospective study on children attending a limb loss clinic in a tertiary hospital in Riyadh, Saudi Arabia, between July 2012 and June 2020. Descriptive statistics were computed to describe the sample characteristics. A Chi-Squared test was conducted to explore the relationship between a child's sex with the type of limb loss (congenital or acquired) and extent of limb loss (major and minor) and the association between child's age and the mechanism of injury in traumatic limb loss.

RESULTS

A total of 122 children aged 2-16 years were included of whom 52% were boys. Congenital limb loss represented 57% of the sample with upper extremity loss accounting for 63.7% of all limb loss in this type. Trauma-related limb loss represented the most frequent etiology (88.2%) in the acquired limb loss group. Road traffic accidents accounted for 51.7% of the mechanism of injuries in trauma-related limb loss. Child's sex was not associated with the type of limb loss nor the extent of limb loss ( p > 0.05). In addition, child's age was not associated with the mechanism of injury in traumatic limb loss ( p > 0.05).

CONCLUSION

Child's sex was not a determinant of type nor the extent of limb loss. Most of the acquired limb loss was trauma-related with road traffic accidents as the most common mechanism of injury. The findings of this study illuminate the importance of ongoing prosthetic care for children with a limb loss because young children may require multiple prostheses as they grow in age and size.

Updated EUROCAT guidelines for classification of cases with congenital anomalies

BACKGROUND

Precise and correct classification of congenital anomalies is important in epidemiological studies, not only to classify according to etiology but also to group similar congenital anomalies together, to create homogeneous subgroups for surveillance and research. This paper presents the updated EUROCAT (European surveillance of congenital anomalies) subgroups of congenital anomalies and the updated multiple congenital anomaly (MCA) algorithm and provides the underlying arguments for the revisions.

METHODS

The EUROCAT methodology is described. In addition, we show how we validated the revised EUROCAT subgroups and MCA algorithm, which are both based on the International Classification of Diseases (ICD10/ICD9) codes.

RESULTS

The updated EUROCAT subgroups and the updated MCA algorithm are described in detail and the updated version is compared to the previous versions.

CONCLUSION

The EUROCAT subgroups and MCA algorithm provide a standardized and clear methodology for congenital anomaly research and epidemiological surveillance of congenital anomalies in order to facilitate the identification of teratogenic exposures and to assess the impact of primary prevention and prenatal screening policies. The EUROCAT subgroups and MCA algorithm are made freely available for other researchers via the EUROCAT Database Management Software.

Clinical outcomes measurement in pediatric lower limb prosthetics: A scoping review

OBJECTIVE

This study aimed to identify clinical measures that have been used to evaluate function, health related quality of life (HRQoL), and/or satisfaction in children who use lower limb prostheses (LLP). The data reported on psychometric properties for children who use LLP were collected for each measure.

METHODS

First, PubMed, CINAHL, and Web of Science databases were searched using broad search terms to identify standardized outcome measures of function, HRQoL, and/or satisfaction with treatment used in pediatric LLP research published in 2001 or after. For each of the eligible measures found, a second search was performed to identify psychometric properties (e.g., validity, reliability) assessed with children who use LLP.

RESULTS

Forty-four standardized outcome measures were identified from 41 pediatric LLP research articles. Five measures (i.e., Gait Outcomes Assessment for Lower Limb Differences, Functional Mobility Assessment, Child Amputee Prosthetics Project- Prosthesis Satisfaction Inventory, Child Amputee Prosthetics Project- Functional Scale Index, and Lower Limb Function Questionnaire) had data on psychometric properties for children who use LLP.

CONCLUSIONS

Few studies report psychometric data for assessing the overall HRQoL, function, and/or satisfaction for children who use LLP. Further research is needed to validate or create new outcome measures that assess the HRQoL, satisfaction, and/or function of children who use LLP.

Difference between affected and unaffected sides of forearm bone length in children with congenital terminal transverse deficiencies at the level of carpal bone

The forearm of the affected sideis often shorter than that of the unaffected side in children with congenital terminal transverse deficiencies at the level of proximal or distal carpals. The aim of this study is to clarify the characteristics of forearm bone length in those children, especially to quantify the difference in forearm bone length between affected and unaffected sides. The subjects were children with carpal partial transverse deficiencies. The lengths of the radius and the ulna were measured in the radiographs. The lengths of affected and unaffected sides (A/U) were compared in order to quantify the discrepancy. The A/U ratio was defined as the length of the affected side divided by that of the unaffected side. The A/U ratios ranged from 77.1 to 99.0% in the radii and from 74.1 to 99.6% in the ulnae. In both the radius and ulna, the A/U ratios were significantly lower than the left/right ratios of normal adults. Additionally, the A/U ratios of the ulna were significantly lower than the A/U ratios of the radius. The forearm bones of affected side are significantly shorter than those of unaffected side. Although the cause remains unclear, it is possible that not only congenital factors but also acquired factors such as infrequent use of the affected upper limb are involved. A future longitudinal study is necessary to investigate whether length discrepancies can be reduced by using prostheses to increase the frequency of use on the affected limb.

Prevalence pattern, phenotypic manifestation, and descriptive genetics of congenital limb deficiencies in Pakistan

BACKGROUND

Congenital limb deficiency (CLD) is a group of very rare disorders characterized by substantial hypoplasia or the complete absence of 1 or more bones of limbs. Congenital limb deficiency has a significant physical, clinical, and psychological burden on the affected individuals and their families. This cross-sectional study aimed to describe the prevalence pattern, phenotypic manifestations, and biodemographic factors associated with CLD in a cohort assembled from the Pakistani population from the Northwestern region.

METHODS

Through a prospective cross-sectional study, 141 individuals having 166 limbs with CLD were recruited during 2017-2021.

RESULTS

There were 77 (55%) individuals with transverse defects, 61 (43%) with longitudinal defects, and 3 (2%) with Intercalary defects. Among the patients with transverse defects, 52 had terminal amputations and 25 had symbrachydactyly. Among the longitudinal defects, thumb aplasia/hypoplasia was the most common presentation (20 patients), followed by oligodactyly (18), and radial hemimelia (18). Eighty six percent had upper-limb deficiencies, 83% had unilateral deficiencies, and 92% were sporadic in nature. The parental consanguinity was observed in 33% individuals, and 79% cases had an isolated presentation which may be indicative of the substantial role of nongenetic factors in the etiology of CLD.

CONCLUSIONS

This study demonstrates marked heterogeneity in CLD subtypes in the involvement of limbs and associated variables. There is a need to establish a national registry for CLD, molecular genetic diagnosis, and multidisciplinary medical and social rehabilitation services for these individuals.

Prenatal radiographic evaluation of congenital transverse limb deficiencies: A scoping review

BACKGROUND

Congenital transverse deficiencies are horizontal deficiencies of the long bones that occur with a reported incidence as high 0.38%. They can occur alone or represent a manifestation of a various clinical syndromes. Diagnosis has traditionally comprised of conventional radiography and prenatal imaging studies. There has been much advancement regarding prenatal imaging modalities to allow for early diagnosis and appropriate treatment.

AIM

To summarize the current state of knowledge on congenital transverse limb deficiencies and to provide an update regarding the radiographic evaluation of congenital transverse limb deficiencies.

METHODS

This IRB-exempt scoping review followed the PRISMA-ScR checklist for scoping reviews strictly. Five search engines were searched for a total of 265 publications. Four authors reviewed these during the screening process. Of these, 51 studies were included in our article. Prenatal magnetic resonance imaging (MRI), 3D Ultrasound, and multidetector Computed tomography (CT) exist are emerging modalities that have the potential to improve diagnosis.

RESULTS

Use of the appropriate classification system, three-dimensional ultrasonography with a maximum intensity projection, and appropriate use of prenatal MRI and prenatal CT can improve diagnosis and inter-provider communication.

CONCLUSION

Further scholarly efforts are required to develop improve standardized guidelines regarding the pre-natal radiographic evaluation of congenital limb deficiencies.

Hypothesis: Central digit hypoplasia

Limb deficiencies are a common birth defect. A malformations surveillance program among many newborns, stillborn fetuses, and malformed fetuses in elective terminations can identify a sufficient number of infants with the same set of abnormalities to characterize a specific limb deficiency phenotype. The active malformations surveillance program was carried out among 289,365 births at Brigham and Women's Hospital in Boston over a 41-year period (1972-2012). The research assistants identified the affected infants and fetuses from reading the findings recorded in each newborn's medical record by the examining pediatricians and consultants and by the pathologists in autopsies. One hundred ninety-four newborn infants and fetuses were found to have a limb deficiency either as an isolated abnormality or as one of multiple malformations. We identified three phenotypes of limb deficiency. We present here the seventeen infants and fetuses with "central digit hypoplasia," a term we suggest for this phenotype: hypoplasia of the thumb and fifth finger with nubbins of soft tissue in place of fingers 2, 3, and 4 at the level of the metacarpal-phalangeal joint. Central digit hypoplasia is to be distinguished primarily from the terminal transverse limb defect that ends at the wrist. In symbrachydactyly, the middle and distal phalanges of the fingers and toes are hypoplastic. In addition, central digit hypoplasia should be distinguished from the amniotic band syndrome, the most common and incorrect diagnosis suggested by the pediatricians and the consultants in this survey. The affected infant and her/his parents benefit from more accurate and specific counseling.

Newborn Male With Fibular Aplasia, Tibial Campomelia, and Oligosyndactyly Syndrome: A New Case Report Putting the Condition Under Spotlight

The syndrome of fibular aplasia, tibial campomelia, and oligosyndactyly (FATCO syndrome) is a rare genetic disease that has been increasingly reported over the past 40 years. We report the case of a newborn boy with unilateral skeletal abnormalities that were evident clinically and radiologically. The baby was an infant of a diabetic mother, and the Egyptian parents were consanguineous with a strong family history of genetic diseases and congenital anomalies. Besides describing a new case report of this syndrome, we emphasize the importance of prenatal diagnosis and genetic counseling, especially for families at high risk for genetic diseases in developing countries.

Special Needs Insurance: More Stability for a Growing Family's Budget

OBJECTIVE.—

To propose an insurance product called special needs insurance. The insurance will pay parents a lump sum up to $100,000 if they have a child that is born with or develops a special needs condition such as Down syndrome, cerebral palsy or autism.

BACKGROUND.—

Raising a child is expensive; raising a child with a special need can be hundreds of thousands of dollars more expensive. These additional costs include direct costs that are not covered by health insurance and indirect costs such as the loss of earnings when a working parent must tend to a special needs child.

METHOD.—

We analyze a gamut of birth and early childhood disabilities, both physical and cognitive, from the medico-actuarial perspective. We describe each condition using relevant medical literature and calculate prevalence rates from epidemiological studies (appendix A1-A15). After accounting for multiple births, we develop a final premium.

RESULTS.—

We find that physical impairments are sufficiently well understood to guarantee a fixed payout, whereas cognitive impairments such as autism are less understood, and so for these we propose a cognitive fund that does not guarantee a fixed payout. We find that an average single premium of $4,600 allows the insurer to profitably pay out the proposed benefits.

CONCLUSIONS.—

Raising a special needs child can put a significant strain on the affected family's budget. We propose an insurance product that provides relief through a large lump sum payout. Although no new insurance product can be guaranteed success, our analysis of this product gives an interested insurer reasonable justification to take on this new risk.

Modification of the effects of nitrogen dioxide and sulfur dioxide on congenital limb defects by meteorological conditions

STUDY QUESTION

Can meteorological conditions modify the associations between NO2 and SO2 exposure and congenital limb defects (CLDs) during the first trimester of pregnancy?

SUMMARY ANSWER

Increases in NO2 and SO2 exposure were consistently associated with higher risks of CLDs during the first trimester of pregnancy; both low- and high-temperature exposure and high air humidity act synergistically with the two air pollutants on CLDs.

WHAT IS KNOWN ALREADY

Animal studies have indicated air pollutants are associated with CLDs, but corresponding epidemiological studies are limited with equivocal conclusions. Meteorological conditions are closely connected to the generation, diffusion, distribution and even chemical toxicity of air pollutants.

STUDY DESIGN, SIZE, DURATION

This case-control study included 972 cases of CLDs and 9720 controls in Changsha, China during 2015-2018.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Cases from the hospital based monitoring system for birth defects (including polydactyly, syndactyly, limb shortening, and clubfoot) and healthy controls from the electronic medical records system were studied. Complete data on daily average NO2 and SO2 concentrations and meteorological variables were obtained from local monitoring stations to estimate monthly individual exposures during the first trimester of pregnancy, using the nearest monitoring station approach for NO2 and SO2 concentrations, and the city-wide average approach for temperature and relative humidity, respectively. The 25th and 75th percentiles of daily mean temperature, as well as the 50th percentile of daily mean relative humidity during the study period were used to classify high- and low-temperature exposure, and high humidity exposure based on existing evidence and local climate characteristics. Multivariate logistic regression models were used to estimate the independent effects per 10 μg/m3 increase in NO2 and SO2 on CLDs, and the attribute proportions of interaction (API) were used to quantify the additive joint effects of air pollutants with meteorological conditions after including a cross product interaction term in the regression models.

MAIN RESULTS AND THE ROLE OF CHANCE

NO2 and SO2 exposures during the first trimester of pregnancy were consistently and positively associated with overall CLDs and subtypes, with adjusted odd ratios (aORs) ranging from 1.13 to 1.27 for NO2, and from 1.37 to 2.49 for SO2. The effect estimates were generally observed to be the strongest in the first month and then attenuated in the second and third months of pregnancy. Synergistic effects of both low and high temperature in combination with NO2 (with APIs ranging from 0.07 to 0.38) and SO2 (with APIs ranging from 0.18 to 0.51) appeared in the first trimester of pregnancy. Several significant modifying effects by high humidity were also observed, especially for SO2 (with APIs ranging from 0.13 to 0.38). Neither NO2 nor SO2 showed an interactive effect with season of conception.

LIMITATIONS, REASONS FOR CAUTION

The methods used to estimate individual exposure levels of air pollutants and meteorological factors may lead to the misclassification bias because of the lack of information on maternal activity patterns and residential mobility during pregnancy. Moreover, we were unable to consider several potentially confounding factors, including socioeconomic status, maternal nutrient levels, alcohol use and smoking during early pregnancy due to unavailable data, although previous studies have suggested limited change to the results after when including these factors in the analysis.

WIDER IMPLICATIONS OF THE FINDINGS

The findings are helpful for understanding the combined effects of air pollution and meteorological conditions on birth defects. Environmental policies and practices should be formulated and implemented to decrease air pollutant emissions and improve meteorological conditions to reduce their harmful effects on pregnancy. Additionally, pregnant women should be suggested to reduce outdoor time when the air quality is poor, especially when ambient temperature is higher or lower than what is comfortable, or when it is excessively humid.

STUDY FUNDING/COMPETING INTEREST(S)

The study is funded by Major Scientific and Technological Projects for Collaborative Prevention and Control of Birth Defects in Hunan Province (2019SK1012), Major Research and Development Projects in Hunan Province (2018SK2060) and Scientific and Technological Department Projects in Hunan Province (2017SK50802). There are no competing interests.

TRIAL REGISTRATION NUMBER

N/A.

Terminal transverse limb defects with "nubbins"

BACKGROUND

A terminal transverse limb defect with absence of the forearm and hand or just the hand is an uncommon limb deformity in an otherwise healthy newborn. Most of the affected infants also have tiny digit-like nubbins on the stump of the affected limb, a finding that could represent an attempt at regeneration following vascular obstruction in early limb development.

METHODS

One hundred ninety-four newborn infants with a limb deficiency were identified among 289,365 births in an active malformations surveillance program at Brigham and Women's Hospital in Boston, MA from 1972 to 2012. Twenty-eight infants with terminal transverse limb defects were identified.

RESULTS

Twenty-four had tiny digit-like nubbins (0.5 cm in length) on the stump at one of three levels: the proximal portion of the forearm, the wrist or the forefoot. The examination of the placentas of eight affected infants showed no evidence of amnion rupture. Three of these 28 infants had associate chromosome abnormalities: trisomy 21, chromosome 11q deletion and the deletion of 22q11.2.

CONCLUSION

Terminal transverse limb defects reflect failure of early limb development. Awareness of this phenotype at birth, or when identified by ultrasound screening, can provide more accurate counseling than occurs with the more common misdiagnosis of "amniotic band syndrome."

Congenital limb defects in a married female population of the Rahim Yar Khan District in Pakistan

Background

Congenital limb defects (CLD) have a range of phenotypes and can be a substantial cause of disability. The prevalence of CLD in the adult population of Pakistan is not well described.

Objectives

To investigate the prevalence of CLD and their associated factors in a married female population of the Rahim Yar Khan (RYK) District in Pakistan.

Methods

A cross-sectional population-based study was conducted in 4 tehsils of RYK District, and married women and girls from 22 different localities were enrolled by convenience sampling in public places and through door-to-door visits. Data regarding limb phenotype and demographic variables were obtained from participants.

Results

We enrolled 2,204 married women and girls. We found 11 participants with CLD suggesting a prevalence of 4.99/1,000 (proportion: 0.005; 95% confidence interval [CI] <0.001-0.01). Polydactyly was the most frequent (n = 5; prevalence: 2.27/1,000), followed by others in the following sequence: brachydactyly (n = 4; prevalence: 1.81/1,000), camptodactyly (n = 1; prevalence: 0.45/1,000), and oligodactyly (n = 1; prevalence: 0.45/1,000). The odds of occurrence of CLD were higher in individuals originating from Khanpur tehsil (odds ratio [OR] 2.05; 95% CI 0.37-11.27), speaking languages other than Punjabi and Saraiki (OR 2.35; 95% CI 0.24-22.80), belonging to Araien caste (OR 2.35; 95% CI: 0.24-22.80), of a nuclear family (OR 3.35; 95% CI 0.79-16.97), or having parental consanguinity (OR 1.87; 95% CI 0.49-7.06).

Conclusion

Preliminary estimate of CLD prevalence in the married female sample population in RYK appears high compared with estimates from birth defects registries in other countries.

Case Report: Congenital Arthrogryposis and Unilateral Absences of Distal Arm in Congenital Zika Syndrome

Zika virus was recognized as a teratogen in 2015, when prenatal Zika infection was associated with neonatal microcephaly. The transmission, virulence, tropism, and consequences of Zika virus infection during pregnancy are currently studied. Decreased neural progenitor cells, arrest in neuronal migration and/or disruption of the maturation process of the fetus central nervous system have been associated. Congenital Zika Syndrome produces a fetal brain disruption sequence resulting in structural brain abnormalities, microcephaly, intracranial calcifications, fetal akinesia and arthrogryposis. Vascular abnormalities like unique umbilical artery and decreased cerebral vascular flow have been described in some patients. This article reports a Zika positive patient with sequence of fetal brain disruption, arthrogryposis and absence of distal third of the right forearm. This report expands the clinical observations of congenital Zika syndrome that may be related to disruptive vascular events.

Evidence for a cluster of rare birth defects in the Ain department (France)

BACKGROUND

REMERA (REgistre des Malformations En Rhône-Alpes) is a registry of congenital malformations that covers 58,000 births annually in Central-East France. In 2010, the registry raised an alarm to the health authorities (Santé publique France, SpF) about three cases of a unilateral isolated transverse upper limb reduction defect (UITULRD) in a small subarea; the general prevalence of this defect is one case in 10,000 births. In the following years, more infants were born with the same malformation in the same territory of the Ain department. Public health authorities, supported by an expert committee, rejected the existence of a cluster, but we aim here at providing evidence for this cluster.

METHODS

Geocoded data for all UITULRD cases (ICD-10 codes Q71.2 and Q71.3) were extracted from the REMERA database. We conducted a Kulldorff cluster analysis of these data, using the spatial SaTScanTM algorithm.

RESULTS

The analysis found a cluster of eight cases of UITULRD among the 8,204 births occurring between 2009 and 2014 within a circle of 16.24 km radius centered on a village of the Ain department, whereas 0.82 cases were expected under a uniform probability of such a birth throughout the registry territory. This represents an almost 10fold excess over the expected number of cases (p = .0057).

CONCLUSIONS

The arguments used to deny the cluster are disputed and we present the evidence supporting its reality. The controversy that has followed the alarm has compromised the search for the cause(s) of this excess of rare malformations.

Association of upper limb meromelia, proximal focal femoral deficiency, fibular hemimelia, and intermetatarsal coalition in a young adult male

Meromelia refers to the partial absence of at least 1 limb and is also referred to as "terminal transverse hemimelia." It can occur in either isolation or with other congenital malformations. There are very few publications in the literature that report meromelia cases accompanied by other congenital anomalies. Proximal focal femoral deficiency is another rare congenital skeletal abnormality and is characterized by the underdevelopment of the proximal part of the femur and shortening of the entire lower extremity. A case of upper limb meromelia accompanied by proximal focal femoral deficiency and fibular hemimelia in a neonate has previously been reported. However, to our knowledge, the association of upper limb meromelia with intermetatarsal coalition has never been reported to date. Here, we present an adult patient showing an unusual association of multiple rare congenital skeletal abnormalities including meromelia, proximal focal femoral deficiency, fibular hemimelia, and intermetatarsal coalition.

Congenital limb reduction defects in 1.6 million births in Argentina

The objectives of this study were to describe the birth prevalence of limb reduction defects (LRD) in Argentina, their clinical features, and to review the literature on this topic. The data source was the National Network of Congenital Anomalies of Argentina, a surveillance system that has been operative since 2009. Data were collected from November 1, 2009 to December 31, 2016. 1,663,610 births and 702 affected patients were registered during this period. The prevalence of LRD was 4.22/10,000 births (CI 95%: 3.93-4.54). In 15,094 stillbirths, prevalence was 30.80/10,000 (CI 95%: 22.31-40.65). Perinatal mortality (stillbirths plus early neonatal deaths) was 24.6%, mostly explained by postnatal deaths. LRD were classified according to different variables, including Gold's anatomic classification. Then, 41.0% of patients had transverse terminal defects and 50.2% had longitudinal defects. We found multiple and syndromic clinical presentation to be associated with both preaxial LRD and lethality. The prevalence of LRD was lower and perinatal mortality was higher in our study compared to that of previously published studies. Because there is heterogeneity in the inclusion and exclusion criteria among publications, a greater effort should be made in order to include similar populations and to use a unified anatomic classification and nomenclature.

Maternal exposure to outdoor air pollution and congenital limb deficiencies in the National Birth Defects Prevention Study

BACKGROUND

Congenital limb deficiencies (CLDs) are a relatively common group of birth defects whose etiology is mostly unknown. Recent studies suggest maternal air pollution exposure as a potential risk factor.

AIM

To investigate the relationship between ambient air pollution exposure during early pregnancy and offspring CLDs.

METHODS

The study population was identified from the National Birth Defects Prevention Study, a population-based multi-center case-control study, and consisted of 615 CLD cases and 5,701 controls with due dates during 1997 through 2006. Daily averages and/or maxima of six criteria air pollutants (particulate matter <2.5 μm [PM2.5], particulate matter <10 μm [PM10], nitrogen dioxide [NO2], sulfur dioxide [SO2], carbon monoxide [CO], and ozone [O3]) were averaged over gestational weeks 2-8, as well as for individual weeks during this period, using data from EPA air monitors nearest to the maternal address. Logistic regression was used to estimate odds ratios (aORs) and 95% confidence intervals (CIs) adjusted for maternal age, race/ethnicity, education, and study center. We estimated aORs for any CLD and CLD subtypes (i.e., transverse, longitudinal, and preaxial). Potential confounding by co-pollutant was assessed by adjusting for one additional air pollutant. Using the single pollutant model, we further investigated effect measure modification by body mass index, cigarette smoking, and folic acid use. Sensitivity analyses were conducted restricting to those with a residence closer to an air monitor.

RESULTS

We observed near-null aORs for CLDs per interquartile range (IQR) increase in PM10, PM2.5, and O3. However, weekly averages of the daily average NO2 and SO2, and daily max NO2, SO2, and CO concentrations were associated with increased odds of CLDs. The crude ORs ranged from 1.03 to 1.12 per IQR increase in these air pollution concentrations, and consistently elevated aORs were observed for CO. Stronger associations were observed for SO2 and O3 in subtype analysis (preaxial). In co-pollutant adjusted models, associations with CO remained elevated (aORs: 1.02-1.30); but aORs for SO2 and NO2 became near-null. The aORs for CO remained elevated among mothers who lived within 20 km of an air monitor. The aORs varied by maternal BMI, smoking status, and folic acid use.

CONCLUSION

We observed modest associations between CLDs and air pollution exposures during pregnancy, including CO, SO2, and NO2, though replication through further epidemiologic research is warranted.

Upper Limb Meromelia with Oligodactyly and Brachymesophalangy of the Foot: An Unusual Association

Meromelia is a rare skeletal abnormality characterized by the partial absence of at least one limb. Several mechanisms have been postulated to explain the etiopathogenesis of the disorder. Most of the cases of meromelia are reported to be sporadic. It can occur either in isolation or with other congenital malformations. VACTERL association, gastroschisis, atrial septal defect, proximal femoral focal deficiency, and fibular hemimelia are the congenital abnormalities reported to be in association with meromelia. However, no other congenital abnormalities in association with meromelia have been recorded to date. We herein present an unusual case of bilateral upper limb meromelia accompanied by unilateral oligodactyly and brachymesophalangy of the foot.

Support, information, and integration of genetics for children with congenital lower limb deficiencies in British Columbia, Canada

Objectives

Children and families affected by congenital limb deficiencies (CLD) require a unique level of emotional support from diagnosis through to adolescence. The following study aims to collect data on Canadian paediatric patients affected by a CLD followed at BC Children's Hospital (BCCH), Department of Orthopaedics.

Methods

Parents of children with a CLD were asked to complete a written questionnaire examining their experiences. Qualitative and quantitative data were collected concerning parent satisfaction with patient referrals, emotional support, and knowledge of their child's diagnosis.

Results

Twenty-five completed questionnaires were returned. Fifty per cent of the parents reported they were either very satisfied, or satisfied, with the emotional support provided by health care providers (HCPs). Twenty-five per cent of the parents were unsatisfied with the emotional support received by HCPs. Forty-eight per cent of the parents could not recall the specific name of their child's diagnosis; 20% of the parents reported their child did not have diagnosis. All the patients in our study had received a clinical diagnosis. Twenty-eight per cent of the parents in this study were also seen in medical genetics.

Conclusions

Families require additional resources for emotional support, peer support, and referrals to support organizations. Gaps in parent knowledge regarding their child's CLD suggest the need for formalized communication strategies for HCPs. Furthermore, patients with CLDs and their families may benefit from improved communication between orthopaedic and medical genetic services at the time of diagnosis. Integration of genetic counsellors may improve emotional supports and education for families with regards to testing and reproductive planning.

Education and work participation among adults with congenital unilateral upper limb deficiency in Norway: A cross-sectional study

Objectives

To describe level of education and work participation among adults with congenital unilateral upper limb deficiency (CUULD) in Norway and to explore associations between work participation and demographic and clinical factors.

Methods

Cross-sectional study. In 2012, a postal questionnaire was sent to 186 persons with congenital limb deficiency (CLD), age ≥ 20 years, registered at the TRS National Resource Center for Rare Disorders. In the original CLD study, 77 persons with CUULD responded. In this paper 64 persons with CUULD of working age (20–67 years) are included. Data on demographic factors as education level and work participation, and clinical factors including limb deficiency characteristics, chronic pain (Standardized Nordic Questionnaire), fatigue (Fatigue Severity Scale), physical and mental health (SF-36) were analyzed through descriptive and comparable statistics and logistic regression analyses.

Results

Sixty-four persons participated, mean age 43.4 (SD 13.7; range 20–67 years), 45 were women. Education level >13 years was reported by 34. Forty- three of the 64 participants were employed, 21 were prematurely retired (disability benefits). 11 of the 43 employed, and 6 of the 21 prematurely retired had completed vocational education. Physically demanding occupations (work activities that required standing, walking and lifting) were reported by 25 of the 43 employed and 13 of the 21 prematurely retired. 17 of the 64 reported need for further adaptions in their workplaces. The strongest predictors of work participation were younger age (OR 0.86) and good physical health (OR 1.21).

Conclusion

Two thirds of persons with CUULD were employed; while one third was prematurely retired and had left work earlier than expected. This suggests that persons with CUULD may experience challenges in work participation. Although levels of education were relatively high, several had chosen careers that required physical strain. Younger age and good physical health were the most important factors mediating work participation.

Parent Experiences and Preferences When Dysmelia Is Identified During the Prenatal and Perinatal Periods: A Qualitative Study Into Family Nursing Care for Rare Diseases

Several rare diseases are regularly identified during the prenatal and perinatal periods, including dysmelia. How these are communicated to parents has a marked emotional impact, but minimal research has investigated this. The purpose of this study was to explore parent experiences and preferences when their baby was diagnosed with dysmelia. Mothers and fathers were interviewed. Data were analyzed using thematic analysis. The overriding emotion parents experienced was shock, but the extent of this was influenced by several factors including their previous experience of disability. Four key needs of parents were identified, including the need for signposting to peer support organizations, for information, for sensitive communication, and for a plan regarding their child's care. Parents wanted immediate information provision and signposting to peer support, and for discussions regarding possible causes of the dysmelia or termination (in the case of prenatal identification) to be delayed until they had processed the news.

Chronic pain and fatigue in adults with congenital unilateral upper limb deficiency in Norway. A cross-sectional study

Purpose

To describe Norwegian adults with congenital unilateral upper limb deficiency (CUULD) regarding self-reported chronic pain (intensity, locations, impact on daily life) and fatigue. Analyze associations between chronic pain and demographic/clinical factors and associations between fatigue and demographic/ clinical factors.

Materials and methods

Cross-sectional study. In 2012, a postal questionnaire was sent to 186 persons with congenital limb deficiency, age ≥ 20 years. Seventy seven persons with CUULD responded and are included in this paper. The questionnaire included questions on demographic and clinical factors, chronic pain (Brief Pain Inventory, Standardized Nordic Questionnaire) and fatigue (Fatigue severity scale (FSS)).

Results

Mean age was 42.7 (SD 16.0), 71% were women. Sixty tree % reported chronic pain, many had bilateral pain, most common pain locations were neck (78%) and shoulder/upper arm (78%). However, reported mean pain intensity (3.3 (SD 2.8)) and mean number of pain locations (3.0 (SD 2.5)) were moderate to low. Thirty seven persons reported that pain started in adult age (≥ 19 years). One third reported severe fatigue (FSS ≥ 5). Persons reporting cold sensitivity and severe fatigue were most likely to have chronic pain.

Conclusions

Congenital upper limb deficiency increases the risk of self-reported pain in neck, shoulder/upper arm, cold sensitivity and severe fatigue. Pain, fatigue and cold sensitivity may individually affect function, and may together reinforce functional problems. This should be to taken into account when rehabilitation programs are developed. Further studies of more representative samples should be conducted to confirm our findings.

Embryonic vascular disruption adverse outcomes: Linking high throughput signaling signatures with functional consequences

Embryonic vascular disruption is an important adverse outcome pathway (AOP) as chemical disruption of cardiovascular development induces broad prenatal defects. High throughput screening (HTS) assays aid AOP development although linking in vitro data to in vivo apical endpoints remains challenging. This study evaluated two anti-angiogenic agents, 5HPP-33 and TNP-470, across the ToxCastDB HTS assay platform and anchored the results to complex in vitro functional assays: the rat aortic explant assay (AEA), rat whole embryo culture (WEC), and the zebrafish embryotoxicity (ZET) assay. Both were identified as putative vascular disruptive compounds (pVDCs) in ToxCastDB and disrupted angiogenesis and embryogenesis in the functional assays. Differences were observed in potency and adverse effects: 5HPP-33 was embryolethal (WEC and ZET); TNP-470 produced caudal defects at lower concentrations. This study demonstrates how a tiered approach using HTS signatures and complex functional in vitro assays might be used to prioritize further in vivo developmental toxicity testing.

The two domain hypothesis of limb prepattern and its relevance to congenital limb anomalies

Functional annotation of mutations that cause human limb anomalies is enabled by basic developmental studies. In this study, we focus on the prepatterning stage of limb development and discuss a recent model that proposes anterior and posterior domains of the early limb bud generate two halves of the future skeleton. By comparing phenotypes in humans with those in model organisms, we evaluate whether this prepatterning concept helps to annotate human disease alleles. WIREs Dev Biol 2017, 6:e270. doi: 10.1002/wdev.270 For further resources related to this article, please visit the WIREs website.

Dinosaurs, Chameleons, Humans, and Evo-Devo Path: Linking Étienne Geoffroy's Teratology, Waddington's Homeorhesis, Alberch's Logic of "Monsters," and Goldschmidt Hopeful "Monsters"

Since the rise of evo-devo (evolutionary developmental biology) in the 1980s, few authors have attempted to combine the increasing knowledge obtained from the study of model organisms and human medicine with data from comparative anatomy and evolutionary biology in order to investigate the links between development, pathology, and macroevolution. Fortunately, this situation is slowly changing, with a renewed interest in evolutionary developmental pathology (evo-devo-path) in the past decades, as evidenced by the idea to publish this special, and very timely, issue on "Developmental Evolution in Biomedical Research." As all of us have recently been involved, independently, in works related in some way or another with evolution and developmental anomalies, we decided to join our different perspectives and backgrounds in the present contribution for this special issue. Specifically, we provide a brief historical account on the study of the links between evolution, development, and pathologies, followed by a review of the recent work done by each of us, and then by a general discussion on the broader developmental and macroevolutionary implications of our studies and works recently done by other authors. Our primary aims are to highlight the strength of studying developmental anomalies within an evolutionary framework to understand morphological diversity and disease by connecting the recent work done by us and others with the research done and broader ideas proposed by authors such as Étienne Geoffroy Saint-Hilaire, Waddington, Goldschmidt, Gould, and Per Alberch, among many others to pave the way for further and much needed work regarding abnormal development and macroevolution.

Prevalence of congenital limb defects: Data from birth defects registries in three provinces in Southern Thailand

This is the first population-based study in Thailand on the prevalence of congenital limb defects (CLD). Data were obtained from recently established birth defects registries in three southern Thailand provinces during 2009-2013. Entries in the birth defects registries included live births, stillbirths after 24 weeks gestational age, and terminations of pregnancy following a prenatal diagnosis of fetal anomaly. The total of 186 393 births recorded included 424 CLD cases, giving an average prevalence of 2.27 per 1000 births (95% CI, 2.05-2.49). The most common CLD was talipes equinovarus (44.1%), followed by polydactyly (13.9%) and syndactyly (9.4%). The prevalence significantly increased with maternal age from 1.81 in mothers aged <30 years to 2.75 in mothers 30 to  < 35 years, and to 2.94 in mothers ≥35 years (P = 0.004). Overall 9.4% of the CLDs were syndromic CLD, again with significantly greater percentages in pregnant women aged ≥35 years than the non-syndromic CLD (32.5% vs 17.5% respectively, P = 0.03). In conclusion, the overall prevalence of CLD in the 3 southern Thailand provinces examined was 2.27 per 1000 births, and syndromic CLD was significantly higher in pregnant women aged ≥35 years than younger pregnant women.

Impact of elective termination on the occurrence of severe birth defects identified in a hospital-based active malformations surveillance program (1999 to 2002)

BACKGROUND

The number of affected infants and the types of malformations identified by a malformation surveillance programs can be impacted if elective terminations for malformations are not included.

METHODS

The occurrence of malformations in all newborn infants was determined in a daily review of the findings in the pediatricians' examinations and those of all consultants. In addition, the findings in autopsies of all elective terminations were reviewed to identify all fetuses with structural abnormalities. A severity scale was used to subdivide the malformations. To establish the impact of elective termination, the malformed infants identified in the Active Malformations Surveillance Program at Brigham and Women's Hospital in Boston were analyzed for the 2 years before and after the hospital decreased significantly the number of elective terminations temporarily (1999-2000 vs. 2001-2002). The effect on the number of malformations identified at birth, as well as malformations of greater severity, was determined.

RESULTS

The number of terminated fetuses with malformations decreased dramatically after termination services were interrupted (p < 0.0001). There were no differences in the prevalence rates of all malformations in the 2 years before and after the change in access to elective terminations. However, there were significant decreases in the number of infants identified with lethal/life-limiting and severe/handicapping malformations.

CONCLUSION

In the surveillance for malformations among newborn infants, the inclusion of malformed fetuses from elective terminations had a significant effect on the number of infants with the more severe malformations identified. Birth Defects Research (Part A) 106:659-666, 2016. © 2016 Wiley Periodicals, Inc.

Congenital limb deficiency classification and nomenclature: The need for a consensus

After the thalidomide epidemic in the early 1960s, many jurisdictions developed congenital anomaly surveillance systems. Congenital limb deficiencies can act as indicators of potential teratogens. The classification of congenital limb deficiencies is essential to determine the precise cause or causes of this anomaly. This article describes the different terminology and classification that have been used over time and the need for a consensus. While there are a variety of studies examining the epidemiology and etiology of congenital limb deficiencies, there is an inconsistent use of terminology and classification which makes comparisons between studies challenging. © 2016 Wiley Periodicals, Inc.

Children with congenital limb deficiency in Norway: issues related to school life and health-related quality of life. A cross-sectional study

PURPOSE

To describe clinical features, issues related to school life and health-related quality of life (HRQOL) for children with congenital limb deficiency (CLD) and compare these children to Norwegian school children on HRQOL.

METHOD

Cross-sectional study. In 2010, a postal questionnaire, designed for this study and the Paediatric Quality of Life Inventory (PedsQL), was sent to 154 eligible parents of children with CLD, aged 6-18 years and registered at TRS National Resource Centre for Rare Disorders in Norway.

RESULTS

Response rate 44% (n = 67), median age 11 years, 42% were girls. Of the total group, 46 had unilateral upper limb deficiency (UULD) and 21 had multiple/lower limb deficiency (MLD/LLD). The most common UULD was below-elbow deficiency, of these, 65% used grip-improving devices, and 35% used prostheses. Children with UULD-reported PedsQL score similar to Norwegian schoolchildren (NSC). The MLD/LLD group was heterogeneous; most had below-elbow/knee deficiency. In this group, PedsQL scores were reduced for physical and social functioning compared with NSC. Compared with children with UULD, more children with MLD/LLD were restricted in participation because of pain and fewer participated in physical education with peers.

CONCLUSIONS

Most children with CLD participated with their peers and managed well in everyday life. Children with MLD/LLD seemed to have more challenges than children with UULD. Approximately one-third of all the children had assistive devices and/or practical assistance in school. Implications for Rehabilitation Most children with upper-limb deficiency (UULD) in Norway manage well in everyday life and have HRQOL equal to other Norwegian children. Many choose grip-improving devices instead of prostheses. Their preferences should be respected and taken into account as the need for new assistive devices arise. For children with pronounced disabilities, access to, and use of, assistive devices, adaptions and practical assistance may be important for participation. Cooperation with the child and the parents is necessary to find useful measures. Physical education and practical subjects may provide special challenges, both for children and their teachers. Children themselves often find good solutions and the tasks should be planned ahead in cooperation with them.

Isolated bilateral transverse agenesis of the distal segments of the lower limbs at the level of the knee joint in a human fetus

Congenital limb anomalies occur in Europe with a prevalence of 3.81/1,000 births and can have a major impact on patients and their families. The present study concerned a female fetus aborted at 23 weeks of gestation because she was affected by non-syndromic bilateral absence of the zeugopod (leg) and autopod (foot). Autopsy of the aborted fetus, X-ray imaging, MRI, and histochemical analysis showed that the distal extremity of both femurs was continued by a cartilage-like mass, without joint cavitation. Karyotype was normal. Moreover, no damaging variant was detected by exome sequencing. The limb characteristics of the fetus, which to our knowledge have not yet been reported in humans, suggest a developmental arrest similar to anomalies described in chicks following surgical experiments on the apical ectodermal ridge of the lower limbs.

Multiple phylogenetically distinct events shaped the evolution of limb skeletal morphologies associated with bipedalism in the jerboas

Recent rapid advances in experimental biology have expanded the opportunity for interdisciplinary investigations of the evolution of form and function in non-traditional model species. However, historical divisions of philosophy and methodology between evolutionary/organismal biologists and developmental geneticists often preclude an effective merging of disciplines. In an effort to overcome these divisions, we take advantage of the extraordinary morphological diversity of the rodent superfamily Dipodoidea, including the bipedal jerboas, to experimentally study the developmental mechanisms and biomechanical performance of a remarkably divergent limb structure. Here, we place multiple limb character states in a locomotor and phylogenetic context. Whereas obligate bipedalism arose just once in the ancestor of extant jerboas, we find that digit loss, metatarsal fusion, between-limb proportions, and within-hindlimb proportions all evolved independently of one another. Digit loss occurred three times through at least two distinct developmental mechanisms, and elongation of the hindlimb relative to the forelimb is not simply due to growth mechanisms that change proportions within the hindlimb. Furthermore, we find strong evidence for punctuated evolution of allometric scaling of hindlimb elements during the radiation of Dipodoidea. Our work demonstrates the value of leveraging the evolutionary history of a clade to establish criteria for identifying the developmental genetic mechanisms of morphological diversification.

Congenital limb deficiency disorders

Congenital limb deficiency disorders (LDDs) are birth defects characterized by the aplasia or hypoplasia of bones of the limbs. Limb deficiencies are classified as transverse, those due to intrauterine disruptions of previously normal limbs, or longitudinal, those that are isolated or associated with certain syndromes as well as chromosomal anomalies. Consultation with a medical geneticist is advisable. Long-term care should occur in a specialized limb deficiency center with expertise in orthopedics, prosthetics, and occupational and physical therapy and provide emotional support and contact with other families. With appropriate care, most children with LDDs can lead productive lives.

Current Role of Fetal Magnetic Resonance Imaging in Body Anomalies

Fetal MR body applications have become more common in recent years as both in utero therapies, including fetoscopic surgery, and improvements in perinatal care have increased the demand for precise antenatal anatomic detail. This article discusses the variety of fast imaging sequences available to the fetal imager and describes their applications to both common and unusual congenital pathologies, including of the neck, chest, abdomen/pelvis and musculoskeletal systems.

Congenital constriction band syndrome with limb defects

BACKGROUND

The purpose of this study was to clarify the spectrum of congenital constriction band syndrome (CBS) and associated anomalies and mortality in Finland.

METHODS

Register-based data were analyzed for children with congenital constriction bands in upper and lower extremities as a part of an ongoing study on 419 upper limb defects and 171 lower limb defects occurring among 753,342 births in Finland during 1993 to 2005.

RESULTS

A total of 71 cases with limb CBS were identified during the 13-year study period. The birth prevalence was 0.9 per 10 000 births (1:10 600). Infant mortality was 4.6% (3/65) and perinatal mortality 12.7% (9/71). In 35 cases (49%) only upper limbs were affected and in 13 cases (18%) there were constriction defects only in lower limbs. In 23 cases (32%) both upper and lower limbs were involved. None of the cases associated with a known syndrome. However, in 21 cases (30%) the child had other anomalies associated with constriction rings: pes equinovarus in 8/21, cleft palate in 5/21, congenital heart defect in 6/21, and other anomalies in 14/21. Eighteen (25%) had low birth weight, 22 (31%) were born preterm, and 8 children (11%) were small for gestational age. Children with associated anomalies showed higher mortality, shorter duration of gestation, and lower birth weight.

CONCLUSIONS

CBS is rare and comprises approximately 12% of all congenital upper limb defects and 14% of lower limb defects. Other skeletal and nonskeletal anomalies are present in 30% of the affected children, suggesting a possible genetic etiology. More detailed characterization of the children with associated anomalies may shed light to the pathogenetic mechanisms of this syndrome.

LEVEL OF EVIDENCE

Population-based register study/II.

Maternal periconceptional alcohol consumption and congenital limb deficiencies

BACKGROUND

Women of childbearing age report high rates of alcohol consumption, which may result in alcohol exposure during early pregnancy. Epidemiological research on congenital limb deficiencies (LDs) and periconceptional exposure to alcohol is inconclusive.

METHODS

Data from the National Birth Defects Prevention Study (NBDPS) were examined for associations between LDs and patterns of maternal periconceptional (1 month before conception through the first trimester) alcohol consumption among LD case (n = 906) and unaffected control (n = 8352) pregnancies with expected delivery dates from 10/1997 through 12/2007. Adjusted odds ratios (aORs) and 95% confidence intervals were estimated from unconditional logistic regression analysis for all LDs combined, specific LD subtypes (preaxial/terminal transverse), and LD anatomic groups (upper/lower limbs); interactions with folic acid (FA) supplementation were tested.

RESULTS

When compared with nondrinkers, inverse associations were found between all LDs combined, preaxial, and upper LDs and any reported periconceptional alcohol consumption (aORs ranged from 0.56-0.83), drinking without binging (aORs: 0.53-0.75), and binge drinking (≥4 drinks/occasion) (aORs: 0.64-0.94); however, none of the binge drinking aORs were statistically significant. Stratification by alcohol type showed inverse associations between all LDs combined, preaxial, transverse, and upper and lower LDs for drinking without binging of wine only (aORs: 0.39-0.67) and between all LDs combined and upper LDs for drinking without binging of combinations of alcohol (aORs: 0.63-0.87). FA did not modify observed associations.

CONCLUSION

Maternal periconceptional alcohol consumption did not emerge as a teratogen for selected LDs in the NBDPS. Future studies should evaluate additional rare LDs among more highly exposed populations.

Vascular limb defects and maternal age

BACKGROUND

The prenatal diagnosis procedure chorionic villus sampling is associated with increased risk of vascular disruption limb defects. Some studies have suggested that these defects are more common among infants born to women 35 years and older while other studies have shown a correlation with younger mothers.

METHODS

All infants with vascular disruption defects were identified in the Active Malformations Surveillance Program at Brigham and Women's Hospital in the years 1972-1974, 1979-2011. We compared the rate of occurrence of infants with vascular limb defects among women in theses age groups: ≤19, 20 to 34, and ≥35 years to the rate of occurrence of infants with preaxial polydactyly, adjusting for race. Infants with an identifiable cause of their defects were excluded.

RESULTS

106 infants with vascular disruption defects and 67 with preaxial polydactyly were identified. Seventeen percent of the infants with vascular disruption defects and 25% of the infants with preaxial polydactyly were born to women 35 and older (p = 0.23). In contrast, 16% of the infants with vascular disruption defects were born to young mothers (≤19 years) compared with 6.0% of the mothers of infants with preaxial polydactyly (adjusted odds ratio vs. 35+ years = 5.3, 95% confidence interval 1.4-21, p = 0.017).

CONCLUSION

Women 35 years old or older did not have increased risk for having a child with vascular disruption defects, but these defects were more common among infants of young (≤19) mothers, compared with the preaxial polydactyly group.

Crossmodal representation of a functional robotic hand arises after extensive training in healthy participants

The way in which humans represent their own bodies is critical in guiding their interactions with the environment. To achieve successful body-space interactions, the body representation is strictly connected with that of the space immediately surrounding it through efficient visuo-tactile crossmodal integration. Such a body-space integrated representation is not fixed, but can be dynamically modulated by the use of external tools. Our study aims to explore the effect of using a complex tool, namely a functional prosthesis, on crossmodal visuo-tactile spatial interactions in healthy participants. By using the crossmodal visuo-tactile congruency paradigm, we found that prolonged training with a mechanical hand capable of distal hand movements and providing sensory feedback induces a pattern of interference, which is not observed after a brief training, between visual stimuli close to the prosthesis and touches on the body. These results suggest that after extensive, but not short, training the functional prosthesis acquires a visuo-tactile crossmodal representation akin to real limbs. This finding adds to previous evidence for the embodiment of functional prostheses in amputees, and shows that their use may also improve the crossmodal combination of somatosensory feedback delivered by the prosthesis with visual stimuli in the space around it, thus effectively augmenting the patients' visuomotor abilities.