Fetal neurology: Principles and practice with a life-course perspective

Clinical service, educational, and research components of a fetal/neonatal neurology program are anchored by the disciplines of developmental origins of health and disease and life-course science as programmatic principles. Prenatal participation provides perspectives on maternal, fetal, and placental contributions to health or disease for fetal and subsequent neonatal neurology consultations. This program also provides an early-life diagnostic perspective for neurologic specialties concerned with brain health and disease throughout childhood and adulthood. Animal models and birth cohort studies have demonstrated how the science of epigenetics helps to understand gene-environment interactions to better predict brain health or disease. Fetal neurology consultations provide important diagnostic contributions during critical or sensitive periods of brain development when future neurotherapeutic interventions will maximize adaptive neuroplasticity. Age-specific normative neuroinformatics databases that employ computer-based strategies to integrate clinical/demographic, neuroimaging, neurophysiologic, and genetic datasets will more accurately identify either symptomatic patients or those at risk for brain disorders who would benefit from preventive, rescue, or reparative treatment choices throughout the life span.

Inborn errors of metabolism

Inborn errors of metabolism, also known as inherited metabolic diseases, constitute an important group of conditions presenting with neurologic signs in newborns. They are individually rare but collectively common. Many are treatable through restoration of homeostasis of a disrupted metabolic pathway. Given their frequency and potential for treatment, the clinician should be aware of this group of conditions and learn to identify the typical manifestations of the different inborn errors of metabolism. In this review, we summarize the clinical, laboratory, electrophysiologic, and neuroimaging findings of the different inborn errors of metabolism that can present with florid neurologic signs and symptoms in the neonatal period.

Neonatal hypotonia and neuromuscular conditions

The differential diagnosis of neonatal hypotonia is a complex task, as in newborns hypotonia can be the presenting sign of different underlying causes, including peripheral and central nervous system involvement and genetic and metabolic diseases. This chapter describes how a combined approach, based on the combination of clinical signs and new genetic techniques, can help not only to establish when the hypotonia is related to peripheral involvement but also to achieve an accurate and early diagnosis of the specific neuromuscular diseases with neonatal onset. The early identification of such disorders is important, as this allows early intervention with disease-specific standards of care and, more importantly, because of the possibility to treat some of them, such as spinal muscular atrophy, with therapeutic approaches that have recently become available.

Gestational Diabetes Mellitus: Mechanisms, Treatment, and Complications

Gestational diabetes mellitus (GDM) is the most common metabolic disturbance during pregnancy. The prevalence is rising and correlates with the increase in maternal obesity over recent decades. The etiology of GDM is complex, with genetic and environmental factors implicated in mechanistic and epidemiological studies. GDM begets important short- and long-term health risks for the mother, developing fetus, and offspring. This includes the high likelihood of subsequent maternal type 2 diabetes (T2DM), and possible adverse cardiometabolic phenotypes in the offspring. The most clinically and cost-effective methods of screening for GDM remain uncertain. Whilst treatments with lifestyle and pharmacological interventions have demonstrated short-term benefits, the long-term impact for the offspring of intrauterine exposure to antidiabetic medication remains unclear.

Skills attained by infants with congenital Zika syndrome: Pilot data from Brazil

The recent Zika outbreak and its link to microcephaly and other birth defects in infants exposed in utero have garnered widespread international attention. Based on the severity of birth defects the extent of impairment in these infants is expected to be profound; however, virtually nothing is known regarding the developmental and behavioral sequela of congenital Zika syndrome. This pilot study collected parent-reported patterns of development and sleep in 47 infants with confirmed congenital Zika syndrome who are being followed for clinical services at the Altino Ventura Foundation (FAV) in Recife, Brazil. With assistance from clinicians at FAV, caregivers completed Brazilian Portuguese versions of the Ages and Stages Questionnaire, 3^rd edition (ASQ-3) and the Brief Infant Sleep Questionnaire (BISQ). All infants were between 13–22 months of age at the time of the assessment. At 16 months of age, none of the children displayed age appropriate developmental skills. Most (~ 75%) mastered some communication and gross motor skills at around a 6–8-month level. Communication and gross motor skills were relative strengths for the sample, while problem-solving and fine motor skills were relative weaknesses. Sleep was noted to be a problem for around 18% of the sample. In utero exposure to the Zika virus will have lifelong consequences for affected children and their families. Understanding the developmental and behavioral trajectories of affected infants will help identify appropriate family supports to improve quality of life.

[Follow-up observation of catch-up growth of preterm infants after discharge and risk factors for extrauterine growth retardation]

OBJECTIVE

To investigate the catch-up growth of preterm infants within a corrected age of 6 months and the risk factors for extrauterine growth retardation (EUGR).

METHODS

A total of 321 preterm infants who were discharged after treatment in the neonatal intensive care unit and had regular follow-up documents with complete follow-up records were enrolled. According to the Prenatal Health Care Norms in 2015, these infants were divided into low-risk group with 69 infants and high-risk group with 252 infants. The Z-score method was used to evaluate body weight, body length, and head circumference, and the catch-up growth of the preterm infants within a corrected age of 6 months was analyzed. A multivariate logistic regression analysis was performed to identify the risk factors for EUGR at the corrected age of 6 months.

RESULTS

The percentage of preterm infants with Z scores of body weight, body length, and head circumference of < -2 (not reach the standard for catch-up growth) in both groups decreased gradually with increasing corrected age. At the corrected age of 6 months, the percentages of preterm infants whose body weight, body length, and head circumference did not reach the standard for catch-up growth in the low-risk group were reduced to 1.4% (1/69), 2.9% (2/69), and 1.4% (1/69) respectively, while in the high-risk group, these percentages were reduced to 1.2% (3/252), 1.6% (4/252), and 3.6% (9/252) respectively. The high-risk group had a significantly higher incidence rate of EUGR at the corrected age of 6 months than the low-risk group (28.2% vs 15.9%, P=0.039). The multivariate logistic regression analysis showed that multiple birth (OR=2.68, P=0.010), low birth weight (<1 000 g: OR=14.84, P<0.001; 1 000-1 499 g: OR=2.85, P=0.005), and intrauterine growth retardation (IUGR) (OR=11.41, P<0.001) were risk factors for EUGR at the corrected age of 6 months, while nutritional enhancement after birth (OR=0.25, P<0.001) reduced the risk of EUGR.

CONCLUSIONS

Most preterm infants can achieve catch-up growth at the corrected age of 6 months. High-risk preterm infants have a high incidence rate of EUGR at the corrected age of 6 months. Multiple birth, low birth weight, and IUGR are risk factors for EUGR, while rational nutritional enhancement after birth can reduce the incidence rate of EUGR in preterm infants.

[Follow-up observation of catch-up growth of preterm infants after discharge and risk factors for extrauterine growth retardation]

OBJECTIVE

To investigate the catch-up growth of preterm infants within a corrected age of 6 months and the risk factors for extrauterine growth retardation (EUGR).

METHODS

A total of 321 preterm infants who were discharged after treatment in the neonatal intensive care unit and had regular follow-up documents with complete follow-up records were enrolled. According to the Prenatal Health Care Norms in 2015, these infants were divided into low-risk group with 69 infants and high-risk group with 252 infants. The Z-score method was used to evaluate body weight, body length, and head circumference, and the catch-up growth of the preterm infants within a corrected age of 6 months was analyzed. A multivariate logistic regression analysis was performed to identify the risk factors for EUGR at the corrected age of 6 months.

RESULTS

The percentage of preterm infants with Z scores of body weight, body length, and head circumference of < -2 (not reach the standard for catch-up growth) in both groups decreased gradually with increasing corrected age. At the corrected age of 6 months, the percentages of preterm infants whose body weight, body length, and head circumference did not reach the standard for catch-up growth in the low-risk group were reduced to 1.4% (1/69), 2.9% (2/69), and 1.4% (1/69) respectively, while in the high-risk group, these percentages were reduced to 1.2% (3/252), 1.6% (4/252), and 3.6% (9/252) respectively. The high-risk group had a significantly higher incidence rate of EUGR at the corrected age of 6 months than the low-risk group (28.2% vs 15.9%, P=0.039). The multivariate logistic regression analysis showed that multiple birth (OR=2.68, P=0.010), low birth weight (<1 000 g: OR=14.84, P<0.001; 1 000-1 499 g: OR=2.85, P=0.005), and intrauterine growth retardation (IUGR) (OR=11.41, P<0.001) were risk factors for EUGR at the corrected age of 6 months, while nutritional enhancement after birth (OR=0.25, P<0.001) reduced the risk of EUGR.

CONCLUSIONS

Most preterm infants can achieve catch-up growth at the corrected age of 6 months. High-risk preterm infants have a high incidence rate of EUGR at the corrected age of 6 months. Multiple birth, low birth weight, and IUGR are risk factors for EUGR, while rational nutritional enhancement after birth can reduce the incidence rate of EUGR in preterm infants.

Serum cytokine concentrations, chorioamnionitis and the onset of bronchopulmonary dysplasia in premature infants

OBJECTIVE

To investigate the relationships between serum cytokine concentrations and chorioamnionitis (CAM) and CAM-related bronchopulmonary dysplasia (BPD) in premature infants.

METHODS

Serum was collected at 0 and 7 days after birth from 36 premature infants born at <32 weeks of gestation. We examined the relationships between 30 cytokine concentrations and CAM, BPD, and other perinatal factors.

RESULTS

On day 0, GM-CSF, IL-15, IL-17, IL-2, IL-2R, VEGF, and MIG concentrations were significantly higher in the CAM group (n = 17) than in the non-CAM group (n = 19). These concentrations had decreased by day 7 and were similar in both groups. The IL-12p70 concentration on day 0 was significantly lower in the BPD group (n = 16) than in the non-BPD group (n = 15). BPD incidence was similar between the CAM and non-CAM groups.

CONCLUSIONS

These data support the hypothesis that intrauterine inflammation is not a primary risk factor for BPD. The immunological environment at birth or soon after, rather than intrauterine fetal inflammation (e.g., CAM), is a primary risk factor for BPD onset in preterm infants. Decreased inflammatory responses are particularly relevant, as indicated by the relationship between BPD and low serum IL-12p70 concentrations on day 0.

Mild hypoxic ischaemic encephalopathy and long term neurodevelopmental outcome - A systematic review

AIMS

Hypoxic ischaemic encephalopathy (HIE) remains a significant cause of long term neurodisability despite therapeutic hypothermia (TH). Infants with mild HIE, representing 50% of those with HIE, are perceived as low risk and are currently not eligible for TH [1]. This review examines the available evidence of outcome in term infants with mild HIE.

METHODS

Medline, Embase and Cochrane Clinical Trials databases were searched in March 2017. Studies with well-defined HIE grading at birth and standardised neurodevelopmental assessment at ≥18 months were included. Abnormal outcome was defined as death, cerebral palsy or standardised neurodevelopmental test score more than 1 standard deviation below the mean.

RESULT

Twenty studies were included. Abnormal outcome was reported in 86/341 (25%) of infants. There was insufficient evidence to examine the effect of TH on outcome.

CONCLUSION

A significant proportion of infants with mild HIE have abnormal outcome at follow up.

Understanding childhood diabetes mellitus: new pathophysiological aspects

Diabetes mellitus (DM) is not a single disease, but several pathophysiological conditions where synthesis, release, and/or action of insulin are disturbed. A progressive autoimmune/autoinflammatory destruction of islet cells is still considered the main pathophysiological event in the development of T1DM, but there is evidence that T1DM itself is a heterogeneous disease. More than 50 gene regions are closely associated with T1DM and a variety of epigenetic factors and metabolic patterns have been characterized, which may play a role in the development of T1DM. The pathogenesis and genetics of type 2 DM (T2DM) are distinct from T1DM. Genes associated with T2DM are distinct from those in T1DM. Characteristic metabolic patterns, different from those in T1DM were reported in T2DM, and some children with T2DM also express islet-antibodies. Huge progress has been made in the characterization of other specific types of DM, which had been considered very rare before. The molecular clarification of maturity-onset diabetes of the young (MODY) has greatly improved our understanding of the pathophysiology of DM. There are genetic overlaps between T2DM and monogenetic DM. Neonatal DM has been shown to be monogenetic in most cases, and genetic elucidation leads to more precise and individualized therapies. Cystic fibrosis related DM (CFRDM) should be considered a genuine part of cystic fibrosis, and not a complication, since pancreatic fibrosis does not sufficiently explain the pathophysiology of CFRDM. Disturbances of cystic fibrosis transmembrane conductance regulator (CFTR) as well as autoimmunity are involved in the pathogenesis of CFRDM.

Brain lymphatic drainage system in fetus and newborn: Birth of a new era of exploration

A peculiar brain lymphatic drainage system has been recently fully recognized in animals and humans. It comprises different draining pathways, including the lymphatic system, the perivascular drainage pathway, and the cerebrospinal fluid (CSF) drainage routes. Although scant data are available about its function during the neonatal period, it may play a role in neonatal brain diseases. In this review, we focus on the actual knowledge of brain lymphatic drainage system, and we hypothesize potential implications of its impairment and dysfunction in major neonatal neurological diseases.

Thrombopénie sévère chez un nouveau né de mère splénectomisé pour purpura thrombopénique idiopathique

Neonatal thrombopenia is the most common hemostatic abnormality in newborns. It is defined as a platelet count below 150.000/mm3. 40% of newborns to mothers with a history of autoimmune thrombopenia are at risk of developing neonatal thrombopenia while 10-15% of them are at risk of developing severe thrombopenia. We here report the case of a 20 days old newborn to mother splenectomized for idiopathic thrombopenic purpura in order to highlight the relationship between the severity of maternal disease and the severity of the neonatal thrombopenia and thereby to avoid the risk of intracranial hemorrhage resulting in death or neurological sequelae.

Anterior placenta previa is associated with increased umbilical cord blood hematocrit concenrations

OBJECTIVE

We aimed to evaluate the umbilical cord blood (CB) hematocrit (Hct) levels in women with anterior located placenta previa (PP).

METHODS

This is a prospective case-control study performed in a tertiary level maternity hospital. Thirty seven pregnant women diagnosed with anterior PP (study group) and 37 women without PP (control group) included into the study. Groups were matched with regard to age, gestational age, and fetal gender. All women underwent Cesarean section. Umbilical CB Hct levels of the newborns were measured. Demographics, operative features, and neonatal outcomes were recorded.

RESULTS

Umbilical CB Hct levels were statistically significantly higher in the PP patients compared with controls (p: 52.6±5.0 vs. 47.5±5.0, p < 0.001). Preoperative maternal hemoglobin (Hgb) and Hct levels were similar in the two groups. However, postoperative Hb and Hct levels were significantly lower in the study group (p: 0.003, p < 0.001, respectively). Intraoperative complication rates were higher in this group. Neonatal Apgar scores were lower and neonatal intensive care unit admission was more common in the PP group when compared with controls.

CONCLUSION

We think that anterior PP is associated with increased umbilical CB Hct levels. Neonatologists should consider this condition in the infants born to mothers with anterior PP.

The Infant Born to a Woman with Gestational Diabetes

Gestational diabetes mellitus (GDM) is defined as glucose intolerance with onset during pregnancy. During pregnancy, women with GDM develop insulin resistance, which results in altered glucose tolerance. As a result, there are frequent episodes of hyperglycemia and high levels of circulating amino acids, increasing the transfer of nutrients to the fetus. This article discusses the role of the mother-baby nursing in the care of neonates born to women with gestational diabetes.

Predicting Bradycardia in Preterm Infants Using Point Process Analysis of Heart Rate

OBJECTIVE

Episodes of bradycardia are common and recur sporadically in preterm infants, posing a threat to the developing brain and other vital organs. We hypothesize that bradycardias are a result of transient temporal destabilization of the cardiac autonomic control system and that fluctuations in the heart rate signal might contain information that precedes bradycardia. We investigate infant heart rate fluctuations with a novel application of point process theory.

METHODS

In ten preterm infants, we estimate instantaneous linear measures of the heart rate signal, use these measures to extract statistical features of bradycardia, and propose a simplistic framework for prediction of bradycardia.

RESULTS

We present the performance of a prediction algorithm using instantaneous linear measures (mean area under the curve = 0.79 ± 0.018) for over 440 bradycardia events. The algorithm achieves an average forecast time of 116 s prior to bradycardia onset (FPR = 0.15). Our analysis reveals that increased variance in the heart rate signal is a precursor of severe bradycardia. This increase in variance is associated with an increase in power from low content dynamics in the LF band (0.04-0.2 Hz) and lower multiscale entropy values prior to bradycardia.

CONCLUSION

Point process analysis of the heartbeat time series reveals instantaneous measures that can be used to predict infant bradycardia prior to onset.

SIGNIFICANCE

Our findings are relevant to risk stratification, predictive monitoring, and implementation of preventative strategies for reducing morbidity and mortality associated with bradycardia in neonatal intensive care units.

Predictors of Mortality in Neonates with Seizures; a Prospective Cohort Study

OBJECTIVE

The aim of this study was to analyze prognostic indicators for mortality in neonates with seizures in a level III Neonatal Intensive Care Unit (NICU).

PATIENTS AND METHODS

A cohort of 100 neonates with clinically manifested seizures hospitalized in the NICU during 4 years period was prospectively monitored for the first year of life. The cohort consisted of 33 preterm and 67 full-term babies with 60 male and 40 female infants.

RESULTS

The mortality rate in the first year of life of infants with seizures in the neonatal period was 23%. The most common cause of seizures was birth asphyxia for full-term infants and intra-periventricular hemorrhage for preterm infants. Death was more common in pre-term than term infants (p <0,005). Simple regression demonstrated statistically significant associations between death in the first year of life and a cluster of highly associated variables: resuscitation (p<0, 01), mechanical ventilation (p<0,01) and asphyxia (p<0,05). This cluster of variables significantly correlates with: gestational age (p<0, 05), birth weight (p<0, 05) and intracranial hemorrhage (p<0, 05).

CONCLUSION

In this cohort of neonates with seizures asphyxia requiring neonatal resuscitation was the primary risk factor for death.

Hemodynamic instability in the critically ill neonate: An approach to cardiovascular support based on disease pathophysiology

Hemodynamic disturbance in the sick neonate is common, highly diverse in underlying pathophysiology and dynamic. Dysregulated systemic and cerebral blood flow is hypothesized to have a negative impact on neurodevelopmental outcome and survival. An understanding of the physiology of the normal neonate, disease pathophysiology, and the properties of vasoactive medications may improve the quality of care and lead to an improvement in survival free from disability. In this review we present a modern approach to cardiovascular therapy in the sick neonate based on a more thoughtful approach to clinical assessment and actual pathophysiology. Targeted neonatal echocardiography offers a more detailed insight into disease processes and offers longitudinal assessment, particularly response to therapeutic intervention. The pathophysiology of common neonatal conditions and the properties of cardiovascular agents are described. In addition, we outline separate treatment algorithms for various hemodynamic disturbances that are tailored to clinical features, disease characteristics and echocardiographic findings.

Analysis of risk factors for hydrocephalus development in newborn infants with germinal matrix hemorrhage

AIM

The aim of this study was to analyze risk factors for the development of hydrocephalus in newborn infants with germinal matrix (GM) hemorrhage.

METHODS

The study comprised 271 patients admitted to Carlos Haya University Hospital in Malaga with GM hemorrhage. The following data were recorded: gestational age, gender, twin birth, head circumference at birth, weight at birth, and Papile grade. Severe obstetrical (abruption, chorioamnionitis, pregnancy-induced hypertension, tocolytic treatment) and neonatal disorders (respiratory distress syndrome, neonatal infection, coagulation disorder, patent ductus arteriosus, necrotizing enterocolitis) were also recorded. Symptomatic hydrocephalus was diagnosed in the event of a progressive increase in head circumference and ventricular indices requiring shunting.

RESULTS

Of the 271 patients, 139 (51%) developed posthemorrhagic ventriculomegaly; 47 patients (17%) developed symptomatic hydrocephalus and needed shunt implantation. We found a significant relationship between the development of symptomatic hydrocephalus and Papile grade, lower gestational age, lower birth weight, twin birth, and neonatal infection.

CONCLUSION

Awareness of risk factors for the development of hydrocephalus in newborn infants with GM hemorrhage should be emphasized in order to enable an early diagnosis of ventriculomegaly and symptomatic hydrocephalus and thus make a correct therapeutic decision.

Evidence-based versus pathophysiology-based approach to diagnosis and treatment of neonatal cardiovascular compromise

With the advances in biomedical research and neonatal intensive care, our understanding of cardiovascular developmental physiology and pathophysiology has significantly improved during the last few decades. Despite this progress, the current management of circulatory compromise depends primarily on experts' opinions rather than high level of evidence. The lack of reliable, accurate, continuous and preferably non-invasive monitoring techniques has further limited our ability to collect the information needed for the design and execution of more sophisticated clinical trials with a better chance to provide the evidence we need. Given the lack of randomized, placebo-controlled trials investigating clinically relevant outcomes of novel treatments of neonatal cardiovascular compromise, we must now use the available lower level of evidence and our present understanding of developmental physiology and pathophysiology when providing cardiovascular supportive care to critically ill neonates. However, with recent advances in cardiovascular monitoring capabilities, direct and more objective assessment of the changes in cardiovascular function, organ blood flow, and tissue oxygenation have become possible. These advances have helped in our clinical assessment and enabled us to start designing more sophisticated interventional clinical trials using clinically relevant endpoints.

Clinical characteristics and molecular genetic analysis of 22 patients with neonatal diabetes from the South-Eastern region of Turkey: predominance of non-KATP channel mutations

BACKGROUND

Neonatal diabetes mellitus (NDM) is a rare form of monogenic diabetes and usually presents in the first 6 months of life. We aimed to describe the clinical characteristics and molecular genetics of a large Turkish cohort of NDM patients from a single centre and estimate an annual incidence rate of NDM in South-Eastern Anatolian region of Turkey.

DESIGN AND METHODS

NDM patients presenting to Diyarbakir Children State Hospital between 2010 and 2013, and patients under follow-up with presumed type 1 diabetes mellitus, with onset before 6 months of age were recruited. Molecular genetic analysis was performed.

RESULTS

Twenty-two patients (59% males) were diagnosed with NDM (TNDM-5; PNDM-17). Molecular genetic analysis identified a mutation in 20 (95%) patients who had undergone a mutation analysis. In transient neonatal diabetes (TNDM) patients, the genetic cause included chromosome 6q24 abnormalities (n=3), ABCC8 (n=1) and homozygous INS (n=1). In permanent neonatal diabetes (PNDM) patients, homozygous GCK (n=6), EIF2AK3 (n=3), PTF1A (n=3), and INS (n=1) and heterozygous KCNJ11 (n=2) mutations were identified. Pancreatic exocrine dysfunction was observed in patients with mutations in the distal PTF1A enhancer. Both patients with a KCNJ11 mutation responded to oral sulphonylurea. A variable phenotype was associated with the homozygous c.-331C>A INS mutation, which was identified in both a PNDM and TNDM patient. The annual incidence of PNDM in South-East Anatolian region of Turkey was one in 48 000 live births.

CONCLUSIONS

Homozygous mutations in GCK, EIF2AK3 and the distal enhancer region of PTF1A were the commonest causes of NDM in our cohort. The high rate of detection of a mutation likely reflects the contribution of new genetic techniques (targeted next-generation sequencing) and increased consanguinity within our cohort.

Neonatal seizure detection using atomic decomposition with a novel dictionary

Atomic decomposition (AD) can be used to efficiently decompose an arbitrary signal. In this paper, we present a method to detect neonatal electroencephalogram (EEG) seizure based on AD via orthogonal matching pursuit using a novel, application-specific, dictionary. The dictionary consists of pseudoperiodic Duffing oscillator atoms which are designed to be coherent with the seizure epochs. The relative structural complexity (a measure of the rate of convergence of AD) is used as the sole feature for seizure detection. The proposed feature was tested on a large clinical dataset of 826 h of EEG data from 18 full-term newborns with 1389 seizures. The seizure detection system using the proposed dictionary was able to achieve a median receiver operator characteristic area of 0.91 (IQR 0.87-0.95) across 18 neonates.

Perinatal stroke causes abnormal trajectory and laterality in reaching during early infancy

The developmental progression of reaching and early signs of upper extremity neglect is common concern for infants at risk for hemiparesis and cerebral palsy. We investigated the emergence of reaching and laterality in infants at risk for hemiplegic cerebral palsy. Eight infants with perinatal stroke (PS) and thirteen infants with typical development (TD) were assessed bimonthly from 2 to 7 months of age for 10 visits per infant. Reaching number and hand-toy contact duration were measured. Infants with PS demonstrated a linear trajectory of reaching behaviors with asymmetrical upper extremity performance. Infants with TD demonstrated a linear and quadratic trajectory of reaching behaviors and symmetrical upper extremity performance over the same age range. These results suggest that infants with PS have delay reaching and early signs of neglect not currently accounted for in clinical practice.