On the origin of sensory impairment and altered pain perception in Prader-Willi syndrome: A neurophysiological study

The Pivotal Role of Oxytocin's Mechanism of Thermoregulation in Prader-Willi Syndrome, Schaaf-Yang Syndrome, and Autism Spectrum Disorder

Oxytocin (Oxt) regulates thermogenesis, and altered thermoregulation results in Prader-Willi syndrome (PWS), Schaaf-Yang syndrome (SYS), and Autism spectrum disorder (ASD). PWS is a genetic disorder caused by the deletion of the paternal allele of 15q11-q13, the maternal uniparental disomy of chromosome 15, or defects in the imprinting center of chromosome 15. PWS is characterized by hyperphagia, obesity, low skeletal muscle tone, and autism spectrum disorder (ASD). Oxt also increases muscle tonicity and decreases proteolysis while PWS infants are hypotonic and require assisted feeding in early infancy. This evidence inspired us to merge the results of almost 20 years of studies and formulate a new hypothesis according to which the disruption of Oxt's mechanism of thermoregulation manifests in PWS, SYS, and ASD through thermosensory abnormalities and skeletal muscle tone. This review will integrate the current literature with new updates on PWS, SYS, and ASD and the recent discoveries on Oxt's regulation of thermogenesis to advance the knowledge on these diseases.

Oxytocin's Regulation of Thermogenesis May Be the Link to Prader-Willi Syndrome

Prader-Willi Syndrome (PWS) is a genetic neurodevelopmental disorder that is caused by either the deletion of the paternal allele of 15q11-q13, maternal uniparental disomy of chromosome 15 or defects in the chromosome 15 imprinting centre and is characterized by cognitive impairment, hyperphagia and low metabolic rate with significant risk of obesity, as well as a variety of other maladaptive behaviours and autistic spectrum disorder (ASD). Many of the features seen in PWS are thought to be due to hypothalamic dysfunction resulting in hormonal abnormalities and impaired social functioning. The preponderance of evidence indicates that the Oxytocin system is dysregulated in PWS individuals and that this neuropeptide pathways may provide promising targets for therapeutic intervention although the process by which this dysregulation occurs in PWS awaits mechanistic investigation. PWS individuals present abnormalities in thermoregulation an impaired detection for temperature change and altered perception of pain indicating an altered autonomic nervous system. Recent studies indicate that Oxytocin is involved in thermoregulation and pain perception. This review will describe the update on PWS and the recent discoveries on Oxytocin regulation of thermogenesis together with the potential link between Oxytocin regulation of thermogenesis and PWS to create a new groundwork for the treatment of this condition.

Autonomic nervous system dysfunction in Prader-Willi syndrome

INTRODUCTION

Prader-Willi syndrome is a complex neurodevelopmental genetic disorder due to lack of paternal expression of critical imprinted genes in the 15q11.2-q13.1 chromosomal region, generally from a paternal deletion. Predominant features include infantile hypotonia, a poor suck with failure to thrive, craniofacial features, and developmental and behavioral problems including self-injury and childhood onset of obesity. In addition to severe obesity, patients with PWS present with other symptoms of autonomic nervous system dysfunction.

METHODS

We examined the features seen in Prader-Willi syndrome and searched the literature for evidence of autonomic nervous system involvement in this rare obesity-related disorder and illustrative findings possibly due to autonomic nervous system dysfunction. Additionally, we reviewed the literature in relation to childhood obesity syndromes and compared those syndromes to the syndromic obesity found in Prader-Willi syndrome.

RESULTS

We report autonomic nervous system-related symptoms associated with childhood obesity impacting features seen in Prader-Willi syndrome and possibly other obesity-related genetic syndromes. We compiled evidence of both an autonomic route for the obesity seen in PWS and other autonomic nervous system-related dysfunctions. These include decreased salvation, sleep disordered breathing, increased pain and thermal threshold instability, delayed gastric emptying, altered blood pressure readings, and pupillary constriction responses as evidence of autonomic nervous system involvement.

CONCLUSIONS

We summarized and illustrated findings of autonomic nervous system dysfunction in Prader-Willi syndrome and other obesity-related syndromes and genetic factors that may play a causative role in development.

Evaluation of Autonomic Nervous System Dysfunction in Childhood Obesity and Prader-Willi Syndrome

The autonomic nervous system (ANS) may play a role in the distribution of body fat and the development of obesity and its complications. Features of individuals with Prader-Willi syndrome (PWS) impacted by PWS molecular genetic classes suggest alterations in ANS function; however, these have been rarely studied and presented with conflicting results. The aim of this study was to investigate if the ANS function is altered in PWS. In this case-control study, we assessed ANS function in 20 subjects with PWS (6 males/14 females; median age 10.5 years) and 27 body mass index (BMI) z-score-matched controls (19 males/8 females; median age 12.8 years). Standardized non-invasive measures of cardiac baroreflex function, heart rate, blood pressure, heart rate variability, quantitative sudomotor axon reflex tests, and a symptom questionnaire were completed. The increase in heart rate in response to head-up tilt testing was blunted (p < 0.01) in PWS compared to controls. Besides a lower heart rate ratio with Valsalva in PWS (p < 0.01), no significant differences were observed in other measures of cardiac function or sweat production. Findings suggest possible altered sympathetic function in PWS.

Pain research and children and adolescents with severe intellectual disability: ethical challenges and imperatives

Children with severe intellectual disabilities encounter inequities in pain-related care, yet little pain research involves this population. A considerable issue with pain research in this population is its ethical complexity. This Viewpoint delineates the ethical challenges of pain research involving children (aged 2-12 years) and adolescents (aged 13-21 years) with severe intellectual disabilities. There are two main issues. First, some of the standard methods for assessing pain and pain sensitivity are not suitable for individuals with severe intellectual disability, who are often non-verbal and unable to understand or follow instructions. Second, children and adolescents with severe intellectual disability cannot provide informed consent or assent to participate in pain research, and their dissent is not always recognised. The existing ethical guidelines for pain research by the International Association for the Study of Pain provide helpful, but general, guidance. This Viewpoint supplements these guidelines and uses a well established framework for assessing the ethics of clinical research to highlight points relevant to designing, doing, reviewing, and evaluating research involving children and adolescents with severe intellectual disability, focusing on issues that are unaddressed in existing guidance.

Modulation of the thermosensory system by oxytocin

Oxytocin (OT) is a neurohormone involved early in neurodevelopment and is implicated in multiple functions, including sensory modulation. Evidence of such modulation has been observed for different sensory modalities in both healthy and pathological conditions. This review summarizes the pleiotropic modulation that OT can exercise on an often overlooked sensory system: thermosensation. This system allows us to sense temperature variations and compensate for the variation to maintain a stable core body temperature. Oxytocin modulates autonomic and behavioral mechanisms underlying thermoregulation at both central and peripheral levels. Hyposensitivity or hypersensitivity for different sensory modalities, including thermosensitivity, is a common feature in autism spectrum disorder (ASD), recapitulated in several ASD mouse models. These sensory dysregulations occur early in post-natal development and are correlated with dysregulation of the oxytocinergic system. In this study, we discussed the potential link between thermosensory atypia and the dysregulation of the oxytocinergic system in ASD.

Behavioral Changes in Patients With Prader-Willi Syndrome Can Mask Severe Physical Illness

Behavioral and psychiatric problems are common in patients with Prader-Willi syndrome (PWS), while physical complaints such as pain, fever, and vomiting are rare due to a high pain threshold and dysregulation of temperature control. PWS patients have an increased mortality rate, some due to undiagnosed life-threatening diseases. We describe 2 patients with PWS whose behavioral changes, initially thought to be part of their behavioral phenotype, delayed the final diagnosis of a life-threatening underlying illness. A 13-year-old girl with PWS presented with a sudden change in behavior including aggression, scratching, and self-injury. She was seen by several health care providers, and after 5 months the diagnosis of pyosalpinx was made, for which laparoscopic resection of an infected tailgut cyst was performed, resolving the behavioral symptoms. A 38-year-old man with PWS presented with recurrent vague inguinal pain and nonepileptic seizures. After several years of consulting physicians and psychiatrists, including several hospital admissions, the diagnosis of bilateral inguinal hernia was made. After surgical correction, the pain and seizures ceased. In PWS patients presenting with unexplained behavioral changes and unusual somatic complaints, clinicians should perform an extensive clinical examination and consider underlying physical illness rather than attribute the problem to the behavioral phenotype.

Unique Pain Responses in Different Etiological Subgroups of Intellectual and Developmental Disabilities

We studied whether there exist variations in pain responses between different intellectual and developmental disability (IDD) etiologies. Self-reports and facial expressions (Facial Action Coding System = FACS) were recorded during experimental pressure stimuli and compared among 31 individuals with IDD-13 with cerebral palsy (CP), nine with Down syndrome (DS), nine with unspecified origin (UIDD)-and among 15 typically developing controls (TDCs). The CP and DS groups had higher pain ratings and FACS scores compared to the UIDD and TDC groups, and steeper stimulus-response functions. The DS group exhibited the most diverse facial expressions. There were variations in the foci of facial expressions between groups. It appears that different IDD etiologies display distinct pain responses.

Pathophysiology of Nociception and Rare Genetic Disorders with Increased Pain Threshold or Pain Insensitivity

Pain and nociception are different phenomena. Nociception is the result of complex activity in sensory pathways. On the other hand, pain is the effect of interactions between nociceptive processes, and cognition, emotions, as well as the social context of the individual. Alterations in the nociceptive route can have different genesis and affect the entire sensorial process. Genetic problems in nociception, clinically characterized by reduced or absent pain sensitivity, compose an important chapter within pain medicine. This chapter encompasses a wide range of very rare diseases. Several genes have been identified. These genes encode the Nav channels 1.7 and 1.9 (SCN9A, and SCN11A genes, respectively), NGFβ and its receptor tyrosine receptor kinase A, as well as the transcription factor PRDM12, and autophagy controllers (TECPR2). Monogenic disorders provoke hereditary sensory and autonomic neuropathies. Their clinical pictures are extremely variable, and a precise classification has yet to be established. Additionally, pain insensitivity is described in diverse numerical and structural chromosomal abnormalities, such as Angelman syndrome, Prader Willy syndrome, Chromosome 15q duplication syndrome, and Chromosome 4 interstitial deletion. Studying these conditions could be a practical strategy to better understand the mechanisms of nociception and investigate potential therapeutic targets against pain.

Relationship Between Sensory Processing and Autism Spectrum Disorder-Like Behaviors in Prader-Willi Syndrome

The relationship between sensory processing and ASD-like and associated behaviors in patients with Prader-Willi Syndrome (PWS) remains relatively unexplored. Examining this relationship, 51 adults with PWS were administered the Pervasive Developmental Disorders Autism Society Japan Rating Scale (PARS), Short Sensory Profile (SSP-J), Food-Related Problem Questionnaire (FRPQ), and Aberrant Behavior Checklist (ABC-J). Based on SSP-J z-scores, participants were classified into three severity groups. Analysis of variance was performed to compare the behavioral scores of these three groups. Statistically significant group differences were observed in PARS (p = .006, ηp2 = .194) and ABC-J (p = .006, ηp2 = .193) scores. Our findings suggest that the level of sensory processing may predict ASD-like and aberrant behaviors in adults with PWS, implying the importance of a proper assessment for early intervention.

Variance in the pathophysiological impact of the hemizygosity of gamma-aminobutyric acid type A receptor subunit genes between Prader-Willi syndrome and Angelman syndrome

INTRODUCTION

Angelman syndrome (AS) and Prader-Willi syndrome (PWS) are neurodevelopmental disorders caused by loss of function of maternally expressed UBE3A and paternally expressed contiguous genes on chromosome 15q11-13, respectively. A majority of these syndromes suffer from a large deletion of the relevant chromosome (AS Del or PWS Del), which includes biallelically expressed gamma-aminobutyric acid type A receptor subunit (GABAaR) genes, while remaining individuals present without the deletion (AS non-Del or PWS non-Del). We previously reported that AS Del, but not AS non-Del individuals, show aberrantly desynchronized somatosensory-evoked magnetic fields (SEFs) and speculated that it might reflect GABAergic dysfunction due to the hemizygosity of GABAaR genes. To verify its pathophysiological impact on PWS and AS, we analyzed the SEFs of PWS individuals.

METHOD

SEFs were recorded from eight PWS Del and two PWS non-Del individuals. The latency and strength of the first peak (N1m) were compared with those of AS Del/non-Del individuals and controls, most of which were obtained earlier.

RESULTS

In contrast to AS, both PWS Del and PWS non-Del showed normal SEF waveforms. Desynchronized response with delayed N1m peak latency was exclusively indicated in AS Del. N1m strength was statistically higher in AS Del and AS non-Del, but not in PWS Del and PWS non-Del.

CONCLUSIONS

Our results indicate that the pathophysiological impact of the hemizygosity of GABAaR genes is lower in PWS than AS. UBE3A deficiency and the hemizygosity of GABAaR genes could synergistically deteriorate neuronal function, resulting in aberrant SEFs in AS Del.

Benefits of multidisciplinary care in Prader-Willi syndrome

Introduction: Prader-Willi syndrome (PWS) is the most well-known condition of genetic obesity. Over the past 20 years, advances have been achieved in the diagnosis and treatment of PWS with a significant improvement in prognosis.Areas covered: This review focuses on the benefits of multidisciplinary approach in children and adolescents with PWS. In particular, the neonatologist and geneticist play a key role in early diagnosis and the clinical follow-up of the PWS patient must be guaranteed by a team including pediatric endocrinologist, psychologist, nutritionist/dietician, neurologist/neuropsychiatrist, sleep specialist, ears, nose and throat specialist (ENT), lung specialist, dentist, orthopedist and ophthalmologist and, eventually, gastroenterologist. We searched PubMed and critically summarized what has been reported in the last 10 years on PWS.Expert opinion: The multidisciplinary care in association with an early diagnosis and GH treatment postpones overweight development and decreases prevalence of obesity in individuals with PWS. Further prognostic improvements are expected through the selection of teams particularly experienced in the management of individuals with PWS and the discovery of new drugs.

Specific Behavioral Responses Rather Than Autonomic Responses Can Indicate and Quantify Acute Pain among Individuals with Intellectual and Developmental Disabilities

Individuals with intellectual and developmental disabilities (IDD) are at a high risk of experiencing pain. Pain management requires assessment, a challenging mission considering the impaired communication skills in IDD. We analyzed subjective and objective responses following calibrated experimental stimuli to determine whether they can differentiate between painful and non-painful states, and adequately quantify pain among individuals with IDD. Eighteen adults with IDD and 21 healthy controls (HC) received experimental pressure stimuli (innocuous, mildly noxious, and moderately noxious). Facial expressions (analyzed with the Facial Action Coding System (FACS)) and autonomic function (heart rate, heart rate variability (HRV), pulse, and galvanic skin response (GSR)) were continuously monitored, and self-reports using a pyramid and a numeric scale were obtained. Significant stimulus-response relationships were observed for the FACS and pyramid scores (but not for the numeric scores), and specific action units could differentiate between the noxious levels among the IDD group. FACS scores of the IDD group were higher and steeper than those of HC. HRV was overall lower among the IDD group, and GSR increased during noxious stimulation in both groups. In conclusion, the facial expressions and self-reports seem to reliably detect and quantify pain among individuals with mild-moderate IDD; their enhanced responses may indicate increased pain sensitivity that requires careful clinical consideration.

Adults with Prader-Willi syndrome exhibit a unique microbiota profile

Objective

Adults with Prader–Willi syndrome (PWS) require less energy intake to maintain body weight than the general adult population. This, combined with their altered gastrointestinal transit time, may impact microbiota composition. The aim of the study was to determine if the fecal microbiota composition of adults with PWS differed from non-affected adults. Using usual diet/non-interventional samples, fecal microbiota composition was analyzed using 16S rRNA gene amplicon sequencing and data from adults with PWS were merged with four other adult cohorts that differed by geographical location and age. QIIME 2™ sample-classifier, machine learning algorithms were used to cross-train the samples and predict from which dataset the taxonomic profiles belong. Taxa that most distinguished between all datasets were extracted and a visual inspection of the R library PiratePlots was performed to select the taxa that differed in abundance specific to PWS.

Results

Fecal microbiota composition of adults with PWS showed low Blautia and enhanced RF39 (phyla Tenericutes), Ruminococcaceae, Alistipes, Erysipelotrichacaea, Parabacteriodes and Odoribacter. Higher abundance of Tenericutes, in particular, may be a signature characteristic of the PWS microbiota although its relationship, if any, to metabolic health is not yet known.

Disorders of hypothalamic function: Insights from Prader-Willi syndrome and the effects of craniopharyngioma

Either physical damage or being born with a specific genetic abnormality can impact on the functioning of the hypothalamus, resulting in diverse physical manifestations and/or specific behavior disorders. The impact of physical damage due to craniopharyngioma (CP) and/or surgery to remove a craniopharyngioma is compared and contrasted with the impact resulting from the genetic abnormalities associated with Prader-Willi syndrome (PWS). Similarities between PWS and CP posttreatment include hyperphagia and weight gain, low growth hormone levels, low bone density in adults, hypogonadism, disturbed temperature regulation, disturbed sleep and daytime sleepiness, memory difficulties, and problems with behavior and with peer relationships. These disturbances are an indication of the hypothalamus's central role in homeostasis. Most of the abnormalities appear to be more severe postoperatively in people with CP. Differences include higher ghrelin levels in PWS, complete absence of pituitary hormones in many cases of CP, higher incidence of thyroid dysfunction in CP, "growth without growth hormone" in obese children with CP, different types of diabetes (diabetes insipidus in CP and diabetes mellitus in PWS), and evidence of developmental delay and low IQ in people with PWS.

Parenting stress in families of children with Prader-Willi syndrome

Prader-Willi syndrome (PWS) is a neurodevelopmental disorder characterized by multiple endocrine, metabolic, respiratory, cognitive, and behavioral/psychiatric symptoms that may lead to severe emotional strain in their caregivers. In this study, we evaluated parenting stress by the Parenting Stress Index-short form (PSI/SF) and parent-reported behavioral symptoms by the Child Behavior Checklist (CBCL/6-18) in families of children with PWS. Sixty-seven home-resident PWS patients and their families were recruited in this study. The patients' mean age was 14.9 ± 8.3 years, and 33 (50.8%) were male. High parenting stress was reported by 41.5% families, as determined by high total stress scores of PSI/SF. The patients in high stress families were significantly older than those in low stress families (18.2 ± 8.0 vs. 12.6 ± 7.8 years, p = .007). CBCL/6-18 was used to evaluate the somatic and neuropsychiatric symptoms of PWS patients aged between 6 and 18 in the subgroup of the 35 families. In this subgroup, 37.1% of families reported high parenting stress. High stress families reported a higher T-score in anxiety/depression, withdrawn behavior, somatic complaints, thought problems, attention problems, and delinquent and aggressive behavior of their children with PWS. After multivariate stepwise logistic regression analysis, the T-score of somatic complaints was the only factor related to high parenting stress, with an odds ratio of 1.279. Our data demonstrated the high care burden of families with PWS and highlighted the importance of having dedicated medical care for both somatic and neuropsychiatric symptoms.

Comparison of Hip and Knee Arthroplasty Rates of Individuals With and Without Prader-Willi Syndrome

BACKGROUND

Prader-Willi syndrome (PWS) is a complex genetic condition, affecting between 1:10,000 and 1:30,000. The prevalence of hip dysplasia in children with PWS is reportedly between 8% and 30%, but the long-term consequences of residual hip dysplasia remain largely unknown in this population. The purpose of this study was to comparatively estimate the number of total hip arthroplasty (THA) and total knee arthroplasty (TKA) procedures performed on adults with and without PWS, using a national hospital discharge database, in an effort to elucidate long-term outcomes and guide clinicians treating orthopaedic concerns in younger individuals with PWS.

METHODS

The National Inpatient Sample of the Healthcare Cost and Utilization Project is the largest all-payer inpatient care database, containing annual data from >7 million hospital stays; sampling weights and stratification variables are provided for producing estimates of >35 million hospitalizations nationwide. THA and TKA procedures were identified, then stratified by whether or not the patient had a diagnosis of PWS. The ages of the 2 groups and sex mix were compared, as was the length of stay for the procedure, and discharge status.

RESULTS

From 2004 to 2014, 9.4 million patients nationwide, by weighted estimate, underwent THA (3.1 million) or TKA (6.3 million). Sixty-five patients were identified as having the diagnosis of PWS (39 with THA, 26 with TKA); 7 patients per million having hip or knee arthroplasties had PWS. Sixty-eight percent of those with PWS were younger than 50 years, compared with only 7% of those without PWS (P<0.001). The female:male prevalence was 47:53 for patients with PWS and 60:40 for the total group. The mean length of stay was similar, but patients with PWS were more likely to be transferred to another facility after surgery (77% vs. 36%; P=0.008).

CONCLUSIONS

Hip dysplasia prevalence is higher in persons with PWS, but the rate of late treatment with THA is much lower than in the general population. We recommend only active observation for stable and improving hips in young children with PWS, as the consequences of overtreatment can be serious, including further delaying their neuromuscular development, and exposure to possibly unnecessary perioperative risks.

LEVEL OF EVIDENCE

Nation-wide database analysis, Level IV.

The RDoC approach for translational psychiatry: Could a genetic disorder with psychiatric symptoms help fill the matrix? the example of Prader-Willi syndrome

The Research Domain Criteria project (RDoc) proposes a new classification system based on information from several fields in order to encourage translational perspectives. Nevertheless, integrating genetic markers into this classification has remained difficult because of the lack of powerful associations between targeted genes and RDoC domains. We hypothesized that genetic diseases with psychiatric manifestations would be good models for RDoC gene investigations and would thereby extend the translational approach to involve targeted gene pathways. To explore this possibility, we reviewed the current knowledge on Prader-Willi syndrome, a genetic disorder caused by the absence of expression of some of the genes of the chromosome 15q11-13 region inherited from the father. Indeed, we found that the associations between genes of the PW locus and the modification identified in the relevant behavioral, physiological, and brain imaging studies followed the structure of the RDoC matrix and its six domains (positive valence, negative valence, social processing, cognitive systems, arousal/regulatory systems, and sensorimotor systems).

Firing activity of locus coeruleus noradrenergic neurons decreases in necdin-deficient mice, an animal model of Prader-Willi syndrome

BACKGROUND

Prader-Willi syndrome (PWS) is a neurodevelopmental disorder characterized by multiple respiratory, cognitive, endocrine, and behavioral symptoms, such as central apnea, intellectual disabilities, exaggerated stress responses, and temper tantrums. The locus coeruleus noradrenergic system (LC-NE) modulates a diverse range of behaviors, including arousal, learning, pain modulation, and stress-induced negative affective states, which are possibly correlated with the pathogenesis of PWS phenotypes. Therefore, we evaluated the LC-NE neuronal activity of necdin-deficient mice, an animal model of PWS.

METHODS

Heterozygous necdin-deficient mice (B6.Cg-Ndntm1ky) were bred from wild-type (WT) females to generate WT (+m/+p) and heterozygotes (+m/-p) animals, which were examined of LC-NE neuronal activity, developmental reflexes, and plethysmography.

RESULTS

On slice electrophysiology, LC-NE neurons of Ndntm1ky mice with necdin deficiency showed significantly decreased spontaneous activities and impaired excitability, which was mediated by enhanced A-type voltage-dependent potassium currents. Ndntm1ky mice also exhibited the neonatal phenotypes of PWS, such as hypotonia and blunt respiratory responses to hypercapnia.

CONCLUSIONS

LC-NE neuronal firing activity decreased in necdin-deficient mice, suggesting that LC, the primary source of norepinephrine in the central nervous system, is possibly involved in PWS pathogenesis.

Central Adrenal Insufficiency Is Rare in Adults With Prader-Willi Syndrome

CONTEXT

Prader-Willi syndrome (PWS) is associated with several hypothalamic-pituitary hormone deficiencies. There is no agreement on the prevalence of central adrenal insufficiency (CAI) in adults with PWS. In some countries, it is general practice to prescribe stress-dose hydrocortisone during physical or psychological stress in patients with PWS. Side effects of frequent hydrocortisone use are weight gain, osteoporosis, diabetes mellitus, and hypertension-already major problems in adults with PWS. However, undertreatment of CAI can cause significant morbidity-or even mortality.

OBJECTIVE

To prevent both over- and undertreatment with hydrocortisone, we assessed the prevalence of CAI in a large international cohort of adults with PWS. As the synacthen test shows variable results in PWS, we only use the metyrapone test (MTP) and insulin tolerance test (ITT).

DESIGN

Metyrapone test or ITT in adults with PWS (N = 82) and review of medical files for symptoms of hypocortisolism related to surgery (N = 645).

SETTING

Outpatient clinic.

PATIENTS OR OTHER PARTICIPANTS

Eighty-two adults with genetically confirmed PWS.

MAIN OUTCOME MEASURE

For MTP, 11-deoxycortisol > 230 nmol/L was considered sufficient. For ITT, cortisol > 500 nmol/L (Dutch, French, and Swedish patients) or > 450 nmol/L (British patients) was considered sufficient.

RESULTS

Central adrenal insufficiency was excluded in 81 of 82 patients. Among the 645 patients whose medical files were reviewed, 200 had undergone surgery without perioperative hydrocortisone treatment. None of them had displayed any features of hypocortisolism.

CONCLUSIONS

Central adrenal insufficiency is rare (1.2%) in adults with PWS. Based on these results, we recommend against routinely prescribing hydrocortisone stress-doses in adults with PWS.

Skin picking disorder in 97 Italian and Spanish Cri du chat patients

Skin picking (SP) disorder is characterized by recurrent SP resulting in skin lesions. Several studies estimated its prevalence as approximately 2-4 % of the general population. It is also present in a high percentage of patients with intellectual and developmental disabilities, such as Cri du chat (CdC) syndrome, a rare genetic disorder caused by variable size deletions of the short arm of chromosome 5. The aim of this study was to evaluate, in 97 patients with CdC syndrome, the following data: frequency of SP, patient's age at onset, type, and topographic-anatomic distribution of the lesions presented. The results show that 85% of patients confirm a SP disorder, usually concentrated on the hands, fingers, and the face, with onset between 6 and 10 years of age, regardless of patient's sex. Evidence for early appearance of SP behavior, high prevalence in stressful circumstances, and efficacy of distracting actions immediately suggest the possibility that proper parental information about SP behavior and parental education concerning the methods to deal with this problem may result in its efficient reduction already in childhood.

Investigation of the relationship between electrodermal and behavioural responses to executive tasks in Prader-Willi syndrome: An event-related experiment

BACKGROUND

Recent work suggests that maladaptive behaviors in genetic developmental disorders may emerge from autonomic dysfunctions impacting higher order executive functions. In Prader-Willi syndrome (PWS), executive functions are not well understood and investigations of possible underlying causes at the autonomic level are lacking.

AIMS

This study aimed at clarifying the status of inhibition and working memory updating functions in PWS and searched for sympathetic signatures as well as to examine their links with executive performance.

METHODS AND PROCEDURES

The performance of thirty adults with PWS was compared to that of thirty healthy adults on two tasks assessing inhibition and working memory updating while electrodermal activity (EDA) was recorded.

OUTCOMES AND RESULTS

PWS adults underperformed healthy adults in the inhibition and the working memory updating tasks and showed abnormal skin conductance responses. Distinct EDA have been found in PWS and healthy adults. Furthermore, while EDA reflected distinct cognitive processes, correlations between electrodermal and behavioural data were absent when examining the two groups separately.

CONCLUSIONS AND IMPLICATIONS

PWS is associated with a slight impairment of inhibition and a severe impairment of working memory updating. Furthermore, there are specific sympathetic autonomic signatures in PWS that do not present straightforward links with executive dysfunctions.

Oxytocin and Prader-Willi Syndrome

In the chapter, we explore the relationship between the peptide hormone, oxytocin (OT), and behavioral and metabolic disturbances observed in the genetic disorder Prader-Willi Syndrome (PWS). Phenotypic and genotypic characteristics of PWS are described, as are the potential implications of an abnormal OT system with respect to neural development including the possible effects of OT dysfunction on interactions with other regulatory mediators, including neurotransmitters, neuromodulators, and hormones. The major behavioral characteristics are explored in the context of OT dysfunction, including hyperphagia, impulsivity, anxiety and emotion dysregulation, sensory processing and interoception, repetitive and restrictive behaviors, and dysfunctional social cognition. Behavioral overlaps with autistic spectrum disorders are discussed. The implications of OT dysfunction on the mechanisms of reward and satiety and their possible role in informing behavioral characteristics are also discussed. Treatment implications and future directions for investigation are considered.

Gastro-oesophageal reflux - an important causative factor of severe tooth wear in Prader-Willi syndrome?

BACKGROUND

Prader-Willi syndrome (PWS) is the most common genetic human obesity syndrome and is characterized by hypotonia, endocrine disturbances, hyperphagia, obesity and mild mental retardation. Oral abnormalities, such as decreased salivary flow rates and extreme tooth wear, have also been described. Studies have shown a significant increase in reflux symptoms in individuals with obstuctive sleep apnoea syndrome and increased BMI, both of which are typical findings in PWS. Gastro-oesophageal reflux disease (GORD) has been identified in some individuals with PWS and is a significant intrinsic factor in dental tooth wear. The aim of this study was therefore to estimate the prevalence of GORD in adults and children and to evaluate a possible correlation between GORD and tooth wear in adults with PWS. They were all registered at the TAKO-centre.

RESULTS

Twenty-nine individuals, 17 adults with a mean age of 32.6 years (range 18-48) and 12 children with a mean age of 8.8 years (range 3-17), agreed to undergo 24-hour oesophageal pH monitoring, and 90% of those enrolled managed to complete the examination. Four children and eleven adults were diagnosed with pathological gastro-oesophageal reflux, which is defined as acid exposure (pH less than 4) more than 3.6 or 4.3 percent of the time, respectively. Manometry performed in the adult group showed a pathologically high lower oesophageal sphincter pressure in four of the five individuals who had normal oesophageal pH values (pH under 4 less than 4.3% of the time). The two groups (reflux and non-reflux) were well balanced according to BMI, genotype, tooth grinding and hyposalivation. However, twice as many individuals in the reflux group as in the non-reflux group reported high consumption of acidic foods and drinks. Increased tooth wear was significantly correlated with GORD in the two groups (reflux n=6 and non-reflux n=6).

CONCLUSIONS

The prevalence of gastro-oesophageal reflux is high in individuals with PWS. Tooth wear was strongly associated with GORD and acidic drinks, and both may be important aetiological factors underlying the extreme tooth wear in this group. Our data suggest a need for routine screening for GORD and dental wear in young individuals with Prader-Willi syndrome.

A Case-Controlled Investigation of Tactile Reactivity in Young Children With and Without Global Developmental Delay

Assessing tactile function among children with intellectual, motor, and communication impairments remains a clinical challenge. A case control design was used to test whether children with global developmental delays (GDD; n = 20) would be more/less reactive to a modified quantitative sensory test (mQST) compared to controls (n = 20). Reactivity was indexed by blinded behavioral coding across vocal, facial, and gross motor responses during the mQST. On average the children with GDD were significantly more reactive than controls to most tactile sensory modalities including light touch (p = .034), pin prick (p = .008), cool (p = .039), pressure (p = .037), and repeated von Frey (p = .003). The results suggest the mQST approach was feasible and highlights the GDD sample was more reactive than controls to a range of stimuli.

Subclinical dysphagia in persons with Prader-Willi syndrome

Prader-Willi Syndrome (PWS) is caused by a genetic imprinting abnormality resulting from the lack of expression of the paternal genes at 15q11-q13. Intellectual disability, low muscle tone, and life-threatening hyperphagia are hallmarks of the phenotype. The need for the Heimlich maneuver, death from choking, and pulmonary infection occur in a disproportionally high number of persons with PWS. The widely held belief is that eating behaviors are responsible for choking and aspiration; yet, no investigation had sought to determine if swallowing impairments were present in persons with PWS. To address this research and clinical gap, simultaneous videofluoroscopy and nasal respiratory signals were used to record swallowing function and breathing/swallowing coordination in 30 participants with PWS. Subjects consumed thin liquid and barium cookies under two randomized conditions as follows: (i) controlled (cues to swallow and standardized bolus sizes); (ii) spontaneous (no cues or bolus size control). Under videofluoroscopy, the cohort showed disordered pharyngeal and esophageal swallowing in both conditions with disturbances in timing, clearance, and coordination of swallowing with the respiratory cycle. No participant showed a sensory response such as attempting to clear residue or coughing; thereby supporting the lack of overt symptoms. We conclude that the high death rate from choking and pulmonary infection in children and adults with PWS may be related, in part, to underlying, asymptomatic dysphagia. The combination of rapid eating and dysphagia would increase the risk of aspiration-related morbidity and mortality. © 2016 Wiley Periodicals, Inc.

A Case-controlled Investigation of Pain Experience and Sensory Function in Neuronal Ceroid Lipofuscinosis

OBJECTIVES

This case-control study explored pain experience and expression among individuals with neuronal ceroid lipofuscinosis (NCL) through parental report, tactile sensory testing, and infrared thermography (IRT).

MATERIALS AND METHODS

Participants with NCL (n=8; M=14.8 y) and their unaffected siblings (n=8; M=23.5 y) were characterized in terms of pain response to a brief tactile sensory test (light touch, Von Frey monofilament). During sensory testing, behavioral expression was measured using the Battens Observational Pain Scale and infrared thermography (IRT) was used to quantify changes in skin/eye temperature.

RESULTS

Children with NCL experienced pain frequently and from multiple sources that negatively impacted their lives. Children with NCL were reactive to the sensory testing as indexed by significant increased IRT temperature change (P<0.001). Across combined sensory conditions, individuals with NCL were significantly more reactive (Battens Observational Pain Scale total score) to sensory testing compared with siblings (P<0.05). Similarly, IRT difference scores between sensory conditions revealed a significant increase in temperature for individuals with NCL compared with siblings (P<0.001).

DISCUSSION

Ongoing reported pain was a problem for the children with NCL in this sample. Increased pain expression during the repeated Von Frey filament suggests that the pathophysiology of the ongoing pain may be centrally mediated.

Weight control and behavior rehabilitation in a patient suffering from Prader Willi syndrome

BACKGROUND

This study reports a case of Prader Willi syndrome (PWS), a genomic imprinting disease related to chromosome regions 15q11.2-q13 15, which includes hypothalamic dysfunction leading to hyperphagia, obesity, shortness, sleep abnormalities. Our case is extremely severe, in comparison to other PWS cases described in literature, due to the association with severe emotional and psychiatric symptoms: oppositional behaviour, rigidity of thought, skin picking and pathological hoarding.

CASE PRESENTATION

We described the case of a Caucasian male patient suffering from PWS, treated in outpatient care by local Mental Health Centre and supported by Social Service, who was admitted to a residential rehabilitative facility. After a 2-year follow-up, the patient showed a global improvement in symptoms and functioning, as registered by the rating scales administered. At the end of observation period, we also reported an important improvement in weight control, reducing the risk of obesity and related diseases, therefore improving the prognosis of life.

CONCLUSION

This case highlights the need for long-term, individualized and multi-professional treatment in patients suffering from a complex genetic syndrome with both organic and psychological alterations, for which medical care setting and pharmacological treatments are not sufficient. Clinical observation of this case leads us to compare PWS to drug addiction and indirectly endorse the neurophysiological hypothesis that food and drugs stimulate the same brain circuits in the limbic system.

Practitioner Review: Self-injurious behaviour in children with developmental delay

BACKGROUND

Self-injurious behaviour is shown by a significant minority of children with developmental delay and has a substantial impact on child and carer wellbeing. Characteristics such as a greater degree of intellectual disability, autism spectrum disorder, some genetic syndromes and repetitive and impulsive behaviours are positively associated with self-injury. Prevalence generally increases with age into midadulthood and the behaviour is notably persistent.

SCOPE

In this review, we discuss the dominant causal theory of self-injury which draws on the principles of operant learning. We evaluate the utility of this theory to account for all empirical observations of self-injury.

FINDINGS

A model of self-injury is presented that extends a previous model described by Guess and Carr. The new model integrates child characteristics and operant learning principles in a phenotype × environment paradigm to explain the variance in developmental trajectory of the severity of self-injury.

CONCLUSIONS

Behaviour dysregulation, as evidenced by the associations between self-injury, self-restraint, repetitive and impulsive behaviours, is identified as potentially influencing the severity and persistence of self-injury. Risk markers for self-injury are identified and the extended model indicates points of intervention and highlights the possibility of risk-related, targeted early intervention. The need for increased training of practitioners in the delivery of demonstrably effective interventions for self-injury is identified.

Neural correlates of self-injurious behavior in Prader-Willi syndrome

Individuals with Prader-Willi syndrome (PWS), a genetic disorder caused by mutations to the q11-13 region on chromosome 15, commonly show severe skin-picking behaviors that can cause open wounds and sores on the body. To our knowledge, however, no studies have examined the potential neural mechanisms underlying these behaviors. Seventeen individuals with PWS, aged 6-25 years, who showed severe skin-picking behaviors, were recruited and scanned on a 3T scanner. We used functional magnetic resonance imaging (fMRI) while episodes of skin picking were recorded on an MRI-safe video camera. Three participants displayed skin picking continuously throughout the scan, three participants did not display skin picking, and the data for one participant evidenced significant B0 inhomogeneity that could not be corrected. The data for the remaining 10 participants (six male, four female) who displayed a sufficient number of picking and nonpicking episodes were subjected to fMRI analysis. Results showed that regions involved in interoceptive, motor, attention, and somatosensory processing were activated during episodes of skin-picking behavior compared with nonpicking episodes. Scores obtained on the Self-Injury Trauma scale were significantly negatively correlated with mean activation within the right insula and left precentral gyrus. These data indicate that itch and pain processes appear to underlie skin-picking behaviors in PWS, suggesting that interoceptive disturbance may contribute to the severity and maintenance of abnormal skin-picking behaviors in PWS. Implications for treatments are discussed.

Growth hormone treatment improves vitality and behavioural issues in children with Prader-Willi syndrome

AIM

Prader-Willi syndrome is a neurogenetic disorder, with characteristics such as obesity, short stature, muscular weakness, intellectual deficiencies and deviant social behaviour. This study evaluated whether growth hormone treatment of children with Prader-Willi syndrome resulted in possible and lasting effects on their cognition and behaviour.

METHODS

We randomised six girls and 13 boys to either a treatment group or a control group. The treatment group received growth hormone (Genotropin(®) 0.033 mg/kg/day) for 2 years, while the control group did not receive treatment in the first year and then received a double dose in the second year. Treatment was then stopped in both groups for 6 months.

RESULTS

Both groups showed the same intellectual disabilities at the start of the study, and no difference was found after the first and second years. The parents reported that the children showed increased vitality during treatment. When treatment was stopped, the children showed a marked exacerbation of behavioural problems, a significant increase in body fat and a decrease in insulin-like growth factor 1 levels.

CONCLUSION

We believe this is the first study to show that abrupt-ceasing growth hormone treatment led to a successive deterioration in behavioural problems in children with Prader-Willi syndrome.

Challenges in the optimisation of post-operative pain management with opioids in obese patients: a literature review

An increasing number of obese patients are undergoing surgery, particularly bariatric and orthopaedic surgery. The physiological differences between obese and normal-weight subjects may modify not only anaesthetic requirements during surgery but also post-operative analgesic management, raising a number of challenges in a critical period. In this review, we analyse studies of post-operative pain management with opioids in obese subjects. We discuss the genetic factors common to pain and obesity and the factors potentially modifying opioid pharmacokinetics and pharmacodynamics in obese patients, and we analyse the overall efficacy and safety of opioids for pain management during the post-operative period in obese patients. Both modifications to surgical methods and additional analgesic treatments to decrease the requirement for opioids may improve early rehabilitation and quality of care and reduce adverse effects in obese patients.

The use of medical care and the prevalence of serious illness in an adult Prader-Willi syndrome cohort

INTRODUCTION

Adults with Prader-Willi syndrome (PWS) have an increased occurrence of several medical conditions. We report on the consequences of high morbidity rates such as prevalence rate of hospital admissions, medication use and surgery in a Dutch cohort of adults with PWS. Special attention is paid to causes and symptoms of serious illness.

METHOD

Participants were contacted via the Dutch Prader-Willi Parent Association and through physicians specializing in persons with ID. The persons with PWS and their main caregivers were visited at home. Information was collected through semi-structured interviews on 102 adults with PWS.

RESULTS

The need for medical care in the neonatal period is associated with hypotonia and feeding problems. Hospital admissions for respiratory tract infections are frequent. During childhood most hospital admissions were due to PWS syndrome specific surgery. During adolescence hospital admissions occurred for scoliosis surgery and endocrine evaluations. At adult age, hospitalization was associated with inguinal hernia surgery, diabetes mellitus, psychosis, erysipelas, water and drug intoxications. In the older group, respiratory infections were again the main reason for hospital admissions. Frequently used medications at adult age included psychotropics, laxatives, anti-diabetics and dermatologic preparations. Abnormal drinking patterns, problems with anesthesia, decreased ability to vomit, abnormal pain awareness and unpredictable fever responses were frequent and often lead to delayed diagnoses of serious conditions.

DISCUSSION

People with PWS are frequent users of medical-care. Reasons for hospitalization and medication use are age specific. Knowledge on the different presentation of symptoms in people with PWS is needed. In case of unexplained illness, disturbances of consciousness and behavioral changes in people with PWS, an infection should be ruled out in the first place. Information from this study may help in preventing conditions and recognizing conditions in an early stage. Adequate preventive management and treatment of PWS related morbidity, could reduce medical care use in the long term and could improve quality adjusted life years.

Sensory impairment in obese patients? Sensitivity and pain detection thresholds for electrical stimulation after surgery-induced weight loss, and comparison with a nonobese population

INTRODUCTION

Obese patients have a high prevalence of painful musculoskeletal disorders that may decrease after massive weight loss. Pain thresholds may be different in obese participants.

OBJECTIVES

To assess the sensitivity and pain detection thresholds, through the application of an electrical sensitivity, before and after massive weight loss, and to compare the thresholds obtained with those in a control population.

METHODS

The sensitivity and pain detection thresholds obtained in participants subjected to electrical stimulation were determined in 31 obese individuals (age: 40.3 ± 10.5 y) before (body mass index: 45.7 ± 6.8 kg/m) and 6 months after a mean weight loss of 32 kg induced by gastric bypass. The results obtained were compared with those for 49 nonobese control participants (38.5 ± 11.2 y; body mass index: 22.6 ± 2.6 kg/m). Body composition and metabolic biomarkers, such as leptin, adiponectin, insulin, and interleukin 6, were assessed and single-nucleotide polymorphisms of the mu opioid receptor [OPRM1 (c.118A > G) and COMT (p.Val158Met)] were genotyped in obese patients.

RESULTS

Sensitivity and pain detection thresholds (3.9 ± 1.1; 11.6 ± 6.0) were significantly higher in obese than in nonobese participants (3.1 ± 1.1; 6.0 ± 3.0), respectively (P < 0.0001), and were not affected by drastic weight loss (mean change: 32 kg). Pain thresholds in obese participants were not correlated with any of the clinical and biological variables studied. The obese participants in the highest quartile for both sensitivity and pain detection thresholds were significantly older than those in the lowest quartile.

CONCLUSIONS

Further studies are required to explore sensory dysfunction in obese individuals and to investigate the implications of this dysfunction for pain management.

Dysfunction of autonomic nervous system in childhood obesity: a cross-sectional study

OBJECTIVE

To assess the distribution of autonomic nervous system (ANS) dysfunction in overweight and obese children.

METHODS

Parasympathetic and sympathetic ANS function was assessed in children and adolescents with no evidence of impaired glucose metabolism by analysis of heart rate variability (low frequency power ln(LF), high frequency power, ln(HF); ln(LF/HF) ratio, ratio of longest RR interval during expiration to shortest interval during inspiration (E/I ratio), root mean square of successive differences (RMSSD); sympathetic skin response (SSR); and quantitative pupillography (pupil diameter in darkness, light reflex amplitude, latency, constriction velocity, re-dilation velocity). The relationship of each ANS variable to the standard deviation score of body mass index (BMI-SDS) was assessed in a linear model considering age, gender and pubertal stage as co-variates and employing an F-statistic to compare the fit of nested models. Group comparisons between normal weight and obese children as well as an analysis of dependence on insulin resistance (as indexed by the Homeostasis Model Assessment of Insulin Resistance, HOMA-IR) were performed for parameters shown to correlate with BMI-SDS. Statistical significance was set at 5%.

RESULTS

Measurements were performed in 149 individuals (mean age 12.0 y; 90 obese 45 boys; 59 normal weight, 34 boys). E/I ratio (p = 0.003), ln(HF) (p = 0.03), pupil diameter in darkness (p = 0.01) were negatively correlated with BMI-SDS, whereas ln(LF/HF) was positively correlated (p = 0.05). Early re-dilation velocity was in trend negatively correlated to BMI-SDS (p = 0.08). None of the parameters that depended significantly on BMI-SDS was found to be significantly correlated with HOMA-IR.

CONCLUSION

These findings demonstrate extended ANS dysfunction in obese children and adolescents, affecting several organ systems. Both parasympathetic activity and sympathetic activity are reduced. The conspicuous pattern of ANS dysfunction raises the possibility that obesity may give rise to dysfunction of the peripheral autonomic nerves resembling that observed in normal-weight diabetic children and adolescents.

Risk for ingestion of toxic substances in children with Prader-Willi syndrome

Individuals with Prader-Willi syndrome (PWS) have several common findings that may predispose to ingestion of potentially dangerous items. This study examined whether individuals with PWS have an increased prevalence of toxic ingestions. A survey regarding history of ingestions in PWS individuals and sibling controls was designed, piloted, and distributed on-line. The subjects were individuals with PWS (N = 129). The subjects' non-PWS siblings served as controls (N = 134). Participants who completed the anonymous online survey were either the parents or the primary caretaker of individuals with PWS. Responses were submitted by 141 participants, providing information about 130 PWS subjects (M/F: 66:64) and 134 sibling controls. Subjects and controls ranged in age from 2 to 18 years at the time of the survey. Eleven participants did not answer the questions regarding ingestions. History of toxic ingestion was more prevalent in PWS subjects (20% vs. 2% of controls). Several features of PWS, including history of searching for food and eating unusual objects, along with decreased cognitive ability, appeared to associate with increased prevalence of toxic ingestion in PWS individuals. PWS children appear to have an ∼12-fold increased risk of ingesting toxins compared to the general population. Geneticists should include this information in counseling and in recommendations to primary care providers. Also, poison control centers need to be aware of this association and of the physiological and behavioral aspects of PWS that may complicate the diagnosis and management of a toxic ingestion.

Severe tooth wear in Prader-Willi syndrome. A case-control study

BACKGROUND

Prader-Willi syndrome (PWS) is a rare complex multsystemic genetic disorder characterized by severe neonatal hypotonia, endocrine disturbances, hyperphagia and obesity, mild mental retardation, learning disabilities, facial dysmorphology and oral abnormalities. The purpose of the present study was to explore the prevalence of tooth wear and possible risk factors in individuals with Prader-Willi syndrome.

METHODS

Forty-nine individuals (6-40 years) with PWS and an age- and sex-matched control group were included. Tooth wear was evaluated from dental casts and intraoral photographs and rated by four examiners using the Visual Erosion Dental Examination (VEDE) scoring system and the individual tooth wear index IA. In accordance with the VEDE scoring system, tooth wear was also evaluated clinically. Whole saliva was collected.

RESULTS

Mean VEDE score was 1.70 ± 1.44 in the PWS group and 0.46 ± 0.36 in the control group (p < 0.001). Median IA was 7.50 (2.60-30.70) in the PWS group and 2.60 (0.90-4.70) among controls (p < 0.001). In the PWS group tooth wear correlated significantly with age (VEDE; r = 0.79, p < 0.001, IA; r = 0.82, p < 0.001) and saliva secretion (VEDE; r = 0.46, p = 0.001, IA; r = 0.43, p = 0.002). Tooth grinding was also associated with tooth wear in the PWS group, as indicated by the mean VEDE 2.67 ± 1.62 in grinders and 1.14 ± 0.97 in non-grinders (p = 0.001) and median IA values 25.70 (5.48-68.55) in grinders and 5.70 (1.60-9.10) in non-grinders (p = 0.003). Multivariate linear regression analysis was performed with tooth wear as the dependent variable and PWS (yes/no), age, tooth grinding and saliva secretion as independent variables. PWS (yes/no), age and tooth grinding retained a significant association with tooth wear, VEDE (p < 0.001) and log IA (p < 0.001). The only factor significantly associated with tooth wear in the control group was age.

CONCLUSIONS

Our study provides evidence that tooth wear, in terms of both erosion and attrition, is a severe problem in Prader-Willi syndrome. There is therefore considerable need for prosthodontic rehabilitation in young adults with PWS.

Qualitative evaluation of a pain intensity screen for children with severe neurodevelopmental disabilities

The population of individuals with severe and profound intellectual disabilities (ID) is extremely heterogeneous, and the unique pain-related behaviors of each individual might not be satisfactorily captured using a standardized checklist such as the Noncommunicating Children's Pain Checklist or the Revised Faces, Legs, Arms, Cry, and Consolability tools. There has been increasing appreciation of the importance of recognizing the idiosyncratic pain behaviors of these individuals. The investigators developed a tool, the Tailored Observational Pain Screen (TOPS), to facilitate recognition of pain in the individual who lacks verbal communication, based on caregivers' descriptions of the individual's unique pain-related behaviors. The aim of this study was to elicit caregivers' evaluations of this personalized pain screen, using qualitative analysis of semi-structured interviews. The participants were the primary caregivers of 13 children with severe or profound ID and ongoing pain issues who were interviewed after they had used the TOPS for 6 weeks. The investigators identified themes from the interviews, including: using the TOPS to recognize and evaluate pain; using the TOPS to facilitate communication; limitations of the TOPS; and recommendations for its improvement. For clinical purposes, the TOPS shows promise as a tool for helping caregivers to share with others the ways that pain of these children can be detected.

Orofacial dysfunction in individuals with Prader-Willi syndrome assessed with NOT-S

OBJECTIVE

The objective of the study was to evaluate orofacial dysfunction in individuals with Prader-Willi syndrome (PWS) and compare it with a healthy reference group.

METHODS AND MATERIALS

The Nordic Orofacial Test-Screening (NOT-S) protocol was used for evaluation of orofacial function in 45 (23 Male, 22 Female) individuals with PWS, aged 19.8 ± 9.5 years, and a reference group of 40 (18 M, 22 F) healthy individuals, aged 24.0 ± 16.3 years.

RESULTS

The NOT-S score was markedly higher for the individuals with PWS than for the healthy reference group (3.9 ± 2.1 vs 0.3 ± 0.5, p < 0.001). The most common domains of dysfunction in individuals with PWS were Oral motor function (60.0%), Habits (55.6%), Face at rest (53.3%), Speech (44.4%), Drooling (44.4%) and Breathing (42.2%).

CONCLUSIONS

Eighty-seven per cent of the participants with PWS demonstrated dysfunction in two or more domains, particularly in the domains Oral motor function, Habits and Face at rest.

The effect of vision on postural strategies in Prader-Willi patients

The aim of this study was to quantify the role of visual contribution in patients with Prader-Willi syndrome (PWS) on balance maintenance using a force platform. We enrolled 14 individuals with PWS free from conditions associated with impaired balance, 44 obese (OG) and 20 healthy controls (CG). Postural sway was measured for 60s while standing on a force platform (Kistler, CH; acquisition frequency: 500 Hz) integrated with a video system. Patients maintained an upright standing position with Open Eyes (OE) and then with Closed Eyes (CE). The ratio between the value of the parameter under OE and CE conditions was measured. Under OE condition PWS and OG were characterized by higher postural instability than CG, with the PWS group showing poorer balance capacity than OG. The Romberg ratio showed that while OG and CG had lower balance without vision, PWS maintained the same performance changing from OE to CE. The integration of different sensory inputs appears similar in OG and CG with higher postural stability under OE than CE. Balance in PWS is not influenced by the elimination of visual input.

Autonomic nervous system dysfunction in obesity and Prader-Willi syndrome: current evidence and implications for future obesity therapies

The autonomic nervous system (ANS) controls essential functions like breathing, heart rate, digestion, body temperature and hormone levels. Evidence suggests that ANS dysfunction is associated with adult and childhood obesity and plays a role in the distribution of total body fat and the development of obesity-related complications in humans. This review summarizes our current understanding of ANS involvement in the pathogenesis of obesity and Prader-Willi syndrome. Available evidence of ANS dysfunction in the control of energy balance is limited and, in some cases, contradictory. Further investigation in this area is warranted in order to better understand the important contributions of the ANS to regulation of body fat, development of obesity and its comorbidities. Results from these studies will guide the development of novel obesity therapeutics targeting specific ANS dysfunction.

Linking MECP2 and pain sensitivity: the example of Rett syndrome

Recent animal studies suggest links between MeCP2 function and sensitivity to pain. This study investigated the nature and prevalence of atypical pain responses in Rett syndrome and their relationships with specific MECP2 mutations. Families enrolled in the Australian Rett Syndrome Database (ARSD) and InterRett database participated in this study. Cases with a known MECP2 pathogenic mutation, whose families had completed a questionnaire on registration and had answered questions on pain sensitivity were included (n = 646). Logistic regression was used to analyze relationships between the atypical pain responses and genotype. Descriptions of decreased pain sensitivity were content analyzed. The prevalence estimate of reporting an abnormal pain response was 75.2% and a decreased sensitivity to pain was 65.0% in the population-based ARSD. Families of ARSD and InterRett subjects with a C-terminal (OR 2.6; 95% CI 0.8-8.0), p.R168X (OR 2.1; 95% CI 0.7-6.1), or p.R306C (OR 2.7; 95% CI 0.8-9.6) mutation were more likely to report decreased sensitivity to pain. Parents and carers described decreased and delayed responses in situations judged likely to cause pain such as injections, falls, trauma, and burns. This study has provided the first precise estimate of the prevalence of abnormal sensitivity to pain in Rett syndrome but specific relationships with genotype are not yet clear. Clinical practice should include a low threshold for the clinical assessment of potential injuries in Rett syndrome.