Prader-Willi syndrome

Neuromodulation for the treatment of Prader-Willi syndrome - A systematic review

Prader-Willi syndrome (PWS) is a complex, genetic disorder characterized by multisystem involvement, including hyperphagia, maladaptive behaviors and endocrinological derangements. Recent developments in advanced neuroimaging have led to a growing understanding of PWS as a neural circuit disorder, as well as subsequent interests in the application of neuromodulatory therapies. Various non-invasive and invasive device-based neuromodulation methods, including vagus nerve stimulation (VNS), transcranial direct current stimulation (tDCS), repetitive transcranial magnetic stimulation (rTMS), and deep brain stimulation (DBS) have all been reported to be potentially promising treatments for addressing the major symptoms of PWS. In this systematic literature review, we summarize the recent literature that investigated these therapies, discuss the underlying circuits which may underpin symptom manifestations, and cover future directions of the field. Through our comprehensive search, there were a total of 47 patients who had undergone device-based neuromodulation therapy for PWS. Two articles described VNS, 4 tDCS, 1 rTMS and 2 DBS, targeting different symptoms of PWS, including aberrant behavior, hyperphagia and weight. Multi-center and multi-country efforts will be required to advance the field given the low prevalence of PWS. Finally, given the potentially vulnerable population, neuroethical considerations and dialogue should guide the field.

Prader-Willi Syndrome: A spectrum of anatomical and clinical features

Prader-Willi Syndrome (PWS) is estimated to affect 400,000 people worldwide. First described clinically in 1956, PWS is now known to be a result of a genetic mutation, involving Chromosome 15. The phenotypical appearance of individuals with the syndrome follows a similar developmental course. During infancy, universal hypotonia accompanied by feeding problems, hypogonadism, and dolichocephaly are evident. Characteristic facial features such as narrow bifrontal diameter, almond-shaped eyes, and small mouth (with downturned corners and thin upper lip) may also be evident at this stage. In early childhood, the craniofacial features become more obvious and a global developmental delay is observed. Simultaneously, individuals develop hyperphagia that leads to excessive or rapid weight gain, which, if untreated, exists throughout their lifespan and may predispose them to numerous, serious health issues. The standard tool for differential diagnosis of PWS is genetic screening; however, clinicians also need to be aware of the characteristic features of this disorder, including differences between the genetic subtypes. As the clinical manifestations of the syndrome vary between individuals and become evident at different developmental time points, early assessment is hindered. This article focuses on the clinical and anatomical manifestations of the syndrome and highlights the areas of discrepancy and limitations within the existing literature. Clin. Anat. 29:590-605, 2016. © 2016 Wiley Periodicals, Inc.

Physical health problems in adults with Prader-Willi syndrome

Prader-Willi syndrome (PWS) is a genetic disorder which is characterized by severe hypotonia and feeding problems in early infancy. In later childhood and adolescence, this is followed by hyperphagia and extreme obesity if the diet is not strictly controlled. Data on physical health problems in adults with PWS are scarce. We report on the prevalence of physical health problems in a Dutch cohort of adults with PWS in relation to age, BMI, and genetic subtype. Participants (n = 102) were retrieved via the Dutch Prader-Willi Parent Association and through physicians specializing in persons with intellectual disabilities (ID). Details regarding physical health problem spanning the participants' lifespan were collected from caretakers through semi-structured interviews. Cardiovascular problems included diabetes mellitus, hypertension, and cerebrovascular accidents. Respiratory infections were frequent in adulthood. In males, cryptorchidism was almost universal, for which 28/48 males had a history of surgery, mostly orchidopexy. None of the women had a regular menstrual cycle. Sixteen individuals had a diagnosis of osteoporosis. Spinal deformation, hip dysplasia, and foot abnormalities were common. Skinpicking, leg edema, and erysipelas were frequent dermatological problems. The findings in our group support the notion that the prevalence of physical health problems is underestimated. This underscores the importance of developing monitoring programs which would help to recognize physical health problems at an early stage.

Clinical characteristics of hypotonia: a survey of pediatric physical and occupational therapists

PURPOSE

This study extended previous work on defining characteristics of children with hypotonia.

METHODS

A survey regarding previously identified characteristics of hypotonia, examination tools, interventions, and prognosis was sent to a random sample of 500 physical therapists and 500 occupational therapists.

RESULTS

A total of 268 surveys were returned, for a response rate of 26.8%. Characteristics most frequently observed in children with hypotonia included decreased strength, hypermobile joints, and increased flexibility. Observation was the most commonly cited assessment tool and 85% of those surveyed believe that characteristics of hypotonia improve with therapy.

CONCLUSIONS

Despite agreement among physical and occupational therapists on characteristics of hypotonia and potential for improvement, clear clinical guidelines for the diagnosis and quantification of hypotonia have yet to be determined. Research is needed to develop an operational definition of hypotonia, develop valid tests and assess effectiveness of intervention.

Prader-Willi Syndrome: clinical concerns for the orthopaedic surgeon

BACKGROUND

Prader-Willi Syndrome (PWS) is a chromosome 15 disorder characterized by hypotonia, hypogonadism, hyperphagia, and obesity. Musculoskeletal manifestations, including scoliosis, hip dysplasia, and lower limb alignment abnormalities, are well described in the orthopaedic literature. However, care of this patient population from the orthopaedic surgeon's perspective is complicated by other clinical manifestations of PWS. Osteopenia, psychiatric disorders, and diminished pain sensitivity are frequently noted in PWS but are not discussed in the orthopaedic literature. The authors present a clinical review of an 8-year experience of caring for 31 patients with PWS to highlight all clinical concerns that influence orthopaedic management.

METHODS

Thirty-one institutionalized patients diagnosed with PWS were examined and all past medical records were reviewed. Patient demographics, genetic testing, musculoskeletal diagnoses, psychiatric diagnoses, and clinical behaviors were recorded. Radiological studies performed in the course of routine clinical care were evaluated.

RESULTS

Twenty-three men and 8 women, with an average age of 22 years (range, 8-39 years), were studied. A chromosome 15q abnormality was confirmed in 18 patients. Scoliosis was clinically detected in 21 of 30 patients and confirmed by radiographs in 14 of these 24 patients (overall with scoliosis, 45%) with an average primary curve of 27 degrees; 3 were braced, and 2 underwent spinal fusion. Radiographs also revealed diminished cervical lordosis and increased cervicothoracic kyphosis in 16 patients, a previously undescribed finding. Hip radiographs of 26 patients revealed dysplasia in 2 patients (13%); no slipped capital femoral epiphysis were identified. Fourteen patients had sustained a total of 58 fractures, with 6 patients sustaining multiple fractures (range, 2-7). Six patients have undergone orthopaedic surgical procedures with one major complication (spinal infection). Fracture management was associated with frequent minor complications. Bone densitometry was performed on 14 patients; 8 patients had osteopenia, and 4 had osteoporosis based on lumbar spine z scores. Twenty-six patients had Axis I psychiatric diagnoses including impulse control disorder (7), organic personality disorder (6), oppositional defiant disorder (5), dysthymic disorder (4), depressive disorder not otherwise specified (3), attention-deficit/hyperactivity disorder (2), and obsessive-compulsive disorder (2). Nine patients exhibited self-mutilating behaviors.

CONCLUSIONS

Osteopenia, poor impulse control and defiant behaviors, and diminished pain sensitivity are aspects of PWS that may complicate all facets of orthopaedic nonsurgical and surgical management in this patient population. The treating orthopaedic surgeon must plan carefully and proceed with caution when treating children and adults with PWS.

Characteristics of hypotonia in children: a consensus opinion of pediatric occupational and physical therapists

PURPOSE

The term hypotonia is often used to describe children with reduced muscle tone, yet it remains abstract and undefined. The purpose of this study was to identify characteristics of children with hypotonia to begin the process of developing an operational definition of hypotonia.

METHODS

Three hundred physical and occupational therapists were systematically selected from the memberships of the Pediatric Section of the American Physical Therapy Association and the Developmental Delay Section of the American Occupational Therapy Association and asked to complete an open-ended survey exploring characteristics of strength, endurance, mobility, posture, and flexibility.

RESULTS

The response rate was 26.6%. Forty-six physical therapists and 34 occupational therapists participated. The criterion for consensus about a characteristic was being mentioned by at least 25% of respondents from each discipline. The consensus was that children with hypotonia have decreased strength, decreased activity tolerance, delayed motor skills development, rounded shoulder posture, with leaning onto supports, hypermobile joints, increased flexibility, and poor attention and motivation.

CONCLUSION

An objective tool for defining and quantifying hypotonia does not exist. A preliminary characterization of children with hypotonia was established, but further research is needed to achieve objectivity and clarity.