Rett syndrome severity estimation with the BioStamp nPoint using interactions between heart rate variability and body movement

Rett syndrome, a rare genetic neurodevelopmental disorder in humans, does not have an effective cure. However, multiple therapies and medications exist to treat symptoms and improve patients' quality of life. As research continues to discover and evaluate new medications for Rett syndrome patients, there remains a lack of objective physiological and motor activity-based (physio-motor) biomarkers that enable the measurement of the effect of these medications on the change in patients' Rett syndrome severity. In our work, using a commercially available wearable chest patch, we recorded simultaneous electrocardiogram and three-axis acceleration from 20 patients suffering from Rett syndrome along with the corresponding Clinical Global Impression-Severity score, which measures the overall disease severity on a 7-point Likert scale. We derived physio-motor features from these recordings that captured heart rate variability, activity metrics, and the interactions between heart rate and activity. Further, we developed machine learning (ML) models to classify high-severity Rett patients from low-severity Rett patients using the derived physio-motor features. For the best-trained model, we obtained a pooled area under the receiver operating curve equal to 0.92 via a leave-one-out-patient cross-validation approach. Finally, we computed the feature popularity scores for all the trained ML models and identified physio-motor biomarkers for Rett syndrome.

Methylphenidate treatment for cognitive symptoms associated with ADHD in a pediatric epilepsy patient following resection of a left frontal cortical dysplasia

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ADHD symptoms can emerge or worsen after epilepsy surgery.

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Methylphenidate use improved cognitive symptoms of ADHD in our patient.

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Seizure aggravation did not occur following use of a neurostimulant in our patient.

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Our patient benefitted from a multidisciplinary intervention approach.

We present data on a 10-year-old patient with drug-resistant epilepsy who was treated with methylphenidate for symptoms of attention deficit hyperactivity disorder (ADHD) that developed after she underwent surgical resection of a left frontal cortical dysplasia. . The patient’s parents reported methylphenidate was helpful in improving their child’s reading performance. Based on parents’ report, we examined benefits of methylphenidate on our patient’s cognitive problems in a controlled setting. The patient underwent a neuropsychological evaluation completed in three sessions over a five-day period. Methylphenidate was administered prior to the second testing session only and was associated with improvements in the patient’s attention, executive function, processing speed, and short-term memory performances. In comparison, word-reading performance, a task less susceptible to neurological impairment, was stable over the three sessions. The patient remained seizure-free after surgery and use of methylphenidate did not reduce seizure threshold. These findings support the use of methylphenidate in treating targeted cognitive problems associated with ADHD emerging after epilepsy surgery in children.

Assessment of a Clinical Trial Metric for Rett Syndrome: Critical Analysis of the Rett Syndrome Behavioural Questionnaire

BACKGROUND

Rett syndrome is a neurodevelopmental disorder with potential for improvement through novel targeted therapeutics. Reliable outcome measures are critical to the development of treatments. We examined the merits and flaws of the Rett Syndrome Behavioural Questionnaire, an outcome measure for clinical trials.

METHODS

The Rett Syndrome Behavioural Questionnaire was administered alongside other clinical scales in three cohorts, an online survey, a clinic-based study, and the screening period for a clinical trial. Data were collected from individuals with Rett syndrome and related disorders at three time points, separated by a minimum of one week and a maximum of two months. We hypothesized that for clinical trial use, little change should occur among visits. Distribution statistics, internal consistency, intraclass correlation coefficient, percent agreement, and Cohen's kappa were examined.

RESULTS

Among 149 with classic Rett syndrome, the Rett Syndrome Behavioural Questionnaire was completed 377 times. Median total score was 33, ranging from 3 to 73. Of the 51 items tested in the original Rett Syndrome Behavioural Questionnaire study, 24 exhibited either floor or ceiling effects. Friedman's analysis of variance revealed significant difference among visits (P = 0.024), and graphical analysis using Bland-Altman plots demonstrated systematic positive bias with a 95% confidence interval including up to 12.9 points higher to 15.7 points lower at retest. Median agreement measured by kappa was 0.53 for retest at visit 2 and 0.49 for retest at visit 3.

CONCLUSIONS

The Rett Syndrome Behavioural Questionnaire did not achieve acceptable standards as an outcome assessment for clinical trials in Rett syndrome.

The course of awake breathing disturbances across the lifespan in Rett syndrome

Rett syndrome (RTT), an X-linked dominant neurodevelopmental disorder caused by mutations in MECP2, is associated with a peculiar breathing disturbance exclusively during wakefulness that is distressing, and can even prompt emergency resuscitation. Through the RTT Natural History Study, we characterized cross sectional and longitudinal characteristics of awake breathing abnormalities in RTT and identified associated clinical features. Participants were recruited from 2006 to 2015, and cumulative lifetime prevalence of breathing dysfunction was determined using the Kaplan-Meier estimator. Risk factors were assessed using logistic regression. Of 1205 participants, 1185 had sufficient data for analysis, including 922 females with classic RTT, 778 of whom were followed longitudinally for up to 9.0 years, for a total of 3944 person-years. Participants with classic or atypical severe RTT were more likely to have breathing dysfunction (nearly 100% over the lifespan) compared to those with atypical mild RTT (60-70%). Remission was common, lasting 1 year on average, with 15% ending the study in terminal remission. Factors associated with higher odds of severe breathing dysfunction included poor gross and fine motor function, frequency of stereotypical hand movements, seizure frequency, prolonged corrected QT interval on EKG, and two quality of life metrics: caregiver concern about physical health and contracting illness. Factors associated with lower prevalence of severe breathing dysfunction included higher body mass index and head circumference Z-scores, advanced age, and severe scoliosis or contractures. Awake breathing dysfunction is common in RTT, more so than seizures, and is associated with function, quality of life and risk for cardiac dysrhythmia.

Placebo-controlled crossover assessment of mecasermin for the treatment of Rett syndrome

Objective

To measure the efficacy of mecasermin (recombinant human insulin-like growth factor 1, rhIGF-1), for treating symptoms of Rett syndrome (RTT) in a pediatric population using a double-blind crossover study design.

Methods

Thirty girls with classic RTT in postregression stage were randomly assigned to placebo or rhIGF-1 in treatment period 1 and crossed over to the opposite assignment for period 2 (both 20 weeks), separated by a 28-week washout period. The primary endpoints were as follows: Anxiety Depression and Mood Scale (ADAMS) Social Avoidance subscale, Rett Syndrome Behaviour Questionnaire (RSBQ) Fear/Anxiety subscale, Parent Target Symptom Visual Analog Scale (PTSVAS) top three concerns, Clinical Global Impression (CGI), Parent Global Impression (PGI), and the Kerr severity scale. Cardiorespiratory- and electroencephalography (EEG)-based biomarkers were also analyzed.

Results

There were no significant differences between randomization groups. The majority of AEs were mild to moderate, although 12 episodes of serious AEs occurred. The Kerr severity scale, ADAMS Depressed Mood subscale, Visual Analog Scale Hyperventilation, and delta average power change scores significantly increased, implying worsening of symptoms. Electroencephalography (EEG) parameters also deteriorated. A secondary analysis of subjects who were not involved in a placebo recall confirmed most of these findings. However, it also revealed improvements on a measure of stereotypic behavior and another of social communication.

Interpretation

As in the phase 1 trial, rhIGF-1 was safe; however, the drug did not reveal significant improvement, and some parameters worsened.

Longitudinal course of epilepsy in Rett syndrome and related disorders

Epilepsy is common in Rett syndrome, an X-linked dominant disorder caused by mutations in the MECP2 gene, and in Rett-related disorders, such as MECP2 duplication. However, neither the longitudinal course of epilepsy nor the patterns of seizure onset and remission have been described in Rett syndrome and related conditions. The present study summarizes the findings of the Rett syndrome Natural History study. Participants with clinical Rett syndrome and those with MECP2 mutations without the clinical syndrome were recruited through the Rett Natural History study from 2006 to 2015. Clinical details were collected, and cumulative lifetime prevalence of epilepsy was determined using the Kaplan-Meier estimator. Risk factors for epilepsy were assessed using Cox proportional hazards models. Of 1205 participants enrolled in the study, 922 had classic Rett syndrome, and 778 of these were followed longitudinally for 3939 person-years. The diagnosis of atypical Rett syndrome with a severe clinical phenotype was associated with higher prevalence of epilepsy than those with classic Rett syndrome. While point prevalence of active seizures ranged from 30% to 44%, the estimated cumulative lifetime prevalence of epilepsy using Kaplan-Meier approached 90%. Specific MECP2 mutations were not significantly associated with either seizure prevalence or seizure severity. In contrast, many clinical features were associated with seizure prevalence; frequency of hospitalizations, inability to walk, bradykinesia, scoliosis, gastrostomy feeding, age of seizure onset, and late age of diagnosis were independently associated with higher odds of an individual having epilepsy. Aggressive behaviour was associated with lower odds. Three distinct patterns of seizure prevalence emerged in classic Rett syndrome, including those who did not have seizures throughout the study, those who had frequent relapse and remission, and those who had relentless seizures. Although 248 of those with classic Rett syndrome and a history of seizures were in terminal remission at last contact, only 74 (12% of those with a history of epilepsy) were seizure free and off anti-seizure medication. When studied longitudinally, point prevalence of active seizures is relatively low in Rett syndrome, although lifetime risk of epilepsy is higher than previously reported. While daily seizures are uncommon in Rett syndrome, prolonged remission is less common than in other causes of childhood onset epilepsy. Complete remission off anti-seizure medications is possible, but future efforts should be directed at determining what factors predict when withdrawal of medications in those who are seizure free is propitious.

Rett Syndrome: Crossing the Threshold to Clinical Translation

Lying at the intersection between neurobiology and epigenetics, Rett syndrome (RTT) has garnered intense interest in recent years, not only from a broad range of academic scientists, but also from the pharmaceutical and biotechnology industries. In addition to the critical need for treatments for this devastating disorder, optimism for developing RTT treatments derives from a unique convergence of factors, including a known monogenic cause, reversibility of symptoms in preclinical models, a strong clinical research infrastructure highlighted by an NIH-funded natural history study and well-established clinics with significant patient populations. Here, we review recent advances in understanding the biology of RTT, particularly promising preclinical findings, lessons from past clinical trials, and critical elements of trial design for rare disorders.

The Changing Face of Survival in Rett Syndrome and MECP2-Related Disorders

PURPOSE

Survival in Rett syndrome remains unclear. Although early estimates were grim, more recent data suggest that survival into adulthood is typical. We aimed to define survival in Rett syndrome more clearly and identify risk factors for early death.

METHODS

Participants with clinical Rett Syndrome or methyl-CpG-binding protein 2 mutations without clinical RTT were recruited through the Rett Syndrome Natural History study from 2006 to 2015. Clinical details were collected, and survival was determined using the Kaplan-Meier estimator. Risk factors were assessed using Cox proportional hazards models.

RESULTS

Among 1189 valid participants, 51 died (range 3.9-66.6 years) during the 9-year follow-up period. Those who died included 36 (3.9%) classic Rett syndrome females, 5 (5.9%) atypical severe Rett syndrome females, 1 (2.4%) non-Rett syndrome female, the single atypical severe male, 6 (30%) non-Rett syndrome males, and 2 (7.1%) methyl-CpG-binding protein 2 duplication syndrome males. All atypical mild Rett syndrome females, methyl-CpG-binding protein 2 duplication syndrome females, and the single classic Rett syndrome male remain alive. Most deaths were due to cardiorespiratory issues. Only one died from severe malnutrition, scoliosis, and extreme frailty. Survival for classic and atypical Rett syndrome was greater than 70% at 45 years. Overall severity and several modifiable risk factors, including ambulation, weight, and seizures, were associated with mortality in classic Rett syndrome.

CONCLUSIONS

Survival into the fifth decade is typical in Rett syndrome, and death due to extreme frailty has become rare. Although the leading cause of death remains cardiorespiratory compromise, many risk factors for early death are modifiable. Intense therapeutic interventions could further improve the prognosis for individuals with Rett syndrome.

Age of diagnosis in Rett syndrome: patterns of recognition among diagnosticians and risk factors for late diagnosis

PURPOSE

Diagnosis of Rett syndrome (RTT) is often delayed. We sought to determine the type of physician who typically makes the RTT diagnosis and to identify risk factors for delayed diagnosis.

METHODS

A total of 1085 participants from the multicenter longitudinal RTT natural history study with classic and atypical RTT were recruited between 2006 and 2014. Age of diagnosis, diagnostician, diagnostic criteria, and clinical and developmental data were collected.

RESULTS

Among 919 classic and 166 atypical RTT participants, the median diagnosis age was 2.7 years (interquartile range 2.0-4.1) in classic and 3.8 years (interquartile range 2.3-6.9) in atypical RTT. Pediatricians made the diagnosis of classic RTT rarely (5.2%); however, the proportion diagnosed by pediatricians has increased since 2006. Since the first diagnostic criteria, the age of diagnosis decreased among subspecialists but not pediatricians. Odds of a pediatrician making the diagnosis of classic RTT were higher if a child stopped responding to parental interaction, and lower if they possessed gastroesophageal reflux, specific stereotypies, lost babbling, or the ability to follow commands. Delayed acquisition of basic gross motor skills or finger feeding was associated with younger diagnosis; delayed acquisition of higher level fine motor skills, later onset of supportive features, and normal head circumference were associated with late diagnosis. Thirty-three percent with microcephaly before 2.5 years were diagnosed after the median age of 2.7 years.

CONCLUSIONS

Age of RTT diagnosis has improved among subspecialists, and pediatricians have made the diagnosis of classic RTT more frequently since 2006. Strategies for educating diagnosticians should incorporate specific risk factors for delayed diagnosis.

Growth charts for 22q11 deletion syndrome

The purpose of this work was to create growth curves specific to the 22q11.2 deletion syndrome. Growth parameters on 188 patients (86 females, 102 males) followed by a group of three dysmorphologists were collected by retrospective chart review. Growth charts for body mass, length/height, and head circumference were generated using a semi-parametric model with goodness-of-fit tests. The resulting charts show that between 25 and 50% of children with 22q11.2 deletion syndrome fall below the 2nd centile for the normal population for all growth parameters. Establishing norms of growth for 22q11.2 deletion syndrome allows the clinician to identify and investigate those children who deviate substantially from the growth profile of this condition.

Postnatal-onset microcephaly: pathogenesis, patterns of growth, and prediction of outcome

OBJECTIVE

Although children with postnatal-onset microcephaly (POM) generally have poor development, we speculated that better somatic growth would predict better development in these children.

PATIENTS AND METHODS

We followed 57 children with POM for an average of 4.2 years (13 encephaloclastic, 14 dysgenetic, 6 with Rett syndrome, 24 idiopathic) and calculated the developmental quotient (DQ) at each visit (DQ > 0.70 was considered normal). SD scores (SDS) for measurements were analyzed using a repeated measures mixed-effects model to assess effect of weight, height, head circumference (HC), and age on DQ. Pearson's correlation was used to examine the independent influence of each variable on final DQ.

RESULTS

Forty-four children (77%) had a low DQ (mean: 0.33), but 13 (23%) had a normal DQ (mean: 0.93), including 10 idiopathic and 3 encephaloclastic. Mean HC fell below -2 SDS in all before 1 year (destructive at 3.3 months, idiopathic low-DQ at 7.5 months, dysgenetic at 8.5 months, Rett syndrome at 11 months, and idiopathic normal-DQ at 11.5 months). Mean weights and heights both fell below -2 SDS for all low-DQ groups but remained normal in both normal-DQ groups. Weight, height, and HC were independent predictors of DQ (P < .0001). Final DQ correlated with weight (r = 0.27), height (r = 0.41), and HC (r = 0.13).

CONCLUSIONS

Most children with POM have poor later development. Whatever the cause of POM, persons in whom postnatal body growth (weight, height, HC) is better sustained have more favorable development, and in one-quarter of such persons (mostly idiopathic POM), final DQ is normal.