Key Takeaways
- Researchers in the Netherlands developed a wearable device called the EndoWatch to help monitor health problems associated with hypothalamic dysfunction in survivors of childhood brain tumors.
- Ten survivors, including eight children and two adults, tested the first version for 14 days. Median wearing adherence was 99.4%, although two participants stopped early.
- Most parents who completed questionnaires found the device manageable, and seven of eight wanted their child to continue wearing it.
- Participants identified important shortcomings, particularly the lack of remote monitoring for caregivers and limited options for recording symptoms and medication changes.
- The study did not test whether the smartwatch accurately detects dangerous health changes or improves medical outcomes. Its findings concern usability and device development.
Introduction
Researchers in the Netherlands tested the EndoWatch, an experimental wearable designed to monitor health measurements in childhood brain tumor survivors with hypothalamic dysfunction. A 10-person pilot study found high wearing adherence, but did not establish the device’s clinical accuracy.
For some children who survive a brain tumor, the challenges of treatment do not end when the tumor is controlled. Damage to a small region of the brain called the hypothalamus can disrupt body temperature, sleep, appetite, hormone regulation, and other essential functions.
Parents may need to monitor these problems throughout the day and night. Recognizing a developing health problem can be difficult, particularly when a child cannot reliably describe how they feel.
Researchers in the Netherlands are exploring whether a smartwatch could eventually make that responsibility easier.
In a pilot study published October 23, 2026, in Frontiers in Endocrinology, a team developed and tested the EndoWatch, a wearable monitoring system designed specifically for people with hypothalamic dysfunction after childhood brain tumors.
Ten survivors tried the device for up to two weeks. Most wore it consistently, and feedback from families helped researchers redesign the system.
The results represent an early step toward a potentially useful monitoring tool, but the device has not yet demonstrated that it can recognize clinically important problems or reduce complications.
Why Brain Tumor Survivors May Need Continuous Monitoring
The hypothalamus is a small but important region deep within the brain. It helps regulate temperature, sleep-wake rhythms, hunger, energy balance, and several hormonal functions.
Tumors developing near this region, including craniopharyngiomas and some low-grade gliomas, can damage the hypothalamus directly. Surgery and other treatments may also contribute to dysfunction.
Although many children with these tumors survive long term, hypothalamic damage can leave them with substantial health challenges.
These may include persistent fatigue, disrupted sleep, difficulties controlling body temperature, excessive hunger, obesity, and hormone deficiencies.
Some patients also develop central adrenal insufficiency, meaning their bodies cannot produce enough cortisol. During illness or physical stress, they may require additional prescribed hydrocortisone to prevent a potentially dangerous adrenal crisis.
Others have arginine vasopressin deficiency, a condition that interferes with water balance. When this occurs alongside an impaired sense of thirst, caregivers may need to carefully track fluid intake and output.
Managing these problems can place considerable demands on families.
The Dutch researchers described caregivers as effectively serving as an external regulatory system for their children, monitoring symptoms and helping maintain physiological stability.
A wearable device that continuously records relevant measurements could potentially provide useful information between clinical appointments. Whether that information can reliably guide medical decisions remains an unanswered question.
What the Study Examined
The research team developed the EndoWatch through collaboration among clinicians, patients, parents, patient organizations, engineers, and design researchers.
The project involved the Princess Máxima Center for Pediatric Oncology, University Medical Center Utrecht, Eindhoven University of Technology, and the wearable technology company Corsano Health.
Rather than creating an entirely new sensor system, the researchers adapted the existing Corsano CardioWatch 287-2 platform for the needs of patients with hypothalamic dysfunction.
The first design included a wrist-worn sensor and a smartphone application.
It was designed to display information about core body temperature estimates, pulse rate, sleep, and physical activity. The application also included a diary for recording symptoms, stressful events, and medication changes.
Before testing, the team consulted five patient-parent pairs to understand the challenges they faced and identify useful features.
The researchers then conducted a prospective observational pilot study involving ten people with hypothalamic dysfunction following childhood brain tumors.
Eight participants were children, with an average age of 10.8 years. The other two were adults aged 18.9 and 31 years who had developed their conditions following tumors diagnosed during childhood.
Participants were asked to wear the EndoWatch for 14 days and complete a daily diary.
The primary outcome was adherence, estimated using pulse-rate recordings as an indicator of wearing time.
Researchers also collected questionnaires and interviews about ease of use, comfort, usefulness, and potential improvements (Hulsmann et al., 2026).
Importantly, this was not a clinical effectiveness trial. The investigators explicitly stated that they were not evaluating the device’s ability to detect meaningful hypothalamic disturbances.
What Researchers Found
Wearing Adherence Was High, but Not Universal
The researchers reported a median overall wearing adherence of 99.4%, with an interquartile range of 22.8 percentage points.
Adherence was estimated from the availability of pulse-rate recordings during the study period. It measured how consistently participants wore the device, not how accurately the smartwatch measured their health or detected medical problems.
Eight of the ten participants completed the full 14-day study. Two stopped early.
One participant discontinued after three days because visual impairment made the device difficult to understand and use, contributing to discomfort and reduced motivation.
Another discontinued after eight days because of wristband discomfort.
Two participants also reported skin irritation associated with the wristband.
These findings indicate that the device was practical for many participants during a short trial, while revealing important accessibility and comfort concerns.
Because the study involved only ten people and lasted two weeks, the results cannot establish whether patients would continue wearing the EndoWatch over longer periods.
Parents Generally Responded Positively
Questionnaires were completed by four patients and eight parents or parental pairs. Some families submitted both patient and parent responses.
Among parents, six of eight reported that wearing the device was not burdensome for their child.
Seven of eight wanted their child to continue wearing it.
Most parents also reported that having continuous access to health information did not cause additional stress.
However, one of the four patients who completed a questionnaire reported that constant health-related information was stressful.
This difference matters because a device that reassures caregivers may not always feel equally comfortable or useful to the person wearing it.
The researchers emphasized that future designs should consider patient and caregiver preferences separately.
The Biggest Missing Feature Was Remote Caregiver Access
One of the clearest problems involved the smartphone application.
In the first EndoWatch design, the app could be installed on only one smartphone, which needed to remain near the wearable to maintain a Bluetooth connection.
That arrangement limited its usefulness for parents who wanted to check their child’s measurements while at work or away from home.
Caregivers specifically requested a separate application that would allow them to monitor information remotely.
Other suggestions included allowing users to review and edit previous diary entries, document medication adjustments in greater detail, and record circumstances that might explain changes in symptoms.
For example, families wanted more space to describe why a hydrocortisone dose had been increased or whether unusual weather conditions might have contributed to temperature changes.
Parents managing fluid balance also suggested adding a diary for fluid intake and urination.
These requests illustrate an important distinction between collecting health data and making those data useful in everyday care.
A device may record numerous measurements, but its practical value depends partly on whether families can access, interpret, and organize the information they need.
Families Wanted More Flexible Designs
Participants also identified practical concerns involving the wristband itself.
Some appreciated the device’s screenless design because it reduced distractions and the temptation to repeatedly check measurements.
Others wanted different wristband colors or materials.
The research team also recognized that some measurements were not relevant to every participant. For example, step counts were not useful for patients who relied on wheelchairs.
The findings reinforced the need for a personalized system rather than a single interface designed for every patient.
How the Feedback Changed the EndoWatch
The pilot study was intended to inform the next version of the device, not simply measure satisfaction with the first.
Following the interviews and questionnaires, the researchers worked with engineers to implement several changes.
The second design introduced a separate caregiver application intended to allow parents to view health measurements remotely.
The patient diary was expanded to capture more detailed information about symptoms, physical or emotional stress, and medication changes. Users were also given the ability to review historical diary entries.
Alternative wristbands in different colors and materials were incorporated into plans for future testing.
These changes directly addressed concerns raised by participants.
However, the second design had not yet been clinically evaluated in the published pilot study.
How the Research Fits Into Earlier Evidence
The EndoWatch project builds on research showing that acquired hypothalamic dysfunction can produce a wide range of symptoms and requires individualized management.
A 2025 Dutch retrospective cohort study described the varied clinical presentations of acquired hypothalamic dysfunction, reinforcing why patients may require different forms of monitoring and support (van Roessel et al., 2025).
The EndoWatch researchers also drew on earlier work examining what patients and families need when managing hypothalamic dysfunction.
A 2023 international survey of 353 patients or caregivers identified unmet needs in the care of acquired hypothalamic dysfunction, particularly in managing obesity, fatigue, and daily functioning (van Roessel et al., 2023).
The new pilot study takes a different approach from those investigations. Instead of describing symptoms or care needs, it tests whether patients and families can use a monitoring device designed around those needs.
Its contribution is therefore primarily in device development and usability, not evidence of medical effectiveness.
What the Results May Mean for Patients and Families
Continuous Monitoring Could Eventually Support Daily Care
A wearable device that reliably measures relevant physiological changes could eventually help families recognize patterns that are difficult to identify through occasional health checks.
The EndoWatch was designed to display information about body temperature, pulse rate, sleep, and activity. Its application also allowed users to record symptoms, stressful events, and medication changes.
For patients with impaired temperature regulation, continuous monitoring might eventually provide useful information about changes occurring throughout the day or night.
However, the researchers did not establish whether the device’s temperature estimates accurately reflect core body temperature in children and young adults with hypothalamic dysfunction.
Similarly, the study did not determine whether changes in pulse rate, sleep, or activity could reliably identify clinically important disturbances.
Combining wearable measurements with symptom and medication records might help clinicians and families understand daily patterns, but that potential benefit requires further investigation.
The EndoWatch has not been shown to detect adrenal crises, prevent dangerous temperature changes, identify abnormal sodium levels, or determine when hormone replacement doses should be adjusted.
Families should continue following individualized treatment and emergency care plans established by their healthcare professionals. An experimental wearable should not replace prescribed monitoring or medical assessment.
More Information Is Not Always Better
The pilot also raises an important question about the psychological effects of continuous monitoring.
Most parents welcomed access to more health information, but at least one patient found it stressful.
For children and young adults already managing complex health conditions, constant monitoring may create additional reminders of illness.
Future research will need to examine whether the benefits of monitoring outweigh any inconvenience, anxiety, or added responsibilities.
Accessibility Must Be Part of Medical Device Design
The experiences of participants with visual and cognitive impairments showed why accessibility cannot be treated as a minor consideration.
A monitoring device may work technically but still fail to meet a patient’s needs if it is uncomfortable, difficult to understand, or incompatible with their abilities.
The researchers’ approach of involving patients and caregivers throughout development may help identify such problems before larger clinical studies begin.
Limitations
The study was small, involving only ten participants at one Dutch pediatric oncology center.
Because hypothalamic dysfunction after childhood brain tumors is relatively uncommon, recruiting large groups can be difficult. Nevertheless, a sample of ten cannot establish how well the device would perform across the broader patient population.
The testing period was also limited to 14 days.
Adherence during two weeks may not reflect whether patients would continue wearing the device over months or years.
Participants had varied ages, disabilities, and medical needs, making aggregate questionnaire results difficult to interpret.
Questionnaire responses were not available for every participant, and interviews were not conducted with the patient who withdrew after three days.
The qualitative interviews were also analyzed by a single reviewer, which may limit the consistency of theme identification.
Most importantly, the investigators did not validate the device’s measurements for this population or assess whether it could detect clinically important hypothalamic changes.
The underlying Corsano platform had existing medical-device certifications, but the authors explicitly noted that the EndoWatch’s proposed use in children and young adults with hypothalamic dysfunction extended beyond those original certifications.
The results should therefore not be interpreted as proof that the EndoWatch is clinically validated for this purpose.
Research Collaboration and Potential Conflicts of Interest
The EndoWatch was developed through collaboration among Dutch clinical researchers, patient representatives, design specialists, and Corsano Health, the company behind the wearable platform adapted for the project.
A Corsano Health representative was among the study’s authors, and the company contributed engineering expertise to the device’s development.
This collaboration is relevant when interpreting the findings because the research involved evaluating an early version of a technology developed with commercial participation.
The study’s main outcomes were wearing adherence and user experience. It did not establish the device’s clinical effectiveness or validate its measurements for patients with hypothalamic dysfunction.
The funding source and specific author disclosures are detailed below.
Final Thoughts
The Dutch EndoWatch study offers an early look at how wearable technology might eventually support children and young adults living with hypothalamic dysfunction after brain tumors.
The findings indicate that many patients and caregivers were willing to use the device during a short trial. They also reveal important challenges involving accessibility, comfort, caregiver access to health information, and the need for personalized monitoring.
The next step is to determine whether the redesigned EndoWatch can measure relevant physiological changes reliably and provide information that meaningfully supports medical care.
Until those questions are answered, the device should be viewed as an experimental monitoring tool rather than a proven way to prevent complications or improve health outcomes.
The study’s most important contribution is not that a smartwatch can already manage hypothalamic dysfunction, but that patients and families helped researchers identify what a useful monitoring system would need to provide.
Funding and Disclosures
The research was entirely funded by the Dutch Cancer Society (KWF Kankerbestrijding), grant number 14984.
One author, Philippe Fraboulet, was employed by Corsano Health B.V., the company whose wearable technology platform was adapted for the EndoWatch.
The remaining authors declared no commercial or financial relationships that could be construed as potential conflicts of interest.
The study was approved by the regional Medical Ethics Review Committee in Utrecht, Netherlands, under approval number NL87495.041.24. Written informed consent was obtained from participants or their legal guardians, as applicable.
References
Hulsmann, S. C., Petras, S. B., Fraboulet, P., Lu, Y., de Graaf, J. P., Plieger, W., Noordmans, H. J., Tissing, W. J. E., & van Santen, H. M. (2026). Co-creating the EndoWatch – a smart wearable device for the management of hypothalamic dysfunction in pediatric brain tumor survivors: A pilot study. Frontiers in Endocrinology, 17, Article 1963615. https://doi.org/10.3389/fendo.2026.1963615
van Roessel, I. M. A. A., Hulsmann, S. C., Schouten-van Meeteren, A. Y. N., Hoving, E. W., Janssens, G. O., Raphael, M. F., Zijtregtop-Blom, E. A. M., de Vos-Kerkhof, E., Bakker, B., Tissing, W. J. E., & van Santen, H. M. (2025). The many different clinical faces of acquired hypothalamic dysfunction: A retrospective cohort study in the Netherlands. eClinicalMedicine, 85, Article 103313. https://doi.org/10.1016/j.eclinm.2025.103313
van Roessel, I. M. A. A., de Graaf, J. P., Biermasz, N. R., Charmandari, E., & van Santen, H. M. (2023). Acquired hypothalamic dysfunction in childhood: ‘What do patients need?’ – an Endo-ERN survey. Endocrine Connections, 12(10), Article e230147. https://doi.org/10.1530/EC-23-0147
