Project coordination
International Nepal Fellowship

Aim: The study aimed to further validate the use of thermography in leprosy diagnosis and monitoring of nerve impairment.

Full project title:
Thermographic assessment of autonomic innervation in Leprosy

Final project summary:
Early diagnosis of leprosy is essential to prevent nerve damage and disability. When nerve impairment is already present at the time of diagnosis, patients are at greater risk of developing long-term complications. However, some forms of nerve damage are difficult to detect using routine clinical assessments, such as tests of muscle strength and sensation. In particular, early or “hidden” nerve damage may go unnoticed.

One aspect of nerve function that is not routinely assessed is the autonomic nervous system, which helps regulate functions such as skin temperature and sweating. Changes in these functions may provide early indications of nerve damage before more obvious symptoms appear.

This study investigated whether infrared thermography, a simple and non-invasive method that measures skin temperature, could help identify early nerve damage in people affected by leprosy. Because nerve impairment can affect the body's ability to regulate temperature, thermography may provide an additional way to detect abnormalities in nerve function.

The study was conducted at two INF hospitals in Nepal and involved 160 participants, including 77 newly diagnosed leprosy patients and 83 healthy individuals. An infrared camera was used to measure the temperature of participants’ palms before and after a cold challenge test, in which the hand was exposed to a cold stimulus. Temperature changes were analysed using specialised software, and the results were compared between the two groups.

Before the cold challenge test, hand temperatures were similar in both groups. However, clear differences emerged after cold exposure. People affected by leprosy showed different temperature responses and recovery patterns compared with healthy participants. These differences were observed immediately after the test and remained evident during the recovery period at 5, 10, and 15 minutes.

The findings suggest that infrared thermography has potential as a tool for detecting early nerve damage in leprosy. The cold challenge test helped reveal differences in nerve function that were not apparent under normal conditions. As a result, thermography may provide a useful additional method for assessing and monitoring nerve function in people affected by leprosy, supporting earlier identification of nerve impairment and more timely intervention.

 Impact

Knulst, A. J., van den Bogaert, F., Kuipers, A., Roelofs, L., Dankelman, J., Brandsma, W., ... & Maharjan, S. (2025). Pre-clinical evaluation of a low-cost tool for skin temperature measurements as a proxy to assess autonomic nerve function in leprosy neuropathy. Plos one, 20(7), e0327815.