Periodic Reporting for period 1 - SOMATOSENSE (Forwarding development of novel somatosensory testing equipment in humans)
Période du rapport: 2023-04-01 au 2024-09-30
The assessment, diagnosis, and prognosis of clinical conditions affecting somatosensation in humans, including touch, temperature, and pain, is highly complex. Many different disorders present with somatosensory disturbances that can have numerous possible causes. Diagnoses are based upon standard tests, such as nerve conduction studies, skin biopsies, and quantitative sensory testing (QST). QST, in particular, is widely used to assess somatosensory function of touch, temperature, and pain in health and disease. These tests are useful, but can often lack diagnostic sensitivity and be painful. Somatosensory disorders range from common conditions, such as generalized peripheral neuropathy, to rare genetic cases where particular populations of sensory afferents are lost. Diabetic peripheral neuropathy, in particular, has substantial social and economic costs, where there are ~422 million people in the world who live with diabetes and about half of these will have neuropathy. Peripheral neuropathy can result in several deficits and problems for patients, with effects on touch and proprioception (large diameter peripheral nerve fibers), as well as on temperature and pain sensing (small diameter fibers). Deficits are often accompanied by pathological pain, ongoing in the absence of any stimulation, or caused by light touch. Such deficits are generally poorly understood and there is an increasing need to have specialized tools to identify and categorize somatosensory dysfunction efficiently and early, to intervene for better health outcomes.SOMATOSENSE aims to exploit the in-depth knowledge of our team on somatosensation in humans to explore other potential methods to help diagnose somatosensory disorders in a specific and integrative manner. We aim to advance the variety and specificity of tools available for somatosensory assessments, by developing new tests and technology. There are two parts to our project: (1) the development of additional simple-to-use somatosensory tools that can probe more complex, integrative aspects of skin sensations than threshold tests alone, and (2) the development of a multi-site electrode microneurography system to record from human peripheral nerves. Together, these scientific and technological developments will contribute to tackling the issues in somatosensory assessment, diagnosis, and prognosis in a more efficient and specific way.
WP1 developed small devices to measure different aspects of somatosensation, with a focus on non-painful approaches. We have working prototypes for a movement touch test, airflow perception, and wetness perception. The movement touch test is a miniaturized version of a larger, well-used robot called the Rotary Tactile Stimulator, the can stroke over skin at a well-defined speed, direction, and force. This robot is highly precise, but large and costly, making it impractical for short clinical tests. We have designed and made a small, handheld stroking device that can move over the skin in a similar rotary way with a controlled speed and direction. Our force can be relatively-controlled by using a soft brush that applies around 0.4 N. This device can be used in any setting, including in the clinic, in a scientific experiment, or even at home for remote testing. The airflow perception test is based on a small stream of air that can be regulated in terms of force via air flow and distance from the skin. The nozzle delivering the air can also be adjusted to change the focus (more or less diffuse, therefore changing the force and area stimulated) of the air stream. This small device can be applied anywhere on the skin and in tests, We have found that it is a highly sensitive test for touch detection. The wetness perception test is a small device that can apply liquid drops to the skin. The finalized prototype can deliver different volumes of drops to any flat-to-moderately-curved surface, over different heights, thus changing the force of drop impact, and to a lesser extent, the area of drop impact (drop size). Future versions will allow changing of temperature of the drop, as well as the possibility of using different liquids and not just water. It is, so far, a non-invasive, innocuous, simple test of tactile detection. A spatial touch test was also started, but a finalized prototype has not been finished, as this has posed some complex issues. WP2 focused more on long-term technical developments of microneurography, to allow this to become more efficient and be applied in clinical use. In collaboration with an industrial partner, we are developing a multi-site electrode that can record up to 32 channels while in a human peripheral nerve. This is highly challenging, but a prototype should be tested soon. In conjunction with this, we have developed a prototype of a system that can record from multiple channels in microneurography, as this currently does not exist, but is required to use the new electrode. Overall, the outcome of SOMATOSENSE has produced a variety of small devices for simpler, non-painful, and more efficient somatosensory testing, including potential at-home use, as well as a full system to record multiple peripheral nerves signals concomitantly.
The results are highly positive for the development of cost-effective and simple tools to better diagnose and monitor somatosensory disorders, as well as having a high impact for fundamental experimental research. The main results from WP1 include a movement touch test, an airflow perception test, and a wetness drop perception test. These are full prototype devices that are accompanied by tested and validated psychophysical paradigms to allow the user to gain a threshold for sensory detection. A fourth device has been designed, a spatial touch test, but the prototype is not complete, due to unforeseen complexity. The three full prototypes can be used in fundamental touch experiments and in clinical testing to look at differences in skin touch sensitivity all over the body. They are accessible and inexpensive to construct, as well as being non-painful, meaning they could be applied widely and delivered by any user knowledgeable in sensory testing. WP2 explored a more conceptual approach, attempting to forward the technology of single afferent recordings in humans (microneurography) to allow multiple recordings at once, making it much more efficient and opening up its use as a precise clinical somatosensory diagnostic tool. We have successfully designed a system to allow for this, including the conception of a new type of electrode and the associated recording system to accompany it. These devices from both work packages will require further development to ensure their stability and usefulness, which will be achieved with the BodySense platform at the Centre of Research for Psychology and Neuroscience (CRPN) in Marseille. As well as having this dedicated support platform, we are also in contact with the local division of the partnership and commercialization department (Service Partenariat et Valorisation, SPV), belonging to the national CNRS research entity. The SPV functions to provide support for partnership initiatives, advice, and the protection and promotion of research and we are in contact with them to support and forward our work. Overall, these scientific and administrative facilities allow us to drive the work's potential commercialization and internationalization in a secure way.