Note: Nerve Health Score (NHS) is only available for Body Comp scales purchased in Europe.

What is Nerve Health Score ?

Nerve Health Score is an EU-only medically-approved metric that gives an indication of your nervous system’s control of sweat gland activity in your feet. 

Nerve Health Score (NHS) measures and assesses the activity of the sweat glands in the soles of your feet and helps detect and follow-up peripheral autonomic neuropathies. Sweat gland activity is measured by stimulating the nerves that control the sweat glands in your feet and seeing how they respond.

Your Nerve Health Score (NHS) gives an indication of your nervous system’s control of sweat glands (also known as sudomotor function) in your feet.

What is a peripheral autonomic neuropathy ?

The peripheral nervous system sends information from the brain and spinal cord to the rest of the body. There are three main types of peripheral nerves: motor, sensory, and autonomic. The autonomic nerve system is responsible for controlling involuntary or semi-voluntary functions, such as heart rate, blood pressure, digestion, and sweating. Peripheral neuropathy means there is damage to the peripheral nerves, or the nerves at the extremities such as the feet. Symptoms can include tingling, painful, or burning sensations in these areas. Thus, a peripheral autonomic neuropathy is damage specifically to the peripheral nerves of the autonomic system.

Since the small autonomic fibers of the foot’s sweat glands are some of the longest and most fragile, they are the first ones to be damaged. They also can regenerate more quickly than the other types of peripheral nerves. The degeneration of the foot’s small nerve fibers reduces sweat gland innervation (nerve stimulation) and impairs sudomotor function. An impaired sudomotor function is one of the most common and earliest manifestations of small fiber neuropathies. There are many different causes of peripheral neuropathy, including diabetes, infections, some chemotherapy medications, injury, and some autoimmune conditions.

Diabetic neuropathy, a very common diabetic complication, most often affects nerves in the legs and feet. Small peripheral nerves in the feet may be among the first nerves to be affected. Peripheral neuropathy can lead to tingling, pain, or loss of feeling in the legs and feet. A loss of sensation is particularly important, as it may lead to foot injuries that are not noticed by the patient and result in infections, ulcers, and even possible amputations. Regular screening for diabetic neuropathy is the standard of care in diabetes management.

Poorly controlled diabetes is one of the most common causes of peripheral neuropathy in the United States. Up to 60-70% of people with diabetes have mild to severe forms of damage to sensory, motor, and autonomic nerves that cause such symptoms as numbness, tingling, or burning feet, one-sided bands or pain, and numbness and weakness on the trunk or pelvis [1].

What is the tech behind Nerve Health Score?

Your scale measures the sweat glands activity on the feet, an area with one of the highest sweat gland densities, by applying a low voltage on the soles of the feet via the glass plate and its ITO conductive electrodes. The device records the conductance related to the quantity of chloride ions attracted from the sweat glands and detected by the electrodes. The level of conductance depends on the number of chloride ions that react with the electrodes. Your device measures the current for several voltage steps and deduces a conductance that corresponds to your Nerve Health Score.

When nerves have a high amount of innervation, this direct current extracts a considerable amount of chloride ions from the sweat ducts to the surface of your skin. Therefore, if the density of nerves around the sweat glands is high, the sweat gland activity measured by your device will be high.
In the presence of normal sweat function, the Nerve Health Score is high.

When the density of the small nerves around the sweat glands is reduced, the sweat gland stimulation decreases due to reduced innervation, thus fewer chloride ions are drawn to the electrodes.
In the presence of low sweat function, the Nerve Health Score is low, which may be a sign of peripheral autonomic neuropathy.

What are the different results I can get?

NHS is available as a number between 0 and 100 in the application and a qualitative indication “Normal” or “Low” depending on whether the score is above or below 50.

How do I perform a NHS measurement? 

1. Step on the scale barefoot. 
2. Make sure your feet are well centered on the scale as pictured:
   
   
3. Remain completely still and do not talk during the NHS measurement. 

Note: that you might not get a score at every weigh-in (a pending status might be shown on the scale and in the app). 

The NHS algorithm will perform routine checks in order to give you a final reading at the end of the month. During the month, depending on the confidence level of the algorithm, a predictive score may be shown. A final/confirmed score will be shown at the end of the month in the application. 

What is a Guided Scan?

Your Nerve Health Score can fluctuate based on the conditions when taking your measurement. When your scale is not able to accurately assess your score based on these fluctuations, a Guided Scan might be required in order to get a reading. A Guided Scan replicates the environment of a medical consultation to ensure optimal weigh-in conditions. 

A Guided Scan can be launched at any time from the application on the NHS page. To do this, follow these steps:

1. Open the Withings App.
2. Select your most recent NHS measurement to access its measurement graph. You can also select the Measure tab, scroll down, and then select Nerve Health to access the graph. 
3. Scroll to the bottom of the NHS graph screen to 'Options' and select Take a Guided Scan.

A Guided Scan will provide the following instructions: 

1. You should have been on your feet throughout the past hour.
2. Remove your shoes prior to taking a measurement, but ensure that you are not barefoot for more than 10 minutes before weighing yourself.
3. Make sure that the scale & your feet are dust-free.

Note: To get the most accurate measurements, always take the NHS measurements under the conditions described in the Guided Scan instructions. Ignoring guidelines can impact your result.

[1] Peripheral Neuropathy Fact Sheet | National Institute of Neurological Disorders and Stroke. (n.d.). National Institute of Neurological Disorders and Stroke. Retrieved December 22, 2021, from https://www.ninds.nih.gov/Disorders/Patient-Caregiver-Education/Fact-Sheets/Peripheral-Neuropathy-Fact-Sheet