Quantitative sensory testing
Quantitative sensory testing (QST) is a set of non-invasive tests that help us to diagnosis your condition, and choose the right therapy. It also helps to monitor the progress and recovery of patients who have peripheral sensory disorders.
QST examines how the nerve endings work and measures the sensation and pain thresholds for temperature, touch, pressure, and vibration. The results will be compared to normal values. Abnormal results could be a sign of damage to the nerve endings. This can occur in long-term (chronic) pain conditions, such as diabetes and complex regional pain syndrome (CRPS).
Location and time of the tests
A trained member of the pain management team will do the QST in a clinical room in the pain management and neuromodulation centre at St Thomas’ Hospital. The room has a clinical bed, chairs and some equipment.
The testing usually lasts for 1 hour. If you need more than 1 area tested, it might take longer.
Before the test starts, we will make sure you are sitting comfortably in the bed. We will put a temperature sensor on the skin of the painful area, usually your hand or foot.
The sensor can be made hotter or colder. We will ask you to push a button when you start to feel changes in temperature (such as cool, cold, warm or hot). We will also apply different nylon hairs, brushes or blunt probes to the skin and ask how they feel.
We might measure your blood glucose levels. A small finger-prick test is done and a drop of blood is used to measure your glucose levels.
Preparing for QST
As we might need to put sensors on your feet, try to avoid wearing tights, or be prepared to remove them for the test.
Risks of QST
There are no side effects for these tests. You should feel little or no discomfort during the test.
You can stop the test at any time by pressing your control button, or by asking us to stop. As an extra safety measure, a computer controls the temperature and stops it before it becomes too strong, even if you do not press the control button.
You will not get the results of the tests on the same day, as it takes time to analyse them. You should be contacted by the department to arrange a routine follow-up appointment unless you are told otherwise. Your consultant will discuss your results during the follow-up appointment.