Measurement of analgesia using pain reflexes

Since the 1970s, nociceptive reflexes have been used in pain research and also increasingly in clinical pain therapy in recent years. The most researched reflex in this area is the nociceptive flexion reflex of the lower limb (RIII-Reflex) which is characterised by the withdrawal movement of the upper leg after a painful stimulus is applied to the foot.

Pain reflexes such as this flexion reflex are involuntary reflex responses that cannot be controlled by the patient and are elicited using a specific stimulus. The extent of the reflex response correlates to the painfulness of the stimulus.

Therefore, the pain reflex can be used to provide information about the painfulness of the stimulus without having to factor in the subjective evaluation of the patient.

Because pathological pain or pain medications directly affect the magnitude of the reflex, such reflexes can be used to provide an objective and patient-independent quantification of pain or the effect of pain medications.

Because the pain reflex can be determined without the conscious involvement of the patient, reflex measurement also provides information about the processing of pain by non-communicative patients, for example, those who are sedated.

Automatic and continuous reflex measurement

The founders of Dolosys GmbH have developed a technique, for which they have also applied for a patent, to automatically determine such pain reflexes continuously and over a longer period.

The reflexes measured in this way are automatically evaluated and translated into direct and transparent treatment recommendations for the patient to optimise individual analgesia.

Possible applications

The technique can be used in a number of different areas in pain research and clinical pain therapy:

• Determining individual analgesic effect for chronic pain patients, independent of the subjective evaluation by the patient

• Testing the individual time course of action of analgesics for chronic pain patients

• Quantifying the effect and determining the time courses of the effects of analgesics in the clinical testing of analgesics

• Ensuring continuous analgesia monitoring for non-communicative patients, for example, those under sedation in intensive care units