Electrodes in the brain to predict the intensity of pain

Chronic pain is an important public health problem that often does not receive the attention it deserves due to the difficulties posed by its proper diagnosis and treatment..

It is not always possible to establish the origin of the pain and being able to measure the severity of the symptoms depends, to a large extent, on the patient's testimony, which complicates the approach to the problem..

Research published this week in 'Nature Neuroscience' could, however, pave the way for obtaining objective biomarkers of pain, which could be useful to guide both diagnosis and the use of effective treatments..

Based on their data, it is possible to use signals from the brain to measure and predict the intensity of pain a person is experiencing..

These scientists, led by Prasad Shirvalkar and Edward F. Chang, from the University of California in San Francisco (USA), have tested their strategy in four individuals with refractory neuropathic pain -one of the most intense forms of pain and that does not respond to therapies- who were implanted with electrodes intracranial in different areas of the brain related to pain.

Over a period of between three and six months, the electrodes recorded the brain activity of these four individuals.. At the same time, these patients had to write down in detail the episodes of pain they suffered as well as the intensity of the symptoms they suffered..

Using 'machine learning' techniques, the researchers developed an analysis method capable of accurately predicting the levels of pain intensity experienced by each patient through markers of their brain activity. Furthermore, the approach also made it possible to distinguish between types of pain, such as acute pain (mostly related to activity in the anterior cingulate cortex of the brain) or chronic pain (which was mainly associated with changes in the activity of the orbitofrontal cortex). ).

The researchers emphasize that these data, although they have been obtained in a sample of only four patients, can be very useful for the development of systems that detect pain circuits in the brain and can guide the diagnosis or find out why in some cases the symptoms become chronic. In addition, they add, they can also serve to guide the treatment of chronic pain problems, such as that experienced by many patients after a stroke or if they suffer from the so-called phantom limb syndrome after limb amputation..

According to data from the Spanish Society of Neurology, 32% of the Spanish adult population suffers from some type of pain and 11% suffers from it chronically..

Consultations for pain currently account for 50% of primary care visits and of these, 25% are related to neuropathic pain, a neurological condition that appears as a consequence of nervous system disorders.

According to the aforementioned society, more than 3 million people in Spain suffer from neuropathic pain and 77% suffer from it chronically.. In addition, it is estimated that approximately 50% of these patients do not respond to the prescribed treatment, which leads to a significant loss of quality of life and marked functional limitation over time.