A multidisciplinary Bochum-based research group, led by Prof. Dr. Martin Tegenthoff (Bergmannsheil Neurology Department) and Prof. Dr. Christoph Maier (Bergmannsheil Department of Pain Therapy), has now demonstrated for the first time that with unilateral CRPS excitability increases not only in the brain area processing the sense of touch of the affected hand. In addition, the brain region representing the healthy hand is simultaneously "disinhibited". The researchers report the new findings in the renowned journal "Neurology".
The figure shows fMRI signals of a CRPS patient´s somatosensory cortex after stimulation of the affected and unaffected hand compared to a healthy subject. While fMRI activation is smaller in the affected side, the diagram shows disinhibition of paired-pulse SEPs in both hemispheres of CRPS patients - although only one hand is affected
The "disinhibited" brainNew findings on CRPS – a disease characterized by severe pain
Is there a predisposition for CRPS?
CRPS can develop after even slight injuries and often leads to long-lasting severe pain, impairment of sensation and movement, as well as changes to the skin and the bones of the affected extremity - in many cases it even causes permanent disability. The precise cause of the syndrome is not known. Alongside inflammatory phenomena, changes in the brain also contribute to the disease becoming chronic. "Although the symptoms are mainly limited to one side of the body, some changes in the brain appear to affect both sides - a finding which could hint at an individual predisposition for the development of CRPS“, says Prof. Martin Tegenthoff.
Faulty programming in the brain
As yet, the origins of the disease remain largely unclear. Pain researchers assume that not only inflammatory factors, but also changes in the central nervous system may be a possible cause. For example, in a number of studies researchers found the representation of the affected hand on the brain’s "body map" to have shrunk, a phenomenon closely associated with the patients' pain intensity and tactile discrimination abilities.
Excitability changes on both sides
In a previous study, the Bochum group already made an astonishing discovery in the motor system of CRPS patients: the excitability of their motor hand area in the brain is increased - not only in the half of the brain controlling the affected side, but also in the half correlating to the healthy side. Following these findings hinting at a systemic disorder of the central nervous system, in the current study the group examined whether bilateral disinhibition can also be found in the brain area processing the sense of touch (somatosensory cortex). CRPS patients with unilateral symptoms of the hand were examined. After an electrical stimulation, the researchers measured the brain waves in the somatosensory brain area of the affected and the unaffected hand. Results show: the reduction of inhibition which is found on both sides in CRPS is not limited to motor areas. Those areas of the brain that process sensory perception of the hands exhibit distinct changes too.
"Disinhibition": typical of neuropathic pain
The scientists validated these findings by comparing CRPS patients with healthy volunteers and with patients suffering from pain that – in contrast to CRPS – was not caused by a disease of the nerves (so-called non-neuropathic pain). Here too, the researchers found an amazing result: the control patients showed no altered inhibition whatsoever in the hand area, they did not differ from the healthy volunteers. "This shows that the disinhibition of the brain in CRPS patients appears to be specific for neuropathic pain“, says Prof. Tegenthoff.
Systemic changes raise questions
The results indicate that the changes in the central nervous system caused by CRPS are much more complex than scientists have assumed up to now. Bilateral changes in the central sensorimotor systems that manifest in unilateral symptoms raise questions - for example: are they a cause or a consequence of the disease? The RUB scientists are presently undertaking a first approach at answering this question: in a long-term study they will accompany the patients to perform two further measurements in intervals of six months between dates. In this way, they can relate potential changes in the brain to the healing process. If a successful therapy reverses these changes, they are most probably a consequence of the disease.
Factoring in the brain
"Our research results make clear that changes in the brain play a prominent role in CRPS", says Prof. Dr. Christoph Maier. "As we already do in current pilot studies performed in the Department of Pain Therapy at Bergmannsheil, future therapies should take this aspect into account, in order to improve the treatment of what continues to be a problematic illness."
Lenz M, Höffken O, Stude P, Lissek S, Schwenkreis P, Reinersmann A, Frettlöh J, Richter H, Tegenthoff M, Maier C.: Bilateral somatosensory cortex disinhibition in complex regional pain syndrome type I. Neurology. 2011 Sep 13;77(11):1096-101. Epub 2011 Aug 31.
Prof. Dr. Martin Tegenthoff, Neurological Department and Out-Patients',BG-Universitätsklinikum Bergmannsheil, Tel. +49 234 302 6810, firstname.lastname@example.org
Prof. Dr. Christoph Maier, Department of Pain Therapy, BG-Universitätsklinikum Bergmannsheil, Tel. +49 234 302 6366, email@example.com
Editorial: Jens Wylkop
Dr. Josef König | idw
New application for acoustics helps estimate marine life populations
16.01.2018 | University of California - San Diego
Unexpected environmental source of methane discovered
16.01.2018 | University of Washington Health Sciences/UW Medicine
What enables electrons to be transferred swiftly, for example during photosynthesis? An interdisciplinary team of researchers has worked out the details of how...
For the first time, scientists have precisely measured the effective electrical charge of a single molecule in solution. This fundamental insight of an SNSF Professor could also pave the way for future medical diagnostics.
Electrical charge is one of the key properties that allows molecules to interact. Life itself depends on this phenomenon: many biological processes involve...
At the JEC World Composite Show in Paris in March 2018, the Fraunhofer Institute for Laser Technology ILT will be focusing on the latest trends and innovations in laser machining of composites. Among other things, researchers at the booth shared with the Aachen Center for Integrative Lightweight Production (AZL) will demonstrate how lasers can be used for joining, structuring, cutting and drilling composite materials.
No other industry has attracted as much public attention to composite materials as the automotive industry, which along with the aerospace industry is a driver...
Scientists at Tokyo Institute of Technology (Tokyo Tech) and Tohoku University have developed high-quality GFO epitaxial films and systematically investigated their ferroelectric and ferromagnetic properties. They also demonstrated the room-temperature magnetocapacitance effects of these GFO thin films.
Multiferroic materials show magnetically driven ferroelectricity. They are attracting increasing attention because of their fascinating properties such as...
The oceans are the largest global heat reservoir. As a result of man-made global warming, the temperature in the global climate system increases; around 90% of...
08.01.2018 | Event News
11.12.2017 | Event News
08.12.2017 | Event News
17.01.2018 | Health and Medicine
17.01.2018 | Health and Medicine
17.01.2018 | Health and Medicine