A new study on the treatment of neuropathic facial pain and post-stroke pain using deep brain stimulation (DBS) is currently underway at the Department of Neurosurgery, Inselspital Bern. This study will compare classic tonic DBS with burst DBS to see which of these two forms of stimulation has a more long-lasting effect in reducing pain. We are still looking for study participants for this study. If you are interested, please contact the study leader PD Dr. med. Andreas Nowacki.
Unlike inflammatory pain, which is caused by damage in the affected tissue (e.g., from injury or inflammation such as rheumatism or osteoarthritis), neuropathic pain is caused by damage to the nervous system itself (e.g., from injury or inflammation to the nerves, spinal cord, or brain). When certain areas of the brain are affected by a stroke, this can also cause neuropathic pain. This type of pain is also called central pain because its cause lies in the brain itself.
Central pain significantly affects patients' quality of life and is difficult to treat. Conventional painkillers such as ibuprofen, voltaren and opioids have no effect, and more specific drugs for neuropathic pain such as gabapentin, pregabalin and amitriptyline are often not sufficiently effective either.
Pain perception is a function of the brain in which different brain areas integrate sensory information ("Where does it hurt?", "How does the pain feel?" and "How intense is the pain?") with emotional aspects (suffering pressure, depressed mood) to form a coherent "pain experience". The thalamus, a deep brain region, plays a crucial role here, both in the perception of pain in healthy individuals and in the development of pain in the diseased brain.
Deep brain stimulation can be used to treat neuropathic pain. In DBS, electrodes are implanted in specific brain regions with high precision and connected to a pacemaker device under the skin. For neuropathic pain, the electrodes are implanted in the thalamic region.
Classically, the pacemaker then sends continuous pulses to the electrodes in the brain, which is called tonic stimulation. The electrical stimulation affects the neural circuits in the brain by influencing the activity of nerve cells. This can regulate or reduce excessive activity or dysfunction in the pain centers of the brain. Thus, through this modulation of brain activity, DBS can help relieve or control pain.
However, the effectiveness of this therapy often diminishes over time, and pain returns. Previous studies have therefore failed to provide convincing results on the long-term effectiveness of DBS for pain.
In contrast to the continuous current pulses of classic tonic deep brain stimulation, bursts of high-frequency current pulses are much more like a natural form of nerve cell signals. This form of high-frequency stimulation is called Burst stimulation.
We hope that Burst stimulation will improve efficacy in the long-term treatment of neuropathic pain. The purpose of this study is to compare the efficacy and safety of tonic stimulation and Burst stimulation for the treatment of chronic neuropathic pain after stroke.
Burst Deep Brain Stimulation of the Thalamus for Neuropathic Facial Pain and Central Post Stroke Pain: a Prospective, Randomized Cross-over Feasibility Trial
The classic stimulation form and the Burst stimulation form are each used for a period of one week. The effectiveness of the two forms of stimulation is then compared. Patients have the opportunity to decide for themselves which form of stimulation they prefer for their long-term treatment, and they can switch to the other form of stimulation at any time.
Regular clinical monitoring will be conducted over the one-year period to assess efficacy. We plan to enroll a total of 20 patients in the study.
The study is aimed at patients suffering from neuropathic facial pain (after facial herpes zoster, after trauma, after dental surgery, etc.) or from central post stroke pain. Potential study participants should have severe pain with substantial distress that has persisted for more than 12 months despite adequate drug treatment.
The further criteria for participation in the study are checked by the study physician after special examinations. In a first step, the patients are presented in the consultation hours of the neurosurgery department.
For participating patients, there is a potential opportunity for improved and long-lasting efficacy of deep brain stimulation compared to the conventional tonic form of stimulation.
Potential study participants receive detailed information about the study in order to make an informed decision about participation. Patients who decide to participate in the study undergo various steps and examinations:
- Pre-study: Before the start of the study, patients receive a detailed physical examination and several questionnaires to gather information about their pain. A psychosomatic assessment is also performed to address possible psychological factors. In addition, an MRI examination of the skull is performed.
- After study inclusion: After patients are enrolled in the study, surgery to implant the electrodes is performed according to established standards.
- Test phase: In a test phase lasting approximately two weeks, the general effectiveness of the electrostimulation is tested. The two different types of stimulation are tested one after the other in a block of seven consecutive days. The order of these blocks is determined at random (randomized). After each of these blocks of stimulation, a clinical examination is performed to evaluate the effectiveness of the stimulation in relation to the pain, and the safety of the stimulation is assessed.
- Patient Decision: At the end of the trial period, patients can decide whether they have benefited sufficiently from either type of stimulation and whether they want to use it as a long-term therapy. If the decision is positive, the internal pulse generator is implanted in a second surgical procedure.
- Follow-up: Affected patients are followed up again after 12 months for a final clinical examination to assess the long-term efficacy of the chosen therapy.
- Removal of the electrode system: If patients do not experience sufficient improvement with stimulation, surgical removal of the electrode system is performed.