The field of functional neurosurgery and pain syndromes includes all those diseases that have no obvious structural cause, but whose basis is a malfunction of the nervous system itself. Thus, in chronic pain syndromes, movement disorders or psychiatric diseases, no direct image signs are found in magnetic resonance imaging or computed tomography. In these disorders, the goal is to "modulate" the nervous system at the points of its dysfunction, i.e., to alter brain activities and thus alleviate symptoms of disease.
Inselspital is the leading center for functional neurosurgery in Switzerland. With over 250 procedures of this kind per year, we have the necessary experience and routine for the safe and successful treatment of our patients.
With Prof. Claudio Pollo and Prof. Paul Krack in the field of functional neurosurgery and movement disorders and Prof. Sebastian Walther in the field of psychiatry, the leadership of functional neurosurgery at Inselspital is in the hands of internationally renowned physicians.
In addition, Inselspital plays a leading role in the development of new therapeutic approaches in this field. For example, innovative directional stimulation electrodes for deep brain stimulation were implanted at Inselspital for the first time worldwide
Basically, neuromodulation distinguishes between procedures by lesions and procedures by electrostimulation.
Procedures by lesions
In lesional procedures, specific structures of the nervous system are switched off. This can be done, for example, by applying high heat or using focused ultrasound. The severing of nerves involved in the perception of pain is also one of the lesional procedures. The result of such lesional procedures cannot be reversed.
Procedures by electrostimulation
In contrast, neuromodulatory procedures with electrostimulation use electrostimulation to stimulate targeted structures of the nervous system, thus modulating the function of nerves. No permanent lesion is performed.
This method can be used to stimulate peripheral nerves, the spinal cord, or specific nuclei of the brain. The required current is delivered through small implanted electrodes and is chosen to be so small that it is usually not perceived.
While lesional procedures are irreversible, a major advantage of neuromodulatory procedures is their reversibility. Furthermore, side effects can be avoided by adjusting the stimulation settings such as current intensity or frequency.
A distinction is made between the following procedures, depending on the site of stimulation:
Nerve cells (neurons) are the elementary unit of our nervous system. They constantly communicate with each other in complex chemical and electrical processes. Groups of millions of nerve cells are arranged as networks in the brain and regulate perceptions, feelings, emotions, thought processes and learning processes.
Within a nerve cell, an incoming signal is transmitted electrically. Between two nerve cells, signals are transmitted chemically via so-called neurotransmitters. The site of signal conversion from an electrical signal to a chemical signal and back is called a synapse.
This is where neuromodulatory procedures come in. Since neurons are electrically excitable and electronic impulse transmission forms the basis of signal processing, we can use electrodes to generate current impulses that excite or inhibit the nerve cells. Thus, we alter the synaptic transmission of neurotransmitters. Put simply, we alter or modulate pathological network properties that underlie diseases and restore a healthy balance.
In patients who have suffered from severe chronic pain for many years, which cannot be treated or can only be treated inadequately with medication and other measures, neurosurgical treatment is useful to improve the quality of life of the pain patients.
The treatment of patients with severe chronic pain such as spastic movement disorders, trigeminal neuralgia or pain after back surgery (failed back surgery syndrome) is a challenge for the treating physician. When conventional therapeutic measures fail, neuromodulation therapy is an option. Neuromodulation affects the transmission of nerve impulses through current (neurostimulation) or drugs. It includes the following therapy options:
- Spinal cord stimulation
- Spinal ganglion stimulation
- Drug pump
- Motor cortex stimulation
- Peripheral nerve stimulation, e.g. for occipital nerve neuralgia, cluster headache or migraine
In addition to neuromodulation, we perform infiltrations, radiofrequency therapy or thermocoagulation for diagnostic as well as therapeutic purposes in collaboration with the colleagues of the Pain Center of the Inselspital:
- Nerve root infiltration
- Facet joint infiltration
- Medial branch block (injection of the fine nerve branch responsible for the perception of pain originating from the facet joints)
- Sacral block (peridural infiltration on the spine)
- Infiltration of the sacroiliac joint (sacroiliac joint)
For readers who would like to take a closer look at the subject, we have compiled a small selection of important study results from recent years below. The papers can be viewed in Pubmed, a medical database of journal articles.
- Parkinson's disease
These multicenter, randomized controlled trials show that deep brain stimulation in Parkinson's disease patients with severe motor symptoms leads to an improvement in symptoms and thus quality of life compared to drug therapy alone.
Deuschl G, Schade-Brittinger C, Krack P, Volkmann J, Schäfer H, Bötzel K et al. A Randomized Trial of Deep-Brain Stimulation for Parkinson's Disease. New England Journal of Medicine. 2006;355(9):896-908.
Schuepbach W, Rau J, Knudsen K, Volkmann J, Krack P, Timmermann L et al. Neurostimulation for Parkinson's Disease with Early Motor Complications. New England Journal of Medicine. 2013;368(7):610-622.
These studies demonstrate the effect of deep brain stimulation on reducing tremor. The Schuurman study further demonstrates that deep brain stimulation for tremor results in significantly fewer side effects than lesional thalamotomy.
Limousin P, Speelman J, Gielen F, Janssens M, study collaborators. Multicentre European study of thalamic stimulation in parkinsonian and essential tremor. Journal of Neurology, Neurosurgery & Psychiatry. 1999;66(3):289-296.
Schuurman P, Bosch D, Bossuyt P, Bonsel G, van Someren E, de Bie R et al. A Comparison of Continuous Thalamic Stimulation and Thalamotomy for Suppression of Severe Tremor. New England Journal of Medicine. 2000;342(7):461-468.
This multicenter, randomized, controlled trial shows that deep brain stimulation in dystonia patients with generalized dystonia leads to an improvement in symptoms and thus quality of life compared to drug therapy alone.
Kupsch A, Benecke R, Müller J, Trottenberg T, Schneider G, Poewe W et al. Pallidal Deep-Brain Stimulation in Primary Generalized or Segmental Dystonia. New England Journal of Medicine. 2006;355(19):1978-1990.
This prospective, randomized, double-blind study confirms the safety of deep brain stimulation in patients with major depression, showing improvement in depressive symptoms in approximately half of patients.
Bergfeld I, Mantione M, Hoogendoorn M, Ruhé H, Notten P, van Laarhoven J et al. Deep Brain Stimulation of the Ventral Anterior Limb of the Internal Capsule for Treatment-Resistant Depression. JAMA Psychiatry. 2016;73(5):456.
Sindou M, Leston J, Decullier E, Chapuis F. Microvascular decompression for primary trigeminal neuralgia: long-term effectiveness and prognostic factors in a series of 362 consecutive patients with clear-cut neurovascular conflicts who underwent pure decompression. Journal of Neurosurgery. 2007;107(6):1144-1153.
Grewal S, Kerezoudis P, Garcia O, Quinones-Hinojosa A, Reimer R, Wharen R. Results of Percutaneous Balloon Compression in Trigeminal Pain Syndromes. World Neurosurgery. 2018;114:e892-e899.
The largest prospective cohort study to date of 21 patients with severe refractory cluster headache shows that deep brain stimulation is safe and can achieve about 70% headache reduction.
Cappon D, Ryterska A, Lagrata S, Miller S, Akram H, Hyam J et al. Ventral tegmental area deep brain stimulation for chronic cluster headache: Effects on cognition, mood, pain report behaviour and quality of life. Cephalalgia. 2019;39(9):1099-1110.