Deep brain stimulation (THS; synonyms: Deep Brain Stimulation; DBS; “brain pacemaker“; deep brain stimulation) is a therapeutic procedure in neurosurgery and neurology that can be used successfully primarily to treat movement disorders, particularly advanced idiopathic Parkinson’s syndrome. The procedure is based on the implantation of electrodes connected to a pulse generator by means of cables laid subcutaneously (“under the skin“). Depending on the current frequency, a stimulation stimulus or a deactivation stimulus can occur in the respective brain region. Newer methods, which are currently still the subject of research, however, allow stimulation of the target region in the brain that is adapted to the electrical brain currents.
Indications (areas of application)
- Idiopathic Parkinson’s disease – Taking into account the indications and contraindications, deep brain stimulation is a treatment method for patients with drug-refractory on-off fluctuations (alternating over- and under-mobility that can no longer be treated by medication) and dyskinesias (pathological movements) resulting from advanced idiopathic Parkinson’s disease. Treatment involves stimulation of the nucleus subthalamicus, but also of the nucleus ventralis intermedius thalami as part of the thalamus and the nucleus pedunculopontinus. Parkinson’s patients benefit from this already at an intermediate stage of the disease, i.e. at the end of the “honeymoon phase” when the first motor fluctuations (oscillations) occur. This is usually the case only after a disease duration of at least four years. In contrast, at a very early stage, deep brain stimulation seems to bring more risks than benefits.
- Essential tremor (form of tremor (shaking) that occurs without an identifiable underlying neurological disease) – Only half of all patients with inherited essential tremor have sufficient symptoms to be treated with medication. An alternative to this is deep brain stimulation, in which two electrodes are implanted in the nucleus ventralis intermedius of the thalamus.
- Dystonia – Dystonia (postural and movement control disorders) can be treated both with medication and injection of botulinum toxin. Deep brain stimulation targeting the thalamus or globus pallidus internum is another therapeutic option. However, clinical studies showed that stimulation of the globus pallidus is associated with a better therapeutic outcome, which is why this target region has become widely accepted in the treatment of dystonia.
- Multiple sclerosis (MS) – In multiple sclerosis, the success of deep brain stimulation is moderate to poor. Stimulation can be used to treat tremor and ataxia (coordination disorder) associated with the disease.
- Tourette syndrome (synonym: Gilles-de-la-Tourette syndrome, GTS; a neurological-psychiatric disorder characterized by the occurrence of tics (“nervous twitching“)) – In clinical trials, patients suffering from Tourette syndrome are treated with deep brain stimulation. Target regions are for example the thalamus, the globus pallidus internus, the capsula interna as well as the nucleus accumbens. Clear results of the therapy success are not yet available at the current time.
- Obsessive-compulsive disorders – Stimulation of specific regions of the central nervous system may also be of success in obsessive-compulsive disorders, which often involve sexuality, cleanliness, and control. Target regions include the internal capsule, nucleus accumbens, and nucleus subthalamicus.
- Depression – Depression represents an important side effect of stimulation in PD. However, in the therapy of depression itself, the procedure can also be successful. Target regions include the subgenual cingulate cortex and the nucleus accumbens.
- Neuropathic pain (pain caused by a lesion or dysfunction of the nervous system). – Neuropathic pain, which can occur, for example, after a hemorrhage of the thalamus as a so-called thalamic pain syndrome, can sometimes be treated effectively with deep brain stimulation. This is of great importance, because patients often suffer from severe depression with sometimes suicidal thoughts (suicidal thoughts).
- Epilepsy and Cluster Headache – The treatment of epilepsy and cluster headache using deep brain stimulation are currently part of research and are currently only in clinical trials.
Contraindications
- Confusion
- Dementia
- Pronounced insecurity of stance and gait
- Serious concomitant diseases
- Other contraindications must be determined individually.
Before therapy
Before therapy is performed, it must be precisely evaluated (assessed) whether and to what extent a patient may benefit from deep brain stimulation. Furthermore, all risk factors must be weighed against the potential benefits of therapy. Possible contraindications to surgery must be assessed. In addition, the patient must be informed that if side effects occur or the therapy is not successful enough, the stimulation can be stopped and the application removed.
The procedure
Several components are required to stimulate a brain region. The pulse generator is crucial for the function of the stimulation, as the respective pulses are continuously delivered via it. Starting from the pulse generator, the pulses are transmitted via electrode extensions to the electrodes in the target region of the brain. The pulse generator itself is not located intracranially (in the skull), but is installed subcutaneously (under the skin) in the thoracic region. To adjust the stimulation parameters, the pulse generator can be set correctly and patient-specific via telemetry (by radio). Furthermore, it is possible that the device can be partially influenced by the patient himself. For implantation of the brain stimulator, small holes are drilled into the patient’s calvaria (skullcap) in a stereotactic operation, through which the electrodes can be inserted into the respective region of the brain. Typically, this is done while the patient is fully conscious so that the position and function of the electrodes can be checked immediately. The pulse generator itself can be installed as part of the implantation of the electrodes or on the following day. The number of electrodes is variable. Currently, a feedback brain stimulator is being implanted as part of a study, which allows for adapted and thus need-based stimulation of the respective brain area.
After therapy
- Follow-up examinations – checking the success of stimulation and adjusting the therapy if necessary. For adequate function, a reasonable combination with medications must be made, if necessary. In idiopathic Parkinson’s disease, approximately 70% of the total symptoms can be successfully suppressed by deep brain stimulation. Furthermore, the optimal stimulation intensity must be determined individually, which can sometimes take several months.
- Psychological counseling – In case of adverse effects of stimulation, for example depression, psychological or psychiatric therapy may be useful.
- Physiotherapy – Since, among other things, in Parkinson’s syndrome, many movement patterns can not be performed correctly before therapy, physiotherapy must be used after implantation to relearn complex movement patterns.
- Occupational therapy – In the context of occupational therapy, primarily the fine motor skills of patients can be improved. Furthermore, for example, taken incorrect postures must be corrected.
Possible complications
Even with successful implantation of the electrodes and pulse generator, temporary (short-lasting) or persistent (longer-lasting) dysarthria (motor speech disorder) or usually transient manic behavior with inadequately elevated mood, abnormal increase in drive, material wasting behavior, and severe limitation of personal performance may follow. Furthermore, especially in patients suffering from idiopathic Parkinson’s syndrome, a mild to higher-grade depression or depressive episode is found despite improvement of the motor disorders.
