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Stereotactic operations in movement disorders have been carried out for over 50 years. At first the core areas were specifically disabled, which occasionally led to severe side effects.
At present the most modern procedure is deep brain stimulation, in the course of which individual core areas can be controllably influenced through a stimulating electrode. This enables optimal adjustment of the stimulation parameters to the patient’s needs.
The approved indications are: - Parkinson's disease
- Essential tremor
- Tremor in multiple sclerosis
- Tremor in Parkinson's disease
- Dystonia
Further indications that are at present specifically examined: - Tardive dystonias
- Anxity disorder and obsessive-compulsive disorder
- Depression
- Pain syndrome
- Tourette's syndrome
Stereotactic interventions are minimally invasive operations in which through small openings of the skull the finest probes or electrodes can be placed at precisely pre-determined points of the brain.
In the course of this a stereotactic frame (see Fig. A) is attached to the skull under general or local anaesthesia. This happens without occurrence of pain. Subsequently high-resolution computed tomography and/or MRI is carried out. With the help of this image information computer-assisted target point data can be calculated without harming important brain regions.
Fig. 1.
A: Stereotactic frame
B: Placement of microelectrodes
C: Test of a hand at trail stimulation
The data of the target points are then transferred to the stereotactic aiming device. With the help of this system it is possible to precisely select the optimal point for stimulation. Fig. B) At first the electric potentials of the core areas deep in the brain are recorded with the finest microelectrodes.
Because of this the position of target points can be further optimized. At a suitable point the trail stimulation for testing the effect and side effect takes place. At this point various examinations are carried out by neurologists from the surgical team (Fig. C).
If a promising point for an electrode is found and no essential side effects appear, the permanent electrode will be placed in this point and fixed at the skullcap.
In the second surgery under general anaesthetic the impulse generator is implanted at the place previously discussed with the patient. Possible implantation places are next to the area underneath the collar bone, the region below the major pectoral muscle and upper abdomen. The impulse generator is approximately twice as big as a matchbox. The connecting cables are placed underneath the skin and conducted to deep electrodes.
The impulse generator can be optimally adjusted from outside to the patient’s needs through a telemetric device. The patient can turn the generator on and off with the help of a magnet or an automatic controller.
The lifetime of the impulse generator is usually three to five years. Only when using special stimulation parameters consuming strong energy is a shorter lifetime possible. If the battery becomes flat, the generator can be replaced in a short-term intervention.
In 80-90% of patients after implantation of the impulse generator there is a noticeable improvement of the Parkinson’s disease symptoms. First of all there is cessation of muscle stiffness and hypokinesia. Also muscle tremor responds very well to this therapy. In the case of stimulation of the subthalamic core area the medication dose can also be reduced, so that the unpleasant hypermobility ceases.
In patients who suffer from essential tremor, it also results in a dramatic improvement of symptoms. However, in the case of double-sided stimulation the occurrence of dysphonia (dysarthria) can prevent suppression of the entire tremor, so that a minor rest tremor remains. But as a rule the patient is able after such an intervention to do all important activities without restrictions.
Experience with patients with dystonia is still relatively small. However, dramatic improvements can be achieved in this area, particularly with generalized dystonia. The excellent results of the multicentre study on deep brain stimulation in the case of dystonia, in which our clinic also participated, will be published shortly in a prominent journal.
Like all surgical interventions, stereotactic surgery entails a risk. However, the danger of bleeding and inflammation is at 2-3% relatively small. We are available for you for a personal counselling interview concerning further deliberations.
Functional stereotactic intervention is a recognized treatment procedure. Costs of treatment are met by private and public health insurance funds.
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